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Virginia Tech
1.
Getzewich, Karen Elizabeth.
Hormonal regulation of the onset of puberty in purebred and crossbred Holstein and Jersey heifers.
Degree: MS, Dairy Science, 2005, Virginia Tech
URL: http://hdl.handle.net/10919/34239 
► The objective of this study was to determine the onset of puberty by using progesterone profiles and anterior pituitary gonadotropin releasing hormone (GnRH) challenges in…
(more)
▼ The objective of this study was to determine the onset of puberty by using progesterone profiles and anterior pituitary gonadotropin releasing hormone (GnRH) challenges in purebred and crossbred Holstein and Jersey heifers. In experiment 1, fifty prepubertal heifers by four sire - dam classifications (18 HH, 11 JJ, 10 JH, and 11 HJ) were used. The HH heifers attained puberty at an older age than the HJ, JH or JJ heifers, and these three classifications were not different from each other. There were significant differences in weight and wither height at puberty and average daily weight gain (ADWG) between all four sire - dam classifications. Season of birth had a significant effect on age and weight at puberty. In experiment 2, four prepubertal heifers from each sire - dam classification in experiment 1 were used at 3, 6, 9 and 12 mo of age to determine the effects of administering 200 μg GnRH on LH secretion. The effects of breed, age at challenge, and their interaction were only significant for time to LH peak. In conclusion, age at puberty in crossbred Holstein X Jersey heifers is regulated by breed and season of birth, and further research with larger sample sizes is needed to establish the relationship of pituitary maturation and the capacity to secrete LH in response to GnRH stimulation as related to onset of puberty in purebred and crossbred dairy heifers.
Advisors/Committee Members: Nebel, Raymond L. (committeechair), Akers, Robert Michael (committee member), Cassell, Bennet G. (committee member).
Subjects/Keywords: GnRH; Crossbreeding; Holstein X Jersey; Puberty
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APA (6th Edition):
Getzewich, K. E. (2005). Hormonal regulation of the onset of puberty in purebred and crossbred Holstein and Jersey heifers. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/34239
Chicago Manual of Style (16th Edition):
Getzewich, Karen Elizabeth. “Hormonal regulation of the onset of puberty in purebred and crossbred Holstein and Jersey heifers.” 2005. Masters Thesis, Virginia Tech. Accessed March 05, 2021.
http://hdl.handle.net/10919/34239.
MLA Handbook (7th Edition):
Getzewich, Karen Elizabeth. “Hormonal regulation of the onset of puberty in purebred and crossbred Holstein and Jersey heifers.” 2005. Web. 05 Mar 2021.
Vancouver:
Getzewich KE. Hormonal regulation of the onset of puberty in purebred and crossbred Holstein and Jersey heifers. [Internet] [Masters thesis]. Virginia Tech; 2005. [cited 2021 Mar 05].
Available from: http://hdl.handle.net/10919/34239.
Council of Science Editors:
Getzewich KE. Hormonal regulation of the onset of puberty in purebred and crossbred Holstein and Jersey heifers. [Masters Thesis]. Virginia Tech; 2005. Available from: http://hdl.handle.net/10919/34239
Virginia Tech
2.
Wilkes, Crafton O.
Impact of relocation on dairy cows.
Degree: MS, Dairy Science, 2005, Virginia Tech
URL: http://hdl.handle.net/10919/34733
► Several indicators of animal welfare were measured to determine the impact of relocation on lactating dairy cows. In experiment one, locomotion was scored on a…
(more)
▼ Several indicators of animal welfare were measured to determine the impact of relocation on lactating dairy cows. In experiment one, locomotion was scored on a 4-point scale where 1 = normal and 4 = lame. Cleanliness was scored on a 4-point scale where 1 = little or no manure visible and 4 = heavy plaques of manure on 3 body regions: udder, lower leg, and flank/upper leg. In experiment two, milking parlor behaviors observed were cow reactivity (REACT), latency to enter the parlor (LAT), and plasma cortisol (CORT). REACT was evaluated on a numeric scale (0 = ideal milker to 3 = steps and kicks frequently) to define behavior during udder preparation, claw fitting, and milking. LAT was the time necessary for each cow to enter the milking parlor. In these studies, the effects of treatment or breed on MY, lameness, parlor behaviors, stress, and cow cleanliness were monitored. In experiment one, cows with access to a rubber mat in front of the feed bunk had lower locomotion scores and cleaner lower legs. There were no breed effects on locomotion, but Jerseys had cleaner lower legs than Holsteins. The effect of the new facility on locomotion occurred gradually. Cows with higher locomotion scores had decreased milk production, but the results were not significant. In experiment two, relocation caused an increase in plasma cortisol and LAT. Milk yield decreased the p.m. on the day of relocation, but overall milk yield was not affected. Jerseys had lower plasma cortisol levels and latency to enter the parlor, but had a greater decline in p.m. milk yield the day of relocation. In conclusion, alternative flooring may alleviate some locomotion problems caused by relocation to a new facility. Additionally, moving to a new facility may have an effect on behavior and stress, but these effects are short-lived and effects on overall milk production minimal.
Advisors/Committee Members: Gwazdauskas, Francis C. (committeechair), Nebel, Raymond L. (committee member), McGilliard, Michael L. (committee member).
Subjects/Keywords: stress; relocation; animal welfare; locomotion; hygiene
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APA (6th Edition):
Wilkes, C. O. (2005). Impact of relocation on dairy cows. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/34733
Chicago Manual of Style (16th Edition):
Wilkes, Crafton O. “Impact of relocation on dairy cows.” 2005. Masters Thesis, Virginia Tech. Accessed March 05, 2021.
http://hdl.handle.net/10919/34733.
MLA Handbook (7th Edition):
Wilkes, Crafton O. “Impact of relocation on dairy cows.” 2005. Web. 05 Mar 2021.
Vancouver:
Wilkes CO. Impact of relocation on dairy cows. [Internet] [Masters thesis]. Virginia Tech; 2005. [cited 2021 Mar 05].
Available from: http://hdl.handle.net/10919/34733.
Council of Science Editors:
Wilkes CO. Impact of relocation on dairy cows. [Masters Thesis]. Virginia Tech; 2005. Available from: http://hdl.handle.net/10919/34733
Virginia Tech
3.
Pickin, Charles Benjamin.
Reproductive performance of Holstein cows treated with prostaglandin F2a, gonadotropin releasing hormone, and recombinant bovine Somatotropin.
Degree: MS, Dairy Science, 1997, Virginia Tech
URL: http://hdl.handle.net/10919/10171
► The objective of this study was to examine the effects of presynchronization and recombinant bovine somatotropin (rbST) on conception rates following a timed insemination (TAI)…
(more)
▼ The objective of this study was to examine the effects of presynchronization and recombinant bovine somatotropin (rbST) on conception rates following a timed insemination (TAI) protocol in lactating dairy cows. A further objective included the evaluation of the efficacy of the Early Conception Factor (ECF) test kit. Recombinant bST may offer some benefit when used in conjunction with estrus synchronization and TAI. Presynchronization treatment consisted of two injections of PGF2α given 14 d apart, with the second dose administered 14 d prior to the initiation of a TAI protocol. A total of 216 lactating Holstein cows were presynchronized with PGF2α and then received GnRH (100μg) at 67 ± 7 d post partum (PP), administration of PGF2α (25 mg) 7 d later, another GnRH (100μg) administration 2 d after PGF2α, and were inseminated 8-18h later (OvSynch). First service conception rate (CR) was determined by rectal palpation at 42 ± 7 d after artificial insemination (AI). Treated cows (n=113) received rbST 67 ± 7 d PP whereas control cows (n = 113) were presynchronized without rbST. The cycling status of all cows was determined by paired milk P4 levels at 53 and 67 ± 7 d PP. No differences (P > 0.10) in conception rate were observed between control and rbST treated cows (44.7 and 40.7% respectively), nor was there any interaction of cyclicity and rbST. Milk samples were collected 7 d following AI for use in ECF test kit evaluation. Samples were stored at -20ºC (n=216) and at 5ºC (n=113) until assayed. Test results for frozen and refrigerated samples were compared to conception rates determined by rectal palpation at 42 ± 7 d after AI. The rate of false positive and negative results for frozen milk samples were 36.1 and 14.8% respectively, and 40.7 and 7.1% for refrigerated milk samples. Treatment with rbST at the time of the first GnRH injection of an OvSynch protocol did not significantly alter first service conception rates. Additionally, an acceptable 92.9% accuracy of the ECF test for the detection of open cows 7 d after AI using milk samples stored at 5ºC was obtained.
Advisors/Committee Members: Nebel, Raymond L. (committeechair), Saacke, Richard G. (committee member), Whittier, W. Dee (committee member).
Subjects/Keywords: bovine somatotropin; ECF; Timed AI; Presynchronization
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APA (6th Edition):
Pickin, C. B. (1997). Reproductive performance of Holstein cows treated with prostaglandin F2a, gonadotropin releasing hormone, and recombinant bovine Somatotropin. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/10171
Chicago Manual of Style (16th Edition):
Pickin, Charles Benjamin. “Reproductive performance of Holstein cows treated with prostaglandin F2a, gonadotropin releasing hormone, and recombinant bovine Somatotropin.” 1997. Masters Thesis, Virginia Tech. Accessed March 05, 2021.
http://hdl.handle.net/10919/10171.
MLA Handbook (7th Edition):
Pickin, Charles Benjamin. “Reproductive performance of Holstein cows treated with prostaglandin F2a, gonadotropin releasing hormone, and recombinant bovine Somatotropin.” 1997. Web. 05 Mar 2021.
Vancouver:
Pickin CB. Reproductive performance of Holstein cows treated with prostaglandin F2a, gonadotropin releasing hormone, and recombinant bovine Somatotropin. [Internet] [Masters thesis]. Virginia Tech; 1997. [cited 2021 Mar 05].
Available from: http://hdl.handle.net/10919/10171.
Council of Science Editors:
Pickin CB. Reproductive performance of Holstein cows treated with prostaglandin F2a, gonadotropin releasing hormone, and recombinant bovine Somatotropin. [Masters Thesis]. Virginia Tech; 1997. Available from: http://hdl.handle.net/10919/10171
Virginia Tech
4.
Peralta, Oscar Alejandro.
Comparison of three estrus detection systems during summer heat stress in a large commercial dairy herd.
Degree: MS, Dairy Science, 2003, Virginia Tech
URL: http://hdl.handle.net/10919/33659
► The objective of the study was to compare three systems for detection of estrus and combinations of these systems on a large commercial dairy (1000…
(more)
▼ The objective of the study was to compare three systems for detection of estrus and combinations of these systems on a large commercial dairy (1000 lactating cows) during stress of summer heat. At 37 to 45 days in milk (DIM), 266 cows were fitted with a HeatWatch (HW) device (HeatWatch; DDx Inc., Boulder, CO), an activity (A) sensor (ALPRO; DeLaval Inc., Kansas City, MO), and observed visually (V) twice daily. Pregnancy status was determined by uterine palpation 35 to 49 d following artificial insemination (AI). The effects of DIM, parity, physical activity, standing events, months, AI technician, and interval between onset of estrus and AI on conception rate were determined using linear contrasts and logistic regression. Efficiencies for detection of estrus, determined by comparing detected periods of estrus with a theoretical total of 707 periods, were 45.8% (V), 33.2% (A), 40.3% (HW), and 71.6% for all three systems simultaneously. Conception rates (LSM ± SE) by method of detection were 16.7 ± 4.9 for HW, 19.8 ± 5.5 for A, 7.9 ± 3.4 for V, 16.3 ± 6.0 for V + A, 27.6 ± 4.6 for V + HW, 21.1 ± 4.9 for A + HW, and 21.9 ± 4.5 for V + A + HW. Conception rate and number of mounts decreased for cows in first versus second and third parity (P < 0.05). For periods of estrus detected by A, the lowest conception rate (P < 0.05) occurred >18 h after the onset of estrus (16.7 ± 7.9). The highest conception rate occurred with the combination of V + HW, which confirms the premise that combination of multiple systems enhances both the efficiency and accuracy of detection.
Advisors/Committee Members: Nebel, Raymond L. (committeechair), Pearson, Ronald E. (committee member), Swecker, William S. Jr. (committee member).
Subjects/Keywords: Detection of estrus; efficiency; ALPRO; HeatWatch; heat stress
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APA (6th Edition):
Peralta, O. A. (2003). Comparison of three estrus detection systems during summer heat stress in a large commercial dairy herd. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/33659
Chicago Manual of Style (16th Edition):
Peralta, Oscar Alejandro. “Comparison of three estrus detection systems during summer heat stress in a large commercial dairy herd.” 2003. Masters Thesis, Virginia Tech. Accessed March 05, 2021.
http://hdl.handle.net/10919/33659.
MLA Handbook (7th Edition):
Peralta, Oscar Alejandro. “Comparison of three estrus detection systems during summer heat stress in a large commercial dairy herd.” 2003. Web. 05 Mar 2021.
Vancouver:
Peralta OA. Comparison of three estrus detection systems during summer heat stress in a large commercial dairy herd. [Internet] [Masters thesis]. Virginia Tech; 2003. [cited 2021 Mar 05].
Available from: http://hdl.handle.net/10919/33659.
Council of Science Editors:
Peralta OA. Comparison of three estrus detection systems during summer heat stress in a large commercial dairy herd. [Masters Thesis]. Virginia Tech; 2003. Available from: http://hdl.handle.net/10919/33659
Virginia Tech
5.
Nadir, Sher.
Effect of high and low dosage of fresh and frozen semen on accessory sperm number, fertility and embryo quality in artificially inseminated cattle.
Degree: MS, Dairy Science, 1992, Virginia Tech
URL: http://hdl.handle.net/10919/45269
► This study was designed to : 1) Determine the effects of fresh vs frozen semen at a high inseminate dosage (lOOxl06sperm) contrasted to their effects…
(more)
▼ This study was designed to : 1) Determine the effects of fresh vs frozen semen at a high inseminate dosage (lOOxl06sperm) contrasted to their effects at a conventional dosage (20xl06 sperm) on accessory sperm per ovum and 2) Evaluate the relationship between accessory sperm number per embry%vum and fertilization status/embryo quality if accessory sperm number were affected by treatment. In this study semen from four bulls routinely giving a minimum of 700/0 morphologically normal and 600/0 motile sperm cells were used. Ejaculates of these bulls were split and prepared for use as fresh and frozen semen at either 100xl06 or 20xI06 cells per dose in.5 mL French straws. Half of the total semen filled straws were frozen in liquid nitrogen at -196°C and half were stored at 5°C for 4 days after collection and used as unfrozen. Cows in standing heat were inseminated with fresh or frozen semen at either high (IOOxl06 sperm) or conventional dose (20xl06 sperm).
Ova/embryos were recovered non surgically on day 6 after breeding. Accessory sperm were counted in the recovered embryos/ova after partial digestion with Pronase followed by compression of the embryo/ovum with a cover slip. From 129 inseminations to normally cycling cows, 98 embryos/ova were recovered. To reduce male effects, embryos/ova used were randomly balanced across treatments, by ejaculate within bull for evaluation of frozen vs fresh semen (n = SO) and by bull for evaluation of high vs low dosage treatments (n = 76). No difference (P > 0.05) in accessory sperm was observed for fresh vs frozen semen at either the high or low dosage. The mean accessory sperm values for fresh high dose (n=21), frozen high dose (n=21), fresh low dose (n= 19), and frozen low dose (n= 19) were 26.S1±30.23 (SD), 36.05±44.74 (SD), 29.37± 55.97 (SD) and 30.l6± 70.18 (SD) respectively. When data for embryos/ova resulting from fresh and frozen semen were pooled within dosage, a significant difference was observed between the median accessory sperm values for high and low doses of semen (P < .05). Mean ± SD and median values for accessory sperm were: 37.8± 38.3 and 27.5; 28.9± 62.8 and 3.0, for the high and low dose, respectively. Increasing accessory sperm number by the higher dosage improved the fertilization status/embryo quality (P < .05). Percentage unfertilized ova, degenerate embryos and embryos classified poor to fair and good to excellent were: 3, 5, 24, 68; and 21, 16, 18, 45, for the high and low dose, respectively. Overall, embryos/ova classified good to excellent, poor to fair, degenerate and unfertilized had median accessory sperm values of 18, 9.5, 5.5 and 0, respectively. However, the lack of accessory sperm in unfertilized ova was significantly different from excellent-good quality embryos (P < .05).
Advisors/Committee Members: Saacke, Richard G. (committeechair), Nebel, Raymond L. (committee member), Vinson, William E. (committee member).
Subjects/Keywords: Sperm banks.; LD5655.V855 1992.N335
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APA (6th Edition):
Nadir, S. (1992). Effect of high and low dosage of fresh and frozen semen on accessory sperm number, fertility and embryo quality in artificially inseminated cattle. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/45269
Chicago Manual of Style (16th Edition):
Nadir, Sher. “Effect of high and low dosage of fresh and frozen semen on accessory sperm number, fertility and embryo quality in artificially inseminated cattle.” 1992. Masters Thesis, Virginia Tech. Accessed March 05, 2021.
http://hdl.handle.net/10919/45269.
MLA Handbook (7th Edition):
Nadir, Sher. “Effect of high and low dosage of fresh and frozen semen on accessory sperm number, fertility and embryo quality in artificially inseminated cattle.” 1992. Web. 05 Mar 2021.
Vancouver:
Nadir S. Effect of high and low dosage of fresh and frozen semen on accessory sperm number, fertility and embryo quality in artificially inseminated cattle. [Internet] [Masters thesis]. Virginia Tech; 1992. [cited 2021 Mar 05].
Available from: http://hdl.handle.net/10919/45269.
Council of Science Editors:
Nadir S. Effect of high and low dosage of fresh and frozen semen on accessory sperm number, fertility and embryo quality in artificially inseminated cattle. [Masters Thesis]. Virginia Tech; 1992. Available from: http://hdl.handle.net/10919/45269
Virginia Tech
6.
Walters, Anneke H.
Analysis of early lactation reproductive characteristics in Holstein cows.
Degree: MS, Dairy Science, 2000, Virginia Tech
URL: http://hdl.handle.net/10919/9859
► Ultrasound-guided transvaginal follicular aspiration was used to obtain oocytes from cows to study follicular development and oocyte morphology. Follicular aspiration was conducted once during wk…
(more)
▼ Ultrasound-guided transvaginal follicular aspiration was used to obtain oocytes from cows to study follicular development and oocyte morphology. Follicular aspiration was conducted once during wk 1 to 12 postpartum on 120 lactating cows with 6 groups, separated by biweekly intervals. Approximately one half of the aspirated cows at each session were from the early groups (wk 1-2, 3-4, or 5-6) and the other half from the later groups (wk 7-8, 9-10, or 11-12). On the day of aspiration the number of follicles on each ovary, and their sizes, small (2-5 mm), medium (6-10 mm) and large (≥ 11 mm), were recorded. The collected oocytes were morphologically classified into 4 grades, with 4 = excellent, 3 = good, 2 = fair, and 1 = poor. Blood samples from the jugular vein and follicular fluid samples from the largest follicle were collected in order to perform hormone and metabolite assays. Environmental data were obtained from the local airport. There was a significant (P < .01) quadratic days pre- and postpartum by parity interaction for BCS. Body condition score for older cattle was the lowest at 90 d prior to calving and changed the least amount over time, while youngest cattle had the highest initial BCS at d 90 prior to calving and had the greatest change in BCS over time. Body condition score was the highest during summer calving season (3.3 ± .06) compared to BCS during winter calving season (2.6 ± .06). But the loss in BCS was greater for cows that calved in summer (-0.53 ± .06) compared to cows that calved in winter (-0.07 ± .08). Increased serum NEFA concentrations with simultaneous decreases in serum insulin concentrations for younger cattle implied a more negative EB status than for older cattle. The total number of follicles and total number of oocytes retrieved was significantly (P < .001) affected by a linear days postpartum by parity interaction with younger cattle having linear increases compared to decreases in the total number of follicles for older cattle. Oocyte quality score was affected by the quadratic days postpartum by parity interaction (P < .01) and calving season (P < .01). Younger cattle had higher initial quality scores compared to older cattle, but older cattle had higher quality oocytes towards the end of the 12 wk period compared with younger cattle. Younger cattle had higher E2 and IGF-I concentrations in follicular fluid associated with a higher number of total follicles and number of oocytes, compared to older cattle. However, oocyte quality of younger cattle seemed to be reduced and oocytes were less competent than for older cattle. Cattle in 3rd and greater lactation showed very little change in BCS and hormone and metabolite measures during early lactation, with no apparent decrease in oocyte quality, despite the aging effect on follicle numbers. This study demonstrated that conditions related to early lactation have a negative effect on oocyte quality and endocrine measures of dairy cattle and that animals of different ages are differentially affected.
Advisors/Committee Members: Gwazdauskas, Francis C. (committeechair), Nebel, Raymond L. (committee member), Pearson, Ronald E. (committee member).
Subjects/Keywords: Oocyte; Follicle; Quality; Calving Season; Parity; Cattle
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APA (6th Edition):
Walters, A. H. (2000). Analysis of early lactation reproductive characteristics in Holstein cows. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/9859
Chicago Manual of Style (16th Edition):
Walters, Anneke H. “Analysis of early lactation reproductive characteristics in Holstein cows.” 2000. Masters Thesis, Virginia Tech. Accessed March 05, 2021.
http://hdl.handle.net/10919/9859.
MLA Handbook (7th Edition):
Walters, Anneke H. “Analysis of early lactation reproductive characteristics in Holstein cows.” 2000. Web. 05 Mar 2021.
Vancouver:
Walters AH. Analysis of early lactation reproductive characteristics in Holstein cows. [Internet] [Masters thesis]. Virginia Tech; 2000. [cited 2021 Mar 05].
Available from: http://hdl.handle.net/10919/9859.
Council of Science Editors:
Walters AH. Analysis of early lactation reproductive characteristics in Holstein cows. [Masters Thesis]. Virginia Tech; 2000. Available from: http://hdl.handle.net/10919/9859
Virginia Tech
7.
Mink, Matthew Ryan.
Evaluation of 72 h Cosynch and 5 or 7 d post-AI gonadotropin releasing hormone on first service pregnancy rate in lactating dairy cows.
Degree: MS, Dairy Science, 2006, Virginia Tech
URL: http://hdl.handle.net/10919/42590
► Two studies were conducted to evaluate the effects of 5 or 7 d post-AI GnRH on first service PR, plasma P4, and CL volume in…
(more)
▼ Two studies were conducted to evaluate the effects of 5 or 7 d post-AI GnRH on first service PR, plasma P4, and CL volume in lactating dairy cows synchronized using 72 h Cosynch. All cows were synchronized and randomly assigned to one of three treatment groups: Control â no additional GnRH; 5 d â GnRH 5 d after TAI; 7 d â GnRH 7 d after TAI. In the first study, P4 concentrations were evaluated in samples collected at five separate times and CL volume and number were recorded at 30 d pregnancy examination for Holstein (n = 77) and Jersey (n = 33) cows. GnRH treatment did not affect PR (Control - 47.2%, 5 d GnRH - 40.5%, 7 d GnRH â 44.7%) or P4, but increased TCLV compared to controls (Control â 7.33 cm3, 5 and 7 d GnRH â 10.77 cm3). Incidence of accessory CL increased PR (94.7 vs. 60.6%), P4 (6.95 vs. 5.88 ng/mL), and TCLV (15.51 vs. 6.78 cm3) compared to cows with a spontaneous CL. Cows classified as cycling based on P4 evaluation had significantly higher PR than acyclic cows (54.4 vs. 16.1%). In the second study, Holstein cows (n = 1055) were submitted to the same experimental protocol and evaluated for first service PR. Post-AI GnRH treatment did not significantly affect PR. Primiparous cows (32.8%) tended to have higher PR than multiparous cows (27.6%), but GnRH treatment had no influence on this relationship. In conclusion, GnRH post-AI did not affect PR. Further evaluation of accessory CL incidence is warranted as it significantly affected PR.
(Abbreviations: AI â artificial insemination, CL â corpus luteum, PR â conception rate, P4 â progesterone, TCLV â total corpus luteum volume)
Advisors/Committee Members: Nebel, Raymond L. (committeechair), Kasimanickam, Ramanathan (committee member), Pearson, Ronald E. (committee member).
Subjects/Keywords: post AI; gonadotropin releasing hormone; synchronization; dairy cow; conception rate
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APA (6th Edition):
Mink, M. R. (2006). Evaluation of 72 h Cosynch and 5 or 7 d post-AI gonadotropin releasing hormone on first service pregnancy rate in lactating dairy cows. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/42590
Chicago Manual of Style (16th Edition):
Mink, Matthew Ryan. “Evaluation of 72 h Cosynch and 5 or 7 d post-AI gonadotropin releasing hormone on first service pregnancy rate in lactating dairy cows.” 2006. Masters Thesis, Virginia Tech. Accessed March 05, 2021.
http://hdl.handle.net/10919/42590.
MLA Handbook (7th Edition):
Mink, Matthew Ryan. “Evaluation of 72 h Cosynch and 5 or 7 d post-AI gonadotropin releasing hormone on first service pregnancy rate in lactating dairy cows.” 2006. Web. 05 Mar 2021.
Vancouver:
Mink MR. Evaluation of 72 h Cosynch and 5 or 7 d post-AI gonadotropin releasing hormone on first service pregnancy rate in lactating dairy cows. [Internet] [Masters thesis]. Virginia Tech; 2006. [cited 2021 Mar 05].
Available from: http://hdl.handle.net/10919/42590.
Council of Science Editors:
Mink MR. Evaluation of 72 h Cosynch and 5 or 7 d post-AI gonadotropin releasing hormone on first service pregnancy rate in lactating dairy cows. [Masters Thesis]. Virginia Tech; 2006. Available from: http://hdl.handle.net/10919/42590
Virginia Tech
8.
Domecq, Joseph John.
Development of an expert system for the evaluation of reproductive performance and management of Virginia dairy farms.
Degree: MS, Dairy Science, 1990, Virginia Tech
URL: http://hdl.handle.net/10919/41979
Subjects/Keywords: Dairy farms; LD5655.V855 1990.D653
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APA (6th Edition):
Domecq, J. J. (1990). Development of an expert system for the evaluation of reproductive performance and management of Virginia dairy farms. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/41979
Chicago Manual of Style (16th Edition):
Domecq, Joseph John. “Development of an expert system for the evaluation of reproductive performance and management of Virginia dairy farms.” 1990. Masters Thesis, Virginia Tech. Accessed March 05, 2021.
http://hdl.handle.net/10919/41979.
MLA Handbook (7th Edition):
Domecq, Joseph John. “Development of an expert system for the evaluation of reproductive performance and management of Virginia dairy farms.” 1990. Web. 05 Mar 2021.
Vancouver:
Domecq JJ. Development of an expert system for the evaluation of reproductive performance and management of Virginia dairy farms. [Internet] [Masters thesis]. Virginia Tech; 1990. [cited 2021 Mar 05].
Available from: http://hdl.handle.net/10919/41979.
Council of Science Editors:
Domecq JJ. Development of an expert system for the evaluation of reproductive performance and management of Virginia dairy farms. [Masters Thesis]. Virginia Tech; 1990. Available from: http://hdl.handle.net/10919/41979
Virginia Tech
9.
Peeler, Iris Dawn.
Synchronization and Resynchronization of Ovulation and Timed Insemination in Lactating Dairy Cows and Heifers.
Degree: MS, Dairy Science, 2004, Virginia Tech
URL: http://hdl.handle.net/10919/9880
► This study was conducted to evaluate the efficacy of intravaginal progesterone (P4) inserts (CIDR) in synchronization protocols combined with timed artificial insemination (TAI) as related…
(more)
▼ This study was conducted to evaluate the efficacy of intravaginal progesterone (P4) inserts (CIDR) in synchronization protocols combined with timed artificial insemination (TAI) as related reproductive performance. In the first study, heifers were synchronized with CIDR inserts followed by TAI. Heifers in the estradiol cypionate (ECP) group were synchronized with a combination of ECP, CIDR, prostaglandin (PGF2α), and ECP (CIDR-ECP), while the gonadotropin-releasing hormone (GnRH) group was synchronized using a combination of ECP, CIDR, PGF2α, and GnRH (CIDR-GnRH). All heifers were bred at either 48, 56, or 72 hours (h) after CIDR removal. Overall pregnancy rate (PR) for synchronized heifers was 60.1%, and embryo survival rate (ESR) was 98%. Pregnancy rate for CIDR-ECP treated heifers was influenced by artificial insemination (AI) time. In conclusion, ECP or GnRH may be used effectively in a CIDR-based TAI program in heifers. In the second study, cows were synchronized with CIDR devices or Ovsynch. The CIDR group received a combination of ECP, CIDR, PGF2α, and GnRH, while the Ovsynch group was synchronized using a combination of GnRH and PGF2α. Cows were bred at either 0, 8, or 24 h after the final GnRH injection. Overall PR for first service was 30.5% with ESR of 82.8%. Overall resynchronization PR was 35.1% with an ESR of 84.8%. In conclusion, Ovsynch and CIDR-based protocols are equally effective in synchronizing ovulation in a TAI program and resulted in comparable PR.
Advisors/Committee Members: Nebel, Raymond L. (committeechair), Nickerson, Stephen C. (committee member), Cassell, Bennet G. (committee member), Pearson, Ronald E. (committee member).
Subjects/Keywords: reproductive performance; timed artificial insemination; dairy cattle; synchronization
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APA (6th Edition):
Peeler, I. D. (2004). Synchronization and Resynchronization of Ovulation and Timed Insemination in Lactating Dairy Cows and Heifers. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/9880
Chicago Manual of Style (16th Edition):
Peeler, Iris Dawn. “Synchronization and Resynchronization of Ovulation and Timed Insemination in Lactating Dairy Cows and Heifers.” 2004. Masters Thesis, Virginia Tech. Accessed March 05, 2021.
http://hdl.handle.net/10919/9880.
MLA Handbook (7th Edition):
Peeler, Iris Dawn. “Synchronization and Resynchronization of Ovulation and Timed Insemination in Lactating Dairy Cows and Heifers.” 2004. Web. 05 Mar 2021.
Vancouver:
Peeler ID. Synchronization and Resynchronization of Ovulation and Timed Insemination in Lactating Dairy Cows and Heifers. [Internet] [Masters thesis]. Virginia Tech; 2004. [cited 2021 Mar 05].
Available from: http://hdl.handle.net/10919/9880.
Council of Science Editors:
Peeler ID. Synchronization and Resynchronization of Ovulation and Timed Insemination in Lactating Dairy Cows and Heifers. [Masters Thesis]. Virginia Tech; 2004. Available from: http://hdl.handle.net/10919/9880
Virginia Tech
10.
Utt, Matthew Douglas.
The effects of varying the interval from follicular wave emergence to progestin withdrawal on follicular dynamics and the synchrony of estrus in beef cattle.
Degree: MS, Animal and Poultry Sciences, 2002, Virginia Tech
URL: http://hdl.handle.net/10919/33769
► The objective of this experiment was to examine the effects of varying the interval from follicular wave emergence to progestin removal on follicular dynamics and…
(more)
▼ The objective of this experiment was to examine the effects of varying the interval from follicular wave emergence to progestin removal on follicular dynamics and the synchrony of estrus. The experimental design was a 2x2x2 factorial with GnRH or estradiol-17 beta (E2) + progesterone (P4), controlled internal drug-releasing device (CIDR) treatment duration, and PG or saline treatment as main effects. Cycling, Angus cows (n=49), on d 6 to 8 of the estrous cycle, were randomly assigned to receive a CIDR treatment for 7 or 9 d. Approximately half of the cows from each CIDR group received either GnRH (100 mcg) or E2+P4 (1 mg E2 + 100 mg P4) at CIDR insertion. Cows in GnRH or E2+P4 groups were further divided into those that received PG (37.5 mg) or saline at CIDR insertion. All cows received PG (25 mg) 1 d prior to CIDR removal. The interval from follicular wave emergence to CIDR removal was longer for cows treated with GnRH (6.6 d) or a CIDR for 9 d (6.5 d) compared to those treated with E2+P4 (4.7 d) or a 7-d CIDR (4.8 d) (P < 0.05). Cows treated with PG or GnRH at CIDR insertion or a 9-d CIDR had a larger dominant follicle (DF) at CIDR removal than those treated with saline, E2+P4, or a 7-d CIDR. (P < 0.07). Altering the interval from wave emergence to progestin removal created differences in size of the DF at CIDR removal but did not affect the synchrony of estrus.
Advisors/Committee Members: Beal, Wilfred E. (committeechair), Saacke, Richard G. (committee member), Estienne, Mark J. (committee member), Nebel, Raymond L. (committee member).
Subjects/Keywords: GnRH; estrus synchronization; estradiol; follicle; progestin
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APA (6th Edition):
Utt, M. D. (2002). The effects of varying the interval from follicular wave emergence to progestin withdrawal on follicular dynamics and the synchrony of estrus in beef cattle. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/33769
Chicago Manual of Style (16th Edition):
Utt, Matthew Douglas. “The effects of varying the interval from follicular wave emergence to progestin withdrawal on follicular dynamics and the synchrony of estrus in beef cattle.” 2002. Masters Thesis, Virginia Tech. Accessed March 05, 2021.
http://hdl.handle.net/10919/33769.
MLA Handbook (7th Edition):
Utt, Matthew Douglas. “The effects of varying the interval from follicular wave emergence to progestin withdrawal on follicular dynamics and the synchrony of estrus in beef cattle.” 2002. Web. 05 Mar 2021.
Vancouver:
Utt MD. The effects of varying the interval from follicular wave emergence to progestin withdrawal on follicular dynamics and the synchrony of estrus in beef cattle. [Internet] [Masters thesis]. Virginia Tech; 2002. [cited 2021 Mar 05].
Available from: http://hdl.handle.net/10919/33769.
Council of Science Editors:
Utt MD. The effects of varying the interval from follicular wave emergence to progestin withdrawal on follicular dynamics and the synchrony of estrus in beef cattle. [Masters Thesis]. Virginia Tech; 2002. Available from: http://hdl.handle.net/10919/33769
Virginia Tech
11.
Bethard, Greg L.
Effect of energy and undegraded intake protein on growth and feed efficiency of growing Holstein heifers.
Degree: MS, Dairy Science, 1994, Virginia Tech
URL: http://hdl.handle.net/10919/42485
► Two trials using 32 heifers each evaluated response to undegraded intake protein (UIP) (30 or SO% CP), energy (supporting .S9 or .91 kg ADG), and…
(more)
▼ Two trials using 32 heifers each evaluated response to undegraded intake protein (UIP) (30 or SO% CP), energy (supporting .S9 or .91 kg ADG), and source of UIP (blood meal or combination protein supplement). Trial one was a 2x2 factorial, with two levels of energy and UIP. High UIP was achieved with blood meal supplementation.
From 6-13 mo of age (phase I), high energy increased ADG and DMI, and high UIP decreased DMI. DM efficiencies (kg DMIlkg BW gain) improved with high energy and high UIP, and roN efficiencies (kg IDN/kg BW gain) improved with high UIP. From 13 mo until calving (phase n), heifers were housed together and fed a common diet. Low energy, high UIP treatment had the highest ADG (1.01 kg/day) for phase I, but the lowest for phase n (.33 kg/day), and low energy, low UIP treatment had the lowest ADG (.62 kg/day) for phase I, but the highest for phase n (.S3 kg/day). Overall ADG from 6 mo until calving averaged .S9 kg/day, and was not affected by energy or UIP. In trial 2, two levels of energy and two sources ofUIP were compared, resulting in four treatments: low energy, high UIP with combination protein supplement; low energy, high UIP with blood meal; low energy, low VIP with soybean meal; and high energy, low UIP with soybean meal. Combination protein supplement contained blood meal, com gluten meal, and fish meal. Trial was 300 days long, and began at 6.5 mo. of age. Dry matter intake and ADO were increased with high energy, but not affected by VIP. Overall DM efficiency was not affected by VIP or energy level. Results of both trials indicate VIP may improve feed efficiency of growing Holstein heifers.
Advisors/Committee Members: James, Robert E. (committeechair), McGilliard, Michael L. (committee member), Nebel, Raymond L. (committee member), Polan, Carl E. (committee member).
Subjects/Keywords: Holstein-Friesian cattle; LD5655.V855 1994.B484
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APA (6th Edition):
Bethard, G. L. (1994). Effect of energy and undegraded intake protein on growth and feed efficiency of growing Holstein heifers. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/42485
Chicago Manual of Style (16th Edition):
Bethard, Greg L. “Effect of energy and undegraded intake protein on growth and feed efficiency of growing Holstein heifers.” 1994. Masters Thesis, Virginia Tech. Accessed March 05, 2021.
http://hdl.handle.net/10919/42485.
MLA Handbook (7th Edition):
Bethard, Greg L. “Effect of energy and undegraded intake protein on growth and feed efficiency of growing Holstein heifers.” 1994. Web. 05 Mar 2021.
Vancouver:
Bethard GL. Effect of energy and undegraded intake protein on growth and feed efficiency of growing Holstein heifers. [Internet] [Masters thesis]. Virginia Tech; 1994. [cited 2021 Mar 05].
Available from: http://hdl.handle.net/10919/42485.
Council of Science Editors:
Bethard GL. Effect of energy and undegraded intake protein on growth and feed efficiency of growing Holstein heifers. [Masters Thesis]. Virginia Tech; 1994. Available from: http://hdl.handle.net/10919/42485
Virginia Tech
12.
Jobst, Shelly Marie.
Evaluation of systematic breeding programs in lactating dairy cows.
Degree: MS, Dairy Science, 1998, Virginia Tech
URL: http://hdl.handle.net/10919/35439
► Observing cows in estrus and inseminating them at the optimal time are necessary steps for effective reproductive management of a dairy herd. However, increasing herd…
(more)
▼ Observing cows in estrus and inseminating them at the optimal time are necessary steps for effective reproductive management of a dairy herd. However, increasing herd sizes can lead to reproductive inefficiency resulting in decreased profits on dairy herds. Synchronization of estrus, through pharmacological control, has been used to improve reproductive efficiency. Systematic breeding programs provide an organized approach for administering artificial insemination (AI) at first service. Moreover, reproductive management is based on a methodical approach for the entire herd rather than for the individual cow. Seven-hundred and thirty four Holstein cows from 16 commercial dairy herds were used to conduct this study evaluating three systematic breeding protocols; 14-d PGF2a, timed AI (TAI), and GnRH-PGF2α, in comparison with an untreated control group. Eight herds relied on visual observation as their primary method for detection of estrus, and 8 herds utilized the HeatWatch® (DDx, Inc., Denver, CO) electronic estrus detection system. The average days to first postpartum AI were longer for untreated control cows when compared to the other breeding protocols. First AI conception rates did not differ among control, 14-d PGF2a, or GnRH-PGF2a protocols, but were higher than the TAI protocol. However, first AI pregnancy rates were higher for untreated controls versus hormonally treated cows. Estrus characteristics associated with each protocol were also evaluated and no difference was detected across treatments. An economic analysis determining cost per pregnancy for each protocol when considering drug costs, and pregnancy rates, resulted in the highest cost per pregnancy for TAI followed by GnRH-PGF2a and 14-d PGF2a. These programs should be considered as tools for convenience and efficiency of estrus detection; however, reduced labor costs from less time spent on estrus detection may be offset by the cost of the drug protocols. Cost effectiveness must be calculated on an individual herd basis when deciding whether a systematic breeding program is the appropriate choice.
Advisors/Committee Members: Nebel, Raymond L. (committeechair), Vinson, William E. (committee member), Pelzer, Kevin D. (committee member), McGilliard, Michael L. (committee member).
Subjects/Keywords: gonadotropin-releasing hormone; estrus synchronization; prostaglandin F2a
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APA (6th Edition):
Jobst, S. M. (1998). Evaluation of systematic breeding programs in lactating dairy cows. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/35439
Chicago Manual of Style (16th Edition):
Jobst, Shelly Marie. “Evaluation of systematic breeding programs in lactating dairy cows.” 1998. Masters Thesis, Virginia Tech. Accessed March 05, 2021.
http://hdl.handle.net/10919/35439.
MLA Handbook (7th Edition):
Jobst, Shelly Marie. “Evaluation of systematic breeding programs in lactating dairy cows.” 1998. Web. 05 Mar 2021.
Vancouver:
Jobst SM. Evaluation of systematic breeding programs in lactating dairy cows. [Internet] [Masters thesis]. Virginia Tech; 1998. [cited 2021 Mar 05].
Available from: http://hdl.handle.net/10919/35439.
Council of Science Editors:
Jobst SM. Evaluation of systematic breeding programs in lactating dairy cows. [Masters Thesis]. Virginia Tech; 1998. Available from: http://hdl.handle.net/10919/35439
Virginia Tech
13.
DeJarnette, James Melton.
The effects of sperm dose, semen quality, and retrograde sperm blockage on accessory sperm number and embryo quality in the artificially inseminated bovine.
Degree: MS, Dairy Science, 1990, Virginia Tech
URL: http://hdl.handle.net/10919/41929
Subjects/Keywords: Cattle; LD5655.V855 1990.D447
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APA (6th Edition):
DeJarnette, J. M. (1990). The effects of sperm dose, semen quality, and retrograde sperm blockage on accessory sperm number and embryo quality in the artificially inseminated bovine. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/41929
Chicago Manual of Style (16th Edition):
DeJarnette, James Melton. “The effects of sperm dose, semen quality, and retrograde sperm blockage on accessory sperm number and embryo quality in the artificially inseminated bovine.” 1990. Masters Thesis, Virginia Tech. Accessed March 05, 2021.
http://hdl.handle.net/10919/41929.
MLA Handbook (7th Edition):
DeJarnette, James Melton. “The effects of sperm dose, semen quality, and retrograde sperm blockage on accessory sperm number and embryo quality in the artificially inseminated bovine.” 1990. Web. 05 Mar 2021.
Vancouver:
DeJarnette JM. The effects of sperm dose, semen quality, and retrograde sperm blockage on accessory sperm number and embryo quality in the artificially inseminated bovine. [Internet] [Masters thesis]. Virginia Tech; 1990. [cited 2021 Mar 05].
Available from: http://hdl.handle.net/10919/41929.
Council of Science Editors:
DeJarnette JM. The effects of sperm dose, semen quality, and retrograde sperm blockage on accessory sperm number and embryo quality in the artificially inseminated bovine. [Masters Thesis]. Virginia Tech; 1990. Available from: http://hdl.handle.net/10919/41929
Virginia Tech
14.
Dorsey, Benjamin Reese.
Effect of Timing of Insemination and Synchronization of Estrus Method on Artificial Insemination (AI) Pregnancy Rates in Beef Heifers.
Degree: MS, Animal and Poultry Sciences, 2005, Virginia Tech
URL: http://hdl.handle.net/10919/42873
► Objectives were to evaluate time of insemination relative to estrus and synchronization with melengestrol acetate (MGA) plus prostaglandin (PG) or progesterone insert (CIDR) plus PG…
(more)
▼ Objectives were to evaluate time of insemination relative to estrus and synchronization with melengestrol acetate (MGA) plus prostaglandin (PG) or progesterone insert (CIDR) plus PG on AI pregnancy rate in beef heifers (n = 662) during Fall or Spring. Fall heifers (n = 349) received MGA-PG (MGA for 14 d followed by PG on d 18) or CIDR-PG (CIDR for 7 d, PG administered 1 d before CIDR removal). Estrus was monitored by HeatWatch® (n = 200) or visually (n = 149). Spring heifers (n = 313) underwent CIDR-PG with detection of estrus by HeatWatch®. Heifers not in estrus by 96-100 h after PG were bred AI as non-responsive AI (NRAI). Across seasons, 548 heifers were bred following estrus (EAI). Heifers synchronized during the Fall with MGA received more (P < 0.05) mounts than Fall CIDR heifers (76.8 ± 6.7 and 47.6 ± 7.4, respectively), but duration of estrus was similar. Fall CIDR heifers had greater (P < 0.05) mounting activity and duration of estrus (47.9 ± 5.2 mounts and 15.5 ± 1.1 h) compared to Spring CIDR heifers (34.5 ± 3.1 mounts and 12.7 ± 0.6 h). Heifers grouped in 4 h blocks from 0 to 24 h had no difference (P > 0.05) in pregnancy rates (mean 62.5 %). Treatment had no effect (P > 0.05) on EAI pregnancy rates. Pregnancy rates across seasons for EAI, NRAI and overall was 61.0 %, 26.3 %, and 54.5%. In conclusion, a 24 h window may exist to successfully AI heifers.
Advisors/Committee Members: Hall, John B. (committeechair), Nebel, Raymond L. (committee member), Whittier, William D. (committee member), Wahlberg, Mark L. (committee member).
Subjects/Keywords: Synchronization of Estrus; Heifers; CIDR; AI
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APA (6th Edition):
Dorsey, B. R. (2005). Effect of Timing of Insemination and Synchronization of Estrus Method on Artificial Insemination (AI) Pregnancy Rates in Beef Heifers. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/42873
Chicago Manual of Style (16th Edition):
Dorsey, Benjamin Reese. “Effect of Timing of Insemination and Synchronization of Estrus Method on Artificial Insemination (AI) Pregnancy Rates in Beef Heifers.” 2005. Masters Thesis, Virginia Tech. Accessed March 05, 2021.
http://hdl.handle.net/10919/42873.
MLA Handbook (7th Edition):
Dorsey, Benjamin Reese. “Effect of Timing of Insemination and Synchronization of Estrus Method on Artificial Insemination (AI) Pregnancy Rates in Beef Heifers.” 2005. Web. 05 Mar 2021.
Vancouver:
Dorsey BR. Effect of Timing of Insemination and Synchronization of Estrus Method on Artificial Insemination (AI) Pregnancy Rates in Beef Heifers. [Internet] [Masters thesis]. Virginia Tech; 2005. [cited 2021 Mar 05].
Available from: http://hdl.handle.net/10919/42873.
Council of Science Editors:
Dorsey BR. Effect of Timing of Insemination and Synchronization of Estrus Method on Artificial Insemination (AI) Pregnancy Rates in Beef Heifers. [Masters Thesis]. Virginia Tech; 2005. Available from: http://hdl.handle.net/10919/42873
Virginia Tech
15.
Yook, Eunsun.
Estimation of the Economic Impact of a Unit Change in Predicted Transmitting Ability for Daughter Pregnancy Rate and Other Predicted Transmitting Ability in the Merit Indexes.
Degree: MS, Dairy Science, 2004, Virginia Tech
URL: http://hdl.handle.net/10919/42809
► These studies deal with lifetime profit analyses for individual cows, and using these estimates to determine the economic value of genetic changes in traits for…
(more)
▼ These studies deal with lifetime profit analyses for individual cows, and using these estimates to determine the economic value of genetic changes in traits for which genetic evaluations (predicted transmitting ability, PTA) are currently available. Data were collected from six states processed by Dairy Records Management Systems (DRMS) from herds on continuous test for at least 10 yr.
The purpose of the first study was to determine how well estimators of lifetime net income based on 305-d lactation yields and a 10-yr opportunity (RNI305.10) and based on complete lactation data but a 5-yr opportunity (RNIc.5) predict the estimate based on complete lactations and a 10-yr opportunity (RNIc.10). Records for 22,854 cows in
Virginia herds born in 1988, 1990, and 1992 from the DRMS in Raleigh, NC were used. Each RNI was calculated using fluid (skim/fat) pricing and milk-fat-protein pricing. Regression analyses including herd and birth year were used in the model to estimate the regression of RNIc.10 on RNIc.5, and RNIc.10 on RNI305.10. The resulting regression coefficients for fluid (skim/fat) pricing were 1.53 and 1.12 explaining 67 and 97% of the variation of RNIc.10, respectively. The corresponding results for milk-fat-protein pricing were 1.52 and 1.14 explaining 68 and 96% of the variation of RNIc.10, respectively. Using RNIc.10 as the measure to estimate lifetime profit is strongly recommended over the two alternatives tested.
In the second study, the economic impacts of a unit change in PTA of daughter pregnancy rate (DPR) and other PTA in the merit indexes on lifetime profit estimates of a bullâ s daughters were estimated to determine an economic weight for the PTADPR and other PTA in economic indexes. Records for 71,094 cows born in 1988, 1990, and 1992 from six states processed at DRMS were used: Florida [10,940 cows], Indiana [8,231 cows], North Carolina [12,280 cows], Texas [4,786 cows],
Virginia [20,341 cows], and Vermont [14,516 cows]. The basic RNI function consisted of [total milk, fat, and protein income ?feed cost for production] (yield income, YI) + [net value of calves + net salvage value] (non yield income, NYI) ?rearing cost (RC) ?[(daily cost for labor, maintenance feed, supplies, and fixed expenses) x days in herd] (daily cost, DC). Some of the economic impacts of PTA described for the merit indexes were not included in the basic RNI. These were added to RNI by multiplying the respective sire PTA by the economic impact. These included -165*PTASCS (M); 33*udder composite + 15*feet and legs composite -14.86*body size composite (T); and 8.064*PTA for daughter pregnancy rate -4.80*PTA for daughter calving ease (PRCE). Each ARNI was calculated using all production records initiated prior to the cowâ s tenth birthday with three milk pricing systems comparable to the prices in USDA three merit indexes: fluid (skim/fat) pricing (FARNI), milk-fat-protein pricing (NMARNI), and cheese pricing (CARNI). Two levels of prices for rearing cost per day and daily cost were used for calculating FARNI, NMARNI,…
Advisors/Committee Members: Pearson, Ronald E. (committeechair), Cassell, Bennet G. (committee member), Nickerson, Stephen C. (committee member), Nebel, Raymond L. (committee member).
Subjects/Keywords: daughter pregnancy rate; relative net income; economic weight; herdlife opportunity; lifetime net income
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APA ·
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MLA ·
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to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Yook, E. (2004). Estimation of the Economic Impact of a Unit Change in Predicted Transmitting Ability for Daughter Pregnancy Rate and Other Predicted Transmitting Ability in the Merit Indexes. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/42809
Chicago Manual of Style (16th Edition):
Yook, Eunsun. “Estimation of the Economic Impact of a Unit Change in Predicted Transmitting Ability for Daughter Pregnancy Rate and Other Predicted Transmitting Ability in the Merit Indexes.” 2004. Masters Thesis, Virginia Tech. Accessed March 05, 2021.
http://hdl.handle.net/10919/42809.
MLA Handbook (7th Edition):
Yook, Eunsun. “Estimation of the Economic Impact of a Unit Change in Predicted Transmitting Ability for Daughter Pregnancy Rate and Other Predicted Transmitting Ability in the Merit Indexes.” 2004. Web. 05 Mar 2021.
Vancouver:
Yook E. Estimation of the Economic Impact of a Unit Change in Predicted Transmitting Ability for Daughter Pregnancy Rate and Other Predicted Transmitting Ability in the Merit Indexes. [Internet] [Masters thesis]. Virginia Tech; 2004. [cited 2021 Mar 05].
Available from: http://hdl.handle.net/10919/42809.
Council of Science Editors:
Yook E. Estimation of the Economic Impact of a Unit Change in Predicted Transmitting Ability for Daughter Pregnancy Rate and Other Predicted Transmitting Ability in the Merit Indexes. [Masters Thesis]. Virginia Tech; 2004. Available from: http://hdl.handle.net/10919/42809
Virginia Tech
16.
Grove, Mary Beth.
Optimal time of insemination in dairy cattle identified in estrus by HeatWatch.
Degree: MS, Dairy Science, 1996, Virginia Tech
URL: http://hdl.handle.net/10919/44510
► Estrus detection programs practiced on most U.S. dairy farms are not intense enough to provide the information needed to accurately time insemination, thus preventing…
(more)
▼ Estrus detection programs practiced on most U.S. dairy farms are not intense
enough to provide the information needed to accurately time insemination, thus
preventing AI from obtaining its full conception rate potential. Herds (n = 17)
participated in a trial designed to evaluate percent pregnant relative to various
characteristics of estrus. Herds utilized HeatWatch® electronic estrus detection
system to detect and record mounting activity for cows in estrus. Inseminations
were performed daily during a three hour interval for all cows identified in estrus
the previous 24 h. Model characterizing percent pregnant for cows (services =
2661) included effects of interval from first mount to AI (P < 0.01), mounts per
estrus (P < 0.01), DIM at insemination (P < 0.01), herd (P <0.05), and season of
AI (P < 0.05). As mounts per estrus and days in milk increased, percent diagnosed
pregnant increased. Interval affected probability of pregnancy with highest odds
ratios for percent pregnant occurring >4 to 16 h following onset of estrus. Model
for heifers (n = 306) included linear effects of interval (P < 0.01), season
(P < 0.05), and herd (P < 0.01). In dairy heifers, as interval from first mount to AI
increased, percent pregnant decreased. Timing of insemination in dairy cows can
now be performed relative to first mount of estrus, with highest probability of
pregnancy occurring between >4 to 16 h after onset. If onset of estrus is not
known, insemination should be performed at the next most convenient time
within 3 h.
Advisors/Committee Members: Nebel, Raymond L. (committeechair), Pearson, Ronald E. (committee member), Bailey, Thomas L. (committee member), Vinson, William E. (committee member).
Subjects/Keywords: estrus detection; artificial insemination; HeatWatch; LD5655.V855 1996.G768
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APA (6th Edition):
Grove, M. B. (1996). Optimal time of insemination in dairy cattle identified in estrus by HeatWatch. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/44510
Chicago Manual of Style (16th Edition):
Grove, Mary Beth. “Optimal time of insemination in dairy cattle identified in estrus by HeatWatch.” 1996. Masters Thesis, Virginia Tech. Accessed March 05, 2021.
http://hdl.handle.net/10919/44510.
MLA Handbook (7th Edition):
Grove, Mary Beth. “Optimal time of insemination in dairy cattle identified in estrus by HeatWatch.” 1996. Web. 05 Mar 2021.
Vancouver:
Grove MB. Optimal time of insemination in dairy cattle identified in estrus by HeatWatch. [Internet] [Masters thesis]. Virginia Tech; 1996. [cited 2021 Mar 05].
Available from: http://hdl.handle.net/10919/44510.
Council of Science Editors:
Grove MB. Optimal time of insemination in dairy cattle identified in estrus by HeatWatch. [Masters Thesis]. Virginia Tech; 1996. Available from: http://hdl.handle.net/10919/44510
Virginia Tech
17.
Krentz, Kathleen J.
Development of mouse morulae after encapsulation in alginate microgels or poly-l-lysine microcapsule.
Degree: MS, Dairy Science, 1991, Virginia Tech
URL: http://hdl.handle.net/10919/45428
► Three experiments were conducted to evaluate in vitro and in vivo development of zona pellucid a-intact (ZPI) and zona pellucida-free (ZPF) mouse embryos after…
(more)
▼ Three experiments were conducted to evaluate in vitro and in vivo development
of zona pellucid a-intact (ZPI) and zona pellucida-free (ZPF) mouse embryos after
encapsulation in either 2% sodium alginate or 0.1% poly-
L-Iysine (PLL). In
Experiment 1, rate of development of ZPI embryos (n = 150) from morulae to
hatched blastocysts was measured after encapsulation in alginate or PLL and as
unencapsulated controls. Following encapsulation, developmental stages were
recorded every 24 h for 120 h. Percentage of encapsulated embryos completely
hatched from the zona pellucid a were not different from each other but were
lower than unencapsulated controls at 48, 72, 96 and 120 h.
Development of ZPI and ZPF mouse embryos after encapsulation in either
alginate or PLL was examined in Experiment 2. Developmental stages and diameters
were recorded every 24 h for 72 h. At 72 h, embryos were stained and
fixed on slides to examine nuclei. Percentage of ZPI embryos developing to expanded
blastocysts, their diameters and nuclear counts were not different from each other or from ZPF embryos. Percentage of ZPI embryos initiating hatching
or completely hatched from the zona pellucida, their diameters and nuclear cell
numbers were also similar.
In the final experiment, ZPI mouse morulae were unencapsulated or encapsulated
in either alginate or PLL and transferred into recipients to examine in vivo development.
Recipients were allowed to develop fetuses to term. Recipients receiving
encapsulated embryos failed to deliver pups. However, five of six
recipients of unencapsulated embryos (n = 71) delivered a total of 16 live pups.
Additional transfers were performed to examine viable fetuses and resorption
sites on day 10 of gestation. Pregnancy rates, diagnosed by the presence of via bIe
fetuses or resorption sites, were similar for all treatments: unencapsulated
(71.4%), a1ginate (87.5%) and PLL (87.5%). However, the total number of viable
fetuses present was higher for unencapsulated embryos (42.1 %) when compared
to embryos in alginate microgels (17%) and embryos in PLL microcapsules
(14.60/0). Additionally, recipients of alginate and PLL encapsulated embryos had
more resorption sites (4 0/0 and 13.4%) when compared to recipients of
unencapsulated embryos (0%).
These investigations demonstrated that development of encapsulated ZPI mouse
morulae is impaired at the hatched blastocyst stage; however, encapsulated ZPI
and ZPF mouse morulae develop similarly in size and nuclear counts. In vivo
development of ZPI morulae was also impaired due to an asynchronous condition
between the uterine environment and the developing embryos.
Advisors/Committee Members: Nebel, Raymond L. (committeechair), Saacke, Richard G. (committee member), McGilliard, Michael L. (committee member), Vinson, William E. (committee member).
Subjects/Keywords: Mice; LD5655.V855 1991.K846
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APA (6th Edition):
Krentz, K. J. (1991). Development of mouse morulae after encapsulation in alginate microgels or poly-l-lysine microcapsule. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/45428
Chicago Manual of Style (16th Edition):
Krentz, Kathleen J. “Development of mouse morulae after encapsulation in alginate microgels or poly-l-lysine microcapsule.” 1991. Masters Thesis, Virginia Tech. Accessed March 05, 2021.
http://hdl.handle.net/10919/45428.
MLA Handbook (7th Edition):
Krentz, Kathleen J. “Development of mouse morulae after encapsulation in alginate microgels or poly-l-lysine microcapsule.” 1991. Web. 05 Mar 2021.
Vancouver:
Krentz KJ. Development of mouse morulae after encapsulation in alginate microgels or poly-l-lysine microcapsule. [Internet] [Masters thesis]. Virginia Tech; 1991. [cited 2021 Mar 05].
Available from: http://hdl.handle.net/10919/45428.
Council of Science Editors:
Krentz KJ. Development of mouse morulae after encapsulation in alginate microgels or poly-l-lysine microcapsule. [Masters Thesis]. Virginia Tech; 1991. Available from: http://hdl.handle.net/10919/45428
Virginia Tech
18.
Cornwell, Jeffrey M.
The Interaction of Sire Fertility and Timing of AI in a Synchronization Protocol.
Degree: MS, Dairy Science, 2005, Virginia Tech
URL: http://hdl.handle.net/10919/42357
► The objectives of this study were to determine if fixed-timed artificial insemination (FTAI) at two different times, 0 or 24 h after GnRH administration, in…
(more)
▼ The objectives of this study were to determine if fixed-timed artificial insemination (FTAI) at two different times, 0 or 24 h after GnRH administration, in a Presynch-Ovsynch protocol influenced the pregnancy rate (PR) when average and high fertility sires were used. Additionally, a second experiment was conducted to determine the effectiveness of CIDR inserts to allow for resynchronization of estrus in cows that did not conceive or maintain the conceptus at FTAI. Lactating Holstein cows (n = 1,457) from two well-managed dairy herds located in the piedmont region of North Carolina were utilized for 12 mo. First artificial insemination (AI) PR differed for fertility group and was 24.1 and 29.2% for average and high fertility group, respectively. Timing of AI did not influence first AI PR and there was no interaction of fertility group and timing of AI. Cows that received a CIDR insert were detected more frequently in estrus during a 4 d period, d 21 to 24, than control cows, 92.5 and 62.0%, respectively. However, the CIDR insert did not increase the detection of estrus compared to control cows over a normal estrus return interval of 7 d, 18 to 24 d after GnRH administration of a FTAI protocol, 28.8 and 34.2% respectively. In conclusion, the use of high fertility sires is a practical recommendation for improving first AI PR and CIDR inserts allowed more cows to be detected in estrus during a shorter interval, but did not increase the estrus detection rate during a normal estrus return interval.
Advisors/Committee Members: Nebel, Raymond L. (committeechair), Akers, Robert Michael (committee member), Kasimanickam, Ramanathan (committee member), McGilliard, Michael L. (committee member).
Subjects/Keywords: CIDR; resynchronization; sire fertility; ERCR
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APA (6th Edition):
Cornwell, J. M. (2005). The Interaction of Sire Fertility and Timing of AI in a Synchronization Protocol. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/42357
Chicago Manual of Style (16th Edition):
Cornwell, Jeffrey M. “The Interaction of Sire Fertility and Timing of AI in a Synchronization Protocol.” 2005. Masters Thesis, Virginia Tech. Accessed March 05, 2021.
http://hdl.handle.net/10919/42357.
MLA Handbook (7th Edition):
Cornwell, Jeffrey M. “The Interaction of Sire Fertility and Timing of AI in a Synchronization Protocol.” 2005. Web. 05 Mar 2021.
Vancouver:
Cornwell JM. The Interaction of Sire Fertility and Timing of AI in a Synchronization Protocol. [Internet] [Masters thesis]. Virginia Tech; 2005. [cited 2021 Mar 05].
Available from: http://hdl.handle.net/10919/42357.
Council of Science Editors:
Cornwell JM. The Interaction of Sire Fertility and Timing of AI in a Synchronization Protocol. [Masters Thesis]. Virginia Tech; 2005. Available from: http://hdl.handle.net/10919/42357
Virginia Tech
19.
Nadir, Sher.
Effect of seminal plasma on cryopreservation and function of bovine spermatozoa.
Degree: PhD, Animal Science, 1995, Virginia Tech
URL: http://hdl.handle.net/10919/39606
► This study was conducted to :1) determine the effect of seminal plasma (SP) on sperm viability parameters (estimated percent motile sperm, computer-aided percent motile sperm…
(more)
▼ This study was conducted to :1) determine the effect of seminal plasma (SP) on sperm viability parameters (estimated percent motile sperm, computer-aided percent motile sperm and percent intact acrosomes) and motion characteristics (average path velocity, VAP; curvilinear velocity, VCL; and straight line velocity, VSL) of cryopreserved ejaculated spermatozoa (Experiment 1) and cauda epididymal spermatozoa, both fresh and frozen (Experiment 2).2) determine the effect of additional SP on sperm transport in the female using cryopreserved ejaculated sperm (Experiment 3) or cryopreserved cauda epididymal sperm (Experiment 4). In Experiment I, addition of SP (1:1, v/v, post-thaw) did not affect (P> .05) viability parameters; however, all sperm motion characteristics were improved at 3 h of incubation (P < .05). In Experiment 2, addition of a normal complement of SP to cauda epididymal sperm significantly improved all motion characteristics and viability parameters except acrosomal integrity (P < .05) and semen freezing did not alter this effect. In Experiment 3 and 4, addition of SP to the inseminate did not affect the mean or median accessory sperm number (P> .05); however, in both experiments there was a trend toward increased median accessory sperm values for the SP-treated semen. In Experiment 3, mean ± SD and median accessory sperm values per embryo/ovum were 19.2± 36.9 and 2.5 for the control (n = 32); and 23.1 ± 71.6 and 6.5 for the treatment (n = 32). In Experiment 4, mean± SD and median accessory sperm values per embry%vum were 9.2± 16.7 and 1.0 for the control (n = 30); and 14.2± 21.2 and 3.5 for the treatment (n = 30). We conclude from these experiments that sperm motion characteristics but not viability parameters of ejaculated frozen-thawed semen are improved by additional SP (Experiment 1) and both motility and motion characteristics are modestly improved by a normal complement of SP added to cauda epididymal sperm (Experiment 2). This positive effect of SP on motility/motion characteristics may favor sperm transport, but not at a statistically significant level to be detected by accessory sperm number.
Advisors/Committee Members: Saacke, Richard G. (committeechair), Nebel, Raymond L. (committee member), Purswell, Beverly J. (committee member), Vinson, William E. (committee member), Beal, Wilfred E. (committee member).
Subjects/Keywords: LD5655.V856 1995.N335
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APA (6th Edition):
Nadir, S. (1995). Effect of seminal plasma on cryopreservation and function of bovine spermatozoa. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/39606
Chicago Manual of Style (16th Edition):
Nadir, Sher. “Effect of seminal plasma on cryopreservation and function of bovine spermatozoa.” 1995. Doctoral Dissertation, Virginia Tech. Accessed March 05, 2021.
http://hdl.handle.net/10919/39606.
MLA Handbook (7th Edition):
Nadir, Sher. “Effect of seminal plasma on cryopreservation and function of bovine spermatozoa.” 1995. Web. 05 Mar 2021.
Vancouver:
Nadir S. Effect of seminal plasma on cryopreservation and function of bovine spermatozoa. [Internet] [Doctoral dissertation]. Virginia Tech; 1995. [cited 2021 Mar 05].
Available from: http://hdl.handle.net/10919/39606.
Council of Science Editors:
Nadir S. Effect of seminal plasma on cryopreservation and function of bovine spermatozoa. [Doctoral Dissertation]. Virginia Tech; 1995. Available from: http://hdl.handle.net/10919/39606
Virginia Tech
20.
Dalton, Joseph C.
Factors Important to the Efficiency of Artificial Insemination in Single-Ovulating and Superovulated Cattle.
Degree: PhD, Dairy Science, 1999, Virginia Tech
URL: http://hdl.handle.net/10919/27139
► To identify factors important to the efficiency of artificial insemination in cattle, four studies were conducted. In the first study, the addition of cream to…
(more)
▼ To identify factors important to the efficiency of artificial insemination in cattle, four studies were conducted. In the first study, the addition of cream to the inseminate was used in an attempt to increase accessory sperm number. On d 6 after insemination, 60 embryos were evaluated. The addition of cream to the inseminate had no effect on accessory sperm number. In the second study, cryopreserved semen of a marked bull (spermatozoa exhibiting a semi-flattened anterior head) was matched with semen from an unmarked bull (conventional sperm head shape) to determine competitively the effect of a deep uterine insemination on accessory sperm number. Forty embryos were recovered 6 d after insemination and the ratio of accessory sperm observed was different: 62:38 for unmarked semen in the uterine body and marked semen in the uterine horn, and 72:28 for unmarked semen in the uterine horn and marked semen in the uterine body (P < .05). In the third study, superovulated cows were utilized to determine the effect of artificial insemination time on fertilization status and accessory sperm number. Cows were inseminated once at 0 h (n=10), 12 h (n=10), or 24 h (n=10) after the first standing event. On d 6 after insemination, 529 embryos(ova) were recovered. Fertilization rates were 29% (0 h); 60% (12 h); and 81% (24 h)(P < .01). Percentages of embryos with accessory sperm were: 5 (0 h); 8 (12 h); and 41(24 h) (P < .01). In the fourth study, three experiments utilizing superovulated cows were conducted to provide a basis for distinguishing unfertilized ova from very early embryonic death. In Exp. 1, recovered d 6 unfertilized ova were classified morphologically as either: 1) typical, 2) satellite, or 3) fragmented. In Exp. 2, recovered d 6 unfertilized ova from the third study were classified morphologically, and typical ova were fixed. In Exp. 3, ultrastructural features of preovulatory, tubal-stage, and typical d 6 unfertilized ova were investigated. Preovulatory ova revealed normal ultrastructure; tubal-stage ova exhibited evidence of degeneration; typical d 6 ova were degenerated and contained no discernable organelles. The first three studies support the use of accessory sperm evaluation as an alternative measure of fertility. The final study provides a basis from which future embryologists may distinguish fertilization failure from very early embryonic death.
Advisors/Committee Members: Saacke, Richard G. (committeechair), Nebel, Raymond L. (committee member), Bailey, Thomas L. (committee member), Lewis, Gregory S. (committee member), Grayson, Randolph Larry (committee member).
Subjects/Keywords: accessory sperm; artificial insemination; cattle; superovulation
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APA (6th Edition):
Dalton, J. C. (1999). Factors Important to the Efficiency of Artificial Insemination in Single-Ovulating and Superovulated Cattle. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/27139
Chicago Manual of Style (16th Edition):
Dalton, Joseph C. “Factors Important to the Efficiency of Artificial Insemination in Single-Ovulating and Superovulated Cattle.” 1999. Doctoral Dissertation, Virginia Tech. Accessed March 05, 2021.
http://hdl.handle.net/10919/27139.
MLA Handbook (7th Edition):
Dalton, Joseph C. “Factors Important to the Efficiency of Artificial Insemination in Single-Ovulating and Superovulated Cattle.” 1999. Web. 05 Mar 2021.
Vancouver:
Dalton JC. Factors Important to the Efficiency of Artificial Insemination in Single-Ovulating and Superovulated Cattle. [Internet] [Doctoral dissertation]. Virginia Tech; 1999. [cited 2021 Mar 05].
Available from: http://hdl.handle.net/10919/27139.
Council of Science Editors:
Dalton JC. Factors Important to the Efficiency of Artificial Insemination in Single-Ovulating and Superovulated Cattle. [Doctoral Dissertation]. Virginia Tech; 1999. Available from: http://hdl.handle.net/10919/27139
Virginia Tech
21.
Jewell, Tracy Michelle.
Artificial Induction of Lactation in Nonbreeder Dairy Cows.
Degree: MS, Dairy Science, 2002, Virginia Tech
URL: http://hdl.handle.net/10919/33721
► Thirty-four cows (26 Holsteins and 8 Jerseys) were subjected to an estrous synchronization protocol administering 2 PGF2Æ Ã injections 11 d apart prior to beginning…
(more)
▼ Thirty-four cows (26 Holsteins and 8 Jerseys) were subjected to an estrous synchronization protocol administering 2 PGF2Æ Ã injections 11 d apart prior to beginning the lactation-induction protocol. Artificial induction of lactation yielded a 92% success rate for Holstein cows with success defined as achieving >9 kg milk/d, and a 88% success rate for Jersey cows with success defined as achieving > 5 kg milk/d. Mean accumulated milk yield for induced cows at 150 DIM was 65% of mean yield for nontreated cows. Mean peak milk yield for lactation- induced Holsteins and Jerseys was 32 kg/d and 20 kg/d, respectively. Mean serum and milk progesterone concentrations for samples collected during the first 6 d of lactation were not different between lactation-induced and nontreated cows. However, mean serum estradiol concentrations for induced cows were higher (P <0.05) in samples collected 3 and 5 DIM. Lactation-induced cows exhibited an increase in serum alpha-lactalbumin concentrations 2 d prior to initiation of milking, reaching values of ~260 ng/ml. Mean days-to-first service was greatly reduced in cows induced into lactation compared to nontreated cows, while mean services per conception was similar between induced and nontreated cows. Mean days to conception was lower for induced cows than for nontreated cows. By 150 DIM, pregnancy rate of induced cows was 70%, whereas nontreated cows averaged 56% pregnancy rate.
Advisors/Committee Members: Barnes, Michael A. (committeechair), Akers, Robert Michael (committee member), Pearson, Ronald E. (committee member), Nickerson, Stephen C. (committee member), Nebel, Raymond L. (committee member).
Subjects/Keywords: estrous cycle; dairy cattle; induction of lactation
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APA (6th Edition):
Jewell, T. M. (2002). Artificial Induction of Lactation in Nonbreeder Dairy Cows. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/33721
Chicago Manual of Style (16th Edition):
Jewell, Tracy Michelle. “Artificial Induction of Lactation in Nonbreeder Dairy Cows.” 2002. Masters Thesis, Virginia Tech. Accessed March 05, 2021.
http://hdl.handle.net/10919/33721.
MLA Handbook (7th Edition):
Jewell, Tracy Michelle. “Artificial Induction of Lactation in Nonbreeder Dairy Cows.” 2002. Web. 05 Mar 2021.
Vancouver:
Jewell TM. Artificial Induction of Lactation in Nonbreeder Dairy Cows. [Internet] [Masters thesis]. Virginia Tech; 2002. [cited 2021 Mar 05].
Available from: http://hdl.handle.net/10919/33721.
Council of Science Editors:
Jewell TM. Artificial Induction of Lactation in Nonbreeder Dairy Cows. [Masters Thesis]. Virginia Tech; 2002. Available from: http://hdl.handle.net/10919/33721
Virginia Tech
22.
Walters, Anneke H.
In vitro assessment of fertilization and embryo development with Bovine spermatozoa after scrotal insulation.
Degree: PhD, Dairy Science, 2004, Virginia Tech
URL: http://hdl.handle.net/10919/29721
► Fertilization and cleavage of bovine embryos depend not only on maternal involvement, but also on the paternal contributions that involve more than just providing the…
(more)
▼ Fertilization and cleavage of bovine embryos depend not only on maternal involvement, but also on the paternal contributions that involve more than just providing the haploid male genome. Therefore, the overall objective of this project was to determine the impact of morphologically abnormal spermatozoa on fertilization, subsequent embryonic development, and embryo quality at the cellular level. Four experiments used morphologically abnormal semen samples collected and cryopreserved from four Holstein bulls before (Pre) and after a scrotal insulation (PI) period of 48 h. Zygotes were cultured for 8 d when a developmental score was assigned to each embryo; subpopulations were subjected to either the TUNEL or caspase assays to determine apoptosis. In the final experiment pronuclear decondensation for presumptive zygotes was evaluated by differential interference contrast microscopy at 3 h time intervals from 6 to 18 h post in vitro insemination (hpi). Morphological evaluation of semen samples revealed a decrease (P < 0.01) in the percentages of normal spermatozoa in the PI samples in comparison with the Pre samples for Bulls I and Bull III (74 to 22.3% and 67.7 to 0.5 %, respectively) and the scrotal insulation effects persisted from the time of cleavage through blastocyst formation for Bulls I and III and corresponded with a similar decrease in blastocyst development for PI samples in experiment 1 regardless of which semen separation method was used. Likewise, the overall pronuclear decondensation rate for the PI zygotes of Bull I and III showed no increase over time and remained predominantly at PN1 stage (1.5 ± 0.17; 1.8 ± 0.22, respectively). In contrast, the development for Bull II and Bull IV were unaffected. The embryo quality assessment revealed that the caspase intensity increased significantly for both Bull I (217 ± 147) and Bull III (229 ± 98) for the PI embryo groups compared to those of Bull II (98 ± 115) and Bull IV (90 ± 111). In conclusion, the tested separation methods used seemed inadequate in their ability to provide potentially competent sperm for IVF. The decrease in embryonic development appears to be multifaceted and related to the changes in head shape morphology and we suggest the failure in normal pronuclear formation is associated with an absence of normal decondensation of the penetrating spermatozoon. The inability to consistently measure apoptosis in early stage embryos complicates the assessment of differences in embryo quality. These observations support the hypothesis of uncompensable seminal traits in IVF with abnormal spermatozoa and provide compelling evidence that the effect of morphologically abnormal spermatozoa occurred prior to cleavage, thus is manifested during the early stages of fertilization.
Advisors/Committee Members: Gwazdauskas, Francis C. (committeechair), Pearson, Ronald E. (committee member), Nebel, Raymond L. (committee member), Eyestone, Willard H. (committee member), Eng, Ludeman A. (committee member).
Subjects/Keywords: Embryonic Development; Fertilization; Morphologically Abnormal Spematozoa; Apoptosis
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APA (6th Edition):
Walters, A. H. (2004). In vitro assessment of fertilization and embryo development with Bovine spermatozoa after scrotal insulation. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/29721
Chicago Manual of Style (16th Edition):
Walters, Anneke H. “In vitro assessment of fertilization and embryo development with Bovine spermatozoa after scrotal insulation.” 2004. Doctoral Dissertation, Virginia Tech. Accessed March 05, 2021.
http://hdl.handle.net/10919/29721.
MLA Handbook (7th Edition):
Walters, Anneke H. “In vitro assessment of fertilization and embryo development with Bovine spermatozoa after scrotal insulation.” 2004. Web. 05 Mar 2021.
Vancouver:
Walters AH. In vitro assessment of fertilization and embryo development with Bovine spermatozoa after scrotal insulation. [Internet] [Doctoral dissertation]. Virginia Tech; 2004. [cited 2021 Mar 05].
Available from: http://hdl.handle.net/10919/29721.
Council of Science Editors:
Walters AH. In vitro assessment of fertilization and embryo development with Bovine spermatozoa after scrotal insulation. [Doctoral Dissertation]. Virginia Tech; 2004. Available from: http://hdl.handle.net/10919/29721
Virginia Tech
23.
Canseco-Sedano, Rodolfo.
Factors affecting the efficiency of gene transfer in mice.
Degree: PhD, Animal Sciences, Dairy, 1992, Virginia Tech
URL: http://hdl.handle.net/10919/37502
► In order to optimize the overall efficiency of pronuclear microinjection, we designed experiments to: 1) test the best developmental stage for transferring injected embryos to…
(more)
▼ In order to optimize the overall efficiency of pronuclear microinjection, we designed
experiments to: 1) test the best developmental stage for transferring injected embryos to
obtain pregnancies and transgenic pups; 2) determine the optimum number of injected
embryos transferred to obtain pregnancies and transgenic pups; 3) investigate whether
addition of non-injected embryos with injected embryos increased pregnancy rate (PR)
and transgenic pups; and 4) establish the time during pregnancy of highest embryonic or fetal loss. Mice (COl; 3 to 4 wk old),were superovulated with 10 iu PMSG and 5 iu hCG 48 h apart. One-cell embryos were collected for microinjection 20 to 24 h after hCG. The gene used was the whey acidic protein promoter linked to a coding sequence of the human protein C gene (W AP-hPC). Embryos were cultured in CZB at 370C in 5% C02 in air. All the live pups born and embryos and fetuses recovered were analyzed by the polymerase chain reaction to detect the presence of the transgene. Experiment one consisted of nine transfer treatments (TRT) which included all the combinations of three developmental stages (I-cell, 2-4 cell and morula/blastocyst) with three quantities of embryos per transfer (15-24, 25-34 and 35-44). Ten transfers were performed for each TRT. The highest PR and total pups born (TOTP) were obtained after transferring 25 to 34 2-4 cell embryos (PR=90% TOTP=3.5/ pregnancy). However, overall analysis
indicated that the percentage of transgenic pups born (%TRS) was highest using I-cell
embryos [33.9%, 20.0% and 11.1% for I-cell, 2-4 cell and morula/blastocyst (mor/bl),
respectively]. The second experiment consisted of six transfer TRT: 20-0, 16-4, 12-8,30-
0, 26-4 and 22-8 injected - non-injected embryos, respectively (10 transfers rrRT). Data
showed that PR and TOTP can be improved by addition of non-injected embryos.
However, the percentage of transgenic pups was significantly (p< .05) higher when alJ
the embryos transferred were injected (53.6 % vs 46.4 % for transfers without and with
non-manipulated embryos, respectively). Additionally, 30 embryos per transfer yielded a
significantly higher percentage (p< .05) of transgenic pups than 20 embryos per transfer
(67.9 % vs 32.1 % for 30 and 20 embryos per transfer, respectively). In experiment three 45 transfers of microinjected embryos were performed (30 embryos per transfer). Fifteen recipients were sacrificed on day 4~ 12 and 18 of gestation. On each day all embryos and fetuses were counted and analyzed for the presence of the transgene. The percentage of transgenic embryos or fetuses was not statistically different at any recovery day (45.8%, 35.5% and 34.6% for days 4, 12 and 18, respectively). However, the number of viable embryos at day 4 was significantly greater than the number of viable fetuses on days 12 or 18 (10 ± 1.1,5.1 ± 1.6, and 2.4 ± 1.3 for days 4,12 and 18, respectively). Collectively, the results indicate that: 1) transfer of 20 to 30 I-cell embryos was the best method to obtain transgenic mice, 2) addition of…
Advisors/Committee Members: Gwazdauskas, Francis C. (committeechair), Pearson, Ronald E. (committee member), Eng, Ludeman A. (committee member), Nebel, Raymond L. (committee member), Velander, William H. (committee member), Vinson, William E. (committee member).
Subjects/Keywords: Transgenic mice; LD5655.V856 1992.C367
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APA (6th Edition):
Canseco-Sedano, R. (1992). Factors affecting the efficiency of gene transfer in mice. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/37502
Chicago Manual of Style (16th Edition):
Canseco-Sedano, Rodolfo. “Factors affecting the efficiency of gene transfer in mice.” 1992. Doctoral Dissertation, Virginia Tech. Accessed March 05, 2021.
http://hdl.handle.net/10919/37502.
MLA Handbook (7th Edition):
Canseco-Sedano, Rodolfo. “Factors affecting the efficiency of gene transfer in mice.” 1992. Web. 05 Mar 2021.
Vancouver:
Canseco-Sedano R. Factors affecting the efficiency of gene transfer in mice. [Internet] [Doctoral dissertation]. Virginia Tech; 1992. [cited 2021 Mar 05].
Available from: http://hdl.handle.net/10919/37502.
Council of Science Editors:
Canseco-Sedano R. Factors affecting the efficiency of gene transfer in mice. [Doctoral Dissertation]. Virginia Tech; 1992. Available from: http://hdl.handle.net/10919/37502
. 
Open Access Theses and Dissertations