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1.
Holland, Sarah C.
Comparison of Luteolysis and Timed Artificial Insemination Pregnancy Rates after Administration of PGF2a in the Muscle or the Ischiorectal Fossa in Cattle.
Degree: MS, Biomedical and Veterinary Sciences, 2015, Virginia Tech
URL: http://hdl.handle.net/10919/56575 
► Prostaglandin F2α (PGF2α) is commonly given to female cattle intramuscularly (IM) for the synchronization of estrus. A novel site for administration of PGF2α that improves…
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▼ Prostaglandin F2α (PGF2α) is commonly given to female cattle intramuscularly (IM) for the synchronization of estrus. A novel site for administration of PGF2α that improves beef quality assurance is the ischiorectal fossa (IRF). The objective of this study was to determine whether administration of PGF2α in the IRF results in a similar physiologic response to administration of PGF2α given IM.
Yearling angus-cross heifers (n=112) were blocked by weight and randomly assigned within blocks to be injected with 5 mL PGF2α either IM in the neck or in the IRF. Blood samples were taken at 0, 8, 16, 24, 36, and 48 h post-injection. Serum samples were analyzed for progesterone concentration using a radioimmunoassay. Progesterone concentration curves for each heifer were plotted to determine luteolysis. The median times to luteolysis for neck and IRF injections were 18.1 hrs and 20.0 hrs, respectively (p=0.06).
Angus cross commercial beef cows (n=1471) at least 30 days post-partum were blocked by age and randomly assigned to be injected with 5 mL PGF2α either IM in the neck muscle or in IRF as part of a 7-Day CO-Synch + CIDR ovulation protocol. Pregnancy diagnosis was performed via ultrasound at 60 days post insemination. Results were analyzed with Proc Glimmix (SAS). Pregnancy rates for neck and IRF injections were 52.6% and 57.2%, respectively (p=0.06).
In summary, injection of PGF2α in the IRF for estrus synchronization and lysis of the corpus luteum did not differ from injection in the neck muscle. Utilizing the ischiorectal fossa as an injection site for PGF2α may be considered as an alternative that more closely aligns with beef quality assurance objectives.
Advisors/Committee Members: Swecker, William S. Jr. (committeechair), Whittier, William D. (committee member), Clark-Deener, Sherrie (committee member).
Subjects/Keywords: Prostaglandin; luteolysis; estrus synchronization; beef quality assurance
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APA (6th Edition):
Holland, S. C. (2015). Comparison of Luteolysis and Timed Artificial Insemination Pregnancy Rates after Administration of PGF2a in the Muscle or the Ischiorectal Fossa in Cattle. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/56575
Chicago Manual of Style (16th Edition):
Holland, Sarah C. “Comparison of Luteolysis and Timed Artificial Insemination Pregnancy Rates after Administration of PGF2a in the Muscle or the Ischiorectal Fossa in Cattle.” 2015. Masters Thesis, Virginia Tech. Accessed March 05, 2021.
http://hdl.handle.net/10919/56575.
MLA Handbook (7th Edition):
Holland, Sarah C. “Comparison of Luteolysis and Timed Artificial Insemination Pregnancy Rates after Administration of PGF2a in the Muscle or the Ischiorectal Fossa in Cattle.” 2015. Web. 05 Mar 2021.
Vancouver:
Holland SC. Comparison of Luteolysis and Timed Artificial Insemination Pregnancy Rates after Administration of PGF2a in the Muscle or the Ischiorectal Fossa in Cattle. [Internet] [Masters thesis]. Virginia Tech; 2015. [cited 2021 Mar 05].
Available from: http://hdl.handle.net/10919/56575.
Council of Science Editors:
Holland SC. Comparison of Luteolysis and Timed Artificial Insemination Pregnancy Rates after Administration of PGF2a in the Muscle or the Ischiorectal Fossa in Cattle. [Masters Thesis]. Virginia Tech; 2015. Available from: http://hdl.handle.net/10919/56575
Virginia Tech
2.
Ligon, Jennifer Marie.
The Effects of Low Stress Cattle Handling and Weaning Training on Post-Weaning Weight Gain and Calf Activity.
Degree: MS, Biomedical and Veterinary Sciences, 2015, Virginia Tech
URL: http://hdl.handle.net/10919/51262
► The objective of this study was to assess the effect of low stress (LS) handling of beef calves on weight gain and calf activity associated…
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▼ The objective of this study was to assess the effect of low stress (LS) handling of beef calves on weight gain and calf activity associated with the weaning process. Cattle were of Angus and Angus cross breeding from two separate herds in
Virginia. Handlers for the LS groups went through a short training session. Handlers for the Control (C) groups did not have any special training and handled their group as they would have with no adjustments. Handling and calf activity were monitored each time (6 times) the cows were worked from calving through one month post-weaning. Weights were taken from birth to one month post-weaning. During the week post-weaning the C calves averaged a gain of 4.38 lbs. and the LS calves averaged a gain of 16.94 lbs. One month post-weaning the C calves averaged a gain of 49.01 lbs., while the LS calves averaged a gain of 68.6 lbs. This showed a difference (p < 0.0001) between handling method for weight gain in calves for one week and one month post-weaning. Pedometers were used to assess calf activity post-weaning. Steps per hour (SPH) for the week post-weaning was numerically higher for those calves handled conventionally and not trained for weaning. The C calves averaged 1048 to 1629 SPH for the first three days, where the LS calves averaged 443 to 644 SPH for the first three days. Additionally, the artificial insemination conception rates (AICR) were calculated in each herd and treatment groups compared, however results were equivocal. This study demonstrated that handling cattle using low stress techniques can make significant improvements with regard to weaning weights and has potential to increase other areas of production in beef cattle.
Advisors/Committee Members: Whittier, William D. (committeechair), Clark-Deener, Sherrie (committee member), Currin, John F. (committee member).
Subjects/Keywords: Low Stress; Beef Cattle; Stockmanship; weaning
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APA (6th Edition):
Ligon, J. M. (2015). The Effects of Low Stress Cattle Handling and Weaning Training on Post-Weaning Weight Gain and Calf Activity. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/51262
Chicago Manual of Style (16th Edition):
Ligon, Jennifer Marie. “The Effects of Low Stress Cattle Handling and Weaning Training on Post-Weaning Weight Gain and Calf Activity.” 2015. Masters Thesis, Virginia Tech. Accessed March 05, 2021.
http://hdl.handle.net/10919/51262.
MLA Handbook (7th Edition):
Ligon, Jennifer Marie. “The Effects of Low Stress Cattle Handling and Weaning Training on Post-Weaning Weight Gain and Calf Activity.” 2015. Web. 05 Mar 2021.
Vancouver:
Ligon JM. The Effects of Low Stress Cattle Handling and Weaning Training on Post-Weaning Weight Gain and Calf Activity. [Internet] [Masters thesis]. Virginia Tech; 2015. [cited 2021 Mar 05].
Available from: http://hdl.handle.net/10919/51262.
Council of Science Editors:
Ligon JM. The Effects of Low Stress Cattle Handling and Weaning Training on Post-Weaning Weight Gain and Calf Activity. [Masters Thesis]. Virginia Tech; 2015. Available from: http://hdl.handle.net/10919/51262
Virginia Tech
3.
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…
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▼ 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
4.
Billings, Angela Renea.
Factors Influencing the Reproductive Efficiency of Dairy Herds in the Dominican Republic.
Degree: MS, Veterinary Medical Sciences, 2002, Virginia Tech
URL: http://hdl.handle.net/10919/31270
► Despite an increase in domestic milk production, the dairy industry in the Dominican Republic (D. R.) has not been able to adequately meet the demand…
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▼ Despite an increase in domestic milk production, the dairy industry in the Dominican Republic
(
D. R.) has not been able to adequately meet the demand of the ever-growing Dominican population, prompting the government and milk processing plants to sponsor programs which will increase the national production of milk and eventually lead to milk self-sufficiency.
One obstacle to this goal is a very low reproductive rate in cows and heifers due in part to the tropical setting. Year-round heat stress may result in abnormal follicular dynamics and decreased oocyte and sperm quality causing reproductive efficiency to decline drastically.
The specific purpose of this project was to examine and characterize the reproductive practices and outcomes of the Dominican dairy industry by region and to attempt to identify factors that influence dairy reproductive efficiency.
During the course of the study, 43 farms were visited over a 10-week period and evaluated. Farms were chosen throughout 4 of the 5 regions of the country and were selected based on their size (preferably 40 adult cows or more), availability of data, and demonstrated motivation by the owner in improving the herd. Individual herd evaluation was broken into four major components: owner interview, farm evaluation, collection of individual cow reproductive data, and adult cow evaluation.
Once observations had been made and catalogued, all data were summarized on the herd level and analyzed descriptively. In addition to descriptive analysis, multiple regression techniques were used to select independent variables which explain most of the variance for each of four reproductive outcomes: days to first service, services per pregnancy, projected calving interval, and service rate.
In general, reproductive management practices varied depending on region and farm size. Average lameness within the herd was the most important factor in explaining the variability within services per pregnancy and projected calving interval.
As average herd lameness increases by 1 point (based on a 1 to 4 scale), services per pregnancy and projected calving interval increase by 0.65 services per pregnancy and 61.1 days respectively according to the model formulated. Increase in the number of employees involved in estrus detection resulted in higher days to first service.
The Santo Domingo region had lower days to first service possibly due to widespread reproductive hormone use within the region. The percentage of Holsteins within the herd was associated with increased services per pregnancy and projected calving interval. Increases in service rate were most closely associated with the type of record category used, indicating that a larger sample population with thorough insemination records may be needed to adequately assess this outcome.
In part, reproductive efficiency in the Dominican Republic can be potentially improved by enhancing methods for estrus detection. Mechanical aids to estrus detection (tailhead chalk, K-marà patches, etc.) may help increase estrus…
Advisors/Committee Members: Whittier, William D. (committeechair), Elvinger, Francois C. (committee member), McGilliard, Michael L. (committee member), Hovingh, Ernest P. (committee member), Madera, Leonardo Rafael Tineo (committee member).
Subjects/Keywords: Dominican Republic; heat stress; reproductive efficiency; reproductive outcomes; dairy; lameness
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APA (6th Edition):
Billings, A. R. (2002). Factors Influencing the Reproductive Efficiency of Dairy Herds in the Dominican Republic. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/31270
Chicago Manual of Style (16th Edition):
Billings, Angela Renea. “Factors Influencing the Reproductive Efficiency of Dairy Herds in the Dominican Republic.” 2002. Masters Thesis, Virginia Tech. Accessed March 05, 2021.
http://hdl.handle.net/10919/31270.
MLA Handbook (7th Edition):
Billings, Angela Renea. “Factors Influencing the Reproductive Efficiency of Dairy Herds in the Dominican Republic.” 2002. Web. 05 Mar 2021.
Vancouver:
Billings AR. Factors Influencing the Reproductive Efficiency of Dairy Herds in the Dominican Republic. [Internet] [Masters thesis]. Virginia Tech; 2002. [cited 2021 Mar 05].
Available from: http://hdl.handle.net/10919/31270.
Council of Science Editors:
Billings AR. Factors Influencing the Reproductive Efficiency of Dairy Herds in the Dominican Republic. [Masters Thesis]. Virginia Tech; 2002. Available from: http://hdl.handle.net/10919/31270
Virginia Tech
5.
Schick, James Henry.
The Virginia Beef Cattle Simulation Model: A bio-economic simulation program modeling the interactions among reproduction, forage availability, nutrition, growth, and marketing in beef cattle.
Degree: PhD, Animal and Poultry Sciences, 1999, Virginia Tech
URL: http://hdl.handle.net/10919/37628
► The Virginia Beef Cattle Simulation Model (VBCSM) is a user-friendly, dynamic, stochastic computer program whose objective is to serve as a decision-aid for Virginia cattlemen…
(more)
▼ The
Virginia Beef Cattle Simulation Model (VBCSM) is a user-friendly, dynamic, stochastic computer program whose objective is to serve as a decision-aid for
Virginia cattlemen dealing with complex management issues such as whether to retain weaned calves through the stocker growth stage. Its five source-code modules are reproduction, forage, nutrition, marketing, and a tool that randomly assigns values to variables from appropriate statistical distributions. The VBCSM contains production statistics for 12 breeds, 21 forage species, and three
Virginia agro-ecological zones. It simulates at the animal level using information obtained from program dialog. Help can be activated on each dialog page. It is event-driven on a daily time increment. The reproduction module simulates puberty, conception, abortion, parturition, dystocia, lactation, pregnancy testing, culling, within-herd replacement female selection, open or pregnant replacement female purchases, cow and calf mortality, and weaning. The forage module simulates daily pasture growth dependent upon month, precipitation, erosion, pasture maintenance, grazing system, farm location, weed infestation, and slope. This module interacts with the nutrition module to calculate each animalâ s forage intake, supplemental feed requirements, and daily gain or loss using National Research Council equations. The marketing routine sells the weanling calves to the stocker herd and sells stocker calves, orphan calves, and cull cows through user-specified markets, including the
Virginia Tel-O-Market auction. After simulating for eight years to achieve equilibrium conditions, the VBCSM provides an income statement for the cow-calf operation and a partial budget for net income or loss from the stocker herd for up to three years. VBCSM was rigorously tested using a mathematical model with two calving seasons, three lengths of breeding season, four culling policies, and a year effect. Descriptive statistics suggest that the program code works in a consistent manner. However, several potential programming inconsistencies were discovered. Simulation results indicate that fall calving may be more profitable for
Virginia cattle producers than spring calving for weanling calf production, but a spring calved stocker program may be more profitable that a fall calved stocker program. Perhaps, VBCSM will help cattlemen to enhance their profits by more efficient market planning and utilization of production resources.
Advisors/Committee Members: Hohenboken, William D. (committeechair), Purcell, Wayne D. (committee member), Notter, David R. (committee member), Whittier, William D. (committee member), McKinnon, B. R. (committee member).
Subjects/Keywords: Beef Cattle; Growth; Reproduction; Forage; Marketing; Simulation Model
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APA ·
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APA (6th Edition):
Schick, J. H. (1999). The Virginia Beef Cattle Simulation Model: A bio-economic simulation program modeling the interactions among reproduction, forage availability, nutrition, growth, and marketing in beef cattle. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/37628
Chicago Manual of Style (16th Edition):
Schick, James Henry. “The Virginia Beef Cattle Simulation Model: A bio-economic simulation program modeling the interactions among reproduction, forage availability, nutrition, growth, and marketing in beef cattle.” 1999. Doctoral Dissertation, Virginia Tech. Accessed March 05, 2021.
http://hdl.handle.net/10919/37628.
MLA Handbook (7th Edition):
Schick, James Henry. “The Virginia Beef Cattle Simulation Model: A bio-economic simulation program modeling the interactions among reproduction, forage availability, nutrition, growth, and marketing in beef cattle.” 1999. Web. 05 Mar 2021.
Vancouver:
Schick JH. The Virginia Beef Cattle Simulation Model: A bio-economic simulation program modeling the interactions among reproduction, forage availability, nutrition, growth, and marketing in beef cattle. [Internet] [Doctoral dissertation]. Virginia Tech; 1999. [cited 2021 Mar 05].
Available from: http://hdl.handle.net/10919/37628.
Council of Science Editors:
Schick JH. The Virginia Beef Cattle Simulation Model: A bio-economic simulation program modeling the interactions among reproduction, forage availability, nutrition, growth, and marketing in beef cattle. [Doctoral Dissertation]. Virginia Tech; 1999. Available from: http://hdl.handle.net/10919/37628
. 
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