+publisher:"University of Arizona" +contributor:("Baumgard, Lance H")

University of Arizona

1. Shwartz, Gilad. Effects of Flunixin Meglumine on Pyrexia, Production, and Bioenergetic Variables in Postparturient Dairy Cows .

Degree: 2007, University of Arizona

URL: http://hdl.handle.net/10150/193377

► During early lactation dairy cows often experience health disorders, which are usually associated with decreased production and reproduction variables. Following parturition, cows use more energy… (more)

Subjects/Keywords: flunixin meglumine; transition cow; pyrexia

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APA (6^th Edition):

Shwartz, G. (2007). Effects of Flunixin Meglumine on Pyrexia, Production, and Bioenergetic Variables in Postparturient Dairy Cows . (Masters Thesis). University of Arizona. Retrieved from http://hdl.handle.net/10150/193377

Chicago Manual of Style (16^th Edition):

Shwartz, Gilad. “Effects of Flunixin Meglumine on Pyrexia, Production, and Bioenergetic Variables in Postparturient Dairy Cows .” 2007. Masters Thesis, University of Arizona. Accessed March 07, 2021. http://hdl.handle.net/10150/193377.

MLA Handbook (7^th Edition):

Shwartz, Gilad. “Effects of Flunixin Meglumine on Pyrexia, Production, and Bioenergetic Variables in Postparturient Dairy Cows .” 2007. Web. 07 Mar 2021.

Vancouver:

Shwartz G. Effects of Flunixin Meglumine on Pyrexia, Production, and Bioenergetic Variables in Postparturient Dairy Cows . [Internet] [Masters thesis]. University of Arizona; 2007. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10150/193377.

Council of Science Editors:

Shwartz G. Effects of Flunixin Meglumine on Pyrexia, Production, and Bioenergetic Variables in Postparturient Dairy Cows . [Masters Thesis]. University of Arizona; 2007. Available from: http://hdl.handle.net/10150/193377

University of Arizona

2. Harris, Mary Ann. The Influence of Omega-3 Fatty Acid Supplementation on Stallion Spermatozoa Survival Following Short- and Long-Term Preservation .

Degree: 2005, University of Arizona

URL: http://hdl.handle.net/10150/195991

► Study objectives were to; 1) determine if supplementing of n-3 fatty acids improves membrane integrity, and hence viability and motility of stallion spermatozoa following cold… (more)

Subjects/Keywords: Stallion; spermatozoa; DHA; n-3

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APA (6^th Edition):

Harris, M. A. (2005). The Influence of Omega-3 Fatty Acid Supplementation on Stallion Spermatozoa Survival Following Short- and Long-Term Preservation . (Doctoral Dissertation). University of Arizona. Retrieved from http://hdl.handle.net/10150/195991

Chicago Manual of Style (16^th Edition):

Harris, Mary Ann. “The Influence of Omega-3 Fatty Acid Supplementation on Stallion Spermatozoa Survival Following Short- and Long-Term Preservation .” 2005. Doctoral Dissertation, University of Arizona. Accessed March 07, 2021. http://hdl.handle.net/10150/195991.

MLA Handbook (7^th Edition):

Harris, Mary Ann. “The Influence of Omega-3 Fatty Acid Supplementation on Stallion Spermatozoa Survival Following Short- and Long-Term Preservation .” 2005. Web. 07 Mar 2021.

Vancouver:

Harris MA. The Influence of Omega-3 Fatty Acid Supplementation on Stallion Spermatozoa Survival Following Short- and Long-Term Preservation . [Internet] [Doctoral dissertation]. University of Arizona; 2005. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10150/195991.

Council of Science Editors:

Harris MA. The Influence of Omega-3 Fatty Acid Supplementation on Stallion Spermatozoa Survival Following Short- and Long-Term Preservation . [Doctoral Dissertation]. University of Arizona; 2005. Available from: http://hdl.handle.net/10150/195991

University of Arizona

3. Hernandez, Laura L. Characterization of the Bovine Mammary Gland Serotonergic System .

Degree: 2007, University of Arizona

URL: http://hdl.handle.net/10150/196049

► Previous research indicates the presence of a feedback inhibitor of lactation (FIL) in milk (Peaker and Wilde, 1996). Recently, tryptophan hydroxylase I (TPH1), the rate-limiting… (more)

▼ Previous research indicates the presence of a feedback inhibitor of lactation (FIL) in milk (Peaker and Wilde, 1996). Recently, tryptophan hydroxylase I (TPH1), the rate-limiting enzyme in serotonin (5-HT) biosynthesis, was identified in the mouse mammary gland and to be regulated by prolactin (PRL). Furthermore, 5-HT was present in rodent milk and addition of 5-HT to in vitro mammary cultures and in vivo administration of 5-HT to lactating mice reduced milk protein synthesis. Studies were conducted to determine the presence of the enzymatic machinery necessary to produce 5-HT in the bovine mammary gland, the presence of specific 5-HT receptors within the bovine mammary gland, the effects of 5-HT and non-selective and selective receptor antagonists on milk protein gene expression in cultures of primary bovine mammary epithelial cells (BMEC), and to determine the effects of intra-mammary infusions of 5-HT and a non-selective 5-HT receptor antagonist on milk production and composition in lactating dairy cows. Tryptophan hydroxylase I, aromatic amino acid decarboxylase (AADC) and the 5-HT reuptake transporter (SERT) were detected in lactating bovine mammary tissue by qRT-PCR and immunohistochemical staining. Additionally, mRNA for the 5-HT 1B, 2A, 2B, 4 and 7 receptors were detected in bovine mammary tissue as well as BMEC by qRT-PCR and in situ hybridization. Tryptophan hydroxylase I mRNA is in BMEC and up-regulated by PRL. Serotonin down-regulates milk protein gene expression but has not apparent effects on apoptosis and methysergide, ritanserin, SB-224289, and pimozide (receptor antagonists) increased milk protein gene expression in BMEC. Intra-mammary 5-HT infusions decreased overall milk yield in late-lactating dairy cows by 11.1%. Intra-mammary infusions of METH increased overall milk yield by 10.9%. In conclusion, the enzymatic machinery for 5-HT biosynthesis and uptake, as well as receptors involved 5-HT signaling are present in the bovine mammary gland. Furthermore, 5-HT appears to be a FIL in the bovine, but further research regarding its cellular mechanism of action and the location of its receptor populations should be conducted. Advisors/Committee Members: Collier, Robert J (advisor), Baumgard, Lance H (advisor), Horseman, Nelson D. (committeemember), Limesand, Kirsten H. (committeemember), Goll, Darrel E. (committeemember).

Subjects/Keywords: Nutritional Sciences

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APA (6^th Edition):

Hernandez, L. L. (2007). Characterization of the Bovine Mammary Gland Serotonergic System . (Doctoral Dissertation). University of Arizona. Retrieved from http://hdl.handle.net/10150/196049

Chicago Manual of Style (16^th Edition):

Hernandez, Laura L. “Characterization of the Bovine Mammary Gland Serotonergic System .” 2007. Doctoral Dissertation, University of Arizona. Accessed March 07, 2021. http://hdl.handle.net/10150/196049.

MLA Handbook (7^th Edition):

Hernandez, Laura L. “Characterization of the Bovine Mammary Gland Serotonergic System .” 2007. Web. 07 Mar 2021.

Vancouver:

Hernandez LL. Characterization of the Bovine Mammary Gland Serotonergic System . [Internet] [Doctoral dissertation]. University of Arizona; 2007. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10150/196049.

Council of Science Editors:

Hernandez LL. Characterization of the Bovine Mammary Gland Serotonergic System . [Doctoral Dissertation]. University of Arizona; 2007. Available from: http://hdl.handle.net/10150/196049

University of Arizona

4. Kay, Jane Kirrily. Effects of Conjugated Linoleic Acid on Lipid Metabolism and Energy Balance in Dairy Cows .

Degree: 2006, University of Arizona

URL: http://hdl.handle.net/10150/193624

► Three experiments were conducted for this dissertation with the goals to; 1) determine conjugated linoleic acid (CLA) effects on net-energy balance (EBAL) and milk production… (more)

▼ Three experiments were conducted for this dissertation with the goals to; 1) determine conjugated linoleic acid (CLA) effects on net-energy balance (EBAL) and milk production parameters during periods of nutrient/energy stress, and 2) investigate temporal CLA effects on mammary lipogenic gene expression. Study one was designed to determine if abomasal CLA infusion could reduce milk fat synthesis and partition nutrients towards alternative milk components in feed restricted rotationally grazed dairy cows. Data indicate abomasally-infusing CLA reduced milk fat synthesis in nutrient restricted grazing dairy cows and improved calculated EBAL and milk protein production. Another period of transitory stress experienced by the lactating dairy cow is immediately postpartum and study two objectives were to feed rumen inert-CLA to evoke milk fat depression (MFD) and investigate production and bioenergetic parameters. Data indicated a high CLA dose (3 x greater than needed in established lactation) inhibited milk fat synthesis immediately postpartum and improved calculated EBAL in grazing dairy cows. A curvilinear relationship existed between the severity of CLA-induced MFD and milk yield response. Moderate CLA-induced MFD (<~35%) tended to increase milk yield whereas severe MFD (>~35%) diminished this response. Previous research speculated that extensive MFD might decrease Δ⁹-desaturase (stearoyl CoA desaturase; SCD) and subsequent membrane fluidity to such an extent as to adversely affect cellular functions and inhibit milk secretion, thus decreasing milk yield. However, SCD inhibition was temporally independent in the present study, offering little support for the aforementioned theory. Mammary sensitivity to CLA increased as lactation progressed and previous speculations attributed this to reduced contribution of de novo synthesised fatty acids or increased competition from circulating non-esterified fatty acids immediately postpartum. However, data indicate that de novo fatty acids and milk fat trans-10, cis-12 CLA content don’t appreciably change during early lactation, (even though MFD became more severe) offering little support for either hypothesis. Study three investigated the effects of intravenous CLA infusion on temporal expression of mammary lipogenic genes to determine if trans-10, cis-12 CLA down regulates expression of a key gene (i.e. acetyl CoA carboxylase, ACC, the rate limiting enzyme in de novo fatty acid synthesis) and reduction in other mammary lipid synthesis genes is due to lack of substrate (i.e. malonyl CoA), or an alternative indirect mechanism. Data indicated however, that mammary lipogenic genes (ACC, fatty acid synthetase and SCD) followed a similar temporal pattern, providing more support for a global regulator (i.e. sterol regulatory element binding protein-1, peroxisome proliferator-activated receptor-γ or nuclear factor- κB) rather than a specific key enzyme effect. Advisors/Committee Members: Baumgard, Lance H (advisor), Collier, Robert (committeemember), Bauman, Dale (committeemember), Allen, Ronald E. (committeemember), Duff, Glenn (committeemember).

Subjects/Keywords: dairy cow; conjugated linoleic acid; lactation; energy balance

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APA (6^th Edition):

Kay, J. K. (2006). Effects of Conjugated Linoleic Acid on Lipid Metabolism and Energy Balance in Dairy Cows . (Doctoral Dissertation). University of Arizona. Retrieved from http://hdl.handle.net/10150/193624

Chicago Manual of Style (16^th Edition):

Kay, Jane Kirrily. “Effects of Conjugated Linoleic Acid on Lipid Metabolism and Energy Balance in Dairy Cows .” 2006. Doctoral Dissertation, University of Arizona. Accessed March 07, 2021. http://hdl.handle.net/10150/193624.

MLA Handbook (7^th Edition):

Kay, Jane Kirrily. “Effects of Conjugated Linoleic Acid on Lipid Metabolism and Energy Balance in Dairy Cows .” 2006. Web. 07 Mar 2021.

Vancouver:

Kay JK. Effects of Conjugated Linoleic Acid on Lipid Metabolism and Energy Balance in Dairy Cows . [Internet] [Doctoral dissertation]. University of Arizona; 2006. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10150/193624.

Council of Science Editors:

Kay JK. Effects of Conjugated Linoleic Acid on Lipid Metabolism and Energy Balance in Dairy Cows . [Doctoral Dissertation]. University of Arizona; 2006. Available from: http://hdl.handle.net/10150/193624

University of Arizona

5. Moore, Chel Earl. CONTROLLED MILK FAT DEPRESSION AS A MANAGEMENT TOOL TO IMPROVE ENERGY BALANCE IN LACTATING DAIRY CATTLE .

Degree: 2005, University of Arizona

URL: http://hdl.handle.net/10150/194107

► Research conducted for this dissertation had three goals; 1) determine if CLA can induce milk fat depression immediately postpartum, 2) determine if CLA can alter… (more)

▼ Research conducted for this dissertation had three goals; 1) determine if CLA can induce milk fat depression immediately postpartum, 2) determine if CLA can alter energy availability, 3) determine the mechanism behind the mammary gland's decreased sensitivity to CLA immediately postpartum. The first study provides strong evidence indicating CLA can decrease milk fat synthesis immediately postpartum, but the dose required is approximately 3x greater than in established lactation. This trial also provided evidence that CLA can alter energy status, as CLA decreased days to EBAL nadir by nearly 5 days. This is relevant as recovery of EBAL from its lowest point provides an important signal for initiating ovarian activity and days to nadir is highly correlated with days to first ovulation. Study two was designed to determine if CLA induced milk fat depression could improve energy status during heat stress. Rumen-inert CLA reduced milk fat synthesis, and was able to improve energy availability, but did not increase milk yield or yield of other milk components. Although production was unchanged in this study, the study did provide further evidence that rumen-inert CLA can alter energy availability. Study three utilized intravenous infusion of CLA in cows in mid and early lactation to determine the mechanism for the mammary gland's decreased sensitivity in early lactation. It is postulated that increased fatty acid oxidation and subsequent enhanced levels of circulating NEFA present during the transition period competitively prevent adequate CLA uptake by the mammary gland. In the current study, trans-10, cis-12 CLA concentration in milk was not different between early and established lactation, while milk fat yield was drastically reduced on d 4 and 5 of trans-10, cis-12 CLA infusion in mid lactation cows, but unaltered in early lactation. Further, NEFA levels were nearly 3 fold higher in early lactation than in mid lactation, providing further evidence that increased circulating NEFAs in early lactation are unlikely to be the source of the mammary gland's decreased sensitivity during this time. Do to the variation in gene expression observed in this trial, we were unable to make any definitive conclusions as to the sensitivity of the expression of genes involved in milk lipid synthesis to CLA in early vs. mid lactation. Advisors/Committee Members: Baumgard, Lance H. (committeemember), Collier, Robert J. (committeemember), Duff, Glenn C. (committeemember).

Subjects/Keywords: Dairy; Milk Fat Depression; Conjugated Linoleic Acid

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APA (6^th Edition):

Moore, C. E. (2005). CONTROLLED MILK FAT DEPRESSION AS A MANAGEMENT TOOL TO IMPROVE ENERGY BALANCE IN LACTATING DAIRY CATTLE . (Doctoral Dissertation). University of Arizona. Retrieved from http://hdl.handle.net/10150/194107

Chicago Manual of Style (16^th Edition):

Moore, Chel Earl. “CONTROLLED MILK FAT DEPRESSION AS A MANAGEMENT TOOL TO IMPROVE ENERGY BALANCE IN LACTATING DAIRY CATTLE .” 2005. Doctoral Dissertation, University of Arizona. Accessed March 07, 2021. http://hdl.handle.net/10150/194107.

MLA Handbook (7^th Edition):

Moore, Chel Earl. “CONTROLLED MILK FAT DEPRESSION AS A MANAGEMENT TOOL TO IMPROVE ENERGY BALANCE IN LACTATING DAIRY CATTLE .” 2005. Web. 07 Mar 2021.

Vancouver:

Moore CE. CONTROLLED MILK FAT DEPRESSION AS A MANAGEMENT TOOL TO IMPROVE ENERGY BALANCE IN LACTATING DAIRY CATTLE . [Internet] [Doctoral dissertation]. University of Arizona; 2005. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10150/194107.

Council of Science Editors:

Moore CE. CONTROLLED MILK FAT DEPRESSION AS A MANAGEMENT TOOL TO IMPROVE ENERGY BALANCE IN LACTATING DAIRY CATTLE . [Doctoral Dissertation]. University of Arizona; 2005. Available from: http://hdl.handle.net/10150/194107

University of Arizona

6. Moore, Heather Corrina. Genetic Profiling of the Bovine Pituitary Gland Using cDNA Microarray Technology .

Degree: 2006, University of Arizona

URL: http://hdl.handle.net/10150/194108

► Goals of this dissertation were to 1) use custom-made cDNA microarrays to identify genes in the bovine pituitary gland that are differentially expressed during the… (more)

▼ Goals of this dissertation were to 1) use custom-made cDNA microarrays to identify genes in the bovine pituitary gland that are differentially expressed during the estrous cycle and 2) characterize their patterns of gene expression. The estrous cycle is a dynamic process that requires coordination between the hypothalamus, pituitary gland, and ovaries. The anterior pituitary gland synthesizes and secretes the gonadotropins, luteinizing hormone (LH) and follicle stimulating hormone (FSH), which regulate steroidogenesis and follicular development. Currently, intrapituitary factors that modulate gonadotropin synthesis, storage, and release are not well described, thus, requiring investigation. To investigate the validity of the microarray results, we performed real-time PCR on 35 genes identified by cDNA microarray as being differentially regulated. Overall, microarray and real-time PCR results were consistent among our experiments suggesting that cDNA microarray is an efficacious tool for profiling gene expression in the bovine pituitary gland. Our first experiment was designed to identify genes that were regulated during the early luteal phase. This period is characterized by steadily increasing concentrations of progesterone (P4) from nadir to maximum. Samples from three different time points, d 2, d 6, and d 10 following initiation of the first follicular wave, were compared. One hundred and sixty nine genes were determined to be differentially expressed. Ten of these genes were validated using real-time PCR. The other two studies were designed to identify genes that were regulated during the preovulatory period as induced by the administration of prostaglandin F2α (PGF2α). This period is characterized by a decrease in circulating concentrations of P4 coincident with an increase in circulating concentrations of estradiol. Prior to the surge, FSH and LH are disconcordinately released but the underlying mechanisms regulating their release is unknown. The second study identified 1406 genes to be differentially regulated during the 72 h following administration of PGF2α. Twenty-seven of these transcripts were validated by real-time PCR. The third study identified 503 genes to be differentially regulated during the 48 h following administration of PGF2α. Twenty two of these transcripts were validated by real-time PCR. Together these experiments have identified several genes as potential intrapituitary factors that may function to regulate the reproductive axis. Advisors/Committee Members: Turzillo, Adele M. (committeemember), Hoyer, Patricia B. (committeemember), Hoying, James B. (committeemember), Braun, Eldon J. (committeemember), Baumgard, Lance H. (committeemember).

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APA (6^th Edition):

Moore, H. C. (2006). Genetic Profiling of the Bovine Pituitary Gland Using cDNA Microarray Technology . (Doctoral Dissertation). University of Arizona. Retrieved from http://hdl.handle.net/10150/194108

Chicago Manual of Style (16^th Edition):

Moore, Heather Corrina. “Genetic Profiling of the Bovine Pituitary Gland Using cDNA Microarray Technology .” 2006. Doctoral Dissertation, University of Arizona. Accessed March 07, 2021. http://hdl.handle.net/10150/194108.

MLA Handbook (7^th Edition):

Moore, Heather Corrina. “Genetic Profiling of the Bovine Pituitary Gland Using cDNA Microarray Technology .” 2006. Web. 07 Mar 2021.

Vancouver:

Moore HC. Genetic Profiling of the Bovine Pituitary Gland Using cDNA Microarray Technology . [Internet] [Doctoral dissertation]. University of Arizona; 2006. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10150/194108.

Council of Science Editors:

Moore HC. Genetic Profiling of the Bovine Pituitary Gland Using cDNA Microarray Technology . [Doctoral Dissertation]. University of Arizona; 2006. Available from: http://hdl.handle.net/10150/194108

University of Arizona

7. Sanders, Sara Ray. Effects of Heat Stress on Energetic Metabolism in Rats .

Degree: 2010, University of Arizona

URL: http://hdl.handle.net/10150/194613

► Studies conducted for this dissertation utilized a rodent model exposed to single or multiple short duration heat loads in an effort to: 1) elucidate the… (more)

▼ Studies conducted for this dissertation utilized a rodent model exposed to single or multiple short duration heat loads in an effort to: 1) elucidate the changes in energy metabolism occurring at the tissue and whole-body level in response to hyperthermia, 2) characterize specific aspects of glucose utilization and hepatic glucose production following a heat load and 3) determine if aspects of mitochondrial function and/or dysfunction might play a role in the metabolic changes that occur in response to heat stress. Study 1 was conducted to determine if rodents exposed to heat stress shared similarities using a bovine heat stress model. Specifically, we were interested in identifying changes in blood metabolites and hormones, as well as gene expression and protein abundance of enzymes associated with energy metabolism in skeletal muscle (type I and type II), liver and adipose tissue. Previous bovine data indicates glucose may be preferentially utilized during heat stress, suggesting alterations in energy metabolism. This study provided evidence that tissue-specific changes occur in response to a heat load and that full glucose oxidation might be reduced, specifically in skeletal muscle where abundance of PDK4 mRNA was increased. Within skeletal muscle, glucose transporters (GLUTs 1 and 4) also tended to be increased in rats exposed to a heat load. Increases in skeletal muscle AMPK-α and PGC-1α as well as increased expression of energy substrate transporters suggests heat stress may impose a cellular energy deficit and/or increased energy demands which subsequently leads to changes in energy metabolism. Few changes were noted in either hepatic or adipose tissue in response to acute heat stress in this pilot study. Study aim of Chapter 3 was to further characterize the effects of heat stress on energy metabolism at the tissue and whole-body level in rats exposed to either 1 or 2 bouts of heat. Rats exposed to a 6 h heat load tended to have higher plasma glucose but reduced insulin levels, compared to thermal neutral controls, suggesting decreased glucose uptake or increased hepatic glucose output. Additionally, although heat stress likely increases whole-body energy demand, plasma NEFA levels were blunted in the early hours following onset of heat, suggesting increased adipocyte insulin sensitivity. Gene expression of enzymes associated with oxidative energy metabolism were increased in the TA (which is comprised primarily of glycolytic muscle fibers) following 2 bouts and in liver following a single bout of heat, while expression of oxidative enzymes were decreased within the soleus (a primarily oxidative muscle type). AMPK mRNA was increased following a single bout of heat in hepatic tissue and after 2 bouts of heat in type I skeletal muscle. AMPK mRNA abundance remained the same following 1 bout but was reduced following 2 bouts of heat within type II skeletal muscle. In the TA, phosphorylated AMPK protein abundance was reduced by HS. Abundance of PGC-1α mRNA was increased in types I and II skeletal muscle but was… Advisors/Committee Members: Baumgard, Lance H. (committeemember), Rhoads, Michelle L. (committeemember), Limesand, Sean W. (committeemember), Duff, Glenn C. (committeemember).

Subjects/Keywords: AMPK; Energy metabolism; Heat stress; Oxidative stress; Rodents

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APA (6^th Edition):

Sanders, S. R. (2010). Effects of Heat Stress on Energetic Metabolism in Rats . (Doctoral Dissertation). University of Arizona. Retrieved from http://hdl.handle.net/10150/194613

Chicago Manual of Style (16^th Edition):

Sanders, Sara Ray. “Effects of Heat Stress on Energetic Metabolism in Rats .” 2010. Doctoral Dissertation, University of Arizona. Accessed March 07, 2021. http://hdl.handle.net/10150/194613.

MLA Handbook (7^th Edition):

Sanders, Sara Ray. “Effects of Heat Stress on Energetic Metabolism in Rats .” 2010. Web. 07 Mar 2021.

Vancouver:

Sanders SR. Effects of Heat Stress on Energetic Metabolism in Rats . [Internet] [Doctoral dissertation]. University of Arizona; 2010. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10150/194613.

Council of Science Editors:

Sanders SR. Effects of Heat Stress on Energetic Metabolism in Rats . [Doctoral Dissertation]. University of Arizona; 2010. Available from: http://hdl.handle.net/10150/194613

University of Arizona

8. Zimbelman, Rosemarie Burgos. Management Strategies to Reduce Effects of Thermal Stress on Lactating Dairy Cattle .

Degree: 2008, University of Arizona

URL: http://hdl.handle.net/10150/195322

► Two strategies to reduce impact of heat stress on high producing dairy cows were examined. The first was to recalculate the temperature-humidity index (THI) using… (more)

▼ Two strategies to reduce impact of heat stress on high producing dairy cows were examined. The first was to recalculate the temperature-humidity index (THI) using high producing dairy cows under diurnal summer conditions. This re-evaluation confirmed that current THI values underestimate the severity of heat stress levels. Therefore, cooling of dairy cattle during warm summer months should begin at a THI of 68. Previously, a THI equal to or greater than 72 has been used to define onset of heat stress. This study demonstrated that a THI greater than or equal to 68 is sufficient to increase body heat storage, respiration rate, skin evaporative heat loss, declines in feed intake and milk yield. A second objective involved three studies carried out to evaluate use of niacin in dairy cow rations to improve evaporative heat loss and resistance to heat stress. Niacin is known to cause intense vasodilation in human and lab species. We hypothesized that increasing vasodilation would improve evaporative heat loss in dairy cows. In the first niacin study, supplementation of lactating dairy cows with an encapsulated rumen by-pass form of niacin (NIASHURE™; Balchem Corporation, New Hampton, NY) at a dose of 12 g/d proved effective in alleviating some affects of heat stress during mild thermal stress. We hypothesized that encapsulated niacin would induce vasodilation effects documented in humans and lab animals increasing evaporative heat loss. Past research demonstrated that the possible mechanism for vasodilation affects seen by niacin were most likely due to prostaglandin D secretions. Niacin may act through increased prostaglandin D and E production and secretion by Langerhans cells which then act upon vascular endothelial prostaglandin D receptors to increase vasodilation. No studies have evaluated impact of encapsulated niacin on milk yield and composition during periods of thermal stress under commercial dairy conditions. The objective of the last study was to examine the effects of encapsulated niacin during heat stress on milk production and composition as well as core body temperatures under commercial conditions. Advisors/Committee Members: Collier, Robert J (advisor), Baumgard, Lance H (committeemember), Duff, Glenn C (committeemember), Bilby, Todd R (committeemember), Foster, Billye (committeemember).

Subjects/Keywords: Heat stress; niacin; temperature humidity index; THI

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APA (6^th Edition):

Zimbelman, R. B. (2008). Management Strategies to Reduce Effects of Thermal Stress on Lactating Dairy Cattle . (Doctoral Dissertation). University of Arizona. Retrieved from http://hdl.handle.net/10150/195322

Chicago Manual of Style (16^th Edition):

Zimbelman, Rosemarie Burgos. “Management Strategies to Reduce Effects of Thermal Stress on Lactating Dairy Cattle .” 2008. Doctoral Dissertation, University of Arizona. Accessed March 07, 2021. http://hdl.handle.net/10150/195322.

MLA Handbook (7^th Edition):

Zimbelman, Rosemarie Burgos. “Management Strategies to Reduce Effects of Thermal Stress on Lactating Dairy Cattle .” 2008. Web. 07 Mar 2021.

Vancouver:

Zimbelman RB. Management Strategies to Reduce Effects of Thermal Stress on Lactating Dairy Cattle . [Internet] [Doctoral dissertation]. University of Arizona; 2008. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/10150/195322.

Council of Science Editors:

Zimbelman RB. Management Strategies to Reduce Effects of Thermal Stress on Lactating Dairy Cattle . [Doctoral Dissertation]. University of Arizona; 2008. Available from: http://hdl.handle.net/10150/195322

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