Browsing by Subject "equine"
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Item Calcium balance and bone density in immature horses fed a high protein diet(Texas A&M University, 2006-10-30) Spooner, Holly SueStudies in other species indicate high protein diets increase urinary calcium (Ca) excretion and may lead to negative calcium balance and reduced bone density. As overfeeding of protein is commonplace in the horse industry, this study was undertaken to determine the effects of excess dietary protein on growth, physiologic response, mineral balance, bone density, and bone geometry in immature horses. Sixteen 10-month-old American Quarter Horses were blocked by age and sex into two dietary treatments. The control diet was formulated to provide the NRC (1989) recommended concentration of crude protein, while the high protein diet provided 130% of NRC (1989) recommendations. All other nutrients were formulated at or slightly above NRC (1989) recommendations. Blood samples, feces, and urine were collected during the 116-day study to determine any diet effect on pH and mineral balance. Radiographs were made of the left third metacarpal (MCIII) to determine bone density via radiographic bone aluminum equivalence (RBAE), and bone geometry was determined metrically from the radiographs. Urine pH decreased over time (p < 0.001), but there were no diet effects on blood pH or urine pH. Conversely, when normalized to day 0 values, fecal pH was reduced by feeding the high protein treatment (p < 0.02). Density of dorsal and palmar cortices increased over time (p < 0.001), but no differences were observed between diets. But, normalized total medial-lateral (ML) width of the MCIII was higher in the control diet (p < 0.05). Fecal Ca loss was greater in horses fed the high protein diet (p < 0.005), while Ca absorption and retention were lower for horses on the high protein treatment (p < 0.02). Phosphorus (P) balance was not different between diets, although feeding the high protein diet resulted in higher P intake overall (p < 0.001). While excess dietary protein may decrease fecal pH, increase fecal Ca excretion, and decrease Ca absorption and retention, there was no consistent effect of the high protein diet on bone density over the course of this study. Further research is necessary to determine if feeding high-protein diets is detrimental to bone quality in the growing horse.Item Channels and sources used to gather equine-related information by college-age horse owners and enthusiasts(2009-05-15) Sullivan, Erin AleneThis thesis identifies the equine-related topics that are important to Texas college-age horse owners and enthusiasts and the channels/sources they use to get equine-related information. Little research has focused on this group to determine their information needs. Therefore, two focus groups were conducted in 2008 in Texas with college-age horse owners and enthusiasts to conduct a needs assessment. Participants were separated into competitive and recreational groups depending on their level of participation in the industry. They were asked what topics they consider important and what channels/sources they use to gain desired information. Training was the most mentioned topic overall, and the most mentioned by recreational participants. Alternative medical treatments was the most mentioned topic by competitive participants. Competitive participants reported a smaller number of topics as important, indicating that they have specialized information needs. Recreational participants emphasized broader, less specialized topics. Participants showed an interest in relevant and controversial topics affecting the equine industry. Participants also used a combination of channels/sources and competitive and recreational participants often placed importance on different channels/sources. Face-to-face communication was important to both groups. Magazines were important to competitive participants, while the Internet was important to recreational participants. Competitive participants doubted the trustworthiness of sources available through the Internet, but wanted more reliable sources to be made available in the future. Participants preferred to get information from industry specialist sources, such as trainers, veterinarians, other owners and enthusiasts, breed associations, and equine magazines. Participants? perceptions of trustworthiness were affected by the source?s ability to demonstrate equine-specific knowledge and the source?s reputation and success among equine industry members. The results suggests that the influence of the Internet has altered the traditional models of communication in which source selection determines channel use. In this study, the participants? Internet channel selection often determined their source use. The results also suggests that communicators wanting to reach this audience should target specific topics to competitive and recreational audiences, use a multi-channel approach, establish trustworthiness, and explore the changing role of the Internet in agricultural communication.Item Cushioned centrifugation of stallion semen: factors impacting equine sperm recovery rate and quality(2009-05-15) Waite, Jessica ArleneCentrifugation of stallion semen is an integral part of the cryopreservation procedure, primarily allowing for the concentration of sperm and removal of seminal plasma. In addition, centrifugation is required for maximizing spermatozoal quality in semen from some stallions subjected to cooled transport, because of the detrimental effects of long-term exposure to high levels of seminal plasma. The centrifugation process, however, has potential deleterious effects, including reduction in sperm quality as well as loss of sperm numbers. Since centrifugation plays such a crucial role in semen processing, two experiments were designed to evaluate more efficient centrifugation methods to meet the demands of the equine industry. In Experiment 1, semen was centrifuged in two different tube types (nipple- or conical-bottom), using a cushioned technique (Eqcellsire? Component B) with two different extenders (opaque-INRA96 or clear-HGLL). For Experiment 2, nipple-tube centrifugation was conducted at two different g forces (400 or 600) for 20 min, using three different iodixanol cushion media, Eqcellsire? Component B, OptiPrep?, or Cushion Fluid?. Regardless of tube or extender types, centrifugation of semen resulted in sperm recovery rates ? 90%; however, centrifugation in INRA 96 extender yielded higher sperm motility values than did centrifugation in HGLL extender (P < 0.05). Cushion type or g force did not impact post-centrifugation semen quality, based on the laboratory values measured (P > 0.05). These results indicate that cushioned centrifugation of stallion semen in either conical-bottom or nipple-bottom tubes can yield a high sperm harvest, while maintaining sperm function. An optically opaque extender, as is typically used in the equine breeding industry, can be used to achieve this goal. The fertility rate (94%; 131/140) following cushioned semen centrifugation in a commercial program this past year indicates that these laboratory results are transferable to the clinical setting.Item Effects of continuous treatment with gonadotropin-releasing hormone during the anovulatory season on gonadotropin secretion, follicular dynamics and ovulation in the mare(Texas A&M University, 2005-02-17) Morton, StephanieObjectives were to determine if low-dose, continuous infusion of GnRH from Fall to Spring, would prevent seasonal anovulation in mares. Twenty Quarter Horse mares, ages 18 mo to 24 yrs, were stratified by age and body condition score and assigned randomly to either a saline control (n = 9) or GnRH (n = 11) treatment group. Treatments were instituted between September 23 and October 9, 2002. Gonadotropinreleasing hormone was delivered in 0.9% physiological saline via Alzet osmotic minipumps (Model 2004) placed sc at the base of the neck, with Silastic sham pumps placed in control mares. Pumps were inserted on day 3 following ovulation or during the follicular phase if ovulation had not occurred. Delivery rate of GnRH was 2.5 ug/h (60 ug/d) for the first 60 d, followed by 5.0 ug/h (120 ug/d) thereafter, with all pumps replaced every 30 d. By December 1, all mares had become anovulatory and remained anovulatory until February. Mean serum concentrations of LH were not affected by treatment in anovulatory mares. In contrast, control mares that exhibited ovulatory cycles after treatment onset had higher (P < 0.05) mean concentrations of LH during all phases of the estrous cycle except diestrus. Mean serum concentrations of FSH were not affected by treatment, but were lower (P < 0.05) from November though January relative to all other months in anovulatory mares. Interovulatory intervals in mares that cycled temporarily did not differ between groups. Ovulatory control mares had slightly larger (P < 0.10) follicles overall than GnRH-treated mares; however, ovulatory follicle diameters for control and GnRH-treated mares did not differ. Ovulatory control mares had higher (P < 0.10) mean concentrations of progesterone during metestrus and late diestrus. In a subgroup of control (n =5) and GnRH-treated (n = 5) mares, total releasable pools of LH in response to 1 mg GnRH did not differ between groups. Ovulation resumed in 3 control and 3 GnRH-treated mares by March 30. Results indicate that continuous infusion of native GnRH at the doses employed herein is not sufficient to maintain ovulatory cycles during the anovulatory season.Item Pregnancy Rates in Mares Inseminated with 0.5 or 1 Million Sperm Using Hysteroscopic or Transrectally Guided Deep-Horn Insemination Techniques(2013-11-08) Hayden, Shelby ShalenePlacement of sperm deep in the equine uterine horn allows fewer sperm to be inseminated while maintaining acceptable fertility, and has been promoted for use in circumstances when fertility would be expected to be low if standard insemination were used (e.g. semen from a subfertile stallion, or frozen-thawed semen). Two main deep- horn insemination techniques, transrectally guided (TRG) and hysteroscopic (HYS) insemination, have been developed for this purpose; however, there is some controversy regarding their comparative efficacy. This study was conducted to compare pregnancy rates when mares were inseminated by TRG or HYS, utilizing sperm numbers approaching and under the threshold for maximal fertility, resulting in reduced fertility. Pregnancy rates were not different between HYS and TRG techniques when 1 x 106 or 0.5 x 106 sperm were inseminated. Combined pregnancy rates for the two techniques were also not different. Pregnancy rates using a subthreshold number of sperm were not significantly affected by a deep-horn insemination technique. Dilution of semen to less than 20 x 106 sperm/mL has been reported to decrease semen quality in multiple species, a phenomenon known as the semen ?dilution effect.? The sperm concentrations utilized in Experiment 1 were 5 and 2.5 x 106/mL (1 and 0.5 x 106 sperm doses, respectively). This experiment was performed to evaluate whether the lower pregnancy rates obtained with 0.5 x 106 sperm was due to lower quality plasma membrane integrity (PMI) and sperm motion characteristics (TMOT, PMOT, VCL, VAP, VSL, STR). Treatments evaluated included 2.5 x 106 sperm/mL with the addition of 0, 7.5, and 25% seminal plasma, 30 x 106 sperm/mL, and 3:1 extender: semen. The 2.5 x 106 sperm/mL treatments have lower initial PMI, TMOT, and PMOT, but they maintain their initial quality following 24 and 48 h of cool-storage. The sperm velocity and straightness parameters suggest that sperm swim faster but have a more circular pattern as seminal plasma increases to 25% at a given concentration. Based on the findings from this experiment, the semen ?dilution effect? may not significantly alter stallion sperm characteristics when a commercially-available semen extender is used for semen dilution.Item Utilizing body temperature to evaluate ovulation in mature mares(Texas A&M University, 2006-08-16) Bowman, Marissa CoralThe equine breeding industry continues to be somewhat inefficient, even with existing technology. On average, foaling rates are low when compared with that of other livestock. One major contributor is the inability to accurately predict ovulation in mares, which ovulate before the end of estrus, leaving much variability in coordinating insemination. A more efficient, less invasive method that could replace or reduce the need for constant teasing and ultrasonography to evaluate follicular activity is needed. In both dairy cattle and women, a change in body temperature has been shown to occur immediately prior to ovulation. Research on horses has been limited, although one study reported no useable relationship between body temperature and ovulation in mares (Ammons, 1989). The current study utilized thirty-eight mature cycling American Quarter Horse mares, and was conducted from March-August 2004. Each mare was implanted in the nuchal ligament with a microchip that can be used for identification purposes, but is also capable of reporting body temperature. Once an ovulatory follicle (>35mm) was detected using ultrasonography and the mare was exhibiting signs of estrus, the mare's follicle size and temperature were recorded approximately every six hours until ovulation. Not only was the temperature collected using the microchips, but the corresponding rectal temperature was also recorded using a digital thermometer. A significant effect (p<0.05) on body temperature was noted in relation to the presence or absence of an ovulatory follicle (>35mm) under different circumstances. When evaluating the rectal temperatures, no significant difference was found in temperature in relation to the presence or absence of a follicle. However, in the temperatures obtained using the microchip, temperature was higher (p<0.05) with the presence of a follicle of greater than 35mm. This may be due to the extreme sensitivity of the microchip implant and its ability to more closely reflect minute changes in body temperature.