The synthetic met-enkephalin syndyphalin-33 (SD-33) increases feed intak in sheep and recently-weaned pigs. An experiment focused on changes in hypothalamic levels of mRNA transcripts from the following genes: μ-opioid receptor (MOR), neuropeptide Y (NPY), orexin (hypocretin; HCRT), melanocortin 4 receptor (MC4R), and agouti-related protein (AGRP). There was no effect of treatment on BW or FI at any point in the study. There is a strong positive correlation (p <0.001) between MOR and MC4 that remains regardless of treatment or time. Weaning resulted in a numerical increase in hypothalamic MOR mRNA expression. There was a treatment effect of MOR expression levels 4 days postweaning. Hypothalamic NPY expression was unchanged through time or treatment. In VEH pigs, weaning resulted in increased hypothalamic expression of the HCRT gene at d 1 and d 7 postweaning (P(time) < 0.01). In SD pigs, an increase in HCRTexpression (relative to d 0) was observed at d 4 postweaning. Expression of HCRT did not significantly differ between treatment groups at d 1 and d 4, but HCRT expression was greater in VEH pigs than in SD pigs at d 7 (P(time x treatment) < 0.05). Expression of hypothalamic MC4R did not change through time, but a trend (P(treatment) = 0.07) was observed such that expression was less in SD pigs than in VEH pigs on d 1 and d 4 postweaning, possibly due to a numerical increase in expression in VEH pigs on d 1 relative to d 0. Expression of AGRP was decreased 1 d postweaning in VEH pigs but not in SD pigs,. On d 4, levels of AGRP expression were lower in SD pigs than in VEH pigs, and lower than d 0 levels as well. On d7, AGRP expression was less in VEH pigs than in SD pigs (P(time x treatment) < 0.01). Syndyphalin-33 has the potential to alleviate the negative effects of stress during weaning, and has the potential to increase feed intake through the melanocortinergic pathway. Further investigation is needed to more fully elucidate the complex mechanisms by which syndyphalin-33 may act to abrogate the post-weaning growth lag in pigs.

Anecdotal observations have suggested that muskrat (Ondatra zibethicus) populations were dramatically reduced in streams where the North American river otters (Lontra canadensis) were reintroduced. Muskrats predate upon freshwater mussels and it was speculated that river otter reintroduction could result in increased mussel numbers. My objectives were to evaluate the ecological relationship between otter, muskrat, and mussels on the Green and Nolin rivers in Mammoth Cave National Park (MCNP). Seventeen river otters were captured in or relocated to MCNP from January to May 2007. The augmentation was only marginally successful with 3 male river otters establishing home ranges within the park; of the remaining 13 animals, 10 individuals dispersed >35 km outside of the study area and 3 died shortly after release. Despite the relatively low success of the augmentation, scent-station surveys, trap-site visitation, and scat collection indicated that otter numbers had significantly increased on the Green River since Asmus‟ (2004) study, probably as a result of natural immigration and range expansion. Although spotlight surveys indicated that there was a concomitant decline in the muskrat population along the Green River from 2002 to 2008 (F1, 73 = 36.56, P < 0.0001), muskrat hair was only found in 1 of 48 (2%) river otter scats examined. That evidence, coupled with a relatively high number of both otters and muskrats on the Nolin River, did not indicate that the relationship between muskrats and otters in MCNP was causal. On a more extensive scale, I collected data on muskrat and otter presence at 95 randomly selected bridge crossings across Kentucky but centered on MCNP. I used a 2-species co-occurrence model in Program PRESENCE to determine if the presence of river otters was related to the presence of muskrats. This occupancy model indicated that muskrats occurred independently of river otters (φ = 1.02). Observer, water level, and substrate were important determinants of otter detection, whereas straight-line distance from original river otter release sites was an important occupancy covariate for river otters. Therefore, both my intensive and extensive data analyses do not support the notion of a negative interaction occurs between river otters and muskrats.

This thesis discusses the background information regarding the physiological effects the pig encounters during weaning as well as a potential factor that can be used to assist the pig during this time. Specifically, the research focus is to assess the ability of the tri-peptide opioid agonist, Syndyphalin-33 (SD-33), to increase feed intake and body weight and modulate immune responses during the post-weaning period. The results of this research have demonstrated that SD-33 increases feed intake, transiently increases growth hormone and cortisol levels, and increases total white blood cell counts while selectively increasing monocyte numbers in healthy weaned pigs. This research also demonstrates that, although co-treatment with SD-33 during an immune challenge of Salmonella enterica did not result in increased feed intake, SD-33 exerted effects relating to increasing the circulating populations of immune cells at 48 h postinjections, selectively increasing monocyte numbers. Based on these results, SD-33 may have the potential to be used as an agent to decrease the negative effects of stress during weaning in pigs. However, further investigation is needed to better understand the timing of effect, and to rule out any immunosuppressive effects, which would be detrimental to the animal’s well-being.

Specific objectives of this study were to examine growth response of the dominant follicle (DF) after administration of Folltropin-V (FSH and LH) at onset of luteolysis and investigate use of human chorionic gonadotropin (hCG) for decreasing ovulation time in lactating Holstein cows. On day 8 or 9 of a synchronized cycle, cows (n = 35) received an EAZI-BREED CIDR plus 100 μg of GnRH. CIDRs were removed 7 days later and cows were administered 500 μg cloprostenol. Concurrently, cows were randomly allocated to receive either 80 mg Folltropin-V (FSH, n = 19) or 4 mL of sterile saline (SAL, n = 16). Forty-nine hours later, cows that had received Folltropin-V or Saline were randomly subdivided to receive either 100 μg dose of GnRH or 3000 IU of hCG. Ultrasonography was performed to assess growth of the ovulatory follicle and confirm ovulation. Data were analyzed using the MIXED procedure of SAS. Size of the ovulatory follicle at time of GnRH/hCG administration was not different between Folltropin-V or Saline groups (17.1 ± 0.7 vs. 17.7 ± 0.6 mm, respectively; P = 0.521). Total growth of the ovulatory follicle from CIDR removal to GnRH/hCG administration did not differ between FSH (3.2 ± 0.6 mm) and Saline-treated cows (3.3 ± 0.4 mm; P = 0.891). When assessed from time of CIDR removal, ovulation occurred at a similar time for Folltropin-V (76.9 ± 0.7 h) and Saline-treated cows (78.0 ± 0.5 h; P = 0.196). When calculated from time of LH or hCG peak to ovulation, FSH-hCG cows presented the shortest time to ovulation (19.9 ± 0.4 h; P = 0.066). Whereas, from GnRH/hCG administration to ovulation, FSH-GnRH presented the earliest ovulation (25.0 ± 1.2 h; P = 0.013). In conclusion, Folltropin-V did not increase size of the ovulatory follicle at the time of GnRH/hCG administration. However, earlier ovulation occurred when combined with hCG as measured from time of gonadotropin peak. Conversely, when ovulation time is calculated from GnRH/hCG administration, FSH-GnRH produced the earliest ovulation.

There is considerable evidence that amphibians are declining globally due to various anthropogenic stressors. Cattle grazing in wetlands is a stressor that may have negative impacts on amphibians and has not been investigated intensively. Cattle could have a negative effect on larval amphibians by decreasing water quality through deposition of nitrogenous waste. Reduction in water quality also may compromise immune function by inducing stress thus making larvae more susceptible to pathogens. My objective was to quantify differences in amphibian larvae community metrics, water quality, and pathogen prevalence between cattle-access and non-access wetlands. I also measured fish abundance and biomass of filamentous algae and detritus, because these variables are known to influence larval amphibian populations, and may be affected by cattle. My study was conducted at the University of Tennessee Plateau Research and Education Center on the Cumberland Plateau, Tennessee. I sampled amphibian larvae and fish 2X per week, water quality 2X per month, and algal and detrital biomass 1X per month at each wetland from March – August 2005 and 2006. I also opportunistically collected American bullfrog (Rana catesbeiana) and green frog (R. clamitans) tadpoles from cattle-access and non-access wetlands during three seasons (winter, summer, and autumn), tested them for pathogens, and noted histopathological changes. In general, relative abundance, species richness, and species diversity of amphibian larvae were greater in non-access wetlands. Mean relative abundance of green frog and American bullfrog (and all other ranid tadpoles) was greater in non-access wetlands. Dissolved oxygen was lower, while specific conductivity and turbidity were higher in cattle-access wetlands. Detrital and algal biomass was lower and greater in cattle-access wetlands in compared to non-access wetlands, respectively. Some changes were noted in aquatic invertebrate and fish abundance between land uses. Tadpoles also were infected by a variety of known amphibian pathogens (e.g., Frog virus 3, Aeromonas hydrophila), but land-use trends often were dependent on species and season. My results suggest cattle negatively impact water quality, detritus, and relative abundance of some larval amphibian species. Fencing cattle from wetlands may be a prudent amphibian conservation strategy.

Objectives were to 1) examine effects of heat stress on maturing oocytes to alter the ability of resulting embryos to develop after fertilization, 2) evaluate blastocyst development of compact morulae derived from control or heatstressed oocytes after culture at 38.5°C or 41.0°C, and 3) evaluate effects of heat stress on compact morulae to alter sex ratio. Culture of cumulus oocytes at 41.0°C did not alter ability of presumptive zygotes (PZ) to cleave; however, the proportion of embryos that cleaved to the 8- to 16-cell stage was lower (P = 0.01). Also, the proportion of 8- to 16-cell embryos derived from heat-stressed oocytes undergoing compaction was lower (P = 0.01). Effects of heat stress to reduce compaction was without consequence on morphology, as quality scores of embryos derived from heat-stressed oocytes were similar to those derived from nonheat-stressed oocytes. Application of heat stress to compact morulae derived from nonheat-stressed oocytes did not affect blastocyst development. Also, blastocyst development of compact morulae derived from heat-stressed oocytes was similar to those derived from nonheat-stressed controls. However, if compact morulae derived from heat-stressed oocytes were exposed to 41.0°C, blastocyst development was reduced (P = 0.007). This effect was coincident with an increase in the proportion of degenerate embryos (P = 0.02). Temperature at which oocytes were matured did not alter sex ratio of resulting blastocysts. Rather, there was a tendency for embryo temperature to increase the proportion of male embryos that survived (P < 0.06). Results described herein are significant as they not only clarify the extent to which heat stress during maturation reduces embryonic development after fertilization but are also informative of heat-induced perturbations that carry over to increase the susceptibility of resulting embryos to heat stress. With this in mind, results raise possible concerns about current practices of utilizing MOET in heat-stressed cattle with the intent of obtaining “developmentally-competent” embryos. Additionally, since it was also demonstrated that developmental competence of oocytes has an impact on the responsiveness of resulting embryos to heat stress, effort to clarify developmental competence of oocytes before utilizing in vitro derived embryos to improve fertility of heat-stressed dairy cows is needed.

Validation of a Three Dimensional Motion Capture System for Use in Identifying Characteristics of the Running Walk A three-dimensional (3-D) motion capture system was adapted for use in characterizing the biomechanics of the Running Walk, a stepping gait of the Tennessee Walking Horse (TWH) breed. Registered TWH (n = 4) were ridden through an arrangement of high-speed digital cameras at the walk (W) and running walk (RW). Infrared reflective markers (65 per horse) were used to track body segments and joint centers. Five trials per gait per horse were recorded. A dynamic 3-D model was created and used to label and track body segments. Temporal stride characteristics and joint angle values were extracted by a custom script file and gait formulas were calculated for each gait per horse. Temporal stride characteristics and gait formulas of both W and RW were found to be similar to those previously reported. Overstride (OS), which has not previously been described, increased from W to RW (P < 0.0001). The increase in OS accounted for 96% of the increase in stride length; only 4% of the increase in stride length is due to an increase in step length. OS was positively correlated to velocity and stride length (P < 0.0001), and negatively correlated to front stance duration, hind stance duration and total stance duration (P < 0.0001). A long OS would appear to be related to the flexibility of the proximal hind limb, the pelvis and possibly the lumbar spine. Hind stance duration as a percent of total stride time, advance placement as a percent of total stride time, and advance liftoff as a percent of total stride time did not differ between W and RW (P > 0.05), suggesting that the RW is not simply a faster version of W. 3-D analysis allowed for thorough analysis of joint angles. The joint angles of the carpus were highly correlated to stride length, OS, and advance placement (P < 0.0001), but were not correlated to velocity (P > 0.05). These joint angles and gait events can be viewed as velocity-independent stride characteristics and may be suitable for making comparisons between horses traveling at different velocities. Identification of joint-specific velocity-independent stride characteristics may enhance our ability to associate lameness with an individual joint. KEYWORDS horse gait biomechanics

Conversion of tall fescue (Festuca arundinacea) to managed native warm-season grasses (nwsg) and associated forbs benefits many wildlife species that depend on early successional habitat. Planting nwsg, however, may not be necessary depending on the composition of the seedbank. Treatments were implemented in a randomized complete block design with replication during 2003 and 2004 at three study sites across Tennessee to determine the effects of seasonal herbicide applications and disking on tall fescue eradication and resulting vegetation composition and structure. Treatments included: fall glyphosate (2.2 kg ai/ha; Gly-4 2qt/ac); fall glyphosate followed by winter disking; fall imazapic (0.2 kg ai/ha; Plateau 12 oz/ac); fall imazapic followed by winter disking; spring glyphosate; spring glyphosate followed by fall disking; spring imazapic; and spring imazapic followed by fall disking. Vegetation composition and structure were measured June – September, and November 2004 and February, April, and June – September 2005. All treatments reduced tall fescue cover compared to control one growing season after treatment. Fall herbicide applications with and without disking decreased tall fescue cover more than spring treatments when measured two growing seasons after treatment. Reduction in tall fescue improved openness at ground level during the brooding season and angle of obstruction during the wintering period for bobwhites. Disking following herbicide application increased cover of bobwhite food plants, including common ragweed (Ambrosia artemisifolia), beggar’s-lice (Desmodium spp.), and beggar-ticks (Bidens spp.). Imazapic increased cover of desirable nwsg, such as broomsedge bluestem (Andropogon virginicus); however on 2 sites, imazapic applications resulted in increased cover of orchardgrass (Dactylis glomerata), which was structurally identical to tall fescue. Fall glyphosate applications are recommended to eradicate tall fescue. If certain undesirable plants are suspected to germinate from the seedbank after tall fescue is removed, an imazapic application may be necessary in April or May to control species such as johnsongrass (Sorghum halapense), crabgrass (Digitaria sanguinalis), and yellow nutsedge (Cyperus esculentus).

Prior research in our lab has demonstrated a significant association between the incidence of subclinical mastitis and neutrophil functions with polymorphisms of the CXCR1 gene in Holstein dairy cattle. The objective of this study was to evaluate the specificity of the response relative to CXCR1 and potential involvement of intracellular signaling pathways. Migration was evaluated in cows of both homozygous genotypes (n=7 each) in response to high and low doses of interleukin-8 (IL -8; specific for CXCR1 and CXCR2), epithelial neutrophil activating peptide (ENA-78; specific for CXCR2) or zymosan activated sera (ZAS; complement receptors). Cows with a GG genotype had significantly more migration in response to both 12.5 and 50 nM doses of IL -8 (p<0.05) compared to cows with a CC genotype. Although a similar trend was observed for 50 nMENA-78 (p<0.07), this was not evident with the 12.5 nM dose. This result was comparable to ZAS, where the 5%dose caused significantly more neutrophil migration in cows with a GG genotype than those with a CC genotype (p<0.03), while the response to the 1% dose of ZAS was similar between genotypes. p38 MAPK and PKB phosphorylation were evaluated prior to and following stimulation with the high doses of each ligand. Relative increases in p38 MAPK phosphorylation were greater in neutrophils from cows with a GG genotype when compared to those with a CC genotype regardless of treatment with rhu-IL-8, rhu-ENA-78, and ZAS or not (p<0.001), But CC cows had higher baseline levels of p38-MAPK phosphorylation than GG cows. Therefore, the lower increase in phosphorylation in neutrophils from CC cows may have been due to higher starting levels. Increases in PKB phosphorylation also were greater in neutrophils from cows with a GG genotype when compared to a CC genotype when treated with ZAS, but not other ligands. Because no differences between genotypes were observed at time zero this may be tied to the altered p38 MAPK pathway. Future research will be aimed at further elucidating the signaling pathways causing functional differences in neutrophils from cows with different CXCR1 genotypes.

Thesis (Ph. D.)--Oregon State University, 1975. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.