No description available.

1. The research which is reported here was concerned primarily with factors affecting the stillbirth rate, attempts to reduce the incidence of intrapartum stillbirths and the examination of factors which influence piglet lying behaviour in early postnatal life with a view to recommending a more suitable creep heating arrangement than those that are currently in use. 2. Past work concerning factors during pregnancy, parturition and in the post-partum period which may influence the intrapartum stillbirth rate and the viability of liveborn piglets in the first few days after birth have been reviewed. 3. The first two investigations were undertaken to determine the relationship of sow parity, body condition at the end of gestation and gestation length to litter size and stillbirth rate in the pig. While in the first study, the incidence of stillbirths tended to increase with advancing parity of the sow, in the second study no significant relationship was found between parity and stillbirth rate. 4. The next experiment involved the evaluation of additional vitamin C in the diet of sows for the last 1 to 3 weeks of gestation. 5. In an attempt to improve the efficiency of parturition and reduce the incidence of intrapartum stillbirths, an injection of 5 mg Prostigmin was compared with a control treatment, involving an injection of 2 ml sterile water, injections in both cases being given following the birth of the fourth or fifth piglet. 6. The next experiment was designed to examine piglet lying behaviour in two contrasting farrowing facilities during the first 4-8 hours post partum. Piglets on the unit with front creeps, underfloor heating and sawdust as bedding in the creep spent significantly more of their resting time lying within the confines of the farrowing crate, usually against the udder of the sow, where they were in danger of being overlain, compared with piglets in pens with a side creep, heated by an infra-red lamp and with wood shavings as bedding. Piglets in both situations exhibited a strong natural desire to lie close to the udder of the sow during the first 12 hours after birth, this tendency declining with age. 7. The observations made in the previous study prompted the undertaking of a more detailed investigation to examine the effects of alternative creep heating arrangements at two house temperatures (means of 20.5&deg;C and 13.6&deg;C) on piglet lying behaviour, mortality and growth rate in the neonatal period. The basic creep heating arrangement consisted of a kennel at the front of the pen heated by an infra-red lamp. The intermediate treatment incorporated an infra-red lamp adjacent to the place of birth during parturition, in addition to the basic heated kennel, while the luxury creep heating arrangement was a further extension of the intermediate treatment incorporating an infra-red lamp in each side creep for the first 48 hours after birth. In the first 3 days, piglets used the kennel area for resting more in the cool house than in the warm house (P < 0.001). In the first day of life, the provision of a lamp in each side creep was effective in reducing by half the proportion of time piglets spent lying in the danger area within the confines of the farrowing crate and this was reflected in lower losses from overlying. Piglet mortality to 7 days of age on the three treatments was 20.03, 11.61 and 6.53 per cent in the basic, intermediate and luxury creep heating arrangements, respectively, thus justifying the use of heat lamps adjacent to the place of birth and in the side creeps. Piglet liveweight gains during the first week of life were greater (P < 0.001) in the warm than in the cool house. 8. In the general discussion at the end of the thesis, the research findings reported have been used to provide a sounder basis to recommendations for reducing piglet mortality and improving viability at birth in the commercial situation. In addition, suggestions for future research in this area have been discussed.

No description available.

Regulation of intracellular pH (pH_i) was studied in ciliated epithelial cells isolated from sheep tracheae. Microspectrofluorimetry of the pH -sensitive dye 2'; 7' - biscarboxyethyl -5(6) -carboxyfluorescein (BCECF) was used to measure pH_i in single cells plated on coverslips and mounted in a temperature regulated superfusion chamber on a microscope stage. In both HCO₃^-containing and HCO₃^- -free conditions, pH_i was ~ 7.20 and buffering capacity was found to be inversely related to pH_i. Recovery from an acid load (induced by NH₄Cl prepulse) was Na⁺-dependent. In HCO₃^- -free conditions, inhibition of pH_i recovery by hexamethylene amiloride (HMA) identified Na⁺/H⁺ exchange as the principal mechanism of acid extrusion. In contrast, in HCO₃^-- role of Na⁺/H⁺ exchange in pH_i regulation under more physiological conditions. However, dihydro- 4,4'-diisothiocyanostilbene-2, 2'-disulphonic acid (H₂DIDS) affected this Na⁺ and HCO₃^- -dependent pH_i recovery and suggested that Na⁺-dependent recovery from intracellular acidification in HCO₃^-- containing conditions was mediated primarily by an H₂DIDS-sensitive component. Inhibition of pH_i recovery by bafilomycin A₁ in HCO₃^- -containing conditions also suggested that a proton pump was present in these cells. The failure of inwardly and outwardly - directed Cl^- gradients to affect pH_i recovery suggested that Cl^- -dependent mechanisms were not present. The effects of HMA and H₂DIDS on Na²⁺ -dependent alkalinisation in cells preincubated in Na⁺-free media were also investigated. Surprisingly, only HMA affected the rate of Na⁺ -dependent alkalinisation. This directly contradicted the data reported above and implied that Na⁺/H⁺ exchange was the primary pH_i regulatory mechanism in HCO₃^- - containing conditions in these cells. In conclusion, pH_iin isolated sheep ciliated tracheal cells appears to be regulated by three acid-extruding mechanisms.

Nutrition and suckling are known to be the most important factors affecting the length of the anovulatory post-partum period in beef cows. In sheep, nutrition and suckling are also important factors when ewes lamb during the season breeding, in more intensive production systems. A number of neurotransmitters have been proposed to be implicated in the activation of the GnRH pulse generator, which controls LH release. The aim of the present study was to investigate the role of the opioid peptides in the mediation of the effects of nutrition and suckling in both cows and ewes, during the post-partum period. Experiment 1 was designed to quantify the effects of post-partum energy intake on post-partum cows. Sixteen Aberdeen Angus and Simmental cows were arranged in a 2x2 factorial, with breed and energy intake as main factors. An opioid peptide antagonist receptor (naloxone) was administered in all cows in two periods of the post-partum (week 4 and 7) and in two consecutive days, in a high (0.8 mg/kg) or a low (0.4 mg/kg) dose. The overall response in LH to naloxone was low, and there was no significant treatment effects. However, a higher opiodergic tone at early, compared with at late, post-partum period was observed. Naloxone failed to evoke any prolactin response. Experiment 2 was designed to investigate the effects of nutrition and suckling intensity on the post-partum of ewes lambing during their breeding season, and to quantify these effects on the opioidergic tone. The experiment involved 40 ewes, in which 32 were assigned to two different diets and all of them suckled, and 80 ewes were assigned to one of these two diets and were weaned. All ewes were challenged with naloxone at day 12 post-lambing, with either a low (0.7 mg/kg) or a high (1.4 mg/kg) dose. Naloxone evoke an LH response in most of the animals, irrespective of the diet in which they were assigned. Naloxone also evoked an LH response in either suckled or weaned ewes. In the experiment 3, the interactive effect of nutrition and suckling on the post-partum interval and opioidergic tone was investigated. Sixteen Simmental cows were involved in a 2x2x2 factorial, with body condition at calving, post-partum energy intake and suckling intensity as main factors. At week 4, naloxone was administered (0.8 mg/kg) when a new follicular wave was detected and the follicle was in a growing stage, and it was also administered using the same dose, when that follicle achieved the dominant phase.

Experiments were designed to determine: a) The effect of undernutrition in utero and in early post-natal life on subsequent activity of the hypothalamic-pituitary-ovarian axis in prepubertal and peripubertal female sheep; b) The effect of undernutrition in utero from the time of mating on development of the ovaries of foetal female sheep at days 47 and 62 of gestation. It is concluded that undernutrition in early life significantly retards pituitary development as demonstrated by the selective hypersensitivity of prepubertal L group pituitary glands but that this is compensated for around 18 months of age, by which time peripubertal L group pituitary glands are hyposensitive to positive GnRH stimulation. As there were no effects of treatment on metabolic hormone profiles or glucose clearance rate, it can be concluded that undernutrition acts directly at the pituitary level and not through differences in L group metabolism. In experiment 2, ewes were fed 150% (High; H) or 50% (Low; L) of maintenance energy requirements from mating until 47 or 62d of gestation in separate studies. At 47d, L lambs exhibited normal foetal weight, foetal ovarian weight and foetal ovary steroidogenic capacity but had significantly retarded germ cell degeneration as indicated by higher concentrations of oogonia in L group foetal ovaries (p<0.001). At 62d, L lambs exhibited significantly retarded germ cell degeneration, as indicated by higher oocyte concentrations (p<0.01), and delayed arrest of meiosis, as indicated by higher meiotic activity (p<0.001). It is concluded that undernutrition of the ewe from the time of mating significantly retards ovarian development in foetal ovaries. This retardation may be responsible for the known reduction in lifetime reproductive performance of ewes undernourished in early life.

Master of Science / Department of Clinical Sciences / Amy Rankin / Objective- The purpose was to compare the efficacy and duration of 0.5% proparacaine, 0.5% bupivacaine, 2% lidocaine, and 2% mepivacaine on corneal sensitivity in clinically normal horses. Animals- 68 clinically normal horses Procedures- In group 1, 60 horses from the Kansas State University horse unit were assigned to receive one topical anesthetic in a completely randomized design. In group 2, 8 privately owned horses were sequentially treated with each of the topical anesthetics in random order with a one week washout period between drugs. Corneal sensitivity was assessed by corneal touch threshold (CTT) measurements which were taken with a Cochet-Bonnet aesthesiometer before anesthetic application (T0), 1 minute after (T1), every 5 minutes until 60 minutes (T5-T60), and then every 10 minutes until 90 minutes (T70-T90) after application. General linear mixed models were fitted to CTT in each design in order to assess the effects of topical anesthetics over time, accounting for repeated observations within individual horses. Results- Corneal sensitivity, as determined by CTT measurements, decreased immediately following application of the topical anesthetic, with persisting effects until T35 for proparacaine and mepivacaine, T45 for lidocaine, and T60 for bupivacaine. Maximal CTT reduction was achieved following application of bupivacaine or proparacaine, while mepivacaine was least effective. Conclusions and Clinical Relevance- All topical anesthetics reduced corneal sensitivity, though maximal anesthesia and effect of duration differed between drugs. For brief corneal anesthesia, 0.5% proparacaine or 2% lidocaine appeared adequate, while 0.5% bupivacaine may be most appropriate for procedures requiring longer periods of corneal anesthesia.

Master of Science / Department of Anatomy and Physiology / Mark Weiss / Artificial insemination and cryopreservation of sperm are important components of any transgenic animal facility because they allow for the reduction in animal colony size and the safe storage of germplasm from valuable strains. In addition, they allow long-term storage of these strains and easy transportation of the genetic material to other research facilities internationally. Thus far, only one laboratory has created live rat pups after sperm cryopreservation and intrauterine insemination. Another laboratory made advances in cryopreservation media that improved sperm motility post-thawing, but no pups resulted from this work. In my study, these two cryopreservation media were utilized to perform intrauterine inseminations with both fresh samples of rat sperm as well as samples that were cryopreserved in liquid nitrogen to replicate and extend these studies. Pharmacoejaculation was tested as a means to obtain spermatozoa without euthanizing the male to collect the epididymis, but results were inconsistent and the samples were not useful for intrauterine inseminations or cryopreservation. Epidiymal sperm was then collected into the various media and frozen in liquid nitrogen. In my hands, the frozen/thawed rat sperm achieved motility of less than 1%. Next, the impact of altering the freezing rate on sperm motility was evaluated. Epididymal sperm was collected and processed using a modified protocol and were then frozen at 2, 4 or 6 cm above the level of liquid nitrogen. Four to six days after freezing, samples were thawed and post-thaw sperm motility was evaluated. Sperm motility was measured prior to freezing as well as after-thawing. The sperm motility was correlated with LIVE/DEAD® staining. Sperm motility did not differ between the groups as a result of the freezing rate (Friedman test p=0.23). The published techniques are not robust and require further development to improve the motility of rat sperm after cryopreservation and achieve pregnancy via intrauterine insemination.

Master of Science / Department of Diagnostic Medicine and Pathobiology / Raymond R. R. Rowland / Three economically important swine diseases: Porcine Reproductive and Respiratory Syndrome (PRRS), Porcine Circovirus Associated Disease (PCVAD) and Swine influenza cost the US swine industry more than a billion dollars each year. This study developed a fluorescent microsphere immunoassay (FMIA) to simultaneously detect antibodies to the causative pathogens: PRRSV, porcine circovirus (PCV2) and swine influenza virus (SIV). The results showed that the multiplex assay possessed the predicted specificities. In the case of PRRSV NA, the assay displayed higher sensitivity when compared to a commercially available ELISA. The assay was employed to measure both IgG and IgM responses. The FMIA was found to possess several advantages over standard ELISA which include reduced sample volume, time and cost and provides a new tool for veterinary diagnostics. The FMIA was applied for swine disease surveillance in Hawaiian and Texan feral swine populations. The antibodies against PCV2 showed the highest prevalence among these three pathogens in both Hawaii and Texas. Hence we consider PCV2 as the most prevalent pathogen in Hawaiian and Texan feral pigs and this pathogen poses the greatest threat to commercial pigs. SIV seroprevelance increased from 2007 to 2010 in Hawaii State, suggesting an increasing risk for commercial pigs. Moreover, yearly surveillance in Texas State shows growth in seropositive response to all pathogens, particularly PCV2. The development of FMIA for detection of antibodies to multiple swine pathogens in serum samples offers an important alternative for swine disease surveillance in commercial and feral herds.

Doctor of Philosophy / Department of Diagnostic Medicine and Pathobiology / Brad J. White and Robert L. Larson / Bovine respiratory disease (BRD) is the most costly disease of cattle in US feedyards and diagnosis based on clinical signs of illness is challenging. Over the course of five independent studies we evaluated the precision of multiple observers assigning clinical illness scores (CIS) to calves with induced Mycoplasma bovis pneumonia. We also evaluated the accuracy of CIS in relation to lung lesions at necropsy. Agreement among observers over all five studies was slight ({kappa]= 0.16; 95% confidence interval, 0.10 to 0.24) and ranged from 0.10 to 0.21 for individual trials. The accuracy of CIS varied based on the pulmonary consolidation score chosen to represent a truly ill animal. Inflammation associated with BRD can lead to significant pulmonary damage and reduced lung function. Treatment for BRD frequently involves antimicrobial administration and occasionally non-steroidal anti-inflammatory drugs. We evaluated how calves experimentally challenged with Mannheimia haemolytica respond to treatment with flunixin meglumine, alone or in combination with the antimicrobial florfenicol. Individual calf response to bacterial pneumonia was highly variable in this study. None of the changes in serum biomarkers, CBC or chemistry parameters provided reliable indicators of the pulmonary inflammation associated with the mild severity of bronchopneumonia in our study. Metaphylaxis is frequently administered to manage the risk of BRD within cohorts of cattle. We evaluated the impact of metaphylactic antimicrobial administration 10 days prior to experimental Mannheimia haemolytica inoculation to mitigate pulmonary lesions. We found that calves receiving tildipirosin had less lung damage and fewer clinical signs of illness compared to calves treated with tulathromycin or saline. Finally, the ability to predict those animals that would not finish the production cycle normally would provide benefits in effectively managing cattle. We evaluated the ability of classification algorithms to accurately predict an individual calf’s outcome based on data available at first identification of and treatment for BRD. We found accuracy of classifiers was dependent on the data recorded by the feedyard and there are sub-groups of calves within feedyard populations where classifiers were highly accurate. These data suggest the importance of pairing the proper classifier with the data available.