Call number: LD2668 .T4 1986 J674 / Master of Science / Animal Sciences and Industry

Call number: LD2668 .T4 1986 P44 / Master of Science / Animal Science and Industry

Call number: LD2668 .T4 1986 R63 / Master of Science / Diagnostic Medicine/Pathobiology

Com o objetivo de validar um protocolo de indução de diarréia osmótica e avaliar comparativamente a eficácia de três diferentes tratamentos, foram utilizados 18 bezerros holandeses hígidos, com idade entre oito e 30 dias, e peso variando entre 37 e 50 Kg. A diarréia e a desidratação foram induzidas por via oral, através da administração de leite integral (16,5 ml/Kg), de quatro gramas de sacarose por quilo e de dois tipos de diuréticos (espirolactona e hidroclorotiazida, em dose de 2mg/Kg), a cada oito horas, por um período de 48 horas. Os bezerros foram distribuídos aleatoriamente por três grupos experimentais, cada um com seis animais, que receberam as seguintes soluções: solução salina hipertônica à 7,5% (SSH-4ml/kg IV), solução eletrolítica oral (SEI-60ml/kg) e a associação dessas duas soluções (SSH+SEI), sendo a SEI administrada por mais duas vezes com um intervalo de oito horas. O exame físico e as colheitas de sangue para determinações do hemograma, de dosagens hemogasométricas e de componentes bioquímicos séricos e plasmáticos foram realizadas nos seguintes momentos: 0h (antes da indução), 24 e 48 horas pós-indução(PI) de diarréia, e com 1, 3, 6, 12, 24, 48 e 72 horas pós-tratamento (PT).As amostras de fezes e urina foram colhidas às 0h, 24 e 48 horas PI, e 24, 48 e 72 horas PT. O protocolo de indução da diarréia obteve 100% de resposta produzindo diarréia aquosa e desidratação severa (equivalente a 13% do peso corpóreo) acompanhada de azotemia pré-renal, aumentos no volume globular, no teor de hemoglobina e na proteína total; hipercalemia; hiperlactemia; hiperfosfatemia; acidose metabólica; elevado déficit de volume plasmático; aumentos da densidade urinária, da concentração de uréia e creatinina urinárias e do lactato urinário e fecal; diminuições da pressão venosa central, do pH urinário e fecal. Os animais tratados com SSH+SEI diminuíram de forma rápida e substancial os valores do volume globular e do déficit de volume plasmático; aumentaram o pH sangüíneo e a pressão venosa central entre 1hPT e 3hPT, além de manterem as concentrações de glicose próximas aos valores basais durante todo o período de tratamento. A SEI também promoveu o restabelecimento das variáveis anteriormente citadas, porém de forma mais lenta quando comparada com o uso da SSH+SEI. Os animais tratados apenas com SSH exibiram, no monitoramento através de exames físico e laboratoriais, sinais de desidratação, de depressão clínica e de acidose metabólica ainda às 24hPT, indicando que o uso isolado dessa solução não é eficaz no tratamento da diarréia em bezerros neonatos. / With the purpose of validating a protocol for osmotic diarrhea induction and to comparatively evaluate the efficacy of three different treatments, 18 healthy Holstein calves, with eight to 30 days old, and 37 to 50 Kg of body weight were used. The diarrhea and dehydration were orally induced, through the administration of whole milk (16.5 ml/Kg bwt), sucrose 4g/Kg bwt and two types of diuretics (spironolactone and hydrochlorothiazide, in a dosage of 2mg/Kg bwt), every eight hours, for a total period of 48 hours. The calves were randomly distributed into three experimental groups, each one with six animals, which received the following solutions: 7.5% hypertonic saline solution (HSS - 4ml/Kg bwt, IV), oral electrolytic solution (OES - 60ml/Kg bwt) and the association of both solutions (HSS+OES), being the OES administered two more times with an interval of eight hours. The physical examination and blood sampling for hemogram determinations, hemogasometric dosages and serum and plasmatic biochemical components were done in the following moments: 0h (before the induction), 24 and 48h post-induction (PI) of diarrhea, and within 1, 3, 6, 12, 24, 48 and 72 hours post-treatment (PT). The protocol for osmotic diarrhea induction had a 100% response with aqueous diarrhea and severe dehydration (corresponding to 13% of body weight), followed by pre-renal azotemia, increases in the globular volume, and hemoglobin and total protein levels; hyperkalemia; hyperlactemia; hyperphosphatemia; metabolic acidosis; high plasmatic volume deficit; increases of urinary density, urinary urea and creatinine concentrations and urinary and fecal lactate; diminished central venous pressure and urinary and fecal pH. The animals treated with HSS+OES rapidly and substantially diminished the values of globular volume and plasmatic volume deficit; had the blood pH and central venous pressure increased between 1hPT and 3hPT, besides they maintained glucose concentrations near basal values along the period of treatment. The OES also promoted the reestablishment of the cited variables, although in a slower manner when compared with the use of HSS+OES. The animals treated only with HSS showed, through the physical and laboratory exams, signs of dehydration, clinical depression and metabolic acidosis still at 24hPT, indicating that the isolated use of this solution is not efficient in the treatment of neonatal diarrhea in calves.

There has been little research conducted on the physiological response of calves to temperatures outside thermal neutrality and its effects on intake and weight gain. The effects of ambient temperature on Holstein dairy calves intakes and weight gain were evaluated over a 12-month period. Ambient temperature was monitored using a weather station located 1.3 kilometers from the Utah State University Caine Dairy. Calf health was monitored daily using the University of Wisconsin-Madison School of Veterinary Medicine scoring criteria. Calves were fed whole milk and free choice calf starter. Weight gain, hip height, starter intake, and weather data (temperature, wind speed, relative humidity, precipitation, and barometric pressure) were averaged for 7-day intervals beginning at birth through 13 weeks of age. A regression model was developed including starter intake, milk intake, hip and wither height, calf heath scores, and weather data with weight gain as the dependent variable for each of the 4 seasons of the year. The fall season (September, October, and November) had a negative impact on calf intake and weight gain (averaging 20 pounds (9.1 kilograms) less at 2 months) than other seasons. Calves raised in the winter months also ate significantly more starter, but had the same weight gain as other seasons. Environmental stress factors impact animal welfare and animal productivity, which in turn impacts the economics of the dairy operation and should also be used in determining husbandry practices.

Inotropic support for the failing myocardium as the therapy for xi congestive heart failure (CHF) is intended to achieve an increase in cardiac output via positive responses in myocardial contractility and vasodilation. A novel approach to differentiate these two responses is the use of an animal with an implanted total artificial heart (TAH). Three inotropic drugs, dobutamine, enoximone, and pimobendan, were tested in eight animals with their natural heart intact and five animals implanted with a TAH. Baseline values of the TAH and natural heart (NH) were compared to determine their hemodynamic similarities. Each of the three drugs was given randomly to the animals in dosages similar to human clinical doses. Peak responses were recorded and analyzed. All three drugs caused an increase in contractility and cardiac output in the NH animals. Dobutamine and pimobendan also caused a significant increase in heart rate at higher dosages whereas enoximone did not. Dobutamine caused an increase in left ventricle work, as did pimobendan at the first dose given; at higher doses of pimobendan, the left ventricular work returned to baseline. However, at the doses tested, the left ventricular stroke work during enoximone administration decreased. Vasodilation (the only drug stimulation response in the TAH model) was also observed with the administration of the drugs in T AH animals, and all three caused decreases in systemic and pulmonary vascular resistance. Dobutamine and pimobendan caused an increase in left and right atrial pressures (because of the mechanical heart not being adjusted to compensate the increased return). There was also a reduction in systemic and pulmonary resistance. Enoximone caused severe pulmonary hypertension in the TAH animals, possibly due to stimulus of platelets to release vasoconstrictive substances. Thus, dobutamine, enoximone, and pimobendan significantly contribute to increases in output by vasodilation in animals with a natural heart. Similarly, dobutamine and pimobendan's vasodilatory action is identified in an animal with a TAH. However, enoximone's hypertensive action on the pulmonary vasculature of a TAH animal may offer an insight to the toxicity of enoximone when used after recent surgery.

Origin and purpose of research Dichloro-diphenyl-trichloroethane or DDT as it is more commonly known, was first used extensively by the armed forces in the Pacific Area during World War II. This insecticide is not only a very toxic contact and stomach poison, but also is quite residual on most types of surfaces. Because of these qualities, it was selected to control the malaria mosquito and thus aided in the conquest of many disease-ridden islands of the Pacific. When DDT became available to the general public after the war, it was found not only to be effective against mosquitoes but also many other types of insects. Among these insects are the alfalfa weevil (Hypera postica hon.) and lygus bugs (Lygus elisus Van D., Lygus hesperus Knight) that had previously impaired the production of alfalfa in Utah and other areas. Although treatment of alfalfa fields is usually confined to alfalfa for seed production, DDT-dusted alfalfa straw and DDT dusted alfalfa hay are fed to farm livestock. In ruminant animals, microorganisms play an important role in the synthesis of protein from nitrogenous non-protein compounds and also aid in the break-down of many complex plant materials so that they may be more fully utilized by these animals. The purpose of this study was to determine the effect of DDT upon the role played by the microflora and fauna of the rumen in the synthesis, digestion and utilization of certain nutrients by dairy calves. Scope Digestion and balance studies were conducted with Holstein bull calves fed different levels of DDT and protein equivalent in the ration. The experiment was designed so that each calf would receive one level of DDT throughout the experiment, and would receive a low protein basal diet plus three additional levels of protein equivalent. These additional protein levels were made up by adding a nitrogenous non-protein compound, urea, to the basal diet to give an increased level of protein equivalent in the diet. The nitrogen, calcium, and phosphorus balance and the digestibility of dry matter, protein, and ether extract were determined.

Calf diarrhea or scours is one of the most significant and costly problems dairy producers face on a daily basis. A study was designed and conducted to evaluate the effects of direct-fed microbials on the performance and digestive tract morphology of neo-natal/transition Holstein bull calves. Treatments consisted of a control (n = 21) and a treatment (n = 22) of direct-fed microbial (5 x 108 cfu) supplemented daily. Samples of the rumen, duodenum, and ileum were harvested at the time of slaughter and examined for differences in morphology. Although the direct-fed microbial did not effect performance, it positively effected the ruminal papillae as well as the ileal villi. These data indicate that direct-fed microbials may increase the nutrient absorptive surface area of the rumen and ileum, resulting in a healthier digestive tract.

This study sought to understand the pathogenesis of hemorrhagic abomasitis in calves by characterizing a type A Clostridium perfringens isolate. The complete genome sequence of an isolate from an outbreak of hemorrhagic abomasitis was compared to the three complete C. perfringens genomes currently available in GenBank. Unique findings included the presence of an integrated plasmid sequence and a frameshift mutation in the virS gene, which encodes the main sensor kinase that controls virulence gene regulation. An ~ 55 kb plasmid similar to pCW3 was found, in addition to two smaller plasmids with no significant similarity to available C. perfringens plasmid sequences. A number of plasmid-related fragments were also identified. Neither genomic nor proteomic approaches identified novel toxins, but an alternate and unexpected picture of virulence has emerged suggesting that anomalous virulence gene regulation might contribute to pathogenicity in this isolate. / Natural Sciences and Engineering Research Council, the Ontario Graduate Scholarship, the Animal Health Strategic Initiative of the Ontario Ministry of Agriculture, Food and Rural Affairs

Prenatal stressors have been reported to affect postnatal cognitive, metabolic, reproductive and immune functions. This study examined immune indices and function in Brahman calves prenatally stressed by transportation of their dams on d 60, 80, 100, 120 and 140 ± 5 d of gestation. Based on assessment of cow’s temperament and their reactions to repeated transportation it was evident that temperamental cows displayed greater pre-transport cortisol (P < 0.0001) and glucose (P < 0.03) concentrations, and habituated slower to the stressor compared to cows of calm and intermediate temperament. Serum concentration of cortisol at birth was greater (P < 0.03) in prenatally stressed versus control calves. Total and differential white blood cell counts and serum cortisol concentration in calves from birth through the age of weaning were determined. We identified a sexual dimorphism in neutrophil cell counts at birth (P = 0.0506) and cortisol concentration (P < 0.02) beginning at 14 d of age, with females having greater amounts of both. Whether weaning stress differentially affected cell counts, cortisol concentrations and neutrophil function of prenatally stressed and control male calves was examined. At 2 d post weaning, all calves had increased cortisol concentration (P < 0.0001) and neutrophil cell counts (P < 0.0001). However, in vitro production of reactive oxidative species by neutrophils was decreased (P = 0.0002) 2 d post weaning. Moreover, prenatally stressed calves demonstrated a larger (P = 0.0203) decrease in their immune function relative to control calves at 2 d post-weaning. Importantly, prenatally stressed calves took longer than controls to recover from the weaning stress. Additional studies are needed to clarify if prenatally stressed calves are more susceptible than control calves to pathogens during the post weaning period. Management practices to improve animal welfare and livestock production may need modification if follow-up studies demonstrate that prenatal stress also affects reproductive development, growth, performance and meat quality.