Genetic structure and diversity among sheep breeds in the United States: identification of the major gene pools

Understanding existing levels of genetic diversity of sheep breeds facilitates in situ and ex situ conservation activities. A comprehensive evaluation of US sheep breeds has not been previously performed; therefore, we evaluated the genetic diversity among and within 28 US sheep breeds. Both major and minor breeds were included in the analysis and consisted of 666 animals from 222 producers located in 38 states. The level of within-breed genetic diversity was variable and not dependent upon status of a breed as a major or minor breed. Bayesian cluster analysis indicated the breeds were grouped more by physiological differences (meat vs. wool production) rather than geographic origin. Results suggest several actionable items to improve in situ and ex situ conservation. The results clearly identify breeds in need of increased in situ and ex situ management (e.g., Hog Island and Karakul) and allow several suggestions for in situ management of flocks. Conversely, several of the breeds appear genetically similar and therefore require less emphasis on collecting germplasm samples for the gene bank. Commercially important breeds (e.g., Rambouillet and Suffolk) were found to have substantial variation, which should enable breeders to proceed, unencumbered by genetic diversity concerns, with selection strategies that maximize profit.     

Heritability of juniper consumption in goats

Data from goats (n = 505), collected over a 4-yr period, were used to estimate the heritability of juniper consumption. Juniper consumption was determined by near-infrared spectroscopy on fecal samples (n = 1,080) collected from female Boer-cross goats grazing pastures with a variety of plants, including juniper. The animals with records were progeny of 72 sires. Individual goats had from 1 to 4 observations over a 4-yr period. Predicted juniper consumption for individual observations ranged from -5 to +62% of the diet. Data were analyzed with a mixed model that included management group as a fixed effect, BW as a covariate, and permanent environment, animal, and residual as random effects. Management group was a significant source of variation. Least squares means of juniper consumption, as a percentage of the total intake, for management groups varied from 19 to 47%. Heritability of juniper consumption was 13%. Repeatability of juniper consumption was 31%. These results suggest that progress to selection for goats that will consume greater amounts of juniper is obtainable, but is expected to be slow.     

Effect of fenoldopam on renal function after nephrotomy in normal dogs

OBJECTIVE: To evaluate effects of fenoldopam on renal function in normal dogs subjected to bisection nephrotomy. In addition, effects of bisection nephrotomy on renal function in normal dogs were evaluated. STUDY DESIGN: Controlled, randomized, blinded experiment. SAMPLE POPULATION: Sixteen mixed-breed adult dogs. METHODS: Dogs were paired for sex, body weight, and approximate age and assigned to 1 of 2 groups: fenoldopam (F) or placebo (P). Baseline glomerular filtration rate (GFR) based on quantitative renal scintigraphy using (99m)Tc-DTPA, blood urea nitrogen (BUN), serum creatinine (SCr), urinalysis, and urine culture were performed before surgery. Left nephrotomy was performed via median celiotomy. Group F dogs were administered intravenous (IV) fenoldopam (0.1 microg/kg/min) for 90 minutes, whereas group P dogs were administered an equivalent volume of saline (0.9 % NaCl) solution for 90 minutes. Temperature, heart rate, respiration, direct arterial blood pressure, and urine volume were recorded during anesthesia. Renal function was assessed by measuring SCr, BUN, and GFR at 1, 21, and 42 days after surgery. RESULTS: There was no significant difference between groups in measured physiologic variables. No significant difference in GFR, BUN, or SCr between groups or between operated or control kidneys was detected. CONCLUSIONS: Bisection nephrotomy in normal dogs with renal arterial occlusion of 15 minutes and using a simple continuous capsular closure does not adversely affect renal function. CLINICAL RELEVANCE: Bisection nephrotomy, as described in this study, does not decrease renal function; perioperative administration of renoprotective agents is not necessary in normal dogs.     

Volatile fatty acid metabolism by epithelial cells isolated from different areas of the ewe rumen

Cells were harvested from four rumen locations in four 2- to 3-yr-old ewes fed fescue hay to determine whether cell origin has an effect on cellular VFA metabolism. Tissue (approximately 150 cm2) was excised from the anterior cranial pillar, ventral sac floor, caudal pillar surface, and dorsal sac ceiling. Cells were isolated using serial tryptic digestion. One milliliter of isolate was incubated for 2 h in 6 mL of medium containing 25 mM propionate and 10 mM butyrate. Incubations were terminated at 0, 30, 60, 90, and 120 min and analyzed for beta-hydroxybutyrate, acetoacetate, lactate, and pyruvate. Cell yield was 22, 22, 24, and 14 (+/- 6) x 106 cells/mL, and viability was 92, 92, 94, and 87% for anterior cranial pillar, ventral sac floor, caudal pillar surface, and dorsal sac ceiling, respectively. All metabolite concentrations and ratios of redox pairs increased throughout the incubations, indicating continuous cellular activity. Final 2-h concentrations (nmol/10(6) cells) were 123, 113, 163, and 158 (+/- 35) for beta-hydroxybutyrate; 38, 42, 24, and 45 (+/- 10) for acetoacetate; 25.3, 20.6, 10.1, and 20.4 (+/- 5.6) for lactate; and 2.54, 0.98, 1.06, and 1.31 (+/- 0.61) for pyruvate in the anterior cranial pillar, ventral sac floor, caudal pillar surface and dorsal sac ceiling incubations, respectively. Origin of rumen tissue had no significant effect on metabolite production, indicating that cellular location is not a critical factor that affects rate of rumen epithelial cell VFA metabolism under these specific in vitro conditions.     

Severe persistent orf in young goats.

Orf (contagious ecthyma) is a viral disease of small and wild ruminants, humans, and less frequently other species. In sheep and goats, the disease is characterized by the formation of vesiculo-proliferative lesions in the skin of lips and nostril. Here, a form of generalized orf in 16 goat kids from 2 different locations in west Texas is described. The disease was characterized by multifocal, severe, proliferative dermatitis that persisted from about 2 months of age until the goat kids were euthanized 3 months later. All affected goats were Boer or Boer crosses under 1 year of age. The mean immunoglobulin concentration in sera of affected goats was elevated compared with healthy control goats. Severe to moderate lymphadenomegaly of the nodes draining the areas of the skin affected with orf lesions was present in all 16 goat kids. Suppurative arthritis, chronic fibrinous pneumonia, and premature thymic involution were found in 3, 5, and 7 of the goat kids, respectively. The skin lesions of 3 goat kids were infested with larvae of the opportunistic black garbage fly (Ophira sp.). The orf virus was identified in skin lesions by isolation in Marbin-Darby ovine kidney cells, electron microscopy, and amplification of viral DNA by polymerase chain reaction. The orf virus was not detected in peripheral blood or lymph node mononuclear cells of any of the goats. Cross-neutralization experiments showed that an ovine orf virus antiserum raised in sheep was more effective in neutralizing a sheep orf virus isolate than a caprine orf virus isolate. The clinical and epidemiological characteristics of these orf cases may be the result of susceptibility factors within some individuals of the Boer breed of goats.     

A role for balance of interferon-gamma and interleukin-4 production in protective immunity against Neospora caninum infection

A suitable balance in the production of Th1/Th2-type cytokines has a crucial role in the control of microbial infections. We investigated cytokine production patterns and effects during Neospora caninum infection, based on two mouse models and an in vitro system. In the acute infection of N. caninum, BALB/c-background IFN-gamma-deficient mice that were sensitive to the N. caninum infection showed high levels of IL-10 production, whereas significant levels of interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) production were observed in resistant wild type mice. BALB/c mice vaccinated with recombinant vaccinia virus expressing N. caninum surface protein NcSRS2 resisted parasite spread throughout the body, low levels of IFN-gamma production and high levels of IL-4 production were observed compared to unvaccinated animals. The treatment of N. caninum-infected cells with IFN-gamma or IL-10 decreased the host-cell viability in an in vitro system using mouse macrophage J774A.1 cells. On the other hand, IL-4, but not IL-10 administration, increased the viability of N. caninum-infected and IFN-gamma-treated cells. In the light of the balance of Th1/Th2-type cytokine production, an IFN-gamma/IL-4 balance may have a crucial role for the control of cellular responses against the parasite invasion.     

Primary tracheal collapse in a cat

A 7-year-old, neutered male, domestic shorthair cat was presented for severe inspiratory dyspnea of 2 to 3 days' duration. Radiography and tracheobronchoscopy confirmed the diagnosis of primary extrathoracic tracheal collapse. The cat was treated with oxygen, dexamethasone, and terbutaline, but no improvement was seen. Surgical correction was performed using nine prosthetic tracheal ring implants. Clinical signs improved after surgery, and the cat continued to do well 11 months after surgery, despite development of unilateral laryngeal paralysis.     

Increased litter size in Rambouillet sheep: I. Estimation of genetic parameters.

The variance and covariance components needed to estimate heritabilities of and genetic correlations among litter size, ovulation rate, scrotal circumference, and BW in a flock of Rambouillet sheep were estimated using REML via an expectation-maximization type algorithm. The heritability estimates from univariate analyses were .14, .21, .25, .36, and .15 for litter size, ovulation rate, scrotal circumference, 180-d BW of females, and 180-d BW of males, respectively, and average heritability estimates from bivariate analyses were .19, .20, .20, .34, and .10 for litter size, ovulation rate, scrotal circumference, 180-d BW of females, and 180-d BW of males, respectively. The genetic correlation between litter size and ovulation rate was near unity. Body weight in ewes had a moderate genetic correlation with both litter size (.22) and ovulation rate (.20) and a low residual correlation with both litter size (.03) and ovulation rate (.09). The genetic correlation between BW in rams and scrotal circumference was 0, whereas the residual correlation was .71. The genetic correlations of scrotal circumference with litter size and ovulation rate were -.25 and +.20, respectively.