Estimation of linkage disequilibrium in a sample of the United Kingdom dairy cattle population using unphased genotypes

The association between genetic marker alleles was estimated for two regions of the bovine genome from a random sample of 50 young dairy bulls born in the United Kingdom between 1988 and 1995. Microsatellite marker genotypes were obtained for six markers on chromosome 2 and seven markers on chromosome 6, spanning 38 and 20 cM, respectively. Two different methods, which do not require family information, were used to estimate population haplotype frequencies. Haplotype frequencies were estimated for pairs of loci using the expectation-maximization algorithm and for all linked loci using a Bayesian approach via a Markov chain-Monte Carlo algorithm. Significant (P = 0.0007) linkage disequilibrium was detected between pairs of loci in syntenic groups (that is, loci in the same linkage group), extending to about 10 cM. No significant linkage disequilibrium was detected between markers in nonsyntenic regions. Given the observed level of linkage disequilibrium, mapping methods based on population-wide association might provide a better resolution than traditional quantitative trait loci mapping methods in the U.K. dairy cattle population and may reduce the required sample sizes of the experiments.     

Strategies to reduce feedlot cattle heat stress: effects on tympanic temperature

Three experiments were conducted to evaluate the effect of different management strategies on body temperature of feedlot steers finished in the summer months. In Exp. 1, 24 crossbred steers were chosen to assess the effect of altered feed intake and feeding time on tympanic temperature (TT) response. Managed feeding (MF) treatments were applied for 22 d only and provided 1) ad libitum access to feed at 0800 (ADLIB), 2) feed at 1600 with amount adjusted so that no feed was available at 0800 (BKMGT), 3) feed at 1600 at 85% of predicted ad libitum levels (LIMFD). During heat stress conditions on d 20 to 22 of MF, LIMFD and BKMGT had lower (P < 0.05) TT than ADLIB from 2100 through 2400. A carryover effect of limit-feeding was evident during a severe heat episode (d 36 to 38) with LIMFD steers having lower (P < 0.05) TT than ADLIB. In Exp. 2, TT were obtained from 24 crossbred steers assigned to three treatments, consisting of no water application (CON), water applied to feedlot mound surfaces from 1000 to 1200 (AM) or 1400 to 1600 (PM). From 2200 to 0900 and 1200 to 1400, steers assigned to morning sprinkling treatment had lower (P < 0.05) TT than steers assigned to afternoon sprinkling treatment. In Exp. 3, 24 steers were utilized in a 2 x 2 factorial arrangement of treatments with factors of feeding time [0800 (AMF) and 1400 (PMF)] and sprinkling (WET and DRY). Tympanic temperatures were monitored under hot environmental conditions on d 30 to 32 and 61 to 62. A feeding time x sprinkling interaction (P < 0.001) was evident on d 30 to 32, although AMF/DRY steers had the highest (P < 0.05) TT. On d 61 to 62, TT of PMF steers was higher (P < 0.05) than AMF between 1500 to 1800. Use of sprinklers can effectively reduce TT of feedlot cattle, whereas shifting to an afternoon vs morning feeding time was most beneficial when bunks were empty several hours prior to feeding.     

Canine cyclic hematopoiesis: blood gas and 2,3-diphosphoglyceric acid studies

Cyclic hematopoiesis in gray Collies was first described in 1967. These dogs are anemic in comparison with the healthy littermates, and their erythropoiesis is abnormal. Although the basic disorder appears to be an as yet unidentified abnormality of hematopoietic progenitor cells, an inherent difference in responses to blood gas control mechanisms remains as a possible cause. In a study of these mechanisms in dogs with cyclic hematopoiesis, the P50 and 2,3-diphosphoglyceric acid concentrations were increased. Differences in pH, PCO2, PO2, and oxygen saturation were not observed.     

Chicken anemia agent: an electron microscopic study

Particles of chicken anemia agent (CAA) negatively stained with uranyl acetate were found to be 26.5 nm in diameter. The surface detail evident on the particles indicated that the virus capsid was composed of 32 structural subunits arranged as in a class P = 3 icosahedron with a triangulation number of 3. Using mouse monoclonal antibodies to CAA and a gold-labeled goat anti-mouse IgG, CAA-specific structures were observed by thin-section electron microscopy in infected MDCC-MSB1 cells and in thymic lymphocytes from experimentally infected chicks. These consisted of electron-dense, granular, non-membrane-bound nuclear inclusions, which were often ring-shaped, and cytoplasmic accumulations of microtubules. Aggregates of virus-like particles were sometimes observed in the nuclei of infected MDCC-MSB1 cells. The nucleolar involvement that is characteristic of the morphogenesis of parvoviruses was not observed with CAA.     

Ultrasonographic appearance of torsion of a testicular seminoma in a cryptorchid dog

An intra-abdominal testicular tumour was diagnosed in a 10-year-old, male, cryptorchid golden retriever. Upon surgical removal, torsion of the testis was found. The histopathological diagnosis was seminoma. The ultrasound examination in this case revealed a parenchymal mass lesion. An ultrasound examination is a useful supplemental diagnostic tool for differentiation of abdominal mass lesions.     

Ante mortem diagnosis of pancreatitis in four cats

The ante mortem detection of pancreatitis in four cats is reported. Clinical findings included vomiting, lethargy and constipation in all the cats, diabetes mellitus in two cats and severe jaundice and a vitamin K responsive coagulopathy in one cat. Serum amylase was normal in all the cats and serum lipase was elevated in one azotaemic cat. Ultrasonography revealed predominantly hypoechoic masses in the right cranial quandrant of the abdomen of each cat. The anatomical location of these masses was consistent with the pancreas. Gross examination supported these ultrasonographic observations. The pancreatic lesions were characterised histologically as acute necrotising pancreatitis, acute necrotising pancreatitis with abscessation, chronic active pancreatitis with cystic dilatation of the pancreatic duct causing bile duct obstruction and chronic active pancreatitis with nodular hyperplasia. This report indicates that pancreatitis is a clinically significant disease in cats that may be diagnosed ante mortem.     

Surgical management of ameloblastic fibroma in the cat

A 14-month-old spayed female domestic short-haired cat was presented for evaluation of a rostral mandibular mass diagnosed from biopsy as an ameloblastic fibroma. Radiographs of the mandible demonstrated marked osteolysis and cortical expansion. A rostral mandibulectomy was performed extending from the caudal edge of the second premolar on the right side to the caudal edge of the canine tooth on the left side. Histological evaluation of the excised mass confirmed the diagnosis of ameloblastic fibroma. Follow-up evaluation at eight months revealed normal oral function with the exception of occasional saliva soiling of the chin. The owner was satisfied with the cosmetic result.