Effects of scrotal circumference of sire on age of calving in Ontario beef heifers

Calving records for daughters of 667 Record of Performance tested sires were examined to study factors related to age at first calving. For the 3025 heifers analyzed, mean age (± SD) at first calving was 791.5 ± 161.6 days (26.4 ± 5.4 months). There were significant effects of the breed of sire on age of heifer at first calving. Daughters of Angus sires calved earlier than daughters of Charolais, Hereford, Limousin, and Simmental sires. Mean ages at first calving for daughters of Hereford, Limousin, and Simmental bulls were significantly (p < 0.05) correlated with the sire's end-of-test age-adjusted scrotal circumference, but these correlations were not significant when farm effects were controlled. It appears that unknown herd level factors are more important in determining age at first calving in Ontario herds than using early maturing sires as determined by scrotal circumference measurements.     

Xanthine-containing urinary calculi in dogs given allopurinol

Clinical features and laboratory findings were evaluated in 10 dogs that formed xanthine-containing urinary calculi during the period that they were given allopurinol (9 to 38 mg/kg of body weight/d). Duration of allopurinol treatment was 5 weeks to 6 years. Of the 10 dogs, 9 (all Dalmatians) had formed uric acid-containing calculi at least once before allopurinol treatment was initiated. It was not possible to recognize xanthine as a crystalline component of the calculi by use of a chemical colorimetric method or by polarized light microscopy. We concluded that the best diagnostic method for recognition of xanthine-containing calculi was high-pressure liquid chromatography because it is quantitative, sensitive, and accurate, and can be conducted on a small amount (1 to 2 mg) of crystalline material.     

Benzimidazole-resistant beta-tubulin alleles in a population of parasitic nematodes (Cooperia oncophora) of cattle

Three anthelmintic classes with distinct mechanisms of action are commercially available. Selection of nematode populations resistant to all these drugs has occurred, particularly in trichostrongyloid parasites of sheep. Anthelmintic resistance in cattle parasites has only recently been recognized and appears to be less pronounced, even though very similar species infect both hosts. To understand the bases for differences in the rate of resistance development in sheep versus cattle parasites, it is important to first demonstrate that the same kinds of resistance alleles exist in both. The benzimidazoles (BZ), which have been used for more than 40 years, were chosen as an example. BZ-sensitive (BZ(S)) and BZ-resistant (BZ(R)) nematodes that parasitize sheep have been distinguished at the molecular level by a single nucleotide change in the codon for amino acid 200 of a beta-tubulin gene, a switch from TTC (phenylalanine) to TAC (tyrosine). PCR primers were designed to completely conserved regions of trichostrongyloid beta-tubulin genes and were used to amplify DNA fragments from Haemonchus contortus (cDNA from a BZ(S) and a BZ(R) library) as positive controls. The technique was then extended to the cattle parasites, Cooperia oncophora and Ostertagia ostertagi (from genomic DNA). Sequence analysis proved the presence of amplified BZ(S) alleles in all three species and BZ(R) alleles in the BZ(R) population of H. contortus. Based on these data, nested PCR primers using the diagnostic T or A as the most 3' nucleotide were designed for each species. Conditions for selective PCR were determined. To demonstrate feasibility, genomic DNA was recovered from individual H. contortus L(3) larvae from both BZ(S) and BZ(R) populations. Genomic DNA was also isolated from >70 individual adult male C. oncophora collected from a cattle farm in New Zealand with reported BZ resistance. Allele-specific PCR discriminated among heterozygotes and homozygotes in both species. This method could find utility in studying the molecular epidemiology of BZ resistance in cattle parasites and for defining the variables that limit the development and spread of anthelmintic resistance in this host.     

Amphibian virology.

Amphibians are a diverse group of species; much work remains to be done to elucidate the viruses of amphibians. Viral diseases may play an important role in wild and captive amphibian populations. Iridoviruses are a leading cause of wild amphibian mortality events in the United States and are a common cause of amphibian mortality events worldwide. In addition to frank viral diseases, viral infections may play a role in the establishment of bacterial, fungal, and parasitic diseases and are an underlying cause of neoplasia. It is important for the amphibian clinician to recognize disease syndromes and pathology that are consistent with viral etiology.     

Lymphoid follicular cloacal inflammation associated with a novel herpesvirus in juvenile alligators (Alligator mississippiensis).

Multifocal hyperemic nodules and plaques associated with the cloacal mucosa of juvenile alligators (Alligator mississippiensis) at a public aquarium were investigated. Grossly, pale pink to dark red multifocal, circular lesions of varying degrees of severity were identified on the cloacal and, in males, phallus mucosa. Cloacal mucosa biopsies were obtained from 2 of the alligators. These samples were examined histologically and by polymerase chain reaction (PCR) using consensus primers targeting a conserved region of the herpesvirus polymerase gene. Microscopically, the lesions were characterized as submucosal lymphoid follicles with hyperemia and hemorrhage. No inclusion bodies were observed. Minimal to no anisokaryosis was present, and no etiologic agents were identified. Through PCR, a band consistent in size with herpesvirus was observed. Tissues showing similar clinical, histopathologic, and PCR findings were collected from animals at an alligator farm several months later. Sequencing of the PCR amplicon resulted in a 180-base pair sequence that shared 85% sequence identity with tortoise herpesvirus-1.     

High resolution g.l.c. specifications for plant spray oils

High resolution g.l.c. chromatograms of a series of reference plant-spraying oils were used for the development of proposed g.l.c standards for spraying oils in Australia. The mean size and size-range of molecules in the oils have been specified in relation to carbon number positions for reference n-paraffins. Problems with reproducibility and precision with reduced pressure distillation (10 mm Hg) of plant-spraying oils have been demonstrated and discussed.     

Frequency of lymphocytes bearing Fc receptors and surface membrane immunoglobulins in normal, persistent lymphocytotic and leukemia cows.

Fluoresceinated, heat-aggregated bovine immunoglobulins (B-IgG) and human immunoglobulins (H-IgG) were used to detect a receptor for the crystallizable fragment (Fc) of the immunoglobulin molecule on peripheral blood lymphocytes (PBL) of cattle. The aggregated and B-IgG and H-IgG bound to the bovine PBL, but aggregated H-IgG was found to be more sensitive for the detection of Fc receptors. The specificity of aggregated H-IgG binding to the Fc receptors was established by demonstrating that antigen-antibody complexes inhibited this binding, and unaggregated H-IgG did not bind significantly to PBL. Double-labeling experiments suggested that all Fc+ cells have surface immunoglobulins (SIg), a marker for B lymphocytes. The percentage of Fc+ and SIg+ cells in normal animals was 9.5% (range 4-15%) and 16.2% (range 4.5-30.2%), respectively. Persistent lymphocytotic cows had 2.71 times more Fc+ and 3.85 times more SIg+ lymphocytes than did normal cows. Cows with lymphosarcoma had a lower percentage of Fc+ and SIg+ cells than did cows with persistent lymphocytosis. Cases with thymic lymphosarcoma and those with the skin form of leukemia had normal percentages of Fc+ and SIg+ cells.