Frequency distributions of sward height under sheep grazing

Cattle and sheep can create and maintain a mixture of relatively tall and short patches in grass swards through selective grazing. In swards that are grazed by cattle this heterogeneous structure can result in the frequencies of height measurements having a skewed distribution that has variously been better described by the double‐normal distribution the gamma distribution and the Weibull distribution than by the more common normal distribution. The fit of these statistical distributions, and the adequacy of the potentially useful log‐normal distribution, to sward height frequencies were tested in sown temperate swards grazed by sheep and compared within a single sward. It was concluded that the single‐normal and Weibull distributions were inadequate and that overall the log‐normal and gamma distributions had the best fit to the measurements.     

Citrinin as a possible cause of the pruritis, pyrexia, haemorrhagic syndrome in cattle

An outbreak of the pruritis, pyrexia, haemorrhagic syndrome affected eight of a herd of 175 cows which was divided into two groups of 115 and 60 according to yield. There was no difference in management between them but citrus pulp pellets were fed only to the larger group in which the eight cows were affected. Silage, which had been made without the use of additives, was also fed to both groups. The citrus pulp was visibly mouldy and contained 30 to 40 parts per billion of citrinin. Signs of the syndrome occurred within three days of the cows starting to ingest the citrus pulp, which was fed for 21 days, and the last case occurred six days after the feeding of citrus pulp ceased. Five calves whose dams had been fed citrus pulp were subsequently born with superior prognathism. In contrast to the eight cows that developed the syndrome only one out of 68 heifers which were fed larger quantities of citrus pulp for 10 days developed mild signs of the syndrome and then recovered, suggesting that older animals may be more susceptible. The clinical signs, gross pathology and histopathology are described and compared with those of previous outbreaks. Mycotoxins, particularly citrinin, were strongly implicated as the cause of this outbreak.     

A Comparison of the Effects of Unilateral Thyroarytenoid Lateralization Versus Cricoarytenoid Laryngoplasty on the Area of the Rima Glottidis and Clinical Outcome in Dogs with Laryngeal Paralysis

OBJECTIVE: To compare the clinical effects of unilateral thyroarytenoid lateralization versus unilateral cricoarytenoid laryngoplasty for the treatment of canine laryngeal paralysis. Study Design-A prospective, clinical trial. ANIMALS: Twenty client-owned dogs admitted to Glasgow University Veterinary Hospital (GUVH) between 1997 and 1999 with a diagnosis of laryngeal paralysis. METHODS: A thorough evaluation of each dog was undertaken that included history, physical and neurologic examinations, complete blood count, serum biochemistry profile, serum thyroxine (T4) level, and thyroid-stimulating hormone (TSH) assay. The exercise tolerance of each dog was investigated by assessing respiratory rate and arterial blood gas analysis at rest and after 5 minutes of mild exercise. Animals were included in the study on the basis of a definitive diagnosis of laryngeal paralysis made by endoscopic observation of the larynx in the lightly anesthetized patient. The animals were randomly assigned to 1 of 2 treatment groups: unilateral thyroarytenoid lateralization or unilateral cricoarytenoid laryngoplasty, with all procedures being performed by the same surgeon. Video images of the rima glottidis were recorded pre- and postoperatively using video endoscopy. Video images were digitized and the area of the rima glottidis measured using image-analysis software. An increase in the area of the rima glottidis was expressed as a percentage of the preoperative area. All animals were reassessed 6 weeks' postoperatively, and exercise tolerance tests were repeated. RESULTS: The mean increase in the area of the rima glottidis postoperatively when compared with the preoperative area was 140% for those animals undergoing unilateral thyroarytenoid lateralization (range, 120%-158%) and 207% for those animals undergoing unilateral cricoarytenoid laryngoplasty (range, 183%-228%). This difference was statistically significant (P < .0001). At the 6-week postoperative examination, there was no significant difference in improvement between the 2 groups when compared on either a clinical basis or exercise tolerance tests. The mean surgical time in the 2 groups was 25 minutes for thyroarytenoid lateralization and 43 minutes for cricoarytenoid laryngoplasty. This was a statistically significant difference (P = .002). CONCLUSION: Although increase in area of the rima glottidis was significantly greater after unilateral cricoarytenoid laryngoplasty compared with unilateral thyroarytenoid lateralization, no difference in clinical outcome could be detected. However, the cricoarytenoid laryngoplasty procedure required significantly more surgical time. CLINICAL RELEVANCE: Both unilateral cricoarytenoid laryngoplasty and unilateral thyroarytenoid lateralization are successful methods for the treatment of laryngeal paralysis; however, thyroarytenoid lateralization requires less surgical time to perform.     

Retarded growth rate and delayed onset of egg production associated with spirochaete infection in pullets

Retarded growth rates and delayed onset of egg production were recorded in 22-week-old pullets reared on deep litter and with indirect contact with pigs. Birds reared in cages or transferred to cages were unaffected. Spirochaetes were isolated and identified from the intestines of the pullets reared on deep litter but not from those reared in cages. Birds kept solely on deep litter were more severely affected, with 24 per cent immature birds and 10 per cent mortality compared with those transferred from deep litter to cages where no mortality was recorded but 15 to 22 per cent were found to be immature. The histopathological changes are described and the significance of the findings is discussed.     

A survey of slaughter procedures used in chicken processing plants

Information was collected on the slaughter procedures used in 12 processing plants in Australia. The processing line speed varied from 25 to 125 birds/minute; the voltage in the electrified waterbath varied from 55 to 165 V; the duration of stunning was 2.0 to 7.5 seconds and the time allowed for exsanguination was 45 to 180 seconds. As a result of the variables, some birds were dead on leaving the stunner and prior to exsanguination, while it was probable that others were not dead before entering the scald tank.     

Importance of pilus-associated antigen in Bacteroides nodosus vaccines

The performances of two cellular vaccines, one sparsely piliated and the other well piliated, were compared on irrigated pasture with those of vaccines containing their respective, purified pili. There were statistically significant differences among the four vaccines in the mean numbers of feet per sheep which developed severe foot rot during 27 weeks of exposure. The incidence of severe foot rot was significantly lower in the two pili-vaccinated groups than in the group vaccinated with well-piliated cells, which were in turn substantially more effective than the sparsely piliated. However, the two pili vaccines did not prevent infection of the interdigital skin so that the differences in vaccine performance were much less marked when interdigital skin lesions were included. The number of feet affected by blowfly strike was closely associated with the presence of the most severe lesions and consequently there were far fewer struck feet in the two pili vaccine groups than in the two cellular vaccine groups. Analysis of serum agglutinin titres led to the same assessment of vaccinal efficacy as that derived from the analysis of severe foot rot lesions. Individually the agglutinin response to vaccination was not universally associated with resistance or susceptibility to severe foot rot but mean titres were significantly higher in the two pili vaccine groups than in the highly piliated-cell vaccine group, which were all in turn significantly higher than in the poorly piliated-cell vaccine group.     

Serological detection of equid herpesvirus 1 infections of the respiratory tract.

An investigation was made of 3 serological tests (virus neutralization, complement fixation and indirect immunofluorescence), which are applicable to epidemiological studies of infections by Equid herpesvirus 1 (EHV-1). Sera from gnotobiotic foals inoculated intranasally with various strains of EHV-1 were unable in some cases to neutralize heterologous strains and these results were not consistent with the existence of clearly-defined subtypes of EHV-1, as previously proposed. The cross-reactions in complement-fixation tests paralleled those with neutralization but immunofluorescence tests were found to be both more sensitive and more broadly reactive than the other two. Complement-fixing antibodies declined more rapidly following experimental infection than did those measured by neutralization or immunofluorescence. The results are discussed in relation to the diagnosis of EHV-1 infection and the significance they may have for the epidemiology of this disease.