A field evaluation of an indirect fluorescent antibody-based broodstock screening test used to control the vertical transmission of Renibacterium salmoninarium in Chinook salmon (Oncorhynchus tshawytscha).

Ovarian fluid samples from erythromycin treated and untreated spawning three year old Chinook salmon were screened independently by two laboratories for the presence of Renibacterium salmoninarum using the indirect fluorescent antibody technique (IFAT). Agreement between the results of the two laboratories could be explained by chance when R. salmoninarum cell numbers as low as one per sample were considered sufficient to represent a positive result. If a positive result was considered to be the detection of larger numbers of R. salmoninarum cells (greater than 51 cells per sample), agreement increased and there was a statistically significant association between the results of the two laboratories. However, the level of agreement did not reach satisfactory levels for a population screening test. Furthermore, approximately 60% of the samples yielded false negative results when IFAT results were compared with positive culture results. These results led to the conclusion that the IFAT screening procedure, as carried out, was unsuitable for the purposes intended. Erythromycin injection of the spawning fish had no statistically significant effect on the results of the IFAT screening test.

Prevalence of Salmonella and Thermophilic Campylobacter in Fresh Pork, Beef, Veal and Poultry in Canada 1.

A national surveillance program was undertaken in Canada to establish the prevalence and distribution of Salmonella and thermophilic Campylobacter biotypes in slaughter animals and poultry. During the years 1983 to 1986, samples were collected from federally inspected abbatoirs across Canada and tested at regional laboratories. The laboratory isolation procedure for thermophilic Campylobacter included selective enrichment and isolates were characterized according to Lior's biotyping scheme. Salmonella were isolated from 17.5% pork, 2.6% beef and 4.1% veal carcasses. Thermophilic Campylobacter were isolated from 16.9% pork, 22.6% beef and 43.1% veal carcasses. Salmonella were isolated from 69.1 % turkey and 60.9% chicken carcasses, and thermophilic Campylobacter were isolated from 73.7% and 38.2% turkey and chicken carcasses, respectively. Salmonella typhimurium was the most frequently isolated serotype, and predominant in broiler chickens from 1983 to 1985. Salmonella brandenburg was predominant in pork, and Salmonella schwarzengrund was the primary serotype from turkey carcasses. Campylobacter jejuni biotypes I and II were the most frequently isolated biotypes from beef, veal and poultry. Although Campylobacter coli biotype I was the predominant thermophilic Campylobacter in pork, 41.1% of the biotyped isolates from pork were C. jejuni biotypes I and II.

Excess rumen product anions in cattle. II. Toxic and lethal effects with butyrate.

Toxicity to butyrate was observed in 100-250 kg male Holstein calves following intravenous injection of 0.7-3.6 mmole/kg body weight, intravenous infusion with 0.12-0.53 mmole/min/kg body weight and intraruminal dosage with 19.4 mmole/kg body weight butyrate. Lower doses produced ataxia and serous nasal discharge. Higher doses produced sudden flaccid paralysis and death from asphyxia. No postmortem lesions, gross or histological, were observed. Plasma K+ was reduced to 2.2-2.5 mEq/L. When infusions were stopped, rapid recovery preceded clearance of butyrate and low K+ remained. Nerve depolarization in the central nervous system may be the cause of the toxic effects. Butyrate acidosis is suggested as a factor in unexplained sudden deaths in ruminants.

Some observations on serum gammaglobulin concentrations in suckled beef calves.

Gammaglobulin concentrations were measured in serum samples collected from 23 single-suckled beef calves immediately after birth and from 346 calves at 48 +/- 12 hours postpartum. Considerable variation in these levels appeared to be associated with age and breed of dam. There were also indications that they might be influenced markedly by herd management. These post-suckling gammaglobulin concentrations were of no value in predicting incidence or severity of undifferentiated neonatal diarrhea in the beef herd as a whole, or in the individual neonate.

Results of a preliminary trial with Sphaerophorus necrophorus toxoids to control liver abscesses in feedlot cattle.

A preliminary field experiment was undertaken to evaluate the efficacy of alum precipitated toxoids of Sphaerophorus necrophorus prepared from sonicated whole cells and cell fractions to reduce the incidence of bovine abscesses. A total of 108 calves were divided into five groups and treated as follows: I. uninoculated control, II. adjuvant inoculated control, III. 15.5 mg protein of sonicated (fragmented cells) toxoid, IV. 10.5 mg protein of cytoplasmic toxoid. V. 15.5 mg protein of cytoplasmic toxoid. All animals were maintained under similar conditions to those prevailing in feedlots in Alberta. Livers were examined at slaughter. The most promising result was achieved with the injection of 15.5 mg protein of cytoplasmic toxoid. In this treatment group, no scars (healed lesions) were found in the liver and the incidence of liver abscesses was reduced to 10% from the average 35% liver abscesses and scars found in the uninoculated and adjuvant inoculated groups. The toxoid from sonicated whole cells did not reduce liver abscess incidence. These data suggest that the incidence of liver abscesses in cattle fattened in feedlots may be reduced by immunization.

A mycoplasma isolated from cattle with infectious bovine keratoconjunctivitis.

A mycoplasma has been recovered from the eyes of calves in two naturally-occurring outbreaks of infectious bovine keratoconjunctivitis; also from a third group of calves accidentally exposed to an animal which had ocular exudates from one of the outbreaks instilled into its eyes.The severity of the ocular lesions in infectious bovine keratoconjunctivis outbreaks may be related to a mixed infection with the mycoplasma and Moraxella bovis. Preliminary typing studies indicate the mycoplasma is not serologically related to any known bovine mycoplasma.

A serological survey for brucellosis in Canadian swine.

The results of a survey which included the testing of 21,275 blood samples collected at various slaughter houses are described.Sixty-three herds had a single reactor with a titre of 1:100 or higher to a tube or plate agglutination test. Investigations in forty-five of these herds failed to detect the presence of brucellosis in the remaining mature swine.The prompt slaughter of the reactors may have eliminated possible sources of infection.