Associations between farm management practices, productivity, and bovine leukemia virus infection in Ontario dairy herds.

The objective of this study was to investigate the associations between herd-level bovine leukemia virus (BLV) status and herd-level management and production variables. The study population consisted of 1330 cows sampled from 102 Ontario dairy herds. The individual-cow prevalence of BLV infection in the population (based on AGID testing) was 23%, with 69.6% of herds having one or more positive animals. The herd-level explanatory variables were divided into two datasets containing winter housing variables and all non-seasonal variables, and summer housing variables and all non-seasonal variables. In both datasets, multivariable analyses found a negative association between herd-level milk production and BLV status, and positive associations between weaning age and purchasing animals from outside sources, and BLV status. Housing pre-weaned calves in hutches or separate calf buildings in either season was associated with an increased risk of BLV. The model containing winter housing variables also included positive associations between contact with older animals and BLV status, and between BLV status and the facilities used to house dry cows in the winter.

Evaluation of a bulk-milk ELISA test for the classification of herd-level bovine leukemia virus status.

The results of a commercial bulk-milk enzyme-linked immunosorbent assay (ELISA) test for herd-level bovine leukemia virus (BLV) status were compared to results obtained from individual agar-gel immunodiffussion (AGID) testing on sampled cattle. A positive herd was defined as a herd having one or more AGID-positive animals. The estimated true herd status was based on the sensitivity and specificity of the AGID test and the number of cattle sampled per herd. Ninety-seven herds were used, with a mean of 13 cows sampled per herd. The AGID test indicated an apparent herd prevalence of 70.1%. After accounting for the number of cows sampled and the sensitivity and specificity of the AGID test, the estimated true herd prevalence of BLV was 52.3%. The ELISA test identified 79.4% of herds as positive for BLV, and had an apparent sensitivity and specificity of 0.97 and 0.62, respectively. However, after accounting for the sensitivity and specificity of the AGID test in individual animals, the specificity of the ELISA test was 0.44. The ELISA test was useful for identifying BLV-negative herds (i.e., ruling out the presence of BLV infection in test negative herds). With the moderately low specificity, herds identified as positive by the ELISA test would require further testing at the individual or herd level to definitively establish their BLV status.

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.

Cryptosporidium antibodies in manitoba cattle: a pilot study using an indirect fluorescent antibody procedure.

An indirect fluorescent antibody test, using feces-derived oocysts as antigen, was used to detect antibodies to Cryptosporidium spp. in bovine sera in Manitoba. Antibodies were detected in 29 of 50 (58%) sera collected from animals of various ages on farms where calves had laboratory-confirmed cryptosporidiosis and in 76 of 186 (40.9%) sera collected at random from culled breeding stock. Serum antibody, presumably colostral in origin, did not appear to protect young calves from the infection. No geographic preference for the infection was demonstrated.

Infection with Cryptosporidium spp. in humans and cattle in Manitoba.

Between October 1, 1983 and October 31, 1984, fecal specimens from 3656 persons with enteritis and 182 calves, representing 148 herds having a neonatal diarrhea problem, were examined for oocysts of Cryptosporidium spp. Oocysts were found in 1% of human and 25% of bovine specimens. All infected persons were immunocompetent. Children under five years of age had an infection rate of 25/100,000 compared to 1.4/100,000 in older people (p less than 0.005). Rates in northern communities were four to seven times as high as those in southern Manitoba. Human infections occurred most commonly in late summer and fall. In beef calves infection occurred in winter and spring, the calving season in Manitoba. Epidemiological association between the infection in people and in cattle could not be established.

Prevalence of salmonella and campylobacter contamination in manitoba Swine carcasses.

Muscle samples from the neck and diaphragm and fecal samples were collected from five hogs from each of 50 lots of market hogs at three Manitoba abattoirs. Environmental samples were also collected. Each sample was tested for Salmonella contamination, and tissue and fecal samples were tested for Campylobacter.Salmonella was isolated from 34 (4.1%) of 821 samples, with 17 of the isolates coming from one lot of hogs and their concurrent environment. Campylobacter was isolated from 175 (26.3%) of 666 samples. Fifty-five percent were Campylobacter coli and 45% were Campylobacter jejuni.

Prevalence of Salmonella contamination in market-ready geese in Manitoba.

Salmonella contamination is a major problem in the poultry industry, but no data are available on the prevalence in geese. From two slaughter facilities in Manitoba, 130 carcass rinsings and 315 cloacal swabs from a total of 17 flocks of domestic geese were examined for salmonellae. Sixty percent of the carcass rinsings and 18.4% of the cloacal swabs were positive. Most of the isolates were serotyped, and some analysis of the results is presented. Three culture media were compared, and a modified dulcitol brilliant-green novobiocin medium was found to be more selective than brilliant-green and brilliant-green sulfa agars.