Effect of diffferent levels of maternally derived antibodies on protection against infectious bursal disease virus.

Fertile eggs were obtained from three different broiler breeder flocks with different levels of virus neutralizing antibodies to infectious bursal disease virus. Egg yolk from these flocks was tested for antibody titers by the virus neutralization test. Flock I eggs had no antibodies, flock II had medium level antibodies (1:200-1600; geometric mean = 1:975), and flock III had a high level of antibodies (1:1600-6400; geometric mean = 1:3365). Chicks from the above flocks were challenged each with 10(2) 50% embryo infective dose of the IN serotype 1 variant virus at 1, 2, and 4 wk of age and examined at 5 and 11 days postchallenge. The average organ/body weight ratios were calculated and statistically analyzed. Chicks with no maternal antibodies were not protected at any age. Chicks with medium levels of maternal antibodies were protected when challenged at 1 and 2 wk of age. Chicks with high levels of maternally derived antibodies were protected when challenged at all the ages tested. The above results were statistically significant (P < 0.05).

Antibody detection in matched chicken sera and egg-yolk samples by commercial enzyme-linked immunosorbent assay kits for Newcastle disease virus, infectious bronchitis virus, infectious bursal disease virus, and avian reovirus.

ELISA kits have been used to detect antibody in egg yolk. The major advantage eggs offer over blood samples is the ability to collect samples without compromising flock biosecurity. A disadvantage to using egg yolk over sera concerns the method of preparing yolk for antibody testing. The technique used in this study involved a simple dilution method with no mixing or extraction. To determine the adequacy of yolk samples to replace serum samples, a serum sample and the first six eggs were obtained from each of 50 commercial leghorn hens. Mean titers were consistently larger for serum than for yolk, but the size of the difference varied with the virus. The variation of mean egg titer was comparable to that of the serum titer. Correlations between a hen's serum titer and the mean titer from hen eggs were only moderate, ranging from 0.35 to 0.85 across viruses and systems. The ability to predict the serum titer of a single hen by the mean titer from hen eggs may be inadequate.

Carbofuran toxicosis in cattle: case history and analytical method.

Thirteen head of crossbred Brahman cattle were exposed to carbofuran which had been mixed with rice to control blackbirds. Three animals died within 20 minutes after eating the contaminated grain, and the other 10 exhibited clinical signs associated with carbamate toxicosis. The 4 most severely affected animals were treated with a subtherapeutic dose of atropine sulfate; they did not respond and subsequently died. The remaining 6 recovered. Samples of rumen contents from the animals that died contained carbofuran concentrations ranging from 2 to 51 mg/kg.