Experimental transmission of turkey viral hepatitis to day-old poults and identification of associated viral particles resembling picornaviruses.

Turkey viral hepatitis (TVH) was experimentally reproduced in two experiments in 1-day-old poults. In the first experiment, an infectious inoculum was prepared from filtered yolk materials harvested from dead embryonating chicken eggs (ECE) previously inoculated with suspensions of liver and pancreas tissues collected from TVH-affected birds in commercial turkey flocks. One-day-old poults given a yolk-sac inoculation or oral gavage with this preparation developed lesions in the liver and pancreas characteristic of TVH at 20 days postinoculation (PI) in 60% and 14% of the experimentally infected birds, respectively. With the identical inoculum, embryo mortality occurred at 8 and 10 days PI in embryonating turkey eggs (ETE) inoculated into the yolk sac. In the second experiment, an infectious inoculum was prepared from filtered yolk materials from dead ETE harvested in the first experiment. One-day-old poults given a yolk-sac inoculation with this filtered yolk material developed lesions in the liver and pancreas within 5 days PI. At 20 days PI, 67% of the experimentally infected birds had similar lesions. With the inoculum given to these poults, embryo mortality occurred at 6, 8, and 10 days PI in ETE inoculated into the yolk sac. Virus particles 26-28 nm in diameter with icosahedral morphology typical of picornaviruses were identified by EM in the yolk sacs of ETE that died in both experiments, and inoculated ETE that died following passage of filtered suspensions of pancreatic tissues collected from affected birds in the first experiment.

Taste aversion learning in horses.

The ability of ponies to learn to avoid a relatively novel food associated with illness was tested in three situations: when illness occurred immediately after consuming a feed; when illness occurred 30 min after consuming a feed; and when illness was contingent upon eating one of three feeds offered simultaneously. Apomorphine was used to produce illness. The feeds associated with illness were corn, alfalfa pellets, sweet feed and a complete pelleted feed. The ponies learned to avoid all the fees except the complete feed when apomorphine injection immediately followed consumption of the feed. However, the ponies did not learn to avoid a feed if apomorphine was delayed 30 min after feed consumption. They could learn to avoid alfalfa pellets, but not corn, when these feeds were presented with the familiar "safe foods," oats and soybean meal. Ponies apparently are able to learn a taste aversion, but there were constraints on this learning ability. Under the conditions of this study, they did not learn to avoid a food that made them sick long after consumption of the food, and they had more difficulty learning to avoid highly palatable feeds.