[en] Feed used to rear farm animals for human consumption has often been implicated as vehicle for dissemination of microbial pathogens that can adversely affect both animals or birds, and humans. Radiation pasteurization of animal feed to improve its microbiological quality should reduce the incidence of feed-borne infection (both clinical and subs clinical) in the herd or flock. This would result in safer food for the consumer, and improved economic performance of the production unit. This latter benefit is particularly important because it could directly offset the treating the feed. The likelihood of occurrence, as well as the magnitude, of any improved economic performance in the herd or flock consuming the irradiated feed must be determined experimentally. Accordingly, short term feeding tests were carried out to determine the effect of radiation pasteurization of poultry feed on growth performance of young chicks. Newly hatched white leghorn cacklers were used in the present studies to examine the effects of (i) control vs irradiated feed; and (ii) control vs stressed (transient chilled) birds. Feed consumption and pen weight were monitored for 21 days. Three experiments were conducted in the summer of 1989, using separate lots of commercially obtained feed ingredients for each experiment, In two of the three feeding tests there was a highly significant (p<.01) increase in feed conversion efficiency in the birds fed the irradiated feed. The magnitude of the increased efficiency was 2.4% and 2.8% in the two positive experiments. In one of the two positive experiments the feed contained antibiotics (Penicillin and Streptomycin) while the feed in other was antibiotic-free these results suggest that radiation pasteurization of poultry feed may have a beneficial effect on the feed conversion efficiency of the birds consuming that feed.8 tab