Effects of Dietary Lactose on Incidence and Levels of Salmonellae on Carcasses of Broiler Chickens Grown to Market Age

Abstract

Two trials were conducted to evaluate the effects of lactose in the diet of broilers grown to market weights on incidence and levels of salmonellae on the carcass. Lactose was substituted for sand in otherwise nutritionally complete diets at levels of 0, 2.5, 5, and 7.5% and fed from day-old to 49 days of age. Birds were reared on used (Trial 1) or new (Trial 2) litter and inoculated via the drinking water on Days 2, 7, and 14 with 108 cfu/mL Salmonella typhimurium (ATCC 14028). At 50 days, 12 (Trial 1) or 24 (Trial 2) birds per treatment were processed and prechill carcasses were evaluated for salmonellae incidence and level by the most probable number (MPN) method. Body weight of male broilers was significantly reduced by feeding diets containing up to 7.5% lactose. Feed intake of broilers fed diets containing lactose was significantly reduced and feed utilization improved, suggesting that lactose provided some metabolizable energy. The degree of litter caking was significantly increased, and cecal pH was significantly decreased as dietary lactose increased. Prechill carcasses of broilers fed diets with 7.5% lactose had significantly higher levels of salmonellae than did prechill carcasses of broilers fed 0% lactose. The results of the present study suggest that supplementing poultry diets with lactose is not a viable means in itself of reducing or eliminating salmonellae incidence or levels on processed broiler carcasses.