Effect of environmental temperature and feeding regimen on quantity of digestive tract contents of broilers

Carcass contamination from contents of the digestive tract during processing is a recurring problem for the broiler industry. Environment and feeding regimen are often implicated as causative factors. The effects of environmental temperature and meal feeding on passage of feed through the digestive tract of broilers were examined. Broilers were reared in environmental chambers in five experiments. In the first experiment, environmental temperatures were constant temperatures of 16 and 27 C and cycles of 16-24-16 and 24-35-24 C and rate of passage of feed through the digestive tract (ROP) was determined with ferric oxide. Temperature did not consistently affect ROP. In the other four experiments, various environmental temperatures were investigated and broilers were fed continuously or for 12 or 16 h/day. Contents of the crop, proventriculus plus gizzard, and small intestine were weighed 2, 4, 6, and 8 h after feeding withdrawal. Environmental temperature did not directly affect the movement of digesta but the feeding regimen affected the quantity of digesta in some segments of the tract. Environmental temperature may have indirectly affected the quantity of feed in the crop by affecting the quantity of feed consumed. Limiting the feeding period resulted in retention of digesta in the crop of some broilers for an extended period. This increased the variability in quantity of crop contents. A feeding regimen X temperature interaction resulted in increased small intestine weight for meal-fed broilers at 16 C.