Feed withdrawal alters small-intestinal morphology and mucus of broilers

In an effort to reduce carcass contamination and consequent reprocessing, market-age broilers are often subjected to feed withdrawal (FW) before processing to reduce intestinal content and intestinal ruptures during processing. However, little is known regarding the effects of FW on mucus content and intestinal morphology. Therefore, 2 experiments were conducted to determine the effects of FW on intestinal characteristics. Male broilers were raised in floor pens on standard industry diets to 42 and 39 d of age for Experiments (Exp.) 1 and 2, respectively. In Exp. 1, feed was removed 24, 12, 8, and 0 h before sampling, respectively (n = 5 birds/time). Birds remained on litter with access to water for the first 4 h of the FW period and were then placed in crates. Body weights, left pectoralis major weights, and distal ileal and jejunal segments were collected for determination of morphological characteristics. For Exp. 2, birds (n = 8 birds/time) were subjected to 0, 12, and 24 h of FW. Birds were injected with 5-bromo-2'-deoxyuridine and thymidine at 24 and 21 h, respectively, before sampling to determine epithelial cell migration rates. Onecentimeter distal ileal segments were collected for mucus quantification at 0, 12, and 24 h. In Exp. 1, ileal villi heights were unaffected by FW, but villus width and crypt depth decreased with increasing FW time (P <= 0.05). Jejunal villus height increased as FW progressed. Jejunal crypt depths increased until 12 h of FW and then declined at 24 h. Mucus content decreased linearly and was reduced by 46% from 0 to 24 h FW (P < 0.05). The intestinal morphology alterations and the depletion of intestinal mucus that occur during a short-term FW may reduce the integrity of the intestine.