EFFECT OF EARLY NUTRIENT RESTRICTION ON BROILER-CHICKENS .1. PERFORMANCE AND DEVELOPMENT OF THE GASTROINTESTINAL-TRACT

An experiment was conducted to determine the effects of early nutrient restriction on performance and development of the gastrointestinal tr act of broiler chickens. Four hundred male broiler (Ross x Ross) chick s raised in floor pens were assigned to two treatment groups. One grou p was given ad libitum access to feed from 1 to 48 d of age. The secon d group was feed restricted from 7 to 14 d of age to an energy intake of 1.5 x BW.67 kcal ME/d and then given ad libitum access to feed from 14 to 48 d. Body weight and feed intake were determined weekly. At 49 d of age, birds were processed for carcass yield, abdominal fat pad m easurement, and body composition analysis. Broilers were also sampled at 7, 14, 21, and 41 d of age for proventriculus, gizzard, small intes tine (duodenum, jejunum, and ileum), pancreas, and liver weights and f or intestinal length measurements. Total DNA, protein:DNA, and RNA:DNA ratios of Livers and jejuna were determined as indexes of changes in cell size and number. Feed-restricted broilers failed to catch up to t he Control birds in BW at 48 d of age but were superior (P < .01) in o verall feed efficiency. No treatment effects were observed on breast m eat yields or abdominal fat. Moreover, percentage carcass fat, crude p rotein, ash, and dry matter were not affected by restricted feeding. B ody weight and weights of gastrointestinal organs were reduced (P < .0 1) by feed restriction at 14 d of age. Restricted feeding, however, di d not decrease the relative weights of organs, except for liver. Feed restriction also resulted in a reduction (P < .01) of Liver cell numbe r and size and a decrease in jejunum cell number. All organs recovered normal weight on refeeding, and all cellular constituent ratios (e.g. , RNA:DNA, RNA:protein, and protein:DNA) returned to normal by 41 d of age. Absolute and relative weights of supply organs (e.g., proventric ulus, gizzard, small intestine, liver, and pancreas) were less affecte d by feed restriction and responded more quickly to refeeding than the whole body.