Metabolic responses to early nutrition

Abstract

Early access to nutrients causes short- and long-term increases in body weight and a higher proportion of breast meat at marketing in both chicks and poults. Utilization of yolk close to hatch is by transport to the circulation and to the gastrointestinal tract. The presence of feed probably increases the latter route. Dramatic increases in size and length of the small intestines occur close to hatch. Growth of the villi and the crypt depth are depressed when feed is withheld. Pancreatic and biliary secretions to the intestine begin before hatch; the amount of secretion per gram exogenous feed intake changes little after hatch. Brush border enzyme activities increase with intestinal mass and exogenous feed intake. Digestion of lipids was high at 4 days whereas starch and N digestion was lower and increased with age. The enhanced growth caused by early feeding may be due to several effects: improved nutritional maturity of the bird, stimulation of the utilization of yolk, increased intestinal development, and long-term metabolic effects.