Effects of starter diet supplementation with arginine on broiler production performance and on small intestine morphometry

the effects of starter diet (days 1 to 21) supplemented with arginine (arg) on the production performance and duodenum and jejunum mucosa morphometry of broilers were studied. male cobb broiler chickens (990) were randomly assigned to one of five treatments in a complete random design. measurements of 33 chicks per treatment were made in six repetitions. the treatments consisted of a basal diet with 1.390% digestible arg (no supplementation) and four dietary levels (1.490%, 1.590%, 1.690%, and 1.790%), providing a relationship with lysine of 1.103; 1.183; 1.262; 1.341 and 1.421%, respectively. from the age of 22 days on, all birds received conventional grower diet. the data were submitted to regression analysis by polynomial decomposition of the degrees of freedom in relation to the levels of arg. the arg supplementation increased (p<0.05) the live weight and the feed conversion ratio without increasing the feed intake of the birds. however, no effect was observed (p>0.05) in the growth phase (days 22 to 42) in the absence of the arg supplementation. the supplementation of arg over of nrc recommendation during the starter phase may be necessary for the expression of the maximal weight gain potential in birds. no effect (p<0.05) of arg dietary supplementation was observed either on small intestine weight and length at any age. however, the duodenum villus:crypt ratio increased and the crypt depth decreased in the first week in response to increasing dietary arg. it is concluded that broiler arg dietary supplementation in the starter diet improved production performance and small intestine morphometry, especially in the first week.