Influence of nutrient density on feed consumption, weight gain and gut capacity of broilers, leghorns and turkeys reared to 26 days of age

Abstract

Four levels of dietary fibre and fat, in a factorial arrangement, were added to diets for 5-day-old male broilers, Leghorns and turkeys for a 21-day experimental period. Broilers gained more weight, but had a poorer feed:gain ratio than did turkeys, while the Leghorns were vastly inferior. The turkeys had a significantly higher concentration of carcass protein and lower concentration of carcass fat than did the other two species. Higher dietary fat levels markedly increased weight gain of the broilers, while the turkeys and Leghorns were little affected. Higher levels of dietary fibre reduced linearly the body weight gain of the broilers and turkeys, but only at the 30% level of inclusion was weight of the Leghorns reduced. Of the three species Leghorns had the largest gut size per unit body weight, while the broiler was significantly larger than the turkey. Dietary fat level had no effect on gizzard weight of Leghorns, while broiler gizzard weight was significantly increased and that of turkeys significantly reduced with increased fat levels. Higher dietary fibre levels increased gizzard weight for all three species. Increased dietary fat levels increased intestinal weight, while increased dietary fibre decreased intestinal weight for all three species. However, while intestinal length per unit body weight differed between species, it varied little with changes in dietary fat level. Specific weight of the diet, on a dry weight basis, decreased with the addition of both fat and fibre. Turkeys ate more volume of feed than did the broilers, even though their overall feed intake, per unit body weight, was less. This is explained by the increased intake in feed volume of the turkey with the higher fat diets. Rate of food passage was similar for the broilers and Leghorns, but was significantly faster for the turkeys.