Influence of Level of Dietary Fat on the Growth of Dwarf Chickens

Abstract

Two strains of chickens, dwarf (dw) and nondwarf (Dw+), and three levels of supplemental dietary fat (none, moderate, and high) were included in a 2 × 3 factorial design to study the effect of dietary fat on growth. The lowered tibial ash, calcium, and phosphorus contents at 4 weeks of age and zinc content at both 4 and 8 weeks of age observed in the dwarf birds may reflect a predisposition to bone abnormalities. Improvements in weight gain (0 to 4 weeks) in response to supplemental dietary fat were observed in all birds but were less pronounced in the dwarfs. At 4 weeks of age, the dwarf birds consuming the fat-supplemented diets had mineral contents of their tibia consistently lower than those of their dwarf counterparts fed the basal diet. At 8 weeks of age, there were no differences between strains in bone mineralization, but the 0 to 8 week weight gains were better for both strains fed the diet supplemented with a moderate level of fat. It appears that optimal bone mineralization of dwarfs to 4 weeks of age occurs at a lower level of dietary fat than that for nondwarfs. Beyond 4 weeks of age, a moderate level of supplemental dietary fat yielded optimal weight gains in both strains of birds.