Influence of diet composition on weight gain and skeletal development of White Leghorn chicks reared to four weeks of age

Abstract

Experiments were carried out with White Leghorn chicks to study the influence of starting diet composition on weight gain and bone growth. Increasing dietary protein level from 15 to 21% had marked influence on weight gain, tibia length and to a lesser extent, tibia weight for chicks reared to 4 and 7 wk of age. Length of tibia plateaued at lower dietary protein levels than did growth suggesting that weight gain, at a young age, is as good if not a better indication of frame size than is a measure of tiba length. While levels of dietary energy ranging from 11.29 to 12.97 MJ kg−1 did reflect changes in weight gain and tibia length, such changes were small in comparison to those noted with changes in dietary protein level. Increasing supplemental methionine level from 0.05 to 0.15% and a 50% increase in the level of calcium and available phosphorus did not enhance weight gain or frame size over the control diet. Body weight gain for the young chick was not enhanced by high dietary levels of methionine and lysine. Thus, the suggestion of rapid feather development increasing the requirement for methionine or rapid weight gain increasing the requirement for lysine at this particular age is not valid. Key words: Chickens, skeletal growth, weight gain