The utilization of rye by growing chicks as influenced by calcium, vitamin D3 and fat type and level. Poultry Sci

ABSTRACT Four experiments were conducted with growing chicks to study the effects of feeding rye and wheat diets supplemented with different calcium levels, two types and two levels of fat, and increasing levels of vitamin D3 and to study the interrelationships of these dietary ingredients on chick performance. In Experiment 1, feed conversion efficiency was reduced to a much greater extent (10 % vs. 1%) when tallow replaced soybean oil in a rye-based diet containing only.6 % calcium compared to a wheat-based diet. When the dietary calcium was increased to 1.1 % the replacement of tallow by soybean oil resulted in only a small reduction in feed efficiency for chicks fed either the rye- (3%) or wheat- (1%) based diets. The retention of fat, particularly tallow, was depressed in rye as com-pared to wheat-fed birds. Fat retention was also influenced by calcium levels. Increasing the dietary calcium from.6 to 1.1 % improved tallow (16%) and depressed (7%) soybean oil retention in rye-based diets, whereas in wheat-based diets the retention for both fats was slightly decreased. Experiment 2 showed that the efficiency of utilization of rye diets containing 7.5 % tallow was improved by 10 % when the level of dietary calcium was increased from.6 to 1.1 % while the corresponding improvement in similarly formulated wheat diets was only 1%. The improvement o