The effect of high rape cake and phytase addition on nutritive value of diets for broiler chickens

Abstract

The aim of the study was to evaluate the effect of high rape cake (RC) content and microbial phytase added to phosphorus and calcium – deficient diet on nutritive value for broiler chickens .Two experiments were performed: a growth- on four groups of one-day-old broilers Ross 308,30 birds per group (6 replications of 5 birds) and digestibility experiment on 60 seven-day-old chickens divided into four groups of 20 birds (4 replications of 5 birds). The digestibility of starter diets evaluated on chickens at 7 days old and grower at 28 days. The diets used in digestibility tests were the same the growth trial. In growth experiment four diets were prepared for due periods: starters (1–21 day) and growers (22–49 day of chicken life). The control diet (SBM) did not contain RC, while experimental diets contained 15% (starters) and 20% (growers) RC of Lirajet cultivar. The experimental diet denoted RC HP had phosphorous (P) and calcuim (C) contents equal the control diet (phosphorus about 7.5g and calcium about 10g·kg−1), while diet denoted as RC LP contained less P and Ca (about 5.8g and about 6.8g·kg−1 respectively) than the respective RC HP and diet denoted RC LP+Phy was supplemented with enzyme preparation contained phytase at quantity (0.35g·kg1). Application of 15% of RC into starter and 20% into grower diets allowed to obtain similar body weight and feed efficiency, but had significantly unprofitable effect on fat digestibility in the first period of fattening, whereas improved of performance results in second period of fattening, had profitable effect on slaughter results and fatty acids composition of meat, but unprofitable on heart. Reduction of phosphorus and calcium contents significantly decreased body weight of younger chickens (pB0.05), and the application of phytase improved the digestibility of crude phosphorus, it did not have a significant effect on rearing and slaughter results. It is concluded that RCs can be used in broiler diets and phytase supplementation can beneficially influence the nutritional value of rape diet with lower content of P and Ca. Introduction of RC with 15% (starter) and 20% (grower) may also negatively affect the heart of birds fed pressed RCs.