Vegetable protein diets are adequate but broiler chicken prefer animal protein diets

Abstract

Vegetable protein (VP) diets are cheaper and safer than animal protein (AP) diets. Performance on VP diets may be similar to that on AP diets, however, the former tend to contain anti-nutritive factors and may be unbalanced in nutrients. In this study, a 2x2x2 factorial experiment, we investigated the performance of broiler chickens on AV vs AP diets, with or without microbial enzyme supplements. Three hundred sixty male and the same number of female broiler (day-old Ross-308) chicks were randomly allocated to 8 treatments, each replicated 6 times, in floor pens. In a sub-experiment, another sixty chicks (mixed-sex) were reared to 14 days, at which point they were randomly allocated to VP or AP diets, both supplemented with microbial enzymes, each replicated 6 times. These birds were reared on grower diet and on finisher diet during 14-21 and 21-28 days of age, respectively. Data were analysed by GLM of MINITAB. In the main experiment, up to 42 days of age, feed intake and live weight were similar on VP and AP diets; male birds consumed more (P<0.001) feed than females but in the finisher phase males were more efficient (P<0.022) in feed utilization. In the grower phase, the chicks preferred the AP diets (62.0 %) to VP diets (38.0%) while selection in the finisher phase was 81.9 and 18.1 %, respectively. This study showed that broiler chicks could perform to optimum on VP diets but when given a choice, the birds preferred AP diets. The cause of the strong aversion to the VP diets is unknown and warrants investigation.