Biological response of broiler chickens fed peas (Pisum sativum L.) expressing the bean (Phaseolus vulgaris L.) α‐amylase inhibitor transgene

Abstract

AbstractThe nutritive value of transgenic peas expressing an α‐amylase inhibitor (α‐Ai1) was evaluated with broiler chickens. The effects of feeding transgenic peas on the development of visceral organs associated with digestion and nutrient absorption were also examined. The chemical composition of the conventional and the transgenic peas used in this study were similar. In the two feeding trials, that were conducted normal and transgenic peas were incorporated into a maize–soybean diet at concentrations up to 500 g kg−1. The diets were balanced to contain similar levels of apparent metabolisable energy (AME) and amino acids. In the first trial, the birds were fed the diets from 3 to 17 days post‐hatching and with levels of transgenic peas at 250 g kg−1 or greater there was a significant reduction in body weight but an increase in feed intake resulting in deceased feed conversion efficiency. In the second trial, in which the birds were fed diets containing 300 g kg−1 transgenic peas until 40 days of age, growth performance was significantly reduced. It was also demonstrated that the ileal starch digestibility coefficient (0.80 vs 0.42) was significantly reduced in the birds fed transgenic peas. Determination of AME and ileal digestibility of amino acids in 5‐week‐old broilers demonstrated a significant reduction in AME (12.12 vs 5.08 MJ kg−1 DM) in the birds fed the transgenic peas. The AME value recorded for transgenic peas reflected the lower starch digestibility of this line. Ileal digestion of protein and amino acids was unaffected by treatment. Expression of α‐Ai1 in peas did not appear to affect bird health or the utilisation of dietary protein. However, the significant reduction in ileal digestion of starch in transgenic peas does reduce the utility of this feedstuff in monogastric diets where efficient energy utilisation is required. Copyright © 2006 Society of Chemical Industry