An estimate of the leucine requirement for young pigs

Abstract

AbstractThree pig trials were done to estimate an objective requirement of young (10 to 20 kg) pigs for leucine (Leu). Within each trial, four or five replicates of five pigs were given ad libitum access to their experimental diet for a period of 21 (trial 1) or 19 days (trials 2 and 3). A Leu-deficient diet (177 g crude protein per kg) based on maize, peanut meal, lactose, sucrose, dried whey, maize starch, soya-bean meal (SBM), and gelatin was used in these trials. Trial 1 showed that the Leu-deficient diet supplemented with Leu produced responses in weight gain and gain/food ratio that were similar (P > 0·10) to that obtained from a maize-SBM-whey positive-control diet containing 213 g crude protein (CP) per kg. Trials 2 and 3 utilized graded levels of crystalline L-Leu to determine the minimal Leu requirement in young pigs. Both trials showed linear increases (P < 0·05) in weight gain and gain/food as a result of Leu supplementation. Closer examination of the data revealed no significant change in gain/food or PUN responses above 11·2 g/kg total Leu in trial 2, or in weight gain or PUN values above 11·5 g/kg total Leu in trial 3. These data indicate that the Leu requirement of young pigs is probably not greater than 11·5 g/kg (10·5 g/kg true digestible), which equates to approximately 0·72 g true digestible Leu per MJ metabolizable energy. The ideal ratio of Leu to Lys appears to be close to 1: 1 for pigs in the weight range of 10 to 20 kg.