The effects of genotype and dietary lysine concentration on the production of weaner pigs

An experiment was conducted to evaluate the effects of genotype and dietary Lys concentration on the growth performance of weaner pigs. A total of 648 piglets were used. All piglets were offspring of Large White×Landrace dams sired by Hampshire (216), Pietrain (216), or Large White (216) boars. Piglets were weaned at 26.7±0.1 d of age at a mean weight of 8.3±0.1 kg and placed on trial for 20 d. Pigs were given ad libitum access to 1 of 3 diets differing in Lys concentrations: 18.2, 16.2, and 14.2 g/kg of Lys for high, medium, and low diets, respectively. Data were analysed as a 3×3 factorial arrangement with 9 replicates for each treatment with 8 piglets/replicate pen. No difference in feed intake was observed among genotypes. Genotype did not affect piglet growth rate in the first 2 wk of the trial. However, in the third week, Hampshire and Large White piglets grew faster than Pietrain piglets (454, 466, and 386 g/d, respectively; P<0.01). Pietrain piglets had a poorer feed conversion ratio (FCR) in week 3 (P<0.01) and overall (P<0.05) compared with Large White piglets. Piglets fed the medium diet were 0.6 kg heavier than piglets receiving the low diet (P<0.01) and 0.5 kg heavier than those receiving the high diet (P<0.05). Piglets ate less of the high diet in weeks 2 (P<0.05) and 3 (P<0.05) of the experiment. The FCR was greatest for piglets fed the low diet compared with piglets fed the medium and high diets (P<0.001) throughout the trial. In conclusion, this study indicated that, in the first 3 wk after weaning, Lys requirement is not substantially different among genotypes in the same environment with 16.2 g/kg being optimal across all 3 genotypes.