Effect of dietary regime and group structure on pig performance and the variation in weight and growth rate from weaning to 20 weeks of age

Abstract

This study aimed to improve lifetime pig performance and reduce variation in growth rate between pigs using managerial and nutritional practices. The experiment (2 × 2 × 2 factorial) compared uniform and mixed weight grouping (SD of weight in group at weaning 0.7 kg and 1.6 kg respectively), offering pigs a high (12 kg) or low (6 kg) allowance of starter diets post weaning and either a special (DE 14.5 MJ/kg, total lysine 11 g/kg) or normal (DE 13.5 MJ/kg, total lysine 9.5 g/kg) finishing diet. Over six time replicates, 960 pigs (Landrace × Large White) were randomly allocated at weaning (28 ± 2 days of age) into groups of 20 according to weight and sex and these groups were split at 10 weeks of age (transfer to finishing accommodation) into two groups of 10. Finishing diet was offered from 11 weeks of age. The FCR of pigs (wean–7 weeks of age) was significantly (P < 0.001) improved when a high allowance of starter diets was offered (1.25) compared with a low allowance (1.34). However, between 7 and 10 weeks of age a high allowance of starter diets only improved the FCR of pigs in uniform groups. A special finishing diet improved (P < 0.05) the ADG of pigs during finish (11–20 weeks of age) (860 g/day) compared with a normal finishing diet (827 g/day). The coefficient of variation (CV) of weight at 10 and 15 weeks of age was significantly lower (both P < 0.001) for pigs in uniform weight groups compared with that of pigs in mixed weight groups. A three-way interaction was observed on the CV of ADG (weaning–20 weeks of age) (P < 0.05) and FCR (11–20 weeks of age) (P < 0.01). The lowest CV of ADG (weaning—20 weeks of age) and lowest FCR (11–20 weeks of age) were achieved when uniform grouped pigs were offered a high allowance of starter diets post weaning and a special finishing diet (0.117 and 2.43 respectively) whereas the highest values were observed when mixed weight groups of pigs were offered a low allowance of starter diets post weaning and a normal finishing diet (0.162 and 2.70 respectively). In conclusion, although uniform grouping appears to aid the reduction in slaughter weight variation and improve FCR, its effect is dependent on dietary regime. Overall, from weaning to 20 weeks of age, uniformly grouped pigs offered a high allowance of starter diets post weaning and a special finishing diet had a low CV of ADG and the most efficient FCR.