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.
E Magowan , MEE Ball, KJ McCracken, VE Beattie, R Bradford, MJ Robinson, M Scott, FJ Gordon and CS Mayne, 2011. Livestock Science, 136: 216–224.