In a 3×2×2 factorial design, this study aimed to compare the lifetime performance of light (average of 7.1 kg), medium (average of 8.9 kg) or heavy (average of 10.4 kg) wean weight pigs when offered either a high (12 kg/pig) or low (6 kg/pig) allowance of starter diets post weaning and either a normal (DE 13.5 MJ/kg, total lysine 9.5 g/kg) or special (DE 14.5 MJ/kg, and total lysine 11 g/kg) finishing diet from 11 weeks of age. Over six time replicates, 720 pigs (Landrace×Large White) were randomly allocated at weaning (28±2 days of age), into groups of 20 which were balanced for sex. These groups were split into two groups of ten at 10 weeks of age (transferred to finishing accommodation). The 20-week weight (88.9 kg), ADG (702 g/day) and ADFI (1841 g/day) between wean and 20 weeks of age was greater for heavy weight pigs (Pb0.001) than for light weight pigs (82.2 kg, 692 and 1715 g/day respectively). However, on a per kg of body weight basis the feed intake/kg (39 g/day/kg) and growth rate/kg (14.8 g/day/kg) of light weight pigs was greater than that of heavy weight pigs (37.4 and 14.4 g/day/kg respectively). A high allowance of starter diets increased 10-week weight, ADG and reduced ADFI and FCR between weaning and 10 weeks of age compared with that of pigs offered a low allowance. There were significant interactions between starter diet allowance and finishing diet on finishing pig performance. The 20-week weight and ADG (11 to 20 weeks) of pigs offered a high allowance of starter diets increased when they were offered a special finishing diet compared with a normal finishing diet. However, that of pigs offered a low allowance of starter diets was lowered when they were offered a special finishing diet compared with a normal finishing diet. On the other hand, the ADFI of pigs offered a high allowance of starter diets was similar whether they were offered a normal (1977 g/day) or special (1976 g/day) finishing diet, whereas those offered a low allowance of starter diets had an increased ADFI (2091 g/day) when offered a normal finishing diet compared with a special finishing diet (1903 g/day). In conclusion, when the ‘nutrient density’ of the diet changed, in particular towards lower supplies, pig weight and growth rate were poorer. In addition light weight pigs at weaning were found to convert feed as efficiently as heavy weight pigs throughout their lifetime. Furthermore, their lifetime growth rate and feed intake on a ‘per kg of body weight’ basis was higher than that of heavy pigs.

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