The effect of feeding strategy during rearing in a commercial setting on gilt body condition, lactation performance and culling rate in modern sows nursing large litters

In intensive pig herds, a large proportion of culled sows are first and second parity sows. However, this is economically unfavorable. Gilt body condition is important in relation to gilt performance and different feeding strategies have been suggested to promote the optimal gilt body condition at first service. However, intensive breeding has led to the need for more knowledge on the effects of feeding strategy during rearing in a commercial setting in modern sows nursing large litters >= 14 piglets. The objective of this study was therefore to study the effect of feeding strategy during rearing on gilt body condition and performance in the first lactation including, litter size and weight, milk production and composition, lactation feed intake and body mobilization, and culling rate postweaning. A total of 270 primiparous gilts of commercial Danish Landrace x Danish Yorkshire were fed two different feed levels (restrictive/semi ad libitum) during rearing in a group housing system and overall production performance was measured where 39 gilts underwent additional recordings. Results showed that there was a large variation in body condition within each of the feeding treatments. However, semi ad libitum fed gilts were fatter compared to restrictively fed gilts (P < 0.05) at first service. However, there was no effect of feeding strategy during rearing on the overall performance and culling rate postweaning. Results from gilts that underwent additional recordings showed that restrictively fed gilts produced litters with a higher birth weight than semi ad libitum fed gilts (21.2 kg vs. 18.6 kg; SEM 1.05; P <= 0.01) and semi ad libitum fed gilts had a higher percentage of milk protein on day 14 (4.8%) and 21 (4.6%) in lactation compared to restrictively fed gilts (4.1 and 4.2%; P < 0.01). In conclusion, increasing feed level during rearing in a commercial setting created a large variation in body condition, but semi ad libitum fed gilts were fatter at first service. This did, however, not affect the overall performance and culling rate of primiparous sows and it is therefore not economically favorable.