THE EFFECT OF ENERGY AND PROTEIN-INTAKE OF SOWS ON THEIR LONGEVITY - A REVIEW

The characterization of the effects of protein and energy intake of so ws on their longevity requires long-term experiments involving large n umbers of females. Results from the studies available show that sows a re culled mainly for reasons involving reproductive failure, locomotio n problems or poor lactation performance. Energy under-feeding during gestation is associated with lower body fat reserves at farrowing or a t weaning and generally return to oestrus is delayed and conception ra te is lower. On the contrary, over-feeding during gestation increases weight and condition of the sow at the end of pregnancy and this can a ffect the occurrence of farrowing and lactation problems and culling f or poor lactation performance or locomotion problems. During lactation , it seems that there are critical levels for energy and for protein b elow which weaning to oestrus interval, rate of return to oestrus and pregnancy rate are affected, especially in primiparous sows. This is t he main reason for early culling of sows. The mechanisms are not yet e lucidated, but the metabolic status or the status of body reserves of the sows at weaning seem to be involved. It is thus necessary to apply a feeding strategy adapted to each sow, in relation to its own level of production, its behaviour and the housing conditions, in order to m aintain body reserves within an optimal zone all along the reproductiv e life and to maximize its longevity.