Measuring backfat depth in sows to optimize feeding strategy

Abstract

Optimization of the reproductive performance of sows and their longevity requires a flexible feeding strategy, based on the control of body reserves, in order to avoidtheir excessive mobilisation or storage, which both have detrimental effects on reproduction. Pregnancy is the favoured period for the restoration of adequate body reserves. This requires to be able to quantify the amount of body reserves, to determine reserve targets adapted toeach physiological stage, and, finally, to derive nutrient requirement from these evaluations. An approach is proposed to quantify the energy requirements of gestating sows according to a factorial approach which takes into account the amount of body reserves to be rebuilt, on the basis of body weight and ultrasonic measurements of backfat depth. According to the information available, from experiments or on farms, targets of 16 to 19 mm of backfat depth (measured at the level of the last rib, 6.5cm from the midline) are recommended at weaning, andtargets of 19 to 22 mm are recommended at farrowing, independently of parity number, for Large White xLandrace crossbred females. In order to meet these objectives in practice, the most important is to favour high feed intake during lactation, and to adapt the feeding level during gestation according to the extent ofmobilisation during the previous lactation.