The effect of grouping time and gonadotrophin treatment on lactational oestrus in multisuckled sows

Abstract

Loose housing of sows and their litters during lactation and removal of the need for early weaning offers substantial benefits for both animal welfare and cost of production. However, commercial application of such a system is dependent on achieving early and synchronous pregnancy in lactating sows. It is known that the occurrence of lactational oestrus can be facilitated by the combined stimuli of grouping, a high plane of nutrition and the presence of a mature boar. However these stimuli were only partially successful in inducing synchronised oestrus in an earlier experiment (Hatet et al, 1994). Administration of exogenous gonadotrophin to newly weaned sows has been shown to shorten and reduce variation in weaning to oestrus interval (Lancaster et al, 1985). The endocrine response of lactating sows to exogenous gonadotrophin has been shown to vary with stage of lactation (Britt et al, 1985). In this experiment, the role of these two factors in the successful induction of early and synchronous pregnancy in multisuckled sows was investigated.