Controlling lactation oestrus: The final frontier for breeding herd management

Abstract

Lactation anoestrus limits the flexibility of modern pig production systems such that any increase in lactation length reduces farrowing frequency, and thus profit. This review focuses on post-partum development of the sow's reproductive system, the physiology of lactation anoestrus and how it can be overcome, as well as the fertility of sows mated while lactating. The propensity for sows to ovulate spontaneously while lactating is high (24-31%), and a high proportion of sows will ovulate rapidly and synchronously in response to combinations of altered suckling (split weaning, interrupted suckling), daily boar contact, exogenous gonadotrophins, and group housing. The apparent ease with which lactation anoestrus can be overcome represents an opportunity to uncouple sow mating from weaning, thus reducing the impact of lactation length on productivity. This is especially true when considering the benefits of the described stimulation methods on the reproductive performance (i.e., shorter weaning to oestrus intervals and higher litter sizes) of the low proportion of sows that maintain lactation anoestrus.fertility, lactation oestrus, sow[The] capacity to uncouple sow mating from weaning[provides] a significant opportunity for producers to maintain sow annual production despite increasing lactation lengths.

Recent advances in pig reproduction: Focus on impact of genetic selection for female fertility

“…Based on recent Dutch and Australian studies van Wettere et al. () concluded that “the capacity of modern sows, of various genotypes, to spontaneously ovulate during a 21‐ to 28‐day lactation period is clearly high,” although most likely, spontaneous ovulations will take place more towards the end of a 28‐day lactation.…”

Reducing Weaning Stress in Piglets by Pre-Weaning Socialization and Gradual Separation from the Sow: A Review

“…There are two main reasons why IS has been examined over the years. The first reason is to induce estrus in lactation, allowing for mating in lactation, which presents an opportunity to uncouple estrus cycling from weaning, therefore extending the weaning age (e.g., to 5-8 weeks) without decreasing the number of litters produced per sow per year ( [146,147]; for reviews). Second, IS has also been studied as a strategy to promote supplementary (e.g., creep) feed intake in piglets during lactation.…”

“…Reducing the suckling stimulus in a controlled manner (i.e., not relying on sows to regulate nursing frequency) by subjecting litters to interrupted suckling techniques such as IS has been used on its own or in combination with the techniques mentioned above to increase gonadotrophin release and can result in a 100% occurrence of estrus in lactation. However, the results are still highly variable, most likely due to factors such as sow parity, metabolism, litter suckling intensity, seasonal effects, and litter creep feed intake [147,150].…”

Selecting the optimal strategies when using nurse sows for supernumerous piglets

“…Using sows as nurse sows increases the likelihood that they exhibit a lactational oestrus caused by changes in litter dynamics during lactation. Lactational oestrus can be induced by intermittent suckling (Langendijk et al, 2009; Soede et al, 2012; van Wettere et al, 2017) or by the transfer of a sow to a new pen (van Wettere et al, 2017). When nurse sows are transferred to a new pen, there is typically a period of time when there is no nursing activity.…”