Variation in plasma luteinising hormone levels, return to ostrus and ovulation rates in sows on different planes of sorghum based rations

Abstract

Twenty one gilts were fed two levels of lactation rations nested within two levels of gestation rations to evaluate the effect of level of feeding on reproductive parameters. Twelve sows were given each of two levels of feeding (High (H) and low (L)) during gestation. The H-sows were subdivided into two groups one of which received the high level (HH) while the other received the low level of feeding (HL). The L sows were similarly subdivided to form 2 groups of sows, the first of which received the level (LH) while the other received the low level (LL) of feeding, respectively. Production of porcine luteinising hormone (pLH) during lactation, and ovulation parameters, in the subsequent gestation, was assessed. Sows fed high (H) had significantly better (P<0.05) ovulation parameters than the low fed sows (L). The ovulation for high fed and low fed sows were 14.2 and 13.6 ova released, the ovary weights were 7.4g and 6g for high fed and low fed sows, respectively. However, gestation level of feeding did not influence the size of the corpora lutea. Lactation level of feeding had a significant (P<0.05) effect on ovulation (7.2 and 6.4 ova) and corpora lutea size (0.49g and 0.56g). Subsequent ovary size was not affected by level of feeding during lactation. There was an interaction between level of feeding during gestation and that during lactation with sows changing from high to low performing poorest among all the four feeding levels. Overall the previous gestation's level of feeding had an over-riding effect on these parameters mediated by its effect on plasma levels of pLH in the previous lactation. Based on results obtained its concluded that level of feeding during gestation was more likely to influence subsequent sow reproductive performance by specifically affecting ovary function as well as early embryo development.