Effects of feeding frequency during lactation in primiparous sows on reproduction performance and diurnal rhythm of endocrine profiles at the weaning-to-ovulation interval

Whether the diurnal rhythm of endocrine hormones in sows are affected by feeding frequency remains to be studied. The present study was conducted to investigate the effects of feeding frequency during lactation in primiparous sows on the diurnal rhythm of glucose, insulin, cortisol and luteinizing hormone (LH) levels during the weaning-to-ovulation interval, as well as their reproductive efficiency. Sixty primiparous Landrace x Yorkshire sows were randomly assigned into two groups during lactation: one treatment received feed twice daily and another treatment three times daily. The results showed that feeding the sows three times daily during lactation decreased weaning-to-estrus interval and lowered the return to estrus rates when compared with feeding the sows twice daily. We observed the diurnal rhythms in glucose, insulin and cortisol level in sows at the weaning-to-ovulation interval, and the daily variations were affected by the feeding frequency during lactation and the LH surge. Our results indicated that the alternation of reproductive performance of sows by feeding frequency may mediate by its effects on the diurnal rhythm of glucose, insulin and cortisol.