Effect of photoperiod on follicular IGF-1 and oocyte quality independently of metabolic status in buffalo heifers

AbstractThe aim of this study was to determine whether buffalo heifers maintained at a constant live weight (LW) and body condition score (BCS) by a restricted diet show changes in reproductive function in response to changes in day length. Heifers were fed a low energy diet (86% daily intake recommended for the species) throughout the study, which involved an 8-week period of decreasing day length and a 7-week period of increasing day length. Weekly, LW, BCS and ovarian follicular/oocyte population were assessed. Blood and follicular fluid samples were taken at the time of ovum pick-up for hormone analyses and at 30-day intervals to measure metabolic substrates. Buffalo heifers maintained LW and BCS throughout the study and blood concentrations of the main metabolic hormones, such as GH, insulin, IGF-1 and thyroid hormones were not influenced by photoperiod. Likewise, there were no differences in metabolic substrates such as glucose, NEFA, triglycerides and HDL cholesterol, suggesting that the metabolic ...