Undernutrition during early follicle development has irreversible effects on ovulation rate and embryos

Abstract

This study assessed carry-over effects of energy level during the early antral phase and subsequent follicular phase on follicle recruitment and ovulation rate. Gilts (n = 45) were fed a standard diet to a low (L, ~1.2 kg day–1) or high (H, ~2.7 kg day–1) level during the early antral (luteal) phase, and subsequently fed a H or L feed level during the follicular phase, resulting in four treatment groups (HH, HL, LH and LL). Follicle size at the end of the luteal phase was greater for gilts fed a high feed level previously (3.3 vs 3.0 mm; P < 0.05). During the follicular phase, high feeding increased follicle size at Day 5 (6.9 vs 6.2 mm; P < 0.005) and plasma oestradiol concentration (P < 0.05). Nevertheless, a low feed level during the luteal phase reduced ovulation rate (14.4 vs 13.2; P < 0.05) and embryo number (12.6 vs 10.5; P < 0.05), and this was not counteracted by feed level during the follicular phase. Plasma progesterone concentration after ovulation was lower for LL gilts than for other treatments (P < 0.05). These results indicate that undernutrition during early antral follicle development may have a residual effect on follicle recruitment and quality.