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

This study assessed carry-over effects of energy level during the early antral phase and subsequent follicular phaseonfollicle recruitment andovulationrate.Gilts(n ¼45)werefedastandarddiettoalow(L,,1.2kgday � 1 )or high (H,,2.7kgday � 1 )levelduringtheearlyantral(luteal)phase,andsubsequentlyfedaHorLfeedlevelduringthefollicular phase, resulting in four treatment groups (HH, HL, LH and LL). Follicle size at the end of the luteal phase was greater for giltsfedahighfeedlevelpreviously(3.3vs3.0mm;P,0.05).Duringthefollicularphase,highfeedingincreased follicle size at Day 5 (6.9vs6.2mm; P,0.005) and plasma oestradiol concentration (P,0.05). Nevertheless, a low feed level during the luteal phase reduced ovulation rate (14.4vs13.2; P,0.05) and embryo number (12.6vs10.5; P,0.05), and this was not counteracted by feed level during the follicular phase. Plasma progesterone concentration after ovulation was lowerforLLgiltsthanforothertreatments(P,0.05).Theseresultsindicatethatundernutritionduringearlyantralfollicle development may have a residual effect on follicle recruitment and quality. Additional keywords: feed level, oestradiol, progesterone. Received 21 November 2011, accepted 7 February 2012, published online 2 March 2012