Effect of long-term or short-term supplementation of high energy or high energy-protein diets on ovarian follicles and blood metabolites and hormones in ewes

•Feeding program affected double ovulation rate and serum metabolites of cyclic ewes.•High energy diets change blood levels of glucose, insulin and oestradiol of ewes.•The period of diet treatment could be reduced to 6 days just before ovulation time.•High energy-protein diets had adverse effect on ovulation rate and serum metabolites.