Follicle development, endocrine profiles and ovulation rate in adult Merino ewes: effects of early nutrition (pre- and post-natal) and supplementation with lupin grain

Abstract

In adult ewes, we tested whether ovarian function, including the response to short-term supplementation, was affected by the nutrition of their mothers during the pre-/post-natal period. A 2!2 factorial design was used with nutrition in early life (low or high) and a 6-day supplement (with or without) as factors. All ewes received three prostaglandin (PG) injections 7 days apart, and the supplement (lupin grain) was fed for 6 days from 2 days after the second until the third PG injection. We measured reproductive and metabolic hormones, studied follicle dynamics (ultrasonography), and evaluated granulosa cell numbers, aromatase activity and oestradiol (E 2 ) concentrations in follicular fluid in healthy follicles at days 3 and 7 of supplementation. Ovulation rate was increased by 25% by exposure to high pre-/post-natal nutrition (1.5 vs 1.2; P!0.05), in association with a small decrease in FSH concentrations (PZ0.06) and a small increase in insulin concentrations (PZ0.07). The number of healthy antral follicles was not affected. Acute supplementation increased the number of granulosa cells (3.7G0.2 vs 3.0G0.2 million; P!0.05) in the largest follicle, and the circulating concentrations of E 2 (4.6G0.3 vs 3.9G0.3 pmol/l; P!0.05) and glucose (3.4G0.03 vs 3.3G0.03 mmol/l; P!0.01). Both early life nutrition and acute supplementation appear to affect ovulation rate through changes in glucose-insulin homoeostasis that alter follicular responsiveness to FSH and therefore E 2 -FSH balance.

The effect of short-term lupin (Lupinus angustifolius) feed supplementation on serum steroid hormones, insulin-like growth factor I, and ovarian follicular development and atresia in Merino ewes

“…The concentration of oestradiol-17β was suppressed in the control ewes on day 3 relative to day -4, but lupin did not affect this hormone concentration in this study, which is consistent with the observations of Somchit et al (14) after an intravaginal progestagen sponge treatment, but contrary to the studies of Viñoles et al (27), who observed increased concentrations of oestradiol using a different experimental model. It can be suggested that oestradiol is affected by IGF-I and that these hormones are reciprocally modulated, as observed in ewes in oestrous season (15,18,20).…”

The effects of diet and arginine treatment on serum metabolites and selected hormones during the estrous cycle in sheep

“…Not only different energy levels but also some components of the diet, such as protein or urea concentrations, or the addition of supplements (e.g., lupin grain and barley, and/or citrus-beet pulp concentrate) may affect reproductive function of livestock species [3,11,20,23,24]. Arginine (Arg), an amino acid and a possible supplement, has been recently reported to improve reproductive performance and the uterine environment for the maintenance of pregnancy in sheep [25][26][27][28].…”

The influence of postnatal nutrition on reproductive tract and endometrial gland development in dairy calves

“…Failure to detect changes in follicle numbers may have been due to the short duration on the diet or conducting follicle counts too soon after beginning estradiol treatment. Visible follicle numbers are an indicator of ovarian follicle reserve status in cattle (Ireland et al, 2009), and links between gestational nutrition and ovarian follicle reserve status are evident in sheep and cattle (Evans et al, 2012;Viñoles et al, 2013). However, no evidence exists to indicate that visible follicle numbers or the underlying ovarian follicle reserve can be adversely affected in the early postnatal period; no such detrimental effects could be detected in this work.…”