Influence of nutrition, body condition, and metabolic status on reproduction in female beef cattle: A review

Nutrition is of fundamental importance in reproductive function of female beef cattle. Nutrition de-termines live weight (LW) and body condition score (BCs) and both were found more than 50 years agoto underpin fertility in pubertal heifers and postpartum cows. In heifers, LW at weaning and averagedaily gain (ADG) after weaning determines age and LW at puberty, and subsequent lifetime fertility. Incows, BCS at parturition is the most important factor that determines the period to re-conceptionpostpartum. Nutrition establishes systemic metabolic homeostasis. Metabolic hormones such as leptin,IGF1 and Ghrelin act as signaling factors that regulate activity of GnRH neurons in the hypothalamus. Therelease of GnRH and function of the reproductive endocrine system is determined by the balance ofpositive signals (IGF1, leptin) and negative signals (Ghrelin) at GnRH neurons. Nutritional factors alsodirectly influence ovarian follicles, oocytes and embryos. Saturated fatty acids (FAs) are detrimental tooocytes and embryos whilst unsaturated FAs may be beneficial. The ratio of FAs (saturated, mono-unsaturated, polyunsaturated) is likely the key to optimal reproductive function. Nutrition controls thelevels of metabolic hormones (leptin, IGF1, Ghrelin) and metabolic factors (FAs) and both have majorroles in reproduction in female beef cattle.