Nutrition, metabolic profiles and puberty in Brahman (Bos indicus) beef heifers.

The aim of the present study was to gain an improved understanding of the relationships between body weight (BW), body condition (BCS), and metabolic homeostasis, and the attainment of puberty in Brahman heifers in a subtropical environment. Brahman heifers (200±3kg BW; 2.00±0.0 BCS) were assigned to a moderate nutrition (MN, n=11) or improved nutrition (IN, n=11) treatment from 11 to 23 months-of-age. The heifers were monitored at regular intervals for circulating concentrations of GH, IGF-1, insulin, glucose and leptin, and ovarian follicular activity was recorded until the first ovulation. From approximately 16 months of age, heifers on IN had a greater (P<0.01) BW and greater (P<0.01) BCS than heifers on MN. Heifers on IN also had a generally improved metabolic homeostasis than heifers on MN which was reflected in greater circulating concentrations of insulin, leptin, IGF-1 and glucose in the former heifers. Heifers on IN attained puberty between 21 and 23 months of age and only one heifer on MN had reached puberty by 23 months. This study has shown that Brahman heifers on IN had a metabolic homeostasis that was supportive of reproductive maturation and puberty.