Blood metabolite profiles in cycling and non-cycling Friesian-Sanga cross-bred cows grazing natural pasture during the post-partum period.

An experiment was conducted to investigate the effect of plasma concentrations of the metabolic hormones [Growth hormone (GH), insulin and insulin-like growth factor -I (IGF-I)] and nutritional metabolites (Glucose, cholesterol, total protein, albumin, globulin, urea and creatinine) on the resumption of post-partum ovarian activity in sixteen Friesian-Sanga cows grazing extensively on native grassland. Blood samples were taken from cows from week 1 to 16 post-partum. Cows were classified as having resumed ovarian activity when a plasma progesterone concentration of ≥ 1.