POSTPARTUM BLOOD METABOLITE CONCENTRATIONS IN GRAZING SANGA AND FRIESIAN- SANGA COWS F. Y. Obese, G. B. Martin, M. A. Blackberry, J. K. Damptey and C. M. Vuvor Joint Collaboration between the Department of Animal Science, University of Ghana and Laboratory of Prof. Graeme Martin, Institute of Agriculture, University of Western Australia UNIVERSITY OF GHANA

INTRODUCTION Crossbreeding programmes involving the exotic Friesian and the indigenous Sanga breed have been embarked upon in Ghana in a bid to increase size and improve milk yield. Friesian–Sanga crossbred has had a major problem with extended postpartum anoestrus, probably exacerbated by under-nutrition during extensive grazing on natural pasture.

OBJECTIVE Tested whether the Sanga and Friesian-Sanga breeds vary in the circulating concentrations of metabolites that mediate the effects of nutrition on reproductive function.

MATERIALS AND METHODS Blood samples were collected from weeks 1 to 9 postpartum from two herds comprising; 16 Sanga, and 16 Friesian–Sanga crossbred cows. Cows were grazed separately on natural pastures. Cows milked 2x daily during the rainy season and once daily during the dry season. Cows were weighed monthly. Body condition score was determined weekly.

MATERIALS AND METHODS While at pasture, cows were monitored for oestrus by visual observations, at least 2x per day. Resumption of postpartum ovarian activity was determined from changes in plasma concentration of progesterone (≥1ng/mL). The concentrations of insulin, IGF-I, leptin, glucose, total cholesterol, total protein, urea and creatinine were measured in the plasma.

Fig. 1. Changes in body condition score in Sanga and Friesian-Sanga cows

Fig. 2. Changes in daily milk yield in Sanga and Friesian-Sanga cows

Fig. 3. Changes in plasma concentrations of IGF-I in Sanga and Friesian-Sanga cows

Fig. 4. Changes in plasma concentrations of Insulin in Sanga and Friesian-Sanga cows

Fig. 5. Changes in plasma concentrations of Leptin in Sanga and Friesian-Sanga cows

Table1. Blood metabolite concentrations in Sanga, and Friesian-Sanga crossbred cows (Mean ± SE) during week 1 to 9 postpartum _______________________________________________________________________ Blood Metabolite Breed ___________________________________ Sanga Friesian-Sanga _________________________________________________________________________ IGF-I (ng/mL) 18.1 ± 0.73 14.3 ± 0.73 Insulin (µU/mL) 4.20 ± 0.14 3.96 ± 0.14 Leptin (ng/mL) 1.12 ± 0.01 0.96 ± 0.01 Glucose (mmol/L) 3.68 ± 0.05 3.34 ± 0.05 Cholesterol (mmol/L) 2.57 ± 0.08 2.43 ± 0.09 Total Protein (g/L) 83.5 ± 1.11 84.4 ± 1.18 Urea (mmol/L) 6.55 ± 0.28 11.13 ± 0.29 Creatinine (mmol/L) 97.6 ± 2.58 57.8 ± 2.75 ________________________________________________________________________

7/16 of Sanga =44% failed 9/16 =56% 6/16 of Friesian-Sanga= 38% failed 10/16 =62% Fig. 6. Resumption of ovarian cyclicity in Sanga and Friesian-Sanga cows

CONCLUSION The data suggest that, under grazing conditions; Sanga breed is better able to avoid the effects of negative energy balance and maintain metabolic homeostasis than the Friesian-Sanga crossbred during the postpartum period. These metabolic differences between the genotypes probably account for the earlier resumption of ovarian cyclicity of the pure Sanga than in the Friesian–Sanga crossbred.