Effect of beta-carotene Supplementation on fertility of dairy Cattle in Kenya

Abstract

A field feeding trial was conducted to determine the effect of B-carotene supplementation on the fertility of dairy cows, and disease resistance in cows and their calves. Using stratified randomization according to parity and milk yield, 95 ayrshire cows were allocated to treatment in a randomized complete block design in three Agricultural Development Corporation (ADC) farms viz: Olngantongo, Katuke, and Zea in Trans Nzoia District of Kenya. Concentrate feeds, were formulated, one to supply 75 mg/kg of B-carotene and the other to supply no B-carotene,for the test and control group, respectively. In addition, both feeds were fortified with 9.38 mg/kg of vitamin E. The feeding trial commenced two weeks prepartum and continued for three months postpartum. Blood samples were taken to monitor plasma B- carotene status. Blood samples for B-carotene analyses were taken 14 days prepartum, and then day one, and 14-90 days post-partum depending on time of heat, to show the B-carotene trend. Pasture and concentrate feed samples were also taken to determine the B-carotene intake. Animals were observed for puerperal conditions, oestrous intensity, and all dates of heat and insemination were recorded. Pregnancy diagnosis was done 70 days post-insemination. Data were collected to determine cows' fertility performance, mastitis, calf diarrhoea, milk yield, and butterfat. B-carotene supplementation improved (P < 0.05) the conception rate, insemination index, and oestrous intensity while service period, uterine involution and incidence of mastitis, metritis, retained placenta, and calf diarrhoea were not affected (P > 0.05). The improvement of some of the fertility indicators suggests that B-carotene supplementation is beneficial to dairy cattle especially under conditions where the pasture supplies less B-carotene to the cows than was the case at the time of this study.