Effects of original source of dairy cows, season and age on milk production in Botswana

Abstract

The objective of the study was to determine the effects of animal and environmental factors on milk yield of Holstein dairy cows kept under intensive system in Botswana. A total of 768 monthly records of 27 Holstein cows of different parities were recorded over 5 years (2004- 2008) at Botswana College of Agriculture (BCA) dairy farm were used. The data was analyzed using General Linear Model of Statistical Analysis System. Higher (p<0.05) higher milk yield was recorded in spring (14.42±0.36 kg/d) than in winter (11.27±0.35 kg/d) with other seasons being intermediate. Third parity cows produced more milk (14.65±1.03 kg/d) than first calvers (11.60±0.66 kg/d). Although not significantly (p>0.05) different, the third parity corresponded with greater lactation yield than the others. Lactation length for third parity was 369.91±57.20days. Milk yield was significantly higher at 4 years of age (16.02±0.51 kg/d) than at 9 years (10.96±0.79 kg/d) and 10 years of age (5.85± 1.15 kg/d). Although the amount of milk produced by cows that were sourced from South African farms (15.26±1.52 kg/d) was higher than those sourced from Botswana College of Agriculture (11.89±1.16 kg/d) and Animal Production Research Unit (11.19. ±1.20 kg/d), these did not differ significantly. Farms should have more cows lactating in spring and at parities and ages that maximize milk yield.