A Retrospective Study on Dairy Cattle Mortality Patterns in Two Farms of South-eastern Botswana

Abstract

Generally, high mortalities of dairy cattle due to infectious and non-infectious diseases cause huge economic losses, unprofitability, and low productivity in the dairy industry. The present study aimed at determining the mortality rates, their causes, and risk factors among 1779 cattle at two dairy farms belonging to the Department of Agricultural Research, Botswana. An 8-year retrospective study was conducted using farm records during 2005-2012. Monthly and annual records of the farms were examined regarding the total dairy cattle population, sex, breed, age, cattle deaths, and causes of death. Mortality was calculated from the total cattle population and expressed as a percentage, and it was analyzed with respect to farm, breed, age, sex, year, season, and mortality causes. The overall mortality rate was 8.5%. The semi-intensively managed Farm II, as well as young stock (<12 months old), and males recorded significantly higher mortalities than their counterparts. Dairy crosses of pure exotic and indigenous Tswana cattle had higher mortalities than the Friesians and Jerseys, and the wet season accounted for over 70% of the total deaths. Only two years (2010 and 2012) out of the 8-year study period had a mortality rate < 5%. Notably, 28.1 % of mortalities with a known cause were due to heartwater disease (n = 57), but most deaths (62.3%) were due to unknown causes. In conclusion, to improve farm herd health and husbandry practices, more efforts should be devoted to preventing heartwater and mortalities in young stock and male animals, particularly during the hot-wet season.