Prevalence of Subclinical Mastitis and its Effects on Reproductive Performance in Dairy Cows during the Postpartum Period in Gasabo District, Rwanda

Mastitis is one of the most important diseases affecting production and reproductive efficiency of dairy cows. The objective of this study was to estimate the prevalence of subclinical mastitis (SCMA) and its effects on reproductive performance in postpartum dairy cows. In a cross-sectional survey, sample cows (n = 200) within their 10-40 days in milk from smallholder farms (n = 159) were selected and tested for SCMA using California Mastitis Test. They were classified into two groups: cows with SCMA (SCMA group, n = 101) and cows without SCMA (WSCMA group, n = 99). Reproductive performance including calving-to-first-oestrus interval (CFOI), calving-to-first service interval (CFSI), calving-to-conception interval Contribution/Originality: This study is one of very few studies which have investigated the occurrence of subclinical mastitis and its effects on subsequent reproductive performance of zero-grazed dairy cows under existing smallholder farming conditions. The study has also contributed to the existing literatures concerning mastitis infections in dairy cows. WSCMA maintenance and sustainability of a optimizing the reproduction efficiency crucial These findings give the animal health service providers a further opportunity to improve the udder health, welfare and performance of Rwandan smallholder dairy herds. The observed findings are in accordance with that previously reported in Turkey & Gunay, 2008). In this study, the NSC and CCI were found to be 1.9±0.1 services and 107.8±7.4 days, respectively, lower than 3.1±0.3 services and 143.5±11.4 days for cows with SCMA reported by Schrick et al. in Knoxville. This shows that increased NSC was reflected in the prolonged CCI indicating a shorter inter calving interval in cows without SCMA leading to a decrease in herd profitability and sustainability. This is because smallholder farmers being unable to ensure proper feeding practices, they have to wait for long periods for dairy cows to resume ovarian functions in the postpartum period. Furthermore, poor body condition of sampled dairy cows as a proxy of inadequate feeding practices may result in more cows having a negative energy and protein balance which increases the exposure of cows to udder infections and this results in poor reproductive performance of dairy cows. Therefore, it is desirable to farmers to ensure good hygiene and proper feeding practices in the transition period to prevent SCMA and consequently improve the reproductive performance of their dairy cows.