Source: National Mastitis Council
Almost three decades ago, a relationship between mastitis incidence and decreased reproductive performance was suggested, using mostly observational studies and qualitative literature reviews. In this study, Dolecheck et al. (2019) conducted a meta-analysis, combining data from multiple studies to quantitatively characterize the effects of mastitis on reproductive performance and to identify factors that interact with this relationship. Criteria for inclusion involved publications that evaluated the effects of naturally occurring clinical or subclinical mastitis on any measure of reproductive performance in dairy cattle, specifically evaluating the relationship between mastitis and:
- time to first service
- days open
- services per conception
- pregnancies per insemination at first service
- pregnancy loss
Exclusion criteria included language other than English, nonpeer-reviewed research, and papers that did not quantitatively report how mastitis incidence affected reproductive performance outcomes of dairy cattle, leaving 29 publications that contributed to this meta-analysis,
- Cows with mastitis pre-first insemination had, on average, an additional 13 days to first service compared with cows with no mastitis.
- Cows with clinical mastitis pre-first insemination had, on average, an additional 22 days open compared with cows with no mastitis.
- Cows with clinical mastitis at pre- or post-insemination had an additional 32 days open compared with cows with no mastitis.
- Cows with subclinical mastitis at pre- or post-insemination had an additional 20 days open compared with cows with no mastitis.
- Cows with mastitis pre-insemination had 0.46 more services per conception than cows with no mastitis.
- Cows with mastitis pre- or post-insemination had 0.72 more services per conception than cows with no mastitis.
- Cows that experience mastitis have, on average, 0.84 times the risk of conceiving at first service and 1.81 times the risk of pregnancy loss during gestation than cows that do not experience mastitis.
The results from this meta-analysis indicate that there is a quantifiable association between mastitis incidence and reproductive performance outcomes in dairy cattle and highlight the importance of mastitis prevention – not only for milk production – but also because it could affect reproductive outcomes.
Access the paper here.