Poor fertility is the most common reason for culling on most dairy farms and the CAFRE dairy herd is no exception to this. Fertility has declined as milk production potential has increased, but this begs the question, as to cause and effect. “Does high milk production result in poor fertility”? Fertility is a multi-factorial trait and its deterioration over time has been caused by a number of genetic, environmental and management factors and their interactions, making it very difficult to determine the exact reason(s) for the decline in fertility over recent decades. However, maiden heifers with similar genetics to their mothers have high conception rates, (generally 60%+), compared to cows, where conception rates <40% are common. Hence, genetics per se are not the issue. It may be surmised that the demands of high milk production negatively impact a number of pathways that reduce the likelihood of pregnancy being established.
Herd longevity is closely associated with both profitability and environmental sustainability. By improving fertility, the number of replacement heifers required decreases. (Replacement heifers represent the second largest cost on a dairy farm after concentrates). The number of replacements needed to sustain cow numbers also has a big impact on the overall emissions of greenhouse gases and also on ammonia production.
With increasing emphasis now being placed on non-production traits in bull pta figures, such as longevity, fertility and somatic cell count, there is evidence that fertility has turned the corner and is generally improving, if only slowly. However, as non-production traits have low heritability in the next generation, improvements will be slow to manifest themselves in measurable outcomes. There is evidence from the CAFRE dairy herd that bulls with high fertility figures do produce daughters that have better conception rates and improved calving interval, compared to bulls with poorer fertility figures.
There is no magic formula that will lead to better fertility in dairy cows, but there are many good management practices that when added together, can make a big difference to overall fertility levels both in the short term and the longer term. See the pdf’s below or click on the following links for more information on management practices adopted within the CAFRE dairy herd which contribute to maintaining and improving the fertility of the herd: