Dairy cow longevity is a key aspect of achieving a sustainable dairy industry. The longer cows remain productive in a herd, the more profitable the herd will be because cows only become profitable after the third lactation, which is when the revenue from selling milk up to that point breaks even with all the costs associated with the rearing period.

Another aspect is the production level. Mature cows that have a third lactation or greater produce more milk and consequently more revenue compared to younger animals. In addition, cows are culled earlier than expected for health and welfare issues; therefore, improved cow longevity means improving cow welfare and vice versa.

The Industrial Research Chair in Sustainable Life of Dairy Cattle, led by Dr. Elsa Vasseur of McGill University, Quebec, focuses on cow longevity in relation to cow profitability and welfare. The chair is funded by Novalait, Dairy Farmers of Canada, Lactanet and the Natural Sciences and Engineering Research Council of Canada.

Current longevity status: Not that easy to decipher

Keeping cows longer in the herd and, consequently, increasing longevity has been identified as a problem in the industry. However, the longevity status is not always consistently reported by Dairy Herd Improvement (DHI) agencies or national databases. The first step of a research project led by Ph.D. student Gabriel M. Dallago was to develop a standard methodology to estimate longevity at a country level, allowing for the analysis of the status and trends over time of longevity and make a fair comparison between countries.

The longevity metric length of productive life, which measures the length of time between first calving and culling/death, was estimated using yearly official statistical publications from high-milk-producing countries. The data indicated that dairy cow longevity decreased over time in most countries evaluated (Figure 1).

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Linear trend of longevity

Once scientific evidence confirmed dairy cow longevity has decreased, the focus of the analysis shifted towards early life conditions potentially associated with longevity that could help increase longevity.

Early life indicators of longevity: A good head-start could go a long way

Early life has been mostly neglected when studying dairy cow longevity. The rearing period represents 40% of a dairy cow’s life if we assume a rearing period of two years and a productive life of about three years, which are both the current average in Canada. Yet most of the research on cow longevity completely overlooks the rearing period, instead focusing only on cows that have already calved for the first time.

The project evaluated the effect of birth ease, birth size and twinning on female Holstein cows’ longevity in Quebec dairy herds. Researchers found that small size at birth, complications in the birth and occurrence of twinning greatly increased the chances of an animal being culled earlier once she reached the productive life stage. This was one of the first scientific studies that showed the long-term effect of such early life conditions on female offspring, providing new insights for early selection of replacement candidates.

Higher cow longevity indicates the animal’s biological functions and health are not impairing the length of her life. From a welfare perspective, this means longevity could be seen as a global indicator of animal welfare. However, there is a lack of scientific knowledge about the relationship among welfare, longevity, profitability and productivity.

For more information and research results, visit CowLife McGill.

Dairy Farmers of Canada (DFC) invests in scientific research to foster innovation in the Canadian dairy sector. DFC supports research initiatives that benefit all Canadian dairy farmers and works in collaboration with its members and other sector partners to address priorities outlined in the National Dairy Research Strategy. The goals of this strategy are to increase farm efficiency and sustainability, enhance animal health, care and welfare practices, and strengthen the role of dairy in human nutrition and health, as well as in sustainable diets. Visit Dairy Farmers of Canada-Research for more information.