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Centre for Genetic
Improvement of Livestock Breeding for Balance
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Selecting cows that
have the ability to eat more during early lactation may reduce
stress-related health problems and make for healthier animals, say
University of Guelph researchers.
Research associate Dr. Paul Boettcher, from the Centre for Genetic Improvement of Livestock (CGIL) and graduate student Bethany Collard are trying to uncover a relationship between a dairy cow's energy balance (the difference between energy consumed and energy used for milk production, growth and maintenance) in early lactation, and health and reproductive problems during the course of that lactation. "We hope to find a role for genetic factors in the relationship between energy intake and milk yield," says Collard. "If we could breed for a cow that eats more in early lactation, then maybe that cow could better withstand stresses and be healthier." Lactation: A Stressful Process Lactation is a stressful process for cattle, and stress appears to increase as milk production climbs. Although plenty of food is offered, many early lactating cows fail to eat enough feed to meet their energy needs. And if the energy a cow requires for milk production and tissue maintenance exceeds what she's consuming in her feed, she'll experience a negative energy balance. That could lead to health problems. However, increasing the feed energy concentration puts the cow at risk for digestive problems. "A negative energy balance causes a cow to mobilize the energy stored in her body tissues and lose weight," says Collard. "We want to see how cows normally deal with this stress and whether it predisposes them to health and reproductive problems." The researchers examined the daily production records in a Holstein herd at the Agriculture and Agri-Food Canada dairy research station in Lennoxville, Quebec. They measured daily feed intake and milk production, and periodically analyzed milk composition. The data was used to calculate the daily energy balance of the herd through a standard mathematical formula. The daily energy balance gives an indication of how long the cattle experienced a negative energy balance and also of the severity of the energy deficit. The team also looked at herd health and reproduction and recorded all observable problems. These records were compared with the calculated daily energy balance for any possible relationships. Results show that cows with a longer period of negative energy balance experienced greater health problems. They had higher incidences of locomotive problems like laminitis - inflammation of the soft tissues of the foot - and digestive problems. This research was sponsored by the Dairy Farmers of Canada through the Cattle Breeders Research Council and Agriculture and Agri-Food Canada. |
