Genomic study looks to improve feed efficiency in dairy cattle

3-31-14 cows_ecoliWith an average adult dairy cow weighing in at about 1,500 pounds, it’s no surprise it takes a lot of feed to keep them at a healthy weight. In Michigan alone, the home to about 400,000 dairy cows, it’s estimated to cost about $5 per day per cow to keep herds well-nourished and producing enough milk to meet consumer demand. This equates to approximately $730 million each year.

However, Michigan State University (MSU) AgBioResearch scientists are working to bring that cost down by combining genomics and nutrition science in an effort to breed cows that require less food to produce the same volume of milk.

Following the Human Genome Project, which also had numerous discoveries for animal science, livestock breeders have taken advantage of the wealth of dairy cow genetic information to select bulls capable of passing along the most desirable traits to their progeny. As explained in a recent article, these include such characteristics as size, milk production and disease resistance.

Genetically selecting bulls for feed efficiency, however, has been more difficult in the past as cows on commercial dairy farms are fed in groups and acquiring data on how much an individual animal consumes is nearly impossible.

But now genomics is allowing researchers to study the DNA of university dairy herds and allowing them to look for genetic markers for feed efficiency, which they will then deliver to the industry.

This research is part of a five-year multi-institutional grant from the U.S. Department of Agriculture (USDA) National Institute of Food and Agriculture, and involves collecting feed intake data from 7,000 cows from university herds in Michigan, Wisconsin, Iowa, Florida, Maryland, Virginia, New York, Alberta, Scotland and the Netherlands. The team identified which animals ate less than expected on the basis of their production and takes genetic samples for analysis.

Most samples are being analyzed by GeneSeek (a subsidiary of Neogen), and the data is submitted to the USDA Animal Improvement Laboratory in Beltsville, Maryland, where much of the genomic data on the U.S. dairy herd is kept. The lab staff processes the samples and sends back the list of individual elements—called single-nucleotide polymorphisms (SNPs)—that make up each animal’s genome. Statistical modeling can be used to determine which SNPs are related to feed efficiency.

So far, 5,000 cows have been genotyped with the remaining 2,000 still being analyzed. Feed intake data is also being collected on 1,000 additional cows. Once the process is complete, a final equation for feed efficiency will be ready to report to the industry.

Extension and educational tools to communicate these findings to breeders, producers and dairy nutritionists are also being prepared, including state-of-the-art web-based tools to analyze feed efficiency and grouping practices on commercial farms.

The article states that results of this effort will reduce feed costs without sacrificing production. For example, an Australian team did a similar project and showed that it is reasonable to believe that feed costs could be reduced by 50 cents per cow per day, or about 10% of the current daily average cost.

In all, this research will give breeders one more tool for selecting bulls to maximize yields and the results will most likely be ready for industry wide implementation within two years.

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