Variation in milk proteins across a contemporary group of Holstein cattle

View the project final report

• 2015 annual report
• 2016 annual report

Commodities

• Animals: bovine
• Animal Products: dairy

Practices

• Animal Production: animal protection and health, livestock breeding

Recently, emphasis has been placed on the value of milk proteins. As individual components, milk proteins are one of the most well studied animal products but there is little data on the variation of the milk protein fractions between cows. Most commonly, milk protein is quantified as crude protein, a measure of the total nitrogen content of milk. This measurement includes protein and non-protein nitrogen sources and is an inaccurate way to assess true protein. At this time, milk sales and genetic selection for milk proteins are based on crude protein and as a result, the true variation in milk protein fractions gets confounded, making genetic selection ineffective. Research on true protein variation would be valuable in terms of determining if genetic selection for individual proteins is realistic in addition to improving production efficiency on a farm and industry level. Selection for superior production of certain milk proteins would allow farmers to increase profitability by matching market demand and impacting human health via increased milk protein consumption. The objective of this study would be to determine the amount of variability in milk protein fractions across a contemporary group. The key components would involve obtaining milk samples to chemically fractionate and determine the amount of variation between cows. To ensure our findings have an impact on the community, we will work with Pro-Dairy to host a meeting with producers, fellow veterinarians and dairy cooperatives to present our findings and make recommendations for effective selection to increase milk protein yields.

Our study will assess the amount of variation in milk protein fractions within a similar managed contemporary group that is reflective of the US Holstein population and whether or not this variation can be utilized to improve protein yields and efficiency on a cow level, on a farm level, and on an industry level. In order to answer this question, we will perform a 1,500 cow study in which we obtain milk samples and use standard fractionation techniques to quantify the fractions of casein, alpha-lactalbumin and beta-lactoglobulin on an individual cow basis. Once the protein fractions have been quantified, we will determine the extent of variation across the sample population. To minimize external variables, the cows will be multiparous, from one farm and in the same stage of lactation. Three samples will be taken from each cow on three different occasions and then pooled. In addition, 15 fresh cows will be chosen randomly and sampled once a month throughout their lactation to examine changes in the protein fractions throughout lactation. Once the variation between fractions is determined, we will collaborate with Pro-Dairy to host a meeting with producers, fellow veterinarians, and other industry leaders to present our findings. In addition, we will create a report summarizing the meeting proceedings and an informational brochure to share our findings and recommendations with Cornell Cooperative Extensions, dairy cooperatives, NEPAS, and other relevant regional associations such as the Vermont Dairy Industry Association.