FROM THE FARM REPORT: MILK COMPOSITION ISCHANGING: WHAT FARMERS & NUTRITIONISTS NEED TO KNOW

Milk composition in the Northeast US has shifted dramatically over the last several years with significant increases in both fat and protein content. At the recent Cornell Nutrition Conference, Mike Van Amburgh and Dave Barbano shared their perspectives on the ever-evolving landscape of milk composition, dairy cow nutrition, and cheese manufacturing. Here are my take aways…

Genetics are driving higher milk components. Genomic selection has dramatically improved milk fat and protein yields. Barbano shared data from the Federal Milk Market Order 1 showing that milk fat increased from 3.70% in 2010 to 4.22% in 2024, a 14% increase, while milk true protein has risen from 3.05% to 3.21%, a 5% increase. Van Amburgh emphasized that high-genomic 1st lactation cows from a NY herd are averaging 84 lb with 5.48% fat and 3.53% true protein and the range for fat is 4.40% to 7.08% and true protein is 2.88% to 4.20%. He suggested that these cows likely represent a “new” genotype with nutrient demands that exceed the current feeding guidelines, requiring a re-evaluation of energy and amino acid requirement much for frequently that is current done. The new target might be every 5 to 10 years.

Nutrition must keep pace with genetics. Nutrition strategies must evolve to support the increased milk component synthesis. Historically, balancing essential amino acids, such as methionine, lysine, and histidine, can significantly boost both milk fat and protein yields. Additional attention is now being paid to 3 other essential amino acids, leucine, isoleucine, and valine, along with nonessential amino acids, proline and glycine. Van Amburgh stated that amino acids are not just for protein synthesis, they also play a critical role in fatty acid production and other metabolic processes. As farmers and nutritionists feed higher genomic cows producing greater fat and true protein, they must feed more amino acids along with optimizing microbial protein. To illustrate the point, Van Amburgh used the example of a dairy cow producing 114 lb of milk at 4.35% fat and 3.29% protein with a metabolizable energy intake of ~87 Mcals/d, and suggested the supply of methionine and histidine should be 103 g/d and the supply of lysine should be 278 g/d. The supplies follow the guidelines of 1.19 g of methionine and histidine per Mcal of energy and 3.2 g of lysine per Mcal of energy for those using CNCPS based formulation software.

Milk fat is rising faster than true protein and has implications for cheese manufacturing. Barbano highlighted how the greater increase in fat content compared with true protein content is impacting dairy processing. The casein to fat ratio in milk is decreasing and affecting aged Chedder cheese texture and flavor. Higher fat in the cheese is leading to softer texture, lower moisture, higher salt content and ultimately negatively impacting flavor development as well as the ability to slice the cheese mechanically. Dairy processors, in particular cheese makers, are investing in equipment, such as cream separators and ultrafiltration systems, to standardize milk to reduce fat or concentration protein.

Practical farm-level observations and approaches. Farmers that are using genomics along with progressive nutrition and management practices are seeing impressive increases in milk component content and yields. Bulk fat milk fat content of 4.8 to 5% are possible and will become more common in the near future. Use of mid-infrared milk analysis during payment testing of bulk milk or milk sampling of pens is allowing farms to monitor de novo, mixed, and preformed fatty acids with provides information for farmers and nutritionists to use to make diet adjustments and management changes. Barbano shared some updated regression equations from 100 farms in NY from 2024: milk fat % = 1.208 x (de novo + mixed origin fatty acids, g/100 g milk) + 1.1726 (R-square = 0.85) and milk protein % = 0.4575 x (de novo + mixed origin fatty acids, g/100 g milk) + 2.0765 (R-squared = 0.53). These equations are similar to previous equations suggesting that as the fat and protein content of milk are increasing, the relationship between them and fatty acid groups are remaining similar.

— Heather Dann

dann@whminer.com