Chasing protein: Dairy’s next nutritional frontier

Protein is having a moment – high-protein diets, protein-fortified foods and even protein-fortified coffee. But it’s leaving dairy farmers and processors wondering why it’s not as easy to bump up protein in the bulk tank as it is to increase butterfat.

According to Mike Van Amburgh, a professor of dairy nutrition at Cornell, butterfat has increased over the past decade because of a better understanding of dairy nutrition. Genomic testing also plays a role; it’s easier than ever to identify animals with the genetic potential to produce higher components. The key to unlocking this potential, however, comes back to nutrition.

Researchers pulled the U.S. out of what Van Amburgh called a “national herd that was milkfat depressed” when they recognized that dairy cows were being overfed unsaturated fats.

They also learned the critical role three amino acids play, when used as supplements, in butterfat production. Meeting exact requirements for these three amino acids stimulates the activity of mammary gland enzymes that are responsible for synthesizing milkfat.

“It’s real easy to get the fat because all we’ve got to do is keep adding some more lysine, methionine and histidine and boy, off they go,” said Van Amburgh.

His research team just completed a study where they supplemented methionine, lysine and histidine along with branched chain fatty acids to meet the requirements for fiber-digesting bacteria. The butterfat of the cows assigned to treatment averaged 4.6% before assignment and increased to 5.3% during the treatment period. A few cows were in the 8% – 10.2% range. The results surprised the researchers; a few asked Van Amburgh to clarify that the study used Holsteins and not Jerseys.

Protein percentages also increased in this study. Van Amburgh said, “We got them up to 3.45 and 3.54 – not quite 4. We can’t seem to break that barrier consistently simply because of the lack of nutrient resources.”

Increasing milk protein, according to Van Amburgh, would require meeting additional amino acid requirements: isoleucine, valine, arginine and proline, plus additional lysine.

Farmers might be tempted to feed more protein, but Van Amburgh said there is no way to meet the additional amino acid requirements without grossly overfeeding protein.

The additional amino acids for casein yield are not widely available because they are expensive to produce; however, Van Amburgh advocated for research and development by animal nutrition and feed additive companies. “We need everybody who makes rumen-protected amino acids to start now, seriously,” he said, “because everybody in the world now wants protein.

“We’re going to have to get the industry to understand that we have to get over the feed additive idea. These amino acids are not feed additives; they’re obligate requirements.”

Van Amburgh believes that dairy farmers will eventually get to the point where they’re feeding 200 – 300 grams of protected amino acids to a dairy cow each day. He suggested that 50 grams of isoleucine, 40 grams of valine, 30 grams of proline, 30 – 40 grams of arginine and about 20 – 30 grams more lysine per day can increase protein levels.

“That sounds like an extraordinary amount, but if you think about how much they consume, if they’re consuming 30,000 grams of dry matter and 200 to 300 of it have to be these additional amino acids, that’s 1%,” he explained.

He also hypothesized that increasing protein levels could help processors facing significant challenges as butterfat production outpaces increases in protein. Systems built to handle fairlife and similar products use a multi-stage ultra-filtration system to separate milk into its five core components. High concentrations of milkfat and proteins can clog the microscopic pores of ultra-filtration membranes and centrifuges.

According to Van Amburgh, cheesemakers are also frustrated because they want protein and do not need the excess fat, requiring them to skim the milk. Then there are processors like Chobani who don’t want the fat at all.

He hypothesized that once the amino acids required to increase protein are supplied, some of the resources currently directed toward fat synthesis within the mammary gland will shift toward protein. This will naturally bring fat and protein closer together and reduce the imbalance impacting processors.

Processors often question Van Amburgh about simply changing the dairy diet to reduce butterfat. His reply? “No. Welcome to the modern genomic cow. We could turn the fat off, but then you’re going to reduce a bunch of other things. You’re going to lose feed efficiency.”

While Van Amburgh continues to advocate for protein-boosting amino acid production, dairy producers do have some ability to increase protein levels. Farmers should aim for a bulk tank true protein average of 3.5% – 3.6%, with a meaningful portion of cows performing close to 4%. Methionine, lysine and histidine levels have to be met and then some other high-quality protein sources are needed to provide the amino acids to accomplish this increase in protein content.

Cow comfort is a foundational requirement. Cows need 12 to 13 hours of lying time per day. Anything that reduces their ability to lie down, chew and ruminate will take away from the nutrients available for milk protein synthesis.

High digestibility forages are essential. The cow needs digestible neutral detergent fiber (NDF) and enough of it to maintain good feed efficiency. According to Van Amburgh, the source of the NDF matters less than its digestibility.

Dietary fat should be kept below 5%. Van Amburgh said that in the diets he develops, fatty acids are kept at 4.4% – 4.5% with total fat not exceeding 4.8%. Going above 5% reduces the de novo and mixed fatty acid yields, which impacts milkfat yield and feed efficiency.

by Sonja Heyck-Merlin