CSI-Dairy: Amino acid balancing
Numerous ‘culprits’ exist on dairy farms, robbing herd performance and injuring the dairy’s bottom line. Identifying and arresting the offender isn’t always easy, and often requires a full investigation, gathering and analyzing evidence on the farm and in the lab. As in this case, solving a mystery leads to long-term benefits.
By Darin Bremmer
Several years ago, Jed and I explored the feasibility of increasing milk protein to take advantage of attractive premiums. The technology was available, but would Jed’s 600 cows respond to the dietary changes?
Milk protein content swings dramatically each year, generally increasing in the middle of August and peaking during November and December, then decreasing in January and reaching lows near the end of July or early August. We don’t know for sure why milk protein decreases, but it has a substantial impact on profitability.
That winter, Jed agreed to balance diets using the protein sub model of the National Research Council (NRC) 2001 Nutrient Requirements of Dairy Cattle, along with using a well-researched rumen-protected methionine. Our thinking switched to amino acids and away from the ration’s crude protein content.
The on-farm trial
The way Jed grouped and moved cows gave us pens with equal days in milk, lactation number, and milk production for dietary comparisons. Within two weeks, we saw pens receiving the diet balanced for the amino acids lysine and methionine producing milk 0.2% higher (see graph) in protein than the control cows.
Although only a portion of the herd’s cows received the amino acid-balanced diet, we saw a higher peak in herd milk protein during November that year. We decided to feed the balanced diet to the entire herd the next spring. That summer, milk protein content remained higher than the summer before.
According to NRC (2001), metabolizable protein is defined as “the true protein that is digested postruminally and the component amino acids absorbed by the intestine.” The amino acids in the metabolizable protein, not the crude protein, are what the cow requires.
At the end of that summer, we increased the amount and concentration of lysine and methionine in metabolizable protein while maintaining a 3:1 lysine-to-methionine ratio. We began to see the largest Fall increase in milk protein content we’d ever seen from Jed’s cows, averaging 3.3% for November 2005. As expected, the milk protein dropped somewhat the following summer, but has not dropped below 3% since, and each November’s peak remains high.
Delactosed whey permeate
During July 2008, we made a significant change to the carbohydrates fed to Jed’s cows. To save money, we substituted delactosed whey permeate for a portion of the corn. Delactosed whey permeate contains 63% lactose (milk sugar) on a dry matter basis. The price of corn spiked, so we definitely saved money replacing starch with lactose. An interesting side benefit was that the summer milk protein did not decrease as much as before we added the lactose. That trend continues through today.
Jed didn’t sacrifice milk production for high milk protein. His herd has nearly tripled to 1,700 cows, while maintaining a 29,000-lb. rolling herd average. The potential to improve performance and profitability has been realized. We will continue to use the tools available to increase milk protein with Jed’s herd. Protein is up, milk volume is steady, and the herd looks great.
• Darin Bremmer, Ph.D., is a Dairy Nutritionist and member of the Technical Services Team at Vita Plus Corp. Contact him via phone 715-305-6559 or e-mail DBremmer@VitaPlus.com or the website www.vitaplus.com.