SPONSORED BY H.J. BAKER
In recent years, dairy producers have sharpened their focus on income over feed cost while maximizing both milk quantity and components. Nutritionists and veterinarians continually strive to find solutions that benefit both the producer and the animal. Limiting total crude protein but balancing for digestible amino acids, for example, is one way that producers can improve production responses and dairy farm profitability.
Recent university testing indicates that amino acids can add value in dairy herd rations, and there is extensive research on balancing for digestible amino acids, particularly lysine and methionine. Studies have shown that obtaining optimal levels of lysine and methionine can be a cost effective way to improve profitability. While rumen protected methionine products have been available for about 20 years, rumen-protected lysine (RPL) products have only come available to the market place within recent years.
Dr. William Chalupa, professor emeritus of nutrition at the University of Pennsylvania, recently reviewed the body of research available on RPL products. “The requirement for protein is a requirement for specific amounts and balances of amino acids, and amino acid supply to the mammary gland can affect amino acid protein content and milk volume,” says Chalupa. “In addition, amino acids can impact productivity by affecting metabolism and immune function.”
After reviewing the body of research available on RPL products, Chalupa made the following observations regarding responses of cows to rations balanced for lysine and methionine:
* The amount of protein synthesized by the mammary gland is increased;
* The efficiency of protein synthesis by the mammary gland is increased;
* In most experiments, lysine fortification increases milk fat percentage, and
* Increases in milk fat percentage along with increases in milk protein percentage and milk yield leads to increased yield of energy-corrected milk (ECM).
Every farm is different so the approach for adding amino acids will vary. Here are some field opportunities to consider:
1. When protein prices drive the price of milk. Maximizing the ratio will be most effective in good producing herds where there is room to increase the lysine/methionine ratio. This is likely to be most cost effective approach in the fresh group and then the high group if the groups can be fed separately.
2. A cost conscious approach. A cost conscious approach can be applied when the herd produces well, but the milk components have room to improve. The first step would be to improve the ratio to 6.6% of MP for lysine and 2.2% of MP for methionine (NRC), which are considered practical levels. An ideal range for a high producing herd would be 180 g of lysine and 60 g of methionine.
3. In diets with no animal protein. The amino acid supply may look ideal on paper, but the cows will respond to an increase in synthetic amino acids. It is important to measure and analyze the response over a three to four week timeframe. Milk is usually the first response followed by components (except in hot weather).
Chalupa suggests that dairy producers, nutritionists and veterinarians select RPL products based on cost per unit of metabolizable lysine. He recommends evaluating the cost per ton in conjunction with the percentage of dietary lysine absorbed to understand the true cost of the product. Chalupa found that on a cost per gram, MetaboLys®, a product that derives its lysine from lysine sulfate, is the most cost effective protected lysine source.
In conclusion, using quality sources of protected methionine and lysine will give dairy producers more certainty that the added cost will result in a production response that adds profitability to the farm.