Running the numbers on protein choices
Digging deeper into the nutrient value of your protein sources and running the numbers on costs will help you make a more informed decision when it comes to formulating your rations.
By Essi Evans, Ph.D., E+E Technical Advisory Services
Proteins and amino acids are key components of dairy cow rations, and these needs must be met for optimal health and productivity of the herd. However, protein ingredients can be expensive, and it’s sometimes difficult to know which option will provide the most value.
Bulk protein purchases are often made based on the total crude protein (CP) content, and soybean meal is often used as the base for price decisions. However, this rule of thumb may cause producers and nutritionists to overlook choices that better suit their herd.
One way to assess options is to take advantage of reliable ration-balancing programs. These programs provide assurance that nutrient needs are met daily, based on the feed ingredients made available to the program. In addition, evaluating the following three data points will help you get the full picture of your protein options:
Dig deeper into protein values
CP is one of the most commonly used values when formulating dairy cattle rations to understand the protein content of the diet. However, it’s important to dig deeper, as CP alone doesn’t tell the full story.
Rumen undegradable protein (RUP), also called escape protein or bypass protein, is the portion of dietary protein that isn’t digested by the rumen microbes and is instead digested in the small intestine. Since it’s not digested by the microbes in the rumen, it’s available for tissue growth or lactation.[1]
Table 1 shows the CP and RUP content for several common vegetable proteins. The values were extracted using the NDS Professional ration-balancing program. As the table shows, both canola meal and cottonseed meal provide more RUP than soybean meal. If you evaluate rations based on crude protein alone, these sources might be overlooked as a valuable protein option.
Avoid wasted protein
Another number to keep in mind when evaluating protein options is milk urea nitrogen (MUN). High MUN levels indicate protein is being wasted, and so it might be necessary to reevaluate both the protein source and the levels of inclusion of protein in the ration. Efficient use of protein results in less waste.
Because proteins tend to be costly, this metric might suggest the need to reevaluate the ration composition to ensure you get the most value from your protein investment.
Table 2 shows the results from a study[2] in which diets were formulated to provide 16.5% CP, with the added vegetable protein supplied by canola meal, extruded soybean meal or conventional solvent-extracted soybean meal.
The extruded soybean meal diet resulted in cows producing less milk protein than when they received the canola meal diet or the conventional soybean meal diet. A greater portion of the protein was wasted, resulting in higher MUN values with this experimental diet.
Get the full picture of costs
Another consideration is the relationship between cost per ton of finished ration and milk yield. A less expensive protein may reduce feed costs per cow per day, but not feed costs per pound of energy-corrected milk. This metric is one that needs to be front of mind for profitability.
For example, in a recent California study,[3] about half of the canola meal in the ration was replaced with high-protein distillers’ grains. While ration costs were reduced by $0.04 per cow per day, income over feed costs was also reduced. It should be borne in mind that prices for both milk and feed ingredients change, and the cost relationships need to be monitored.
Digging deeper into the nutrient value of your protein sources and running the numbers on costs will help you make a more informed decision when it comes to formulating your rations. Talk to your local nutritionist about protein options for your herd.
References
[1] Vanderhoff, S., Kovarna, M. 2023. Understanding protein in feed. South Dakota State University Extension. https://extension.sdstate.edu/understanding-protein-feed. Accessed August 9, 2024.
[2] Lage, C.F.A., Räisänen, S.E., Stefenoni, H., Melgar, A., Chen, X., Oh, J.O.O.N.P.Y.O., Fetter, M.E., Kniffen, D.M., Fabin, R.A. and Hristov, A.N., 2021. Lactational performance, enteric gas emissions, and plasma amino acid profile of dairy cows fed diets with soybean or canola meals included on an equal protein basis. Journal of Dairy Science, 104(3), pp.3052-3066.
[3] Edwards, R.J., Ledgerwood, D.N., Ferreira, F.C. and Rossow, H.A., 2023. Impact of Partially Substituting Canola Meal with Solvent-Extracted Distillers Grain with Solubles as a Protein Source on Milk Production in a Commercial Holstein Dairy Herd. Animals, 13(13), p.2192.
