Choosing a Supplement for the Cowherd

– Jeff Lehmkuhler, PhD, PAS, Beef Extension Specialist, University of Kentucky

The spring of 2019 delayed hay harvest in many parts of the state. This delay resulted in much of the hay being harvested at mature stages. Fescue was in full flower to soft-dough stage or even more mature in some cases. Mature forages have greater cell wall and lower digestibility.

I tried to demonstrate the impact of late cutting on feed value by clipping non-fertilized fescue plants the 3rd week in June. These plants were over three feet tall when I cut them. I proceeded to separate the bottom leaves, stem and seed head for yield and quality. The stem and seed head represented approximately 50% of the biomass. The stem had already matured to the point that it was tan in color. The leaves comprised the remaining 50% of the biomass and contained 10% crude protein and a calculated TDN of 54%. The stem itself was only 3.1% crude protein with a TDN of 45%.

Let me give you a reference to better relate the fescue stem quality (about half the biomass). As we all know, wheat straw is the aftermath from harvesting the grain. Wheat harvest often occurs in late June through July. Did you catch that? The book values for crude protein and TDN of wheat straw are 3.6% and 43%, respectively. Yes, that stem fraction on the hay cut in late June is similar in quality to straw! I know we can’t control weather, and many of you are just trying to make the best out of what you have to feed. Let’s make an action plan.

Step 1) Test the hay for nutrients so we know what we have in the hay. Surprisingly much of the hay may be sufficient in protein for dry, mid-gestation beef cows and only need energy supplementation. However, cows that came into the winter thin, may need additional protein supplementation to regain body condition.

Step 2) Determine the nutrient needs of the class of cattle fed. Fall calving cows that are nursing 90-100-day old calves need more nutrients than a dry, gestating cow that won’t calve until April. Match up lower quality forages with cattle that have lower nutrient requirements.

Step 3) Develop a supplement program to meet the nutrient needs. Having the forage test will let you see if you need to supplement energy, protein or both. A protein tub may balance the protein needs but still not provide enough energy due to limited intake. Focus first on meeting the nutrient needs and then determine what supplement is the most cost effective and/or easiest to handle to provide to the cattle.

Protein source generally is recommended to be a plant-based product. Soybean meal, corn gluten feed, dried distillers grains, cottonseed meal, and other plant protein sources can be utilized. Non-protein nitrogen sources (i.e. urea and biuret) can be utilized but may not be as efficient as plant sources. However, providing non-protein nitrogen on very low-quality forages is better than not supplementing if protein is needed to meet the rumen degradable protein requirements.

In many instances, energy is deficient in the forages and will need to be supplemented to meet the needs of the cows. The energy may be from about any source such as starch, sugar, highly digestible fiber, protein or fat. However, the level or amount supplemented from these sources have limits to avoid digestive upsets. For instance, this year corn may be a cost-effective energy supplement. However, the starch from corn can reduce fiber digestion if there is insufficient degradable protein in the rumen. As a rule of thumb, cows should be limited to not more than three pounds of corn per 1,000 lb of body weight to reduce the risk reducing fiber digestion. Sugars from molasses tend to have less of impact on fiber digestion in the rumen.

However, excessive amounts of sugar consumption can lead to reduced fiber digestion. Fat supplementation can also have a negative impact on fiber digestion at higher intakes. Total dietary fat is typically recommended to not exceed 6%. Forages when often contain 2-3% fat. Fat intake from supplement then should be limited to around 0.75 lb/d for mature cows. Let’s say you had some whole soybeans in the bin that you wanted to feed rather than sell. Soybeans will contain around 18% oil or fat. The amount of whole soybeans that would be recommended to be fed would be four pounds or less. Four pounds supplies about 0.7 lb of fat to the diet. Limiting intake based on fat applies to distillers syrup and other high fat feeds. Feedstuffs with highly digestible fiber work ell on forage-based diets. Soyhulls, rice bran, beet pulp, corn gluten feed, wheat middlings and other feeds can be utilized. Feedstuffs with low starch and highly digestible fiber can be fed at higher rates with minimal risk of digestive upsets. These feeds can be blended with cereal grains and protein sources to develop supplements for the cow herd.

When choosing a supplement to provide to beef cows, begin with a plan. Once the forage nutrient content is known along with the nutrient needs of the cattle, the supplement that will balance the supply and needs can be selected. Several choices will be available. Cost and ease of handling narrows the selection for many. Always work with a nutritionist to ensure to develop a strategy for supplementing your herd. For more information contact your nutritionist or local county extension office.