MSU Extension

Because of the high energy requirements of lactating dairy cows and the need to provide adequate fiber levels to maintain a healthy rumen, feed selection must include considerations of energy content and digestibility while maintaining a healthy rumen environment. Corn grain is fed to dairy cows because of its high energy and starch contents. Forages are fed to dairy cows to maintain a healthy rumen environment, in addition to providing nutrients. Lactating dairy cows typically consume a nutrient dense ration with approximately 50 percent forage and 50 percent concentrate.

Sources of energy
Digestible starch, fiber, sugar and fat supply most of the energy in the ration, but ultimately cows need a certain amount of digestible starch to maximize milk lactose secretion and lactation performance. The most common source of starch in Michigan dairy rations is corn grain. The amount of starch in the ration can vary between 15 to 32 percent of the dietary dry matter depending on level of milk production, stage of lactation and animal health.

Alternative feeds categories
Feed is the single largest expense in dairy farms. When corn price is high or forages are in short supply, can other feeds substitute for corn or forage in the ration? Alternative feeds may be available at competitive prices, but they need to be carefully evaluated as to how they might fit into the ration. It is important to decide which nutrient(s) you are seeking to replace by using alternative feeds. For example, if corn grain is to be replaced by an alternative feed ingredient, then some of the original starch will need to be replaced by the alternative feed. If forage is short on farm, than a filler or digestible fiber type feed can be used to replace forage. Alternative feedstuffs generally can be classified into several categories – fillers, starch, digestible fiber, protein, protein/fiber and fiber/protein/fat.

• Fillers – these feeds have low nutritional value for dairy cows and would be used in situations of fiber or feed shortage. Examples are rice hulls and cottonseed hulls.
• Starch – feeds with higher starch contents include hominy, bakery byproduct and cereal byproduct.
• Digestible Fiber – these feeds are useful to extend forage inventories and include citrus pulp, beet pulp and soy hulls.
• Protein – feeds that are a significant source of protein. An alternative protein source is corn gluten meal.
• Protein/fiber – wheat middlings and brewers grains provide both protein and fiber to the ration.
• Fiber/protein/fat – corn distillers grains and whole cottonseed are significant sources of fiber, protein and fat.

Often, alternative feeds are available for a limited time and need to be purchased and taken on short notice. In deciding whether or not to purchase an alternative feed, consider storage time (especially for wet feeds), market availability, quality, consistency (lack of nutrient variability), storage costs, and any possible negative effects on rumen health. The ultimate question is: can the feed replace corn (or a portion of corn) or a portion of the forage without reducing lactational performance? It can be difficult to predict if a byproduct (alternative feed) is a good choice nutritionally in a particular ration without running a series of ration formulation analyses at varying prices of the byproduct and inclusion rates. This may help the user to become more comfortable that the ingredient probably will work without compromising lactational performance before incorporating the feed into the ration. Additionally, an on-farm evaluation should occur. If a feed does not fit in the lactating ration, perhaps it can fit into the heifer or dry cow ration and spare more suitable feeds for lactating cows.

When using an alternative feedstuff to replace a portion of forage in the diet, make small changes in the forage to concentrate ratio and evaluate rumen health often. A healthy rumen has lots of buffering capacity from saliva produced during rumination. Rumen health can be evaluated by: monitoring the percent of cows lying in the stalls that are ruminating, the number of chews between swallows when ruminating, the extent of rumen fill in cows, and manure consistency. There is no right answer to these measurements, but a baseline must be established before changes are made to know how the rations changes have impacted rumen health.

Planning early for a forage shortage can prevent having to make a drastic change later. For example, a 1,000 cow dairy is feeding seven pounds haylage/cow/day and realizes in August that they will be 64 tons short of haylage. If the decision is made immediately to ration the forage in the diet for the next 11 months, haylage would be reduced by 0.39 pounds/cow/day (128,000 pounds short/ 330 days/1000 cows). If the decision is delayed until April, the haylage would be reduced by 2.13 pounds/cow/day (128,000 pounds short/ 60 days/ 1000 cows) to make it last until the next crop.

After incorporating the alternative feed into the ration, it is important to determine if it was a good feeding decision based on responses in milk yield and components. For example, if you replace corn with a byproduct feed and save $0.30 per cow per day in feed cost without changing milk yield it may seem like a good decision and great savings; but, you must consider production of milk components, not just overall milk yield. To do this, use values from your most recent milk check (component prices, producer price differential and premiums). There are spreadsheets available through Michigan State University Extension as well as some commercially available websites that can help you calculate milk income and ration costs.

The use of alternative byproduct feeds may help to offset cost of the dairy ration. However, monitoring cow health and determining the marginal change in income (loss or gain) with a ration change is the only way to know for sure if purchase and use of an alternative feed is a good decision or not. Making small changes to the ration early can prevent having to make a sudden, significant change that could impact cow health. Also, careful consideration should be given to the handling, storage, variability, availability and the nutrient content of alternative feeds and how the cows respond.

Additional information:

• MSU Extension’s Drought Resources