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0809 PD: Reconsider forage in times of crisis

John Hibma Published on 18 May 2009

In these trying economic times with low milk prices and high feed prices, dairy farmers all over the country are having to re-evaluate their feeding programs. To get through this year they must decide if they should cut back on feedstuffs and which feedstuffs they should cut back on.

For many dairies across the nation, feed costs have climbed to over $10 per hundredweight of milk produced. For some, the milk checks this past spring weren’t much more than that. Just as we, perhaps, might have to get used to gasoline prices over $3 per gallon, we might have to accept the reality that feed prices will also remain high for the foreseeable future and maybe even climb higher regardless of what the price of milk may be.

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For much of the past decade, grains and commodity byproducts have been plentiful and reasonably priced for various reasons, including overproduction and a strong U.S. dollar. More recently, the new dynamics of “feed for fuel,” growing world economies, a weakening U.S. dollar and finally the financial collapse of the U.S. economy, have resulted in the “perfect storm” of high feed prices and low milk prices.

While ruminant nutritionists promote the need for and the value of high-quality forages in dairy diets, “forage quality” is often not taken seriously enough since high-energy and high-protein feedstuffs are close at hand, for a reasonable price, as a partial solution to poor forage management. But with the recent market volatilities there has been a paradigm shift in how dairy rations are formulated. Forages could now very well be the best deal in town.

Forages cannot meet all of the nutritional requirements of our high- producing dairy cows but they will go a long way towards helping make ends meet in times when commodities are expensive. In many cases, a dairy farm that can raise its own forage (or has a high level of control) is in the best place to take advantage of offsetting purchased feed costs. Where many dairies lose money on their own forages, however, is in the poor management of different stages of the process.

While forages such as corn silage and hay crops are essential to properly balanced ruminant diets, they are notoriously variable in quality, making them difficult to balance around. Investments in a field of corn or a truckload of hay can be risky. Corn standing in the field may look great with beautiful ears and lots of grain but the nutritional value can be greatly reduced if the crop is not chopped at the correct moisture level or packed correctly in a pile. Fermentation profiles are critical to whether a pile of corn silage will milk or not.

Corn can provide the most calories per acre of any crop grown. But if it’s harvested or stored incorrectly, the silage will ferment poorly and many tons of dry matter will literally vanish into thin air as sugars are turned into alcohol and vaporize. Sugars, along with the starch in corn silage, are rapidly used by rumen bacteria and have a measurable economic value in a pile of corn silage when substitutions must be made with other purchased feedstuffs.

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Research in recent years has shown that fiber digestibility and moisture levels in corn silage are the two most critical factors influencing the quality of the crop and its consequent milk production potential. Neutral detergent fiber digestibility (NDFd) is now available in laboratory analysis as well as starch digestibility, which can be incorporated into nutritional computer models.

Hay and haylage are also invaluable and economical sources of nutrition. They, too, must be grown, harvested and stored correctly. Quality starts with the maturity of the crop and hay quality is inversely proportional to maturity. The more mature hay becomes before harvesting, the more the plant cell walls and lignification increases in order for the plant to support itself. The more fibrous the plant, the less the rumen microbes can degrade it and the less nutrition can be derived from it.

Haylage, whether it is grass or legume, can present a greater challenge for proper fermentation. As with corn silage, rapid production of lactic acid in haylage is critical for a proper fermentation with as little acetic acid production as possible. However, a pile of haylage is much more susceptible to clostridial fermentation and the production of butyric acid – an unwanted product that can seriously affect rumen health if levels are too high. Moreover, recent research has also shown that high levels of ash in haylage can contribute to excessive levels of butyric acid. Ash levels of over 10 percent in haylage usually indicate that there’s a lot of dirt picked up during the chopping or packing processes.

While protein levels are a good indication of hay quality, much of the carbohydrate digestibility is dependent upon cell wall levels and how much sugar is available. Grasses have a much higher sugar content than they do starch and, when sufficiently immature, will again provide a quickly degradable carb source for rumen microbes – allowing for some reduction in purchased energy and protein.

Our ability to determine the quality of forage has improved in the last decade, as well. University researchers continue to study the various structural and non-structural components of forage to determine how they degrade in the rumen. Starches and sugars degrade differently compared to cellulose. Nutrition models are now sophisticated enough to offer an economic value of the forage based on structural and nonstructural carbohydrates.

Some will say that balancing dairy feed rations is often as much of an art as it is a science. But the improving science of analyzing and understanding forages allows the dairy industry to use them more effectively in feed rations to maintain income-over-feed-costs. Properly grown and managed, forages continue to be a resource that offers economic alternatives in your feeding programs. PD

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John Hibma Nutritionist

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