Farming Magazine - June, 2012


Dairy Nutrition: Taking Forage to the Max

By John S. Hibma

Dairy farms across the country continue to fight the uphill battle to stay ahead of feeding costs on their operations. A number of metrics and indices have been developed over the years comparing milk prices to feed prices, calculating income over feed cost or feed efficiency ratios in an attempt to best measure feed costs and their immediate or long-term impact on the financial health of the business. Grains and commodity and byproducts have found their way into dairy rations when the prices are right. Ironically, it seems the dairy industry works hand in hand with the feed industry to find the most economical combination of feedstuffs that keeps cows making more and more milk.

However, times are changing, and we've seen the prices of all feeds take some unprecedented jumps in the past year or so. Whether you blame it on the weak U.S. dollar and growing world exports, the ethanol industry and scarce resources or environmentalists, the cost of feeding cows and heifers has gone up and will most likely remain that way for the foreseeable future.

The U.S. dairy industry has enjoyed "relatively affordable" commodity pricing in spite of the roller-coaster ride for milk prices during the past decade. However, when corn prices climbed over $6 per bushel in 2010 after hanging around $3 for many years, it was sort of the wake-up call for our industry to take a renewed look at how we feed cows. Some dairy farmers have returned to feeding more forages and refocusing their efforts on improving and maximizing forage quality in order to improve profit margins and stay in business.

In recent times, however, dairy farmers have been inclined to push forage quality aside, thinking that grains and other commodities could cover up the shortcomings of forage. If the corn silage or the hay or haylage wasn't the best for whatever reason, feeding a few more pounds of starch or a protein meal was always an option as long as those feedstuffs weren't too expensive, but now they are.

During a conference at the University of Connecticut in March, Dr. Larry Chase, longtime professor of dairy science and nutrition at Cornell University, explained that there comes a point where feeding more grains to dairy cows could not overcome the effects of lower forage quality. The research he shared showed that by increasing hay crop forages, especially in early lactation cows, net profits would increase through the lowering of supplement costs. Milk production would also increase due to the improvement of rumen function. Chase quoted a dairy producer in New York as saying, "The greatest area to improve profitability is forage quality."

The quality in forages (alfalfa or grass) encompasses four main criteria:

  • high digestibility
  • effective physical fiber
  • palatability
  • good fermentation (in the case of haylage)

The digestibility of forages essentially centers on the maturity of the plant at the time of harvest. The more mature a plant becomes, the greater the levels of fiber and lignin. Lignin is the part of the plant that is nearly indigestible due to its chemical makeup. Rumen bacteria cannot break it down, so it passes through the rumen providing no nutritional benefit. The key to improving the digestibility of a forage, and thus the quality, is making sure the alfalfa or grass has not bloomed or gone to seed at the time of harvest. In most cases, once forages have done either of those, the fiber and lignin have increased to the point where the nutritional value has decreased to an unacceptable level to be used to support high levels of milk production.

Forages must also supply adequate effective fiber to support rumination. While we strive to make our forages as digestible as possible by supplying energy to the rumen microbes, forages must not be so fine or low in fiber (immature) that they prevent a rumen mat from forming, which is necessary to stimulate the papillae. Feeding high levels of forage becomes a balancing act of supplying energy and protein to a diet without compromising rumen function and efficiency.

Palatability and fermentation each can hinder a cow's propensity to respond to a high-forage diet. Coarseness and a poor fermentation profile of the forage can result in sorting or affect rumen health, which defeats the purpose of trying to increase forage in a diet.

A major challenge to making milk on high-forage diets is to maximize the feed intake of the forage. The more mature a forage is, the less of that forage a cow can consume due to "rumen fill" and her limited capacity for chewing and rumination. The current and most useful laboratory assay for measuring forage fiber is "neutral detergent fiber" (NDF). Research has shown that cows can consume about 1 percent of their body weight with forage NDF. So the higher the NDF level in any forage, the less of it a cow can consume throughout a day.

As an example, a 1,400-pound cow can consume about 14 pounds of forage NDF on a dry matter basis (1,400 x 1% = 14). If you have a forage that tests 50 percent NDF, then you can feed 28 pounds (dry matter) of that forage to reach the 14 pounds of forage NDF that the cow can consume per day. If you have higher-quality forage testing 40 percent NDF, you can feed 35 pounds (dry matter) of that forage. The better the forage, the more you can theoretically feed to your cows and reduce other purchased feed ingredients.

Properly balanced rations that increase forage consumption in dairy cows has been shown to improve income over feed costs, improve milk components, decrease acidosis and foot problems, lower vet bills and culling rates and increase lactations per cow. As we face a new paradigm of increasing grain costs, dairy farmers, whenever possible, should be looking to make more efficient use of forages in their herds' diets.

The author is a dairy nutritional consultant and works for Central Connecticut Farmer's Cooperative in Manchester, Conn