Feed & Nutrition

If you find yourself reading the title of this [article] twice, wondering what “space” has to do with the diet of a dairy cow, you are not alone. Nutritionists and producers regularly discuss terms like pounds of dry matter intake (DMI) or percent protein or how many megacalories of energy or grams of calcium or what is the ratio of calcium-to-phosphorus. None of these discussions even comes close to mentioning space as an important consideration when planning or troubleshooting a milking cow’s diet.

The basic premise used by all nutritionists when formulating rations is that each mouthful of the diet is balanced with respect to the known nutrient requirement of the target animal. The diet must contain the necessary nutrients to support maintenance, growth, production and health. Feed additives should be present to provide the appropriate level of protection from disease and other maladies. In all cases, the levels must be controlled so as to be neither deficient nor toxic.

The science surrounding protein and energy nutrition, no matter the livestock species, is a couple of generations ahead of mineral nutrition – particularly trace mineral nutrition. Yet finally there are signs that mineral nutrition science might one day catch up.

One sign of progress is industry and academic interests using ‘organic’ minerals in lieu of inorganic forms of zinc, manganese, copper and selenium. The initial focus is on reproductive issues and on enhancing immune response and milk quality – areas where trace mineral availability may be limiting. Another issue is environmental accumulation of minerals in manure spread on cropland.

The ability of dairy cows to convert feedstuffs into products for human consumption is generally referred to as feed efficiency and is expressed as pounds of milk produced per pound of dry matter (DM) consumed. This expression represents a gross measure of feed efficiency and does not account for nutrients partitioned to reproduction, growth and tissue deposition. Thus, interpretation of the value obtained should consider stage of lactation, age and stage of gestation for the herd in question.

Nutritionist Jess Argyle of Jerome, Idaho, says despite higher prices for rolled corn and regionally imported ration components, dairy producers should push for more milk and higher components, being careful not to lose milk production while looking for good buys on commodities.

“Don’t short-change the cows. Push for production,” Argyle says. “I’ve never been able to cut out or cut back on feed and save money. We always lose more in production than what we can save in cutting back on feed.”

Are your feed costs high? The most expensive feeds are those with high levels of protein (greater than 20 percent protein). Testing for MUN (milk urea nitrogen) in the milk can help you determine the correct level of protein in the feed.

There are other reasons for testing for MUN: