The bovine athlete

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You probably don’t use the term “athletic” when describing your cows, but perhaps you should. The tremendous amount of metabolic work done by dairy cows rivals that of the toughest, strongest athletes.

For example, a cow producing 110 pounds of 3.5 percent butterfat milk per day is secreting 34.5 megacalories of energy in her milk daily. Including maintenance, this requires her to generate 44.2 megacalories of energy for lactation per day. In relation to the amount of energy humans use, this equates roughly to a person running 1.5 mara-thons per day. And, the cow does it every day, day after day!

Even more remarkably, the cow increases her energy expenditure by 300 percent from approximately 10 days before calving to just a few days after calving. To use our athletic analogy, it is like expecting the marathon runner to be ready to compete with only two weeks of training.

When thinking about the cow in these terms, it is not surprising that metabolic diseases occur frequently in these “athletes.” Our efforts to formulate transition rations for dairy cattle are, in some respects, crude attempts to condition or train them for the task of milk production.

Swine producers face a similar challenge in preparing sows for lactation as large, healthy litters require very high milk production, too. The energy requirements of a lactating sow increase approximately threefold from that of late gestation. One way swine nutritionists prepare for the transition is by feeding gestating sows a diet with the same caloric density as the one lactating sows receive. However, the non-lactating sow is limit fed, and the lactating sow eats the diet free-choice.

Nutritional challenges
Unfortunately, in the dairy cow, this strategy is complicated by the presence of the rumen. Over the years, trying to feed high-energy, low-volume diets hasn’t been successful. The small volume of rumen activity during the restricted-feeding can result in displaced abomasums after freshening. Feeding a higher volume of a high-energy diet can lead to fat dry cows and significant problems with ketosis and fatty livers.

Instead, most dairy nutritionists recommend maximizing the dairy cow’s dry matter intake, and then adjusting the fiber and energy levels to meet the cow’s energy needs. Additionally, the energy content of the diet is increased gradually to avoid rumen acidosis. Recommendations that I follow appear in the table below.

Some of my clients and I have started questioning the wisdom and economic sense of taking a cow that’s still milking 80 or 90 pounds per day, drying her off for 50 or 60 days, and then calving her in and expecting her to immediately produce 100 pounds of milk per day. Using the athletic analogy again, that is like expecting a marathon runner to stop and sit idle for two months and then be back at his or her 26-mile daily pace within a few days.

Most of the scientific work suggesting an optimal dry period of six to eight weeks was done 25 or 30 years ago. Could there be differences when cows milk 80 pounds at dry off versus 30 pounds? Would cows be better prepared metabolically if they did not sit idle for two months? Could subclinical rumen acidosis be avoided without a dry period and consequent dietary changes? We are cautiously attempting to find out.

As you look over your dry cows and fresh cows, make sure that you are preparing them for their daily marathon.

Brian Gerloff is a veterinarian and operates Seneca Bovine Service in Marengo, Ill.



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