The value of straw diets for dry cows

I’m confused by all of this discussion about feeding straw to dry cows. Don’t we want to maximize feed intake in dry cows?

That’s a great question and one where the thinking of the dairy industry and researchers has shifted over the years. For a long time, dairy producers heard “maximize feed intake” for dry cows – especially close-up cows. Many herds that changed management to increase dry matter intake (DMI) from low levels – 22 to 24 pounds – to higher levels – 28 to 29 pounds – in close-up cows saw marked improvements in fresh cow health and performance. Their experience reflects research that shows increased post-calving metabolic problems in cows that don’t consume enough energy pre-calving.

So if some increased DMI is good, more must be better, right? Not necessarily. We began to see herds with very high DMI before calving were having significant metabolic problems, such as displaced abomasums (DA) and ketosis after calving. The very high DMI diets supplied 32 to 34 pounds of DMI, usually containing around 14 to 16 pounds per day of corn silage dry matter.

At the same time research showed that overfeeding cows during either the far-off or close-up periods would actually increase insulin resistance in body fat similar to Type II Diabetics. The effects of this weren’t positive: Cows rapidly lost body condition score post-calving, became sluggish in terms of DMI and were predisposed to metabolic problems after calving.

We like to talk about averages for groups of cows, but most cows in groups will either eat above or below the average intake. The challenge is to make sure all cows get enough, but not too much, energy intake. That is where bulky, low-energy feeds like straw or high-fiber grass hays play a role. They are often relatively low in potassium, which is important for close-up cows, and complement corn silage.

By providing as much as 10 pounds of dry matter from these types of feeds in dry cow diets, producers can maximize feed intake while controlling the top end of energy intake. The diets physically fill cows before they can dramatically exceed their energy requirements. This approach for far-off and close-up has improved transition cow health on many herds.

Feeding management of bulky dry cow diets is tricky. Straw or hay must be chopped enough to minimize sorting –large particles usually should be no more than 1.5 inches long. You may also have to add water or something to increase the moisture level and help the ration stick together.

Tom Overton, PhD, answered this month’s Ask Extension question. He is an associate professor in dairy management and nutrition at Cornell University’s Department of Animal Science and associate director of PRO-DAIRY. To learn more about transition cow care and feeding – specifically the high-fill, low-energy straw diet – attend the Dairy Profit Seminar at Empire Farm Days, Seneca Falls, on Tuesday, Aug. 5, beginning at 10:30 a.m. Dr. Overton leads a panel discussion on Transition Cow Tune-up. Panel members include John Knopf of Canandaigua.
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