Rules of Thumb for Winter Cow Rations

Jan 22, 2008 11:24 AM

By Jason K. Ahola, Ph.D.

Considerations for feeding cows a least-cost ration in a new era of high forage prices

Rules of Thumb
For producers who don’t have a computer to use COWculator, there are a few simple rules of thumb for cow feeding. Several rations were developed using COWculator software for a 1,200 lb pregnant cow in late gestation to help provide insight into these “rules” (see Table 3).

A ration consisting only of good alfalfa (Ration 1) for a 1,200 lb pregnant cow should include up to 24 lbs and cost about $1.54/hd/day (if good alfalfa costs $130/Ton). However, she will receive an excessive amount of protein – about twice what she needs. Cheaper and lower quality alfalfa could be fed instead (Ration 2) if a small amount of corn is added, costing about $1.44/hd/day (assuming fair alfalfa is worth $110/Ton and corn $170/Ton).

Grass hay, instead of alfalfa, can provide adequate energy to this pregnant cow, but protein may be deficient if the grass was mature at harvest. Interestingly, in many parts of the U.S. grass hay is more expensive than alfalfa hay on a ‘per pound’ basis (and much more on a ‘per pound of protein’ basis), but provides much less protein and similar energy. Nonetheless, a ration of only “good” grass hay (24 lbs) can meet the pregnant cow’s needs, while mature grass hay needs to be fed with a small amount of supplemental protein (1-2 lbs).

If low quality forage (e.g. straw or corn stalks) and corn can be added to an alfalfa-based ration, cost can be reduced (Ration 3) to about $1.37/hd/day (if straw is $60/Ton). This savings of $0.07/hd/day equals about $10/cow during a typical winter feeding period.

Ration 4, which consists primarily of corn stalks, can maintain body condition in a pregnant cow if protein supplement (containing about 30% CP) is also provided. If baled corn stalks are $75/Ton, it costs $1.35/hd/day. However, the stalks need to have a decent energy content (e.g. TDN of 54% or higher). Conversely, a straw-based ration (Ration 5) must contain about 4 lbs of corn and 4 lbs of a 30% CP protein supplement to meet a 1,200 lb pregnant cow’s requirements. Interestingly, if straw is $60/Ton this ration would cost about $1.32/hd/day, which is truly the “least-cost ration” using the above feedstuffs.

The Bottom Line
Ration cost can be decreased by replacing high-priced feeds (usually alfalfa or good grass hay) with cheaper and lower quality forages (straw or corn stalks) and a small amount of corn and/or protein supplement – resulting in a decrease of about $0.22/hd/day, or more. Once a cow begins lactating, her energy requirement will increase and a new ration will be needed. Similarly, cows that are significantly larger or smaller than 1,200 lbs may need a different ration, as well as cows that should be gaining body weight and condition during late pregnancy. It would be valuable for a cow/calf producer to experiment with a free and user-friendly ration balancing program like COWculator in order to create a least-cost ration. Since forage prices will likely continue to increase in price, as they have done recently, it may be the only way to remain profitable in the future.

Dr. Jason Ahola is an Extension beef specialist with the University of Idaho. Contact him at jahola@uidaho.edu or 208-454-7654.

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