A new multistate study offers some cow insight that may surprise some ranchers. In dry and dusty conditions, smaller cows may be the best way to get the most from your herd.

That's the recommendation from a recent multidisciplinary study involving researchers from Oregon, Wyoming and Oklahoma. The work shows that breeding smaller cattle could be a long-term strategy that will help ranchers and ease pressure on increasingly drought-prone range, according to Leticia Henderson, Oregon State University livestock and range Extension agent.

The research team developed a statistical model showing that smaller cows have a distinct advantage over larger ones in pastures where cows don't have much to chew on. The study is published in the journal Rangelands, and is meant to help cattle producers develop long-term strategies on cattle selection and natural resource management for areas that are expected to have more frequent and severe droughts.

A standard management tactic for many cattle producers in the past, when drought hits, is to reduce herd size or increase the cattle's feed, but these methods are costly and don't solve the problem in the long term, Henderson said.

If the total herd size is larger — 100 head weighing 1,000 pounds, vs. 78 head weighing 1,400 pounds — feed costs will be lower for the larger herd. Also, with all things being equal in a pasture with little to graze, a smaller cow can produce milk more quickly because it doesn't expend as much energy to maintain a larger body size.

Said Henderson: "The perceived benefit of larger cows is that they will be able to produce larger calves. But the smallest cow size in our model was the most efficient at weaning. That's based on a previous study by our group that found larger cows in nutrient-limited rangelands don't always wean larger calves."

Grazed forage remains the least expensive nutrient source to maintain a cow herd, so matching cow size and milk production potential to forage resources should help mitigate the impact of rangeland drought on the herd, Henderson said.

More on the research
The researchers assumed cows in limited-nutrient environments would eat 2.2% of their body weight daily over a 210-day weaning period. An ideal weaned calf should weigh about half as much as its mother, "so the likelihood of a 1,400-pound cow weaning a 700-pound calf on rangeland is highly unlikely in 210 days," Henderson said.

Recent studies suggest the ideal cow weighs between 1,000 and 1,200 pounds on land where grazing opportunities are scarce. Yet, USDA has determined that the average domestic cow size is nearly 1,400 pounds. The model developed by researchers used cow sizes ranging from 1,000 pounds to 1,400 pounds.

That rising size of the average cow is due to a steady trend in selective breeding over the last few decades, and researchers don't expect herds of smaller cows in the next few years. They want their model to be considered by cattle ranchers over the long haul.

Added Henderson: "This isn't a short-term solution. It took a long time to breed 1,400-pound cows. We're not going to get down to 1,100-pound cows overnight, either."

USDA's National Institute of Food and Agriculture funded the research. Derek Scasta, University of Wyoming Extension rangeland specialist, led the study.

Source: Oregon State University