Beef: Good nutrition for pregnant cows gives their offspring an edge

Sunday, January 10, 2010

Research and practical experience show that protein or mineral supplements for late gestating cows can add substantially to weight gain for their young

by SUSAN MANN

The nutrition pregnant cows get during late gestation can affect their offspring's future production, even having an impact on the fat deposition in finishing steers that determines their quality grade, according to a new University of Nebraska study.

Research by Rick Funston, of the university's West Central Research and Extension Center, shows that underfeeding protein or energy to cows can affect the fetus's development in specific ways, such as the growth of muscle, the development of organs and the fetus's operational physiology. The effects can be seen later in the animal's life – for example, on heifer fertility or on fat deposition in finishing steers.

Funston's latest work is one of several multi-year studies he's done on the influence of cow nutrition in late gestation on calf performance. His study focused on supplementing protein during late fall and early winter to a group of 130 Red Angus/Simmental composite cows with one half grazing pasture and the other half grazing corn stalks. Half of the cows in each group got a daily pound of 28 per cent crude protein supplement. 

The study was replicated over three years with almost 400 cows being used in total.

All cows had similar pregnancy rates in the next breeding season, but the supplemented cows went into calving in better body condition.

The steers whose mothers were supplemented on range had a 48-pound weaning weight advantage and they maintained that edge during their lives. Their carcasses were nearly 42 pounds heavier than the group whose mothers had fed on corn stalks.

The important practical note in all of this is that it's more about keeping cows in good body condition than anything else, Funston says. "We did a previous study where we weaned cows earlier and the benefit of supplementation was much less."

Funston says his main message to farmers is to monitor body condition score. "We want cows to calve and go through that last trimester in a moderate body condition."

Cow-calf producer Kim Sytsma of Athens, near Brockville, has had first-hand experience in ensuring cows get adequate nutrition. For the past nine years, Kim and her husband, Charlie, have been giving their 220-brood cows "the best quality mineral we can buy" 365 days a year. The mineral, a combination of magnesium, zinc, calcium, selenium, vitamins D and E with a flavour-enhancer, is offered freechoice to both cows and calves. At different times and trimesters, the cows will eat the mineral like candy, while at other times they won't chomp as much. 

"We have found since doing this that our cows are much healthier," says Kim, adding that they don't have pink eye, foot rot or "those big, stupid calves we used to have."

 When money was tight one year due to poor calf prices, they skipped the minerals and many of those same problems returned. "We'll skimp a lot, but we don't skimp on the minerals," Kim notes, adding that they have a very robust vaccination program which works with the minerals.

They got the idea to use the minerals from a fact sheet from the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) and from studies about cow nutrition.

OMAFRA beef specialist Tom Hamilton says the effects of poor nutrition on pregnant cows are most likely to occur when they're fed low-quality crop residues or hay, or are grazing stands of very mature hay or crop residues in late fall or early winter. In these circumstances, protein supplementation may be cost-effective.

In cases where pregnant cows are being fed a ration of medium-quality hay or the equivalent, their energy and protein needs are likely being met, making protein supplementation less beneficial. It's also important to give cows a mineral supplement that matches the feeds being used.

To determine if pregnant cows would benefit from protein or energy supplementation, farmers should have the nutrient content of feeds tested in a lab and consult a nutritionist, Hamilton says. BF