Milk Production Puts High Nutritional Demands on Beef Cows

Is this year’s weaning date already on your calendar? Traditional fall weaning dates arise from a combination of declining forage supply and quantity, declining milk yield in the cow and having calves off the cow before winter weather sets in. These are all important considerations and ones that should be evaluated closely every year. Milk production is a major driver of cow nutrient needs and how well the forage supply is meeting those needs should be closely monitored.

Dietary needs during peak milk production
Peak milk production is expected to occur at about 60 days after calving in mature cows. At that time dietary protein needs for the cow are at their highest for the year. A 1200 cow producing 20 pounds of milk at peak lactation requires about 2.8 pounds of crude protein per day, whereas a non-lactating cow needs only 1.4 pounds, or half, the amount of protein as a lactating cow. The quantity of protein consumed is a function of both protein content of the forage and dry matter intake by the cow.

Maximum feed intake occurs several weeks after the peak in milk production. The following graph shows the impact of increasing milk yield and time since calving on expected dry matter intake. At the time of greatest intake, intake is 18% greater for a cow producing 30 compared to 10 pounds of milk per day. A non-lactating cow would consume about 1.8 pounds less forage per day than a cow producing 10 pounds of milk at peak lactation.

Weaning considerations when forage supplies are limited
When forage conditions are limiting, in either quantity or quality, it could be worthwhile to consider weaning calves earlier than a more traditional fall date. Early weaning of calves spares forage to help support the cow herd. Not only will the non-lactating cows eat less, the forage that the calves would be eating is also saved.

Because of the forage savings, early weaning is often thought of as a drought management tool. Rightfully so! When forage is sparse due to drought, weaning earlier than traditional fall dates can help manage limited forage resources. But there may also be an advantage to weaning earlier than normal if cows are in thin condition in late summer. Moving up the weaning date could allow those cows time to recover some condition before winter; ultimately saving on winter feed costs.

Very early weaning (before breeding) may be something to consider under certain conditions also. Weaning calves before the breeding season may help improve reproductive performance in young or thin cows. A thin cow producing milk may be in poor energy status and may not begin reproductive cycles after calving. Removing the demand for milk will help improve energy status and chances of an energy-deficient cow cycling. Little benefit in reproduction is expected from early weaning cows with adequate energy stores and feed resources that have begun cycling normally after calving.

Early weaned calves have been shown to gain very efficiently in the feedlot. However, these calves often have lighter carcass weights than calves weaned at the more traditional 7 months of age. Feedlot operators need to know they are managing early weaned calves so they can be fed properly to avoid compromising carcass characteristics.

Weaning time can be determined by a combination of forage and cow condition on a yearly basis. In some years, a traditional weaning date may be the best choice. Early weaning can be a valuable tool when conditions warrant.

Source: Elaine Grings, South Dakota State University 

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