Beef Cow Nutrition

Associate Professor Steve Morris
Veterinary and Animal Sciences Group
Massey University

Good nutrition in beef cow production, as with any animal production, is paramount. Beef cows have the advantage that high levels of nutrition are only required for a specific period of the year. They have the disadvantage, however, that if the nutritional requirement is not met over that critical period, not only poor production will result but large losses can occur.

This article considers the post-weaning and pre-calving period. Body condition scoring has been used as an aid to feeding and management of the herd at critical periods. Condition scoring provides a measure of the level of body reserves of a cow, which is independent of liveweight, and a more reliable description of its condition than is liveweight alone. The method involves assessing the level of fat cover on two areas of the cow's body. A 0-5 scale (in increments of 0.5) is used.

Post-Weaning (weaning up to 4-6 weeks pre-calving)

During the post-weaning period beef cows are considered low priority stock and can function as 'work horses' eating rank pasture, and controlling shrub re-growth. During this time, feeding priority can be given to other classes of stock and cows become one of the few groups available that can be restricted in the interests of better pasture development. This is a major justification for maintaining a breeding cow herd on hill country. Not only has it significant advantages for the farm as a whole, but it has in fact been shown to be beneficial for the cows to lose around 10% of live weight in the post- weaning period. Cows losing that order of weight will have better longevity and will suffer no reduction in performance provided their nutritional requirements are met in the pre- and post?calving periods. Cows too fat (in excess of condition score 3.5 - on a scale 0-5) at calving are more prone to calving difficulties and much more prone to metabolic disease.

Some farmers rotate their cows behind the ewes in a winter rotation. In such situations cow intakes are kept very low e.g. Angus cows 3-3.5kg DM/ day. This shows their efficiency and supports the contention that an efficiently managed beef cow could have a true winter stock unit cost of 3.5 stock units. Minimizing cow?herd feed requirements during maintenance periods can have a significant impact on overall feed efficiency and therefore profitability. This should be a consideration when establishing appropriate stock unit equivalents.

The ability of beef cows to lose weight through the winter is dependent on body condition. Obviously thin cows (condition score less than 2.0) cannot be fed below maintenance for extended periods.

Pre-calving (from 4-6 weeks pre-calving to calving )

Cows that have lost in the order of 10% body weight post weaning will need to regain condition pre-calving. If they do not, there is a risk they will be simply too weak at calving and their calf losses will be high (10%-20%).

A relatively short period (4 weeks) of good nutrition (8kgDM/ day) is usually sufficient enough to have the cows gain the liveweight taken off since weaning. Note that the calf is gaining at 250 grams/day in utero during the last month of pregnancy. If cows calve in good condition (condition score 2.5 - 3.0) it will make the mating condition target of 3.0 a lot easier to meet.

While poor pre-calving nutrition and body condition score will exacerbate post-calving under-nutrition problems, priority in terms of feed allocation should be given to the post -calving period. This can be achieved by shedding cows out from a moderate plane of nutrition to a high plane as they calve, or by strip grazing, or simply by shifting into saved feed at the start of calving. Whatever system is used to apportion feed, it is the condition score at calving that is critical. This is one of the most critical points in cow management.