A herd of Cows in good flesh has more calves and weans heavier calves.
Variation in the body condition of beef cows has a number of practical implications for your herd. The BCS of cows at calving is associated with length of postpartum interval, subsequent milking performance and newborn calf health and vigor. Excessive condition is often overrated as a cause of difficultbirthing in older cows, although fat heifers are known to be prone to calving difficulty. The condition of cows at breeding affects their reproductive performance in terms of service for conception, calving interval and the percentage of open cows.
What producers can do now, a couple of months ahead of spring calving, is sort the cows according to condition. If you can see ribs, they are going to be less than a BCS 5. Feed that group to gain weight. Cows that are 5 to 7 BCS should be sorted to be fed for maintenance to a slight gain. Finally, I have not seen many cows over 7, other than some pets and ET cows. So we’ll leave that group out. (For help judging body condition, see Today’s Farmer Summer 2011, p34.)
Why is having cows in good condition important? Because it makes a difference when cows get bred. If a cow doesn’t get pregnant, she’s a cull or a real money sink. Research in Florida looked at several different measurements, and having a BCS greater than 5 drastically improved the chances of a cow surviving preg check.
In the nearby chart, you’ll see the percent of cows that reached heat within 80 days after calving was lower for cows with a body condition of less than 5 than for cows scoring more than 5. Low body condition can lead to low pregnancy rates consistent with the reports of the other four trials. When cows are thin, the calving interval increases. To compensate for increased production costs, calves from cows with extended calving intervals must have a heavier weaning weight than calves from cows with shorter intervals, or an increase in sale price must occur. Depending on either factor for profit is a questionable assumption. With thin cows, long breeding seasons are sometimes suggested. This is not the profitable answer. Even after five and six months of breeding, the cows scoring less than 5 at calving and during breeding did not conceive at an acceptable level. Until they have regained some body condition or have had their calf weaned, most thin cows will not rebreed regardless of how long they are exposed to bulls.
Getting weight back onto cows
The practical management implication is to supplement cows based on body condition score. Body condition significantly alters the requirement for supplemental energy and slightly alters the need for supplemental protein, but it is not a determining factor of mineral or vitamin supplementation.Mineral supplementation is always required in that plantbased feed sources are always multiple mineral deficient. In addition to body condition, cow nutrient requirements are influenced by weight, mature size, breed type, milk production level, travel and environmental stresses. All things being equal, younger cows are going to need more pounds of supplemental feed than older cows. If we feed to satisfy older cows’ needs, the younger cows will be shorted. Also older, bigger cows are better at pushing and shoving—that has a big impact on supplemental feed intake, especially where supplement is modest (say feeding two pounds of cubes a day on the ground). If possible, separating cows by age, size and BCS is helpful.
One of the most crucial factors influencing the calf’s survival and performance is the degree to which the calf absorbs enough immunoglobulins from the colostrum to protect it until the calf ’s own immune system becomes functional. How the dam is fed influences colostrum quantity and quality. Cows fed lower-energy diets have been shown to have reduced colostrum yield and reduced colostrum solids—in other words, a lower level of immunoglobulins. This is troublesome on both accounts, in that lower yield means less volume to feed, combined with lower concentration reduction in available immunoglobulins to the calf is inevitable. Feeding adequate vitamin E and selenium has been shown to improve colostrum quality, as has feeding beta glucans and mannan oligosaccharides. MFA Ricochet cow products have been fortified with the specific additives and nutrients to encourage higher colostrum quality.
Dr. Jim White is ruminant nutritionist for MFA Incorporated.