Using Body Condition Score to Manage the Nutritional Program
Resource: Dr. Rick Rasby, University of Nebraska - Lincoln.
Previously, the Nine Point Body Condition Scoring System for beef cattle was explained and how Body Condition Scores (BCS) affect cow productivity. In addition, it was explained when Body Condition Scoring should be done and some management strategies. This learning module will explain how you can use this information to increase the efficiency of beef production.
Body Condition Scores Reflect Body Fat
The beef cow has the ability to store energy that exceeds her current nutrient requirements in the form of fat, so that she can draw on it at some future point when requirements exceed the nutrients supplied by her diet. This stored fat has the dual role of leveling out the peaks and valleys of a seasonal feed supply and insulating her against the effects of severe cold weather, thus reducing heat loss. The amount of fat associated with each BCS as a percent of empty body weight is shown in Table 1.
|Table 1: Percent Body Fat Associated With Body Condition Scores|
|% Empty Body Fat
|Nutrient Requirements of Beef Cattle, 7th Revised Edition, 1996. National Academy Press, Washington, DC|
As a rule of thumb, one BCS equates to about 75 pounds of live weight in cows that are weighed full or unshrunk. Thus, a 1200-pound BCS 4 cow would be expected to weight 1275 pounds at BCS 5 and 1350 pounds at BCS 6. These weight changes do not include weight of the fetus, fetal membranes or fetal fluids, which in total amount to about 1.7 times the fetus weight.
The bottom line is that substantial amounts of nutrients are required to elevate a cow herd one full BCS (75 pounds and 4 % fat) and this is increasing difficult after calving during lactation.
Grouping Cows by Body Condition
The ideal BCS for mature cows (4 years +) prior to spring calving should be 5 and is one condition score higher for first calf two-year-old heifers. The higher condition score is warranted for the younger females because after calving they are still growing while suckling a calf plus preparing for rebreeding.
It's much easier to get condition back on cows economically before calving because the nutrient requirements are lower compared to after calving. Two feeding groups prior to calving is often good strategy; one for mature cows in good condition (BCS 5) and a second group for thin cows (BCS 4). Often the thin cows are three-year-olds, pregnant with their second calf, and are thin because they lost body condition while nursing their first calf and didn't recoup their lactation weight loss in the fall after weaning. It may be possible to feed the thin cows with the first calf two-year-olds because the objective for both groups is weight gain while objective in mature cows in good condition is simply to maintain weight and condition. Also, the feedstuffs used for bred heifers is generally more energy dense (high quality hay, grain, corn silage, grain by-products, etc.) as opposed to the common foodstuffs used to feed mature cows in good condition (winter range, hay, crop residue). If mature cows are consistently appearing in the ''thin group'', a thorough re-evaluation of the breeding management program is in order. It could be the genetic production level of the cows simply doesn't fit the feed resource.
Developing Feeding Programs to Increase Body Condition
In order to increase body condition, the ration must meet the nutrient requirements for protein, minerals and vitamins; but exceed the requirement for energy for a given stage of production. Thus, to increase body condition, more energy must be fed, and in a dense enough form that the cow has the capacity to consume it on a daily basis.
Management practices which allow cows to gain body condition by grazing would always be more desirable than feeding harvested forages; however, striving for a BCS greater than 6 for mature cows by either route would likely not be economical.
When developing feeding programs, remember that as cows near calving nutrient requirements increase in percent of the ration and in total pounds. It is wise to feed lower quality forages in mid-gestation and save higher quality forage for late gestation and after calving. Lactating cows, for example, may not have enough capacity to consume enough low-quality forage to meet their needs.
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