Part III: Using Nutritional Management to Even the Score
Previously, we explained the Nine Point Body Condition Scoring
System for beef cattle, how Body Condition Scores (BCS) affect cow productivity
and when Body Condition Scoring should be done. In Part III, we will offer some
suggestions on how producers can put this information to work 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.
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Table 1: Percent Body Fat Associated
With Body Condition Scores
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BCS
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% Empty Body Fat
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| 1 | 3.8 |
| 2 | 7.5 |
| 3 | 11.3 |
| 4 | 15.1 |
| 5 | 18.9 |
| 6 | 22.6 |
| 7 | 26.4 |
| 8 | 30.2 |
| 9 | 33.9 |
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Nutrient Requirements of Beef Cattle,
7th Revised Edition, 1996. National Academy Press, Washington, DC
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As a rule of thumb, one BCS will
equate 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.
Grouping Cows by Body Condition
The ideal BCS for mature cows (4 years +) prior
to spring calving should be 5, but should be one condition score higher for first
calf two-year-old heifers. The higher condition score is warranted for the younger
cattle 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 (grain, corn silage, 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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