The Importance of Monitoring Beef Cattle Body Condition
David Secrist, Utah State University Extension Beef Cattle Specialist
Introduction
The connection between body energy stores, in the form of fat, and reproduction has been quantified for decades (Herd & Sprott, 1986). A body condition scoring system commonly used in the U.S. is an objective effort to quantify a cow’s body condition with ratings from 1 (severely emaciated and weak) to 9 (excessively obese), resulting in a body condition score (BCS). Optimal BCS in commercial cow/calf operation is from 5 to 7, depending on the production stage, feed resources, and the animal’s age. Reproductive efficiency is critical to operational success and is closely tied to BCS.
Body Condition Scoring
The short Angus TV video (2022) How-To: Body Condition Scoring Cattle is an excellent tutorial on evaluating body condition score in the beef herd.
Highlights
• Reproductive efficiency is closely tied to BCS.
• Minimize scoring variability by using the same person to score each herd or train a group to apply a consistent approach.
• Pregnancy rates increase with increased BCS.
• Adding weight to cows and heifers during the second trimester is most effective and economical.
Being consistent in BCS evaluation is important You can minimize variability in body condition scoring by using the same person to score each herd. Person-to-person variation can confuse the results, making management decisions difficult to apply. However, if several people are involved in BCS evaluation, train as a group to calibrate a consistent approach. Recalibrating through the critical second and third trimesters can also be helpful. Appendix 1 includes a table listing BCS and corresponding physical attributes for reference.
Why Is BCS Important?
Studies have shown a strong positive relationship between BCS at calving and overall reproductive performance. Figure 1 demonstrates the relationship between BCS at calving and subsequent pregnancy rates.
Figure 1 Pregnancy Rate With Increasing BCS
Source: Fields & Sand, 1993
Cows rebred 30 percentage points higher as body condition at calving increased from >4 to 6>. Table 1 outlines additional research demonstrating the relationship between BCS at calving and reproductive performance. Cows with a BCS greater than 5 bred much earlier in the breeding season than those with a BCS less than 5 (Richards et al., 1986). Similarly, heifers with higher BCS scores bred earlier in the season (Spitzer et al., 1995)
Table 1. BCS Effects on Reproductive Performance
For cows to calve every 12 months, they must conceive between 80 and 85 days postpartum. Extending the twelve-month calving interval is very costly. A healthy calf will gain approximately 1.8 pounds per day of age. Every day that a cow does not conceive after 85 days postpartum will reduce the calf weaning weight by 1.8 pounds. At that rate, the difference in weaning weight between a calf born on the first day of a 90-day breeding season and one born on the last is over 160 pounds! Furthermore, the cost to keep both cows for a year is the same, but additional revenue from the early calver is significant.
How to Apply BCS
Body condition scoring can be done anytime, but in a typical western range operation calving in the spring, an optimal time to begin BCS evaluations is during the fall pregnancy check. Each cow can quickly be visually assessed in or leaving the chute, keeping a tally of the number of animals that fall into each BCS category Fall/weaning time is also a great time to add body weight, as the cow ’s maintenance requirements are at their lowest during the second trimester, and the weather is usually favorable.
If ranch logistics permit, sorting out thinner cows (BCS 4 or less) may be advantageous to allocate higher-quality feed resources or supplementation to those most in need. Running thinner cows with first- or second-calf heifers is an option, as younger females also need a higher plane of nutrition.
After weaning and pregnancy exams, spot-check each herd to see how body condition changes. In large herds, determine sample size and randomly score the number of animals needed. A cross section of around 20% should provide a good idea of the BCS trends in the herd. Pay special attention to the percentage of cattle that are BCS 4 or below and those that are BCS 6 and above. If the number of 4’s are increasing, consider a supplement or an increase in pasture quality. If the number of 6’s are increasing, consider reducing supplementation. Monitoring the change in BCS over time will allow for a timely intervention if needed. Improving BCS when cows enter the third trimester is much more difficult due to higher maintenance requirements. This is further magnified by the winter weather often experienced during this production stage.
Supplementation
If cows are grazing dormant forages and/or low-quality hay, a small volume of supplemental protein can make a big difference. If deficient, protein supplementation will increase dry matter intake, thereby increasing the energy intake. A relatively modest increase in dry matter intake can change the energy balance and allow the cow to gain weight and body condition. Test forage quality to best assess supplemental protein needs.
The difference in weaning weight between a calf born on the first day of a 90-day breeding season and one born on the last is over 160 pounds!
Maintenance
It is critical to get the mature cow herd to a BCS of 5 or above and keep them there through the third trimester up to calving Fetal development and the physiological demands on the cow leading up to and through calving are tremendous. Weather is often a complicating factor during this time as well. Adding weight to a thin cow at this juncture is very difficult and expensive. Figure 2 demonstrates the effect of BCS at calving on subsequent breeding rates when heifers are fed to gain or maintain their current body weight. Those calving at a BCS greater than 5 bred at 94% when fed to gain weight, while those fed to maintain still bred at a 91% rate. Contrast that with heifers calving at BCS less than 5. Those that only maintained their weight bred at 36%, while those fed to gain bred at 67%. Both results are far below those of heifers in better body condition and would be considered unacceptable. Compounding the poor results of the thinner heifers is the cost associated with the attempt to improve their body condition.
Maintain or Gain Weight
Source: Bell et al., 1990
In summary, adding weight to cows and heifers during the second trimester is far more effective and economical than attempting to feed them back into shape after they are already too thin at calving.
Heifers
First-calf heifers require additional attention during the critical second and third trimesters The same can be said for a 3-year-old preparing to have her second calf. Like their older herd mates, young heifers can put on weight very efficiently during the second trimester. Because the heifer is still growing herself, her need for body fat stores is greater than a mature cow. The BCS goal for a first-calf heifer is between 6 and 7. Getting a heifer too fat can increase the likelihood of calving difficulty and should also be avoided.
Following calving, the first-calf heifer can be a challenge to get bred back on time to maintain a twelve-month calving interval. As demonstrated, proper body condition (BCS 6-7) will significantly impact achieving this goal.
Figure 2. Postpartum Body Weight Change of Heifers With BCS <5 and >5 Fed to Either
It may also be advisable to start calving the first-calf heifers 2-4 weeks ahead of the mature cowherd. This will allow additional time for the young females to recover from calving. Additionally, this will aid in allocating scarce labor resources to focus on the heifers during this time of increased stress
Key Points
1. Learn and use the body condition scoring system available through the online resources noted.
2. Regularly monitor and record BCS scores in each herd, especially through the second and third trimesters.
3. Separate young and thinner females to more effectively allocate resources.
4. Maintain mature cows in a BCS 5 or greater Keep heifers between BCS 6 and 7.
5. Make adjustments in the feeding or grazing program early to avoid the need to add weight during the third trimester or after calving.
References
Angus TV. (2022, December 7). How-to: Body condition scoring cattle [Video]. YouTube. https://www.youtube.com/watch?v=BfW97OH02E0
Bell, D., Wettemann, R. P., Lusby, K. S. & Bishop, D. K. (1990). Effects of body condition score at calving and postpartum nutrition on performance of two-year-old heifers. Oklahoma State University Extension.
Fields, M. J., & Sand, R. S. (1993). Factors affecting calf crop. CRC Press.
Herd, D. B., & Sprott, L. R. (1986). Body condition, nutrition and reproduction of beef cows. Texas Agricultural Extension Service.
Richards, M. W., Spitzer, J. C., & Warner, M. B. (1986, February 1). Effect of varying levels of postpartum nutrition and body condition at calving on subsequent reproductive performance in beef cattle. Journal of Animal Science, 62(2), 300–306. https://doi.org/10.2527/jas1986.622300x
Spitzer, J. C., Morrison, D. G., Wettemann, R. P., & Faulkner, L. C. (1995). Reproductive responses and calf birth and weaning weights as affected by body condition at parturition and postpartum weight gain in primiparous beef cows. Journal of Animal Science, 73(5), 1251–1257. https://doi.org/10.2527/1995.7351251x
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November 2024
Utah State University Extension
Appendix 1. Guide to Body Condition Scoring Cattle
aBCS = Body condition score
Sources: Adapted from Herd & Sprott, 1986; Table created from Justin Wagonner, Ph.D., Kansas State University (personal communication)