By Robin Salverson
Weaning is a good time to evaluate your cows to determine average body condition score of your herd.
What does a body condition score (BCS) tell you?
It is a visual estimate of the energy balance of the cow herd. It is based on a 9 point scale with 1 being emaciated and 9 being obese.
What is the optimal BCS at calving?
The goal is to have cows at a BCS 5 at calving. A BCS 5 refers to a cow with a generally good overall appearance, the fat cover over the ribs feels spongy and palatable fat cover on either side of the tail head. Since heifers are still growing, a BCS 6 is recommended at calving. BCS 6 animals will have a high degree of palpable fat over the ribs and around the tail head and firm pressure is needed to feel the spinous processes. View Basics of Body Condition Scoring (BCS) to learn more on how to body condition score.
If I calve in the spring, why am I concerned about BCS this fall at weaning?
To move a cow 1 full body condition score, requires a cow to gain 75 to 100 pounds of body weight. While she is lactating or during rapid fetal growth in late gestation the more challenging and expensive it is to change a BCS. During late gestation, a fetus will grow by 70%, taking up more room in the body cavity and displacing the rumen. As a result a higher quality feed needs to be fed, to offset the inability of the rumen to hold more feed. At the same time the rumen is being displaced, the cow’s requirements are increasing making it more challenging. While at weaning, the cow’s nutrient requirements are at her lowest (see Table 1). Perfect opportunity to put additional condition on a cow.
Table 1. Nutrient requirements of cow based on production phase.
| Production | 1,200 lbs. | 1,400 lbs. |
| Phase | TDN | CP | TDN | CP |
| Phase 1a | 59.70% | 10.10% | 59.10% | 9.80% |
| Phase 2b | 55.80% | 8.60% | 55.20% | 8.40% |
| Phase 3c | 50.30% | 7.10% | 50.10% | 7.10% |
| Phase 4d | 53.50% | 8.00% | 53.50% | 8.00% |
*on a dry matter basis and based on dry matter intake of 2.0% body weight.
a Phase 1: Calving to conception.
b Phase 2: Early gestation and lactation.
c Phase 3: Weaning and mid-gestation.
d Phase 4: Late gestation. |
Why is it important to determine BCS?
A cow’s body condition score prior to calving has the largest impact on re-breeding success. Important research by Selk et al. in 1986 reported 88-98% of the cows in a BCS 5 or greater at calving were cycling at 80 days postpartum, compared to 62% of the cows in BCS 4 or less. Also pregnancy rate was lower amongst BCS 4 or less cows compared to the cows 5 or greater (61% vs. 90%). Based on this research, 38% of the cows that were not cycling by day 80 post calving will not maintain a 365 day calving interval and should be culled from the herd.
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