Observe Body Condition Score at Calving — and Before, by Dr. Shelby Roberts

By DR. SHELBY ROBERTS Alltech

Calving season is game time for a cow herd, and producers want to make sure that their cows are in peak condition prior to kick off. The best way to measure the condition of your cow herd is by utilizing body condition scores (BCS). As the name suggests, a BCS is an estimate of a cow’s condition or the amount of fat they are carrying.

The amount of fat — and its placement — determines BCS. Body condition scoring is an easy and effective tool for producers to use. Still, a familiarity with the fat deposition and skeletal structure of cattle is required to properly determine BCS. The key areas used to evaluate the degree of body fat on cattle are the ribs, brisket, hooks, pins, and tailhead. Typically, for beef cattle, a scale of 1-9 is used to indicate BCS, with 1 being emaciated, with all of the cow’s ribs and bones easily visible, and 9 being obese. • Thin cows have a BCS of 1-3 • Moderate condition cows have a BCS of 4-6 • Fat cows have a BCS of 7-9

The ideal BCS for mature range beef cows at calving is a score of 5, and for calving heifers, an ideal BCS would be a 6. This difference in BCS at calving is because heifers are still growing and have a higher nutrient requirement for growth compared to mature cows.

Evaluate BCS prior to calving and breeding. Timing is important when evaluating body condition scores. Producers should aim to evaluate BCS prior to the calving and breeding seasons. Suggested evaluation timepoints include 90 days prior to calving, breeding, and the start of the winter season. This will give the producer enough time to try to improve BCS if cows aren’t hitting their target prior to breeding and late gestation.

Body condition scores can be used as a nutritional management tool. For instance, depending on a producer’s facilities, cows can be sorted into groups using BCS. Cows that meet or have above target BCS scores need no special nutritional intervention and can maintain condition on quality range pasture. Cows with low body condition scores or replacement heifers could be supplemented with additional nutrients to improve or maintain their body condition during calving and breeding.

Another good time to evaluate BCS is heading into winter grazing. Cows that are thin at the start of winter grazing will require supplemental feed just to maintain their body condition, as energy requirements increase up to 40 percent during the winter. Additionally, trying to improve BCS during the winter is going to cost 20–30 percent more than during the fall.

A poor BCS can negatively affect a cow’s calf. The productivity of a cow herd depends on keeping them within the producer’s ideal BCS. It is well established that a poor BCS can have detrimental effects on a cow’s reproduction. Thin cows take longer to come into heat and, therefore, only have one chance at rebreeding. Over conditioned or fat cows can also negatively impact reproduction rates. However, a poor BCS can also affect the overall health and performance of a dam’s calf.

The relationship between cow BCS and calf performance is based on the energy requirements of the cow. To maintain an ideal BCS, cows must have enough energy to support all of their bodily energy requirements. When a cow’s energy requirements are not met by her diet, then she must use the energy stored in her body as fat. The more stored energy she uses, the further she moves down the BCS scale.

There is a priority use for energy for bodily functions, as outlined below:

Priority energy use by cows (adapted from Short et al., 1990) 1. Basal metabolism 2. Grazing and other physical activities 3. Growth 4. Supporting basic energy reserves 5. Maintaining an existing pregnancy 6. Milk production 7. Adding to energy reserves 8. Estrous cycling & initiating pregnancy 9.Storing excess energy (i.e., fat deposition)

This hierarchy shows that maintaining pregnancy (i.e., gestation), milk production, and reproduction are all lower on the list of energy use priorities. This illustrates the importance of cows consuming enough energy from their diet to meet their maintenance requirements before energy can be used for pregnancy and milk production.

A cow’s BCS affects her reproductive ability, too. Evaluating BCS at 90 days prior to calving — when cows are about to enter late gestation — is critical, as this is a moment in time that could impact the future growth and performance of her calf. About 75 percent of calf growth occurs during the last 60 days of gestation, meaning that the cow’s energy requirements are going to be higher for the last 60 days of her pregnancy. If cows are thin going into the third trimester of pregnancy, then there could be reduced calf growth due to a lack of energy available for supporting the pregnancy.

Smaller calves are more prone to sickness after birth. Weaning weights have also been shown to be lighter when cows have poor body condition. Until weaning, milk is the major energy and nutrient source for calves. If cows are in poor body condition, they lack the energy necessary to produce the quality milk needed for calf growth.

Research has shown that herds that maintain cows with the ideal BCS ranges (5–7) have better calving and weaning percentages, which are a measure of the herd’s overall reproductive and production efficiency. Thin cows are going to have a harder time maintaining pregnancies and growing calves. A poor BCS leads to fewer pregnancies, fewer calves weaned, and calves weaned at a lower weight, which leads to lower overall returns.

Body condition scoring helps evaluate the nutritional status of the cow herd. Producers should routinely check the body condition scores of their herds to continually monitor the condition and nutritional status of the cows. If a large portion of the cow herd has a low body condition score, the herd nutrition should be evaluated to make sure that their energy and protein requirements are being met. A prolonged poor BCS can have a harmful impact on production outcomes, which can also negatively impact the economic returns of an operation. Evaluating BCS to determine not only the herd’s reproduction readiness scores but also its nutritional status is an opportunity to positively impact calf performance. Reference

Short, R.E., R.A. Bellows, R.B. Staigmiller, J.G. Berardinelli, and E.E. Custer. 1990. Physiological mechanisms controlling anestrus and infertility in postpartum beef cattle. J. Anim. Sci. 68:799-816.