Any discussion about getting ready for calving season should start with an evaluation of the body condition of pregnant cows and heifers. There are also significant economic factors to consider.
Several issues recently shifted priorities away from routine body condition scoring, such as beef supply chain disruptions due to COVID-19 and sudden swings in cattle. It is time to rethink the importance of body condition scoring.
Regardless of food sources, cattle require adequate levels of energy, protein, fibre, vitamins and minerals to support maintenance, growth, reproduction, gestation and milk production demands. Support of the dam’s immune system and that of the calf grows in importance as pregnant animals approach term. When sourcing and adding non-conventional feeds to rations, the services of a livestock nutritionist become important to help balance rations.
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Body condition scoring is an effective way of assessing the physical condition of cows during the most demanding period of gestation — winter. Weight loss in cows is not always evident beneath heavy winter coats, or when cattle are not observed regularly as might happen during extended periods of swath grazing. Taking corrective measures early prevents many problems. Resources, including how-to videos, are readily available at beefresearch.ca/tools/body-condition.
Body condition scoring is a subjective, hands-on method of determining how much fat an animal is carrying. While body condition scoring requires the selection of representative groups of animals from the herd (e.g. bred heifers, young cows, older mature cows) and restraining them in a chute, it is a better predictor of body energy content than eyeballing cattle on winter feeding grounds. While experience and training improve your ability to eyeball cattle, looks can still be deceiving. It’s harder to see the shadows that help you detect the dips and hollows on black cattle. The time of year also affects accuracy — the University of Guelph found that even trained evaluators had a hard time accurately eyeballing body condition scores of cows in the winter.
Body condition scoring is easy to learn, fast, simple, cheap, does not require specialized equipment and is accurate enough to make important management situations. A numerical score standardizes the description of body condition for record-keeping purposes rather than using ambiguous rating terms such as “fat,” “moderate” or “thin” based on visual appraisal. A full hair coat can hide poor condition. Females that are too thin or too fat are expensive additions to a herd. Thin cows can have difficulty rebreeding, while fat cows come with excessive feed bills and are prone to things such as vaginal prolapses and calving problems. At the start of winter feeding, the optimum body condition score is 3.0. At calving, the optimum score is 2.5 for mature cows and 3.0 for first-calf heifers. At 30 days before the start of the breeding season, the optimum score is 2.5 for all females.
There are Canadian and U.S. systems of body condition scoring. Either can be used; both are equally accurate. The Canadian system uses a one-to-five point scale, whereas the American system uses a one-to-nine point scale.
Calf health suffers when cows are losing condition. The inherent disease-fighting ability of an immune system primed by high-quality colostrum is compromised. Cold and wet calving grounds on top of a handicapped immune system establish an ideal environment for disease-causing organisms to multiply. Scours and a variety of other intestinal conditions, respiratory disease and navel infections can decimate a calf crop.
In 2013, Drs. Cheryl Waldner and Alvaro García Guerra of the Western College of Veterinary Medicine in Saskatoon published a paper on a two-year study of over 30,000 beef cows from more than 200 herds across Western Canada. Cows were body condition scored three times: during preg testing in the fall, at the start of the breeding season and before calving. Those with a score below 2.5 were less likely to be pregnant than those with higher scores. Cows that lost body condition between calving and breeding, or during the breeding season, were also less likely to be pregnant.
Also consider forage quality. A forage quality survey conducted by the Saskatchewan Ministry of Agriculture in the fall of 2013 found that only 38 per cent of forage samples meet the energy needs of cows starting the last third of pregnancy at -25 C. Only five per cent of samples meet the cow’s energy needs in the last month of pregnancy. Test your feed.
A rule of thumb: one body condition score equates to about 75 to 80 pounds of live weight in cows. It is also important to remember that weight changes do not include weight of the fetus, fetal membranes, or fetal fluids, which in total amounts to about 125 to 155 pounds for cows in late gestation. A cow that is maintaining weight during late gestation is actually losing body weight and, possibly, body condition because the fetus is growing at least one pound per day.
Body condition of beef cows that calve in the spring influences productivity of the herd. Thin cows are slower to rebreed after calving compared to cows in moderate body condition. For a cow to maintain a 365-day calving interval, she must rebreed by 83 days after calving.
