Cattle producers have seen major changes in winter feeding management over the last decade or so.
Many cows are still fed in traditional dry lots on stored feeds, but a significant number of producers have shifted their management to more extensive winter feeding arrangements, such as bale grazing or swath grazing.
Regardless of how cows are fed during winter, it is critical to monitor and manage body condition during their pregnancy.
In Canada, we tend to use a five-point scale for body condition scoring (sometimes known as the Scottish system), while Americans tend to use a nine point scale. People who use the five-point scale often use half increments, which make the scale similar to the American system.
Learning to body condition score is easy and it is an inexpensive way of determining the amount of fat an animal is carrying.
The main areas used to evaluate body condition in cows are the hip bones (hooks and pins), the tail head, the back bone and the short ribs. A cow with a body condition score of one is extremely thin and emaciated. No external fat is present and these cows will have difficulty surviving under any stressful conditions.
Cows with a body condition score of two have very little fat tissue, but have muscle tissue around the tail head and over the hip bones. Individual ribs can still be identified.
Cows with a body condition score of three have a slight cover of fat evident in the tail head area and over the ribs.
Cows with a body condition score of four have more abundant fat deposits, and cows with a score of five are obese with large deposits of fat over the tail head, hip bones and ribs.
Body condition scoring is best done as a hands-on process be-cause it can be difficult to visually assess cattle with heavy winter hair coats.
The traditional targets for body condition score in beef cows are that cows should have a body condition score of three at the start of the winter feeding period and 2.5 to three at the start of calving.
The implications of poor body condition can be significant and are especially noticeable at calving and breeding time the following season.
In addition, very thin cows are serious animal welfare issues. It becomes even more important during bouts of extreme cold when the energy demands for body maintenance become significantly higher.
Condition scoring can be used to sort the herd into groups that have similar nutritional needs. Heifers and thin cows may need more energy in their rations and may also require a situation that allows for less competition for feed.
Numerous research studies have shown the impact of body condition on fertility. By 70 days after calving, only 55 percent of thin cows will have started cycling again.
That compares to 80 percent of cows in moderate condition and 96 percent of cows that are in good body condition.
In addition, the first service conception rates may be as much as 20 percent lower for thin cows. The results are dramatic and can have significant effects on pregnancy rates in the following year. If the cows aren’t cycling, they cannot get pregnant.
Cows should ideally calve in a body condition score of 2.5 to three and maintain or improve that body condition during the breeding season on pasture when feed resources are typically less expensive.
However, if thin cows are identified at weaning time, it is important to improve their body condition before calving. Once cows begin lactating, their energy demands become much higher. It is very difficult to catch up on body condition after calving.
Cows should be assessed for body condition at some point near the beginning of the winter feeding period. This allows producers to sort thin cows and heifers into separate groups so that they can have access to higher quality feed.
Pregnant heifers have greater nutritional demands because they are still growing and thin cows would have a chance to improve body condition before calving.
As many producers move to more extensive winter feeding systems, we need to continue to emphasize the old-fashioned ideals of good husbandry.
Body condition scoring is a simple, inexpensive tool that can help you make important management decisions that will help to maximize future fertility in your cow herd.
John Campbell is head of Large Animal Clinical Sciences at the University of Saskatchewan’s Western College of Veterinary Medicine.