McKinnon: Interested in feeding your cattle more efficiently this winter?

Nutrition with John McKinnon

As we move into fall, one of your “to-do” tasks will be to book a herd health visit with your veterinarian. This will include administering any needed vaccinations, structural soundness evaluations as well as pregnancy checking bred cows and heifers. One management tool that may not be included is body condition scoring. If this is the case, I would encourage you to seriously consider incorporating this relatively simple and cost-effective management tool into your herd health program. It not only can help optimize herd fertility but can also facilitate the development of an efficient winter feeding program.

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Body condition scoring is a hands-on method of evaluating the body fat reserves of your cattle. Since body fat content reflects an animal’s energy reserves, a body condition score can be used as a proxy for the nutritional status of the animal. Simply put, thin cows are in poor nutritional condition with minimal energy reserves, while over-fat cows are in excessive condition.

In Canada, the five-point “Scottish” system is used to evaluate body condition score. Evaluation can include both a visual and physical assessment. Visual evaluation includes an overall assessment of the condition of the cow with a focus on areas where fat accumulates (i.e. tail head, hook and pin bones, brisket and ribs).

Physical assessment involves placing your hands on the animal’s body in areas where you can objectively evaluate body fat reserves. These include the backbone and short ribs. In these areas of the body there is no underlying muscle tissue between the vertebrae and the hide or between the hide and the pointed tips of the short ribs. However, in well-fed animals fat tissue will be deposited under the hide, making it more difficult to palpate the skeleton in these areas. The degree to which fat is deposited will be dependent on the nutritional status of the animal. In underfed animals it is very easy to feel the vertebrae along the backbone or the tips of the short ribs. However, in well-fed animals, it is much more difficult to feel these skeletal markers as fat is deposited between the hide and the bone.

Under the “Scottish” system, a condition score of one equates to an extremely thin, underfed animal. With such an animal, it is very easy to feel individual vertebrae along the backbone as well as the tips of the short ribs. Going to the other extreme, a condition score of five is an over-fat animal that is not only visually over-conditioned, but has so much fat under the hide that it is almost impossible to evaluate skeletal structure upon palpation. Condition scores of two to four are progressive increases in fat reserves that are deposited under the hide. With practice you can become very proficient in separating cattle into groups based on condition score, even to the extent of separating cattle within a given condition score into two groups such as condition score 2.0 and 2.5.

In most Canadian production situations, a condition score range from 2.5 to 3.5 is considered optimal. Animals that fall outside this range can have fertility and calving issues, are a welfare concern in the case of scores less than two and are too expensive to keep in the case of very over-fat cattle.

To efficiently implement a condition score system, one needs to score cattle at least twice a year, once in the fall coming off pasture and at calving. If possible, score before the breeding season as well. Why so often you ask? Scoring cows at these critical points in their reproductive calendar allows you to monitor changes in their nutritional status and gives you the opportunity to implement changes to their feeding program as necessary. For example, if a high percentage of cows are falling into a condition score of two at calving, you would have the opportunity to increase the nutrient density of the ration in order to have them gaining weight prior to breeding, a practice that will improve first service conception rates.

Sorting bred cows into specific winter feeding groups is another example of how this management tool can be used to target nutritional needs and lower feed costs. For example, as part of your fall herd health program, mature cows can be separated based on condition score into three groups: thin cows (less than CS 2.5); cows in good condition (2.5 to 3.5) and over-fat cows (condition score greater than 3.5). These groups can then be fed according to their nutritional needs without over- or underfeeding the other groups. For example, thin cows going into winter will need to be fed to gain weight in addition to their requirements for maintenance and pregnancy if they are going to successfully rebreed in the spring. Mature cows in good body condition can be fed to maintain weight through the second trimester of pregnancy, while over-fat cows can actually be allowed to lose some weight over the winter and by so doing help to reduce feed costs. As the cattle enter the last trimester of pregnancy, adjustments to the feeding program can be made for each group in order to account for the increased nutritional demands of pregnancy.

This is only a brief introduction into the merits of implementing a body condition scoring system. For more information on how to implement a system that works for your operation, talk with your veterinarian.

About the author

Contributor

John McKinnon is a Professor Emeritus at the University of Saskatchewan and a consulting nutritionist who can be reached at [email protected].

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