Body Condition Scoring Guide for Bison
Written by Francie M. Berg
Canada has developed detailed national guidelines or Codes for the care and handling of farm animals, including bison and poultry. The Codes serve as the national understanding of animal care requirements and recommended practices.
The writers of these codes came together from a wide background of experience in studying and handling specific animals. They meet together and make decisions on what Canadian recommendations should be for each species.
Roy Lewis, DVM, is a veterinarian who served on the committee for the updated 2017 Canadian Code of Practice for the Care and Handling of Bison. The decision makers of these codes come from a wide background of experience in studying and handling buffalo.
Dr Roy Lewis, an Alberta veterinarian who has worked with bison many years and served on the committee updating the National Canadian “Code of Practice for the Care and Handling of Bison,” sent me links to the Canadian bison codes.
He also helped plan the International Bison Convention held in Saskatoon, Saskatchewan, July 12-15, 2022, and served as part-time technical services veterinarian for Merck Animal Health.
The Code of Practice for the Care and Handling of Bison was released in 2001 and updated in 2017. In Canada, scoring bison in your herd is considered an important management tool that allows ranchers to monitor and evaluate their feeding programs—and to adjust as needed.
The following comes from Appendix C of the Canadian code which discusses Body Condition Scoring. Much of this is adapted fromWhat’s the Score: Bison—Body Condition Scoring Guide from Alberta Agriculture.
Bison Body Condition Scoring
Body condition scoring (BCS) is a method of assessing the amount of fat cover on an animal, Since hands-on examination is impractical with bison the 5 point system for bison uses primarily visual clues.
The BCS system is a 5-point scale where a score of 1 means that the animal is extremely thin or emaciated and a score of 5 means that the animal is very fat.
Bison’s nutritional requirements and feed intake vary with day length/season.
A certain amount of weight loss is expected over the winter months. However, to accommodate this winter weight loss, bison need to be in good condition in the fall. Adult bison should not lose more than 1 to 1.5 body condition score during the winter feeding.
This table outlines target BCS for different classes of bison at different times of the year, generally scoring 3 to 5.
Table C.1 – Seasonal body condition score targets for breeding herds1
There are several features of bison anatomy that make condition scoring bison different from scoring cattle. Special attention is given to the hip bones, rump and hump.
Body condition scoring should be performed using a consistent procedure by an experienced person or one who has been mentored in the process. Evaluate the key landmarks of the hump, ribs, spine, hip bones, rump and tail head, and then take in the overall appearance of the animal.
Consider factors such as hair coat and the animal’s age, and then record the score on a 1 to 5 scale; half points (2.5/5) or a range (2–3/5) may be used, especially if the scoring is visual only.
All animals should be evaluated and scored if possible, or if that is impractical, a large cross-section of each class of animal in the herd should be scored. Determine the average for each class and note any particularly thin or fat animals.
Adjust feeding and management as necessary in order to meet BCS targets and take corrective action for individuals outside of the target ranges.
What’s the Score?
BODY CONDITION SCORING CAN HELP BISON producers manage their herd for optimal health, production, and profitability. Body condition refers to the amount of fat that an animal is carrying. Body condition scoring is designed to estimate the amount the fat the animal has. It is a useful management tool that helps farmers and ranchers do a better job feeding their stock.
BODY CONDITION SCORING SYSTEMS
THE FIRST BODY CONDITION SCORING SYSTEM was developed for sheep because producers could not determine how fat or thin a ewe was when she was in fleece. The manual palpation method for determining BCS was developed to overcome this problem. This system was later adapted for use with beef and dairy cattle and later for bison.
The system presented for bison in this article has been adapted from the beef and dairy cattle 5 point scale. A body condition score (BCS) of 1 indicates that the animal is very thin. A BCS of 5 indicates that it is very fat. Since bison are seldom caught in a squeeze to allow a “hands on” body condition scoring system, most of the criteria used to assess the animal are visual clues.
While learning how to body condition score bison, it is helpful to feel the bison in a squeeze so that you can feel what you think you are seeing under their thick hair coat. Once a person is experienced in scoring bison, visual clues are adequate.
TARGET CONDITION SCORES
IDEAL CONDITION SCORE DEPENDS ON THE TIME of year. Over the different seasons of a year it is normal for a bison’s weight and body condition score to fluctuate. Most people aim to have their bison fat in the fall so that they do not require as much feed over the winter.
Most experienced producers aim to have their bison lean in the spring because excess fat may lead to calving problems. By the beginning of breeding season, the cows should be back to a moderate to good body condition to ensure optimal conceptions rates.
TIME OF YEAR IDEAL SCORE RANGE
November 4 3-4+
April 2+ 2-3
July 3+ 3-3+
By knowing your herd’s body condition score, you can adjust your feeding to meet the above targets. If the animals are too thin, increasing the amount or quality of feed and supplements will increase their body condition score. If the animals are too fat, the opposite is possible and money can be saved in the winter feed bill.
One must be aware that any change in BCS should be gradual as rapid changes, either up or down, can cause health problems.
Rapid weight loss in fat bison can precipitate a disease called “Fatty Liver Syndrome” and cause death. Rapid weight gains on grain diets are possible but this type of diet can cause digestive upsets and may cause death as well.
BCS AND BODY WEIGHT
IN BISON, ONE UNIT OF BCS IS ROUGHLY EQUIVALENT TO 90 pounds of live tissue weight. The approximate composition of this tissue would be 70% fat, 24% water, 6% protein and 1% mineral (adapted from dairy cow research by Otto and co-workers, 1991).
BCS AND REPRODUCTION
EXPERIENCE INDICATES THAT COWS THAT ARE too fat at calving (BCS >4), were more prone to reproductive diseases such as difficult calving than cows with lower BCS. Cows that are thin (BCS<2) experience reduced fertility.
WHY DO I NEED TO LOOK AT MORE THAN ONE AREA ON THE BISON?
There is variation between animals in how they deposit fat. Factors such as age, sex, subspecies differences, and even individual animal variation will affect the score that they exhibit at each of the scoring areas of the body. By scoring several areas and averaging the scores we get a much more accurate overall body condition score for the animal than just using one area. For example an old bison cow may look like a BCS of 2 when looking at her ribs but the other areas indicate that she is a 3. This cow would get an overall score of 3. The table can be used to score bison in the field.
OFTEN AN ANIMAL BEING EVALUATED DOES NOT meet the exact criteria of a given BCS but falls somewhere between 2 scores. The evaluator can assign them a value with a “+” sign which indicates that they are slightly more than the score given but not at the level of the next score. For example a cow scoring between a BCS of 2 and a BCS of 3 may be scored as a BCS 2+.
For further information about Body Condition Scoring see What’s the Score? Body Condition Scoring for Livestock DVD and PDF materials (available from Alberta Agriculture at: www.agric.gov.ab.ca/app08/ppsropintheweb?PubID=100031).
Dr. Lewis comments
Of course, after studying all this, I had a few more questions for Roy Lewis, DVM, and of course he has more points to make. He’s a believer in this.
How hard is it to learn how to score—are most bison ranchers able to figure it out?
“With bison we’re usually looking at various spots over the animal tail head and transverse processes on the spine at a distance, so we get a pretty accurate but a rougher idea than with cattle. Bison always look thinner than cattle and that is fine.”
Should the herd score similarly or is there a wide variation in conditioning between the best and worst even in one herd?
“As with any herd we’re always going to get variation--some a little over-fat, some a little thinner but we hit for the average. The thinner ones could indicate clinical disease, age or being low on the pecking order.”
What about those big shedding sheets of hair that hang on many buffalo for so much of the summer—don’t they get in the way of seeing what’s going on?
“The shed is an interesting one but for those that have still a massive sheet into the summer there is something wrong, such as parasites or malnutrition.
“For example in the Code 1 under Body Condition the lower right-hand picture was one of a heavily parasitized bison yearling of a client. You can see the shed is still pretty much intact in June. This person was losing bison to parasitism and once they cleared that up and the shed was removed they were slick and pretty easy to body condition score.”
How about owners who might be sensitive about how their animals rate? Do they really want to know if it’s not so great?
“Owners should have no issue rating their bison because this is helping them see how their feed program is working. Body condition will hurt the performance, but also the reproductive rate, so it definitely affects profitability.
“Bison will look after themselves,” Dr Lewis concludes. “But if feed is short we need to supplement.”
BODY CONDITION SCORING WORKSHEET FOR BISON
Make a chart with the following headings:
DATE____________
TAG # RIBS SPINE HIB BONE TAIL HEAD HUMP OVERALL
Assign score (1-5) to each body area for each animal. Then average numbers for an overall score for each animal.
Adapted from What’s the Score: Bison – Body Condition Scoring (BCS) Guide. Alberta Agriculture. Available at: www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex9622/$FILE/bcs-bison.pdf.
Adapted from What’s the Score: Beef Cow – Body Condition Scoring (BCS) Guide. Alberta Agriculture. Available at: www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex9622/$FILE/bcs-beef-cow.pdf.
Adapted from Haigh J. & Grinde J. (2007) Reproductive management of bison. In: Current Therapy in Large Animal Theriogenology. 2nd ed. Eds. R. Youngquist & W. Threlfall. St. Louis: Saunders Elsevier, pp. 1005–1011.
Line drawings and written BCS descriptions for the remainder of the section adapted from What’s the Score: Bison – Body Condition Scoring (BCS) Guide. Alberta Agriculture. Available at: www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex9622/$FILE/bcs-bison.pdf.
Courtesy of National Canadian Codes of Practice.