The practice of assigning a body condition score (BCS) to a cow is a great management tool for identifying nutritional needs in a beef cowherd. There's a strong link between a cow's body condition and her reproductive performance.
The percentage of open cows, calving interval, and calf vigor at birth are all closely related to the body condition of cows both at calving and during the breeding season. BCS is a number used to estimate energy reserves in the form of fat and muscle of beef cows.
BCS numbers range from 1 to 9; 1 is extremely thin and 9 very obese. A cow in “thin” condition (BCS 1-4) is angular and bony with minimal fat over the backbone, ribs, hooks and pins. There's no visible fat around the tail head or brisket. A cow in “ideal” condition (BCS 5-7) has visible hips, though there's some fat over the hooks and pins and the backbone is no longer visible.
An over-conditioned cow (BCS 8-9) is smooth and boxy with bone structure hidden from sight or touch. She may have large protruding fat deposits (pones) around the tail head and on the pin bones.
Be aware that gut fill or pregnancy can change the appearance of moderately fleshy cows, especially over the ribs or in front of the hooks. Visual indicators of each BCS are listed in Table 1.
It's important to remember that the scoring system is a subjective evaluation of fleshing and fat deposition (energy reserves), not hair coat or body weight. For consistent BCS evaluations, a single individual at the ranch should score cattle over successive years.
Consider cow age, breed and frame size in determining BCS. Fat deposition varies by breed or type of cattle; dairy- and Brahman-influenced cattle carry less subcutaneous fat and more internal fat than British or Continental type cattle.
Small- to moderate-framed cows (Angus and Hereford) often score higher than larger cattle.
Keep the scoring system simple. Critical times to monitor BCS of the cowherd are 30 days prior to breeding, 90 days post-breeding, weaning, 100 days prior to calving and at calving.
A BCS below 5 in mature cows adversely affects time to first functional estrus or heat (Table 2).
Data by Glenn Selk, Oklahoma State University Extension reproductive specialist, reinforces the importance of a favorable BCS at calving to breed-back success. His research shows that cows calving in thin body condition (BCS 4 or less) but regaining weight and condition as they go into the breeding season don't rebreed at the same rate as those that calve in good condition and maintain that condition into the breeding season.
“A high probability exists that cows calving in thin body condition (especially young cows) will have an extended postpartum interval relative to those that calve in good body condition,” Selk says. “In addition, calf survival rate and many other production factors favor calving cows in a good body condition.”
The bottom line, says Ron Torell, University of Nevada Extension livestock specialist, is to not let cows fall below a BCS 5 if your goals are a tight calving interval, good conception rate and high weaning percentage.
“Maintaining a moderate-condition cow is cheaper than trying to bring a thin cow back into condition after calving, and not nearly as effective,” Torell says.
Clint Peck is director, Beef Quality Assurance, Montana State University.