High reproductive rates are critical for the success of cow-calf operations. Weaned calf percentage is the most important measurement when evaluating reproductive performance in the cow herd. Good records that include the number of females exposed to bulls at the start of the breeding season, dates when bulls were turned out and removed, and the numbers of calves weaned are critical.
Weaned calf percentage is calculated by dividing the number of calves weaned by the number of females exposed. For example, if 100 cows were exposed to bulls at the start of the breeding season and 88 calves were weaned, the weaned calf percentage for that group of cows would be 88% (88 calves/100 cows exposed = 88%).
Getting and keeping cows and heifers bred and then getting those calves born and raised to weaning are influenced by a number of factors. These include nutrition, disease prevention, parasite management and genetic factors affecting calving ease, to name a few.
Unless there is a major disease outbreak, nutrition – and ultimately, cow body condition score (BCS) – is going to have the biggest impact on reproductive success. For most cow-calf operations, a good forage program is the key to herd nutrition. When energy (calories) and protein needs are not being met, it is critical to supply appropriate energy and protein supplementation to meet their needs, or, if cows are in good body condition, to control weight loss.
Minerals, especially trace minerals, often get more credit or blame than they deserve for improvements or deficiencies in reproductive performance. The key is to make sure animals are in the appropriate body condition and then supply a mineral-vitamin supplement to correct for any deficiencies. Two- and 3-year-old females should have a BCS of 6 or better at calving, and cows four years old or older should have a BCS of 5 or better at calving.
Working with a cattle veterinarian to develop a good preventative herd health plan is also important in achieving high reproductive rates. Numerous diseases and pathogens can reduce reproductive performance. Several of the more common ones are part of most annual vaccine programs including: infectious bovine rhinotracheitis (IBR), bovine viral diarrhea (BVD), leptospirosis and vibriosis. Biosecurity is also part of a good herd health plan to prevent trichomoniasis and other pathogens from entering the herd.
Remember, there are no silver bullets to reproductive success. It is about keeping cows in good condition and health.
