IT’S BASIC BIOLOGY: BREEDING HEIFERS PRIOR TO COWS BUILDS REPRODUCTIVE MOMENTUM

Heifers take longer to start cycling after having their first calf than mature cows do. This means that if heifers are bred to calve at the same time as the main cow herd they are already behind coming into their second breeding season.   “It’s just basic biological math,” says Dr. John Campbell, veterinarian, and Professor in the Department of Large Animal Clinical Sciences at the Western College of Veterinary Medicine. He points out that this is why a lot of what would be second calvers drop out of the herd – they simply don’t have enough time to start cycling and rebreed.   black bull with heifers on straw during breeding season Photo: Stacey Domolewski To calve at the same time the following year, cows and heifers need to be bred about three months after a calf is born. This is easier in cows as they return to estrus 50-60 days after calving, giving them plenty of time to get bred in the first cycle after bulls are turned out. It is more challenging for heifers because they take