Selecting the Calf’s Gender Using the Dam’s Heat Cycle

My grandfather learned this and taught my father, who taught me. Gramps used only natural service while Dad used both natural service and AI for breeding on specific heat cycles to either use a cow to build the herd or to put a pay-cheque in the bank in the Fall. This method has a better than 85% success rate, which defies Biology and all we have learned about spermatozoa determining the sex. I suspect that it might have something to do with pH level since it’s known that male chromosomes are sensitive to acidic pH; thriving in alkaline and have less than a 24-hour lifespan vs. female chromosomes which are not sensitive to acidity and have up to a 72-hour survivability.

The first step to success is detecting heat after calving, knowing when she’s cycling and her cycle frequency. Then, the second step is understanding HOW to get her to have the gender of calf you REALLY want!

Here’s the rule my family of ranchers taught me:

“Odd-numbered heats change the gender and even-numbered heats keep it the same.”

Example 1: Breeding for a heifer calf

A cow has a heifer calf, as in the case of my cow Kerry, and I want another heifer from her. I know her first heat came 3 weeks after calving. And, since 1 is an odd number, that means that was a bull heat (odd numbers change the sex). Kerry’s next heat should be due about 21 days later and as heat number 2 is an even number (even number heats keep the gender), this is a heifer heat. I will breed Kerry to my bull on this heat “to keep it the same” and have a heifer calf in the Spring. So, to KEEP Kerry having heifer calves, I would breed ONLY on even heats; 2, 4, 6, or 8.

Example 2: Breeding for a bull calf

I decided Kerry needs to have a bull calf to fill our freezer. She delivered a heifer calf and cycled 3 weeks later (this is the first heat, a bull heat). I didn’t breed Kerry on the first heat – because February is TOO EARLY on the Canadian prairies for calves! The odd-numbered heats change the gender so I would not breed on the second heat as it would likely produce another heifer. If her heats are coming at regular 21-day intervals, I can expect her third heat (odd number) to come in another 3 weeks. Because the third heat is an odd number, and because I want to CHANGE the gender, I would breed her on that third heat (the odd-numbered heat) for a bull calf. But I could breed Kerry on heats 3, 5, 7, or 9 for the same likely outcome. (It’s not ideal for her health to breed on a first heat though it’s possible.)

Oral History

For 86 years, since 1932 when my grandfather moved from England to begin farming in Canada, my family has used this gender selection rule with our cattle to selectively manipulate the cow families we choose to build from or bring a profit through sales. I have no idea where the knowledge originated, I’m only sharing the oral history I inherited that has been passed down through my family.

“Odd-numbered heats change the gender and even-numbered heats keep it the same.” – and counting the heat cycles begins with the VERY FIRST heat post-calving; no matter if your cow first cycles 10 days or 65 days after calving!

I hope this keeps your freezer full and helps your homestead become more profitable.

About the Author

Tracy Howe, Mother Howe's Little Cows, Ontario, Canada has written 2 posts.

Tracy Howe is the oldest of three children and grew up in Saskatchewan on a mixed farming operation. Of all the family farm endeavors, cattle were always her passion. She worked in the cattle industry in many capacities, including commercial livestock hauling, on feedlots, in auction barns, and as a veterinarian assistant while raising her children. In 2010 Tracy and her husband, Wally, returned to cattle ownership. He runs a small beef herd. The dairy and Miniature cattle are “her thing” and she operates Mother Howe’s Little Cows. She’s been instrumental in starting the Canadian Miniature Jersey Association.