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Drought's impact on breeding

This summer's drought didn't only affect crops around the country -- cattle had a hard time breeding, and they experienced variable success rates. Cows that were bred in the early part of the summer settled a pregnancy quite well, but when summer temperatures began to spike, many cows were too hot to breed, explains South Dakota State University Extension Beef Reproduction Specialist George Perry. 

"Where we've seen the majority of problems occurring this year are actually the animals trying to be bred end of June and into July when we had the really hot weather," Perry said. "If we raise the rectal body temperature as little as 2 degrees, we can actually retard embryo growth and therefore we don't get near as good of pregnancy rates."

Heat stress may also have impacted the semen quality of bulls, according to Perry. "On bulls, there is more of a lasting effect of that heat, even heat for a short period of time, since spermatogenesis in the bull is a 61-day process. If the bulls get too hot or their testes get too hot, the sperm that is actually being formed can be impacted and actually impact fertility up to two months later depending on how severe it was."

The heat stress was compounded by the drought, with summer pastures falling short for many cows' nutritional needs.  "When she starts losing condition, unless that embryo is well established, it's one of the first things that can be lost," he said.  

Since postweaning is the easiest time to improve body score, Perry urges livestock owners to monitor and boost their herd's body condition now, if needed, before winter sets in, which will set the stage for successful calving.

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