weather influence on calf birth weights

[oakview]

I have long believed that spring born calves following colder than normal winters were larger at birth than those born after warmer winters.  I have also observed that my fall born calves were significantly smaller at birth than their similarly bred spring counterparts.  Check out the article in Minnesota's Midwest Beef Producer magazine, "Does the severity of winter temperatures have an impact on spring born calf birth weights?".  Official university research amazingly backs up the claim.  The University of Nebraska study focused on spring born calves, showing a 1:1 relationship between the drop in average temperature and the birth weight of calves.  Regarding fall borns, Oklahoma State research showed that fall born calves averaged 4.5 pounds lighter at birth than the spring born calves.  Nice to see that official research validates what we think we have experienced for years.  Could there be some validity to the claim that Canadian born calves are heavier at birth than they would be if they were born in Missouri, for example?  We may never know until official University research backs it up.  To solve all my problems, I'm going to breed for all fall calves and maintain the cows in southern Arkansas until a week before they calve. 

 

[simba]

Could there be some validity to the claim that Canadian born calves are heavier at birth than they would be if they were born in Missouri, for example?

Interesting post. I certainly think that a colder climate adds birthweight. I live in Saskatchewan and the farm I work for owns a few American bulls. As a rule of thumb when we’re using one we take the birthweight plus 10 pounds and that’s what we expect our calves to average. I’m not at all suggesting that the breeders are lying about the birthweights, it’s just that we have to feed a lot heavier in the winter to maintain condition on our heavy bred cows. I’d guess it would work the opposite when using Canadian bulls down south but I have no evidence to back that up.