Did you know that cows that produce a daughter rather than a son produce more milk?  It’s true! Researchers from Kansas State and Harvard investigated sex-biased milk production using lactation records from 1995 to 1999.  Data from this time period were chosen to avoid the influence of sex-sorted semen.

Using 2.39 million lactation records from 1.49 million cows, researchers showed that the sex of the fetus influences the capacity of the mammary gland to make milk.  First-lactation Holstein cows giving birth to a daughter produced 323 pounds more milk than those having a son.  Milk composition was similar regardless of calf sex.  The disparity between the two groups was largely eliminated with the use of BST.

The sex of the fetus also has an impact across parities.  Cows that produced a son and were gestating a second son synthesized 17,478 pounds of milk.  Gestating a daughter on the second pregnancy could partially rescue milk production (17,721 pounds).  Fetal sex had less of an impact for cows initially birthing daughters (17,896 pounds).

This study reveals that sexed semen use on first calf heifers is an even better investment.  But one point that needs to be made from this article, taken from a recent Hoard’s Dairyman magazine, is that keeping good records is very important in the dairy business.  Arizona DHIA can help you do this.  Let us know if we can be of help.  We have very competitive prices!  Remember that we are a non-profit company owned by you, the dairy farmer.