Created: Fri, 28 Feb 2014 06:03:00 MST
Updated: Mon, 03 Mar 2014 09:06:24 MST
A recent study shows that dairy cows make more milk for heifers than for bulls, meaning momma cows biologically prefer their daughters.
New research shows that daughters may be getting more milk than sons.
Barry Bradford is a researcher with Kansas State University.
"Believe it or not, cows that had given birth to a daughter, or a heifer, actually produced about three percent more milk in their first lactation than those that gave birth to a bull," Bradford said.
Researchers from Kansas State University and Harvard University studied lactation records of more than one million dairy cattle across the country.
What they found was opposite of what evolutionary biology theories predict, instead of favoring sons-cows actually produce more milk for their female offspring.
"I grew up with eight sisters and as the only son, I've been working my whole life to try to prove that I wasn't treated especially so now we finally have some evidence to the opposite, actually," Bradford said.
The study also found that the sex of the first baby might determine the amount of milk produced for the following children. It's possible that the same processes are happening in humans.
You can find more information on this study here.