WHEN it comes to Holstein dairy cows and how much milk they produce for their offspring, Kansas State University and Harvard University researchers have determined that daughters are preferred.
A study of 2.39 million lactation records from 1.49
WHEN it comes to Holstein dairy cows and how much milk they produce for their offspring, Kansas State University and Harvard University researchers have determined that daughters are preferred.
A study of 2.39 million lactation records from 1.49 million dairy cows showed that cows produce significantly more milk for daughters than for sons across lactation, said Barry Bradford, an associate professor in Kansas State's department of animal sciences and industry.
He collaborated on the study with Katie Hinde in Harvard's department of human evolutionary biology, graduate student Abigail Carpenter at Kansas State and John Clay with Dairy Records Management Systems in Raleigh, N.C.
"Our results provide the first direct evidence that the sex of a gestating fetus can influence milk production," Bradford said. "One possible explanation is that a daughter is able to let her mom know, in advance, that she expects to receive more milk than her brothers."
In addition, the researchers found that the sex of the fetus a cow is carrying can enhance or diminish the production of milk during an established lactation and that the sex of the fetus gestated in the first pregnancy has persistent consequences for milk production on the second lactation.
Results of the study are available in PLOS One.
The study also could have implications for humans, Hinde said.
"Among the surprises in this study was the fact that the bias was in favor of daughters rather than sons, as some evolu