Scientists hail study into how pigs breed

Scientists say that sows may be unconsciously influencing the sex of their offspring as their response changes depending on the sperm.

The research by teams at both Sheffield and Murcia Universities has been published today in an academic journal.

The findings show that different genes are active in female pigs’ reproductive system cells in experimental conditions when all X (female) or all Y (male) sperm is present.

This suggests females might be able to change the environment of the oviduct to favour one sex over the other, giving that sperm a better chance of winning the race to the egg.

Studies of humans and animals have shown that the sex ratio of offspring can be affected by factors such as the age of the mother, or environmental factors like famines and wars.

Sheffield University professor Alireza Fazeli said: “What this shows is that mothers are able to differentiate between the sperm that makes boys and girls. That on its own is amazing. It’s also of great scientific and evolutionary importance. If we understand how they can do that, this can revolutionise the field.”

To find out whether females differentiate between female and male sperm, scientists inseminated female pigs with sperm that was either all X or all Y.