Hanover / Greifswald (dpa) - Researchers at the Friedrich-Loeffler-Institut (FLI) have genetically modified pigs in such a way that they develop female reproductive organs despite a male chromosome set.

In the future, the process could offer an alternative to the castration of male piglets, with which the unpleasant "boar odor" is to be prevented, which spoils the appetite of some people for the meat of male pigs.

The research results are published in the "Proceedings" of the US National Academy of Sciences.

The researchers had removed a certain gene region on the Y chromosome - the male sex chromosome - from the genetic make-up.

The manipulated animals still have an X and a Y chromosome - that is, they are genetically male - but are “not to be distinguished from female animals externally and internally”, explains Björn Petersen from the Institute for Farm Animal Genetics near Hanover, which is part of the FLI Headquarters on the island of Riems near Greifswald.

However, the manipulated animals are not completely identical to female conspecifics: after nine months they had significantly smaller sexual organs, and they are sterile.

It is about basic research and nothing that can be transferred to pig production in the short term, says Petersen.

The genetic engineering law alone speaks against it.

"In general, we already have ideas or strategies on how something like this could also be used in breeding."

It is conceivable to change the Y chromosome in boars so that they can only father female offspring.


With a view to ethical questions, Petersen says: "Both consumers and producers ultimately have to ask themselves what they want".

The unwanted boar odor can also be prevented by surgical castration or with injections that hormonally prevent sexual maturity, the so-called immuno-castration.

Castrating male piglets without anesthesia has been banned in Germany since the beginning of the year.

The German Animal Welfare Association criticizes the presented procedure.

Anyone who thinks that they have to fatten pigs and avoid the boar odor can achieve this in a much more uncomplicated and tolerable way through immuno-castration.

The Animal Welfare Association generally rejects genetic engineering on animals.