ETH researchers have found a gene mutation that causes the sperm of boars to immobilize. Their discovery will help pig breeders to exclude animals with this genetic defect from breeding in future.
Thanks to these new findings, pig farmers can now have breeding boars specifically tested for this mutation. At first this might sound like a superfluous examination, since deformed sperm can actually be seen under the microscope.
But there’s a catch: like humans, pigs have a double set of chromosomes, one maternal and one paternal. This means all genes are present in duplicate. If the mutation affects only one copy of the gene, that boar’s sperm tails remain unaffected and the genetic defect goes unnoticed. Only if both copies of the gene have the same mutation does it have a negative effect on the corresponding trait. Geneticists call this recessive inheritance.
Genetic testing lets farmers identify early on which boars and sows within the herd have at least one “bad” copy of the gene. To prevent the mutation from spreading further, these animals are then no longer used for breeding.