What does "Nn" refer to in pig genetics?

In pig genetics, "Nn" signifies a pig that inherits a single copy of the stress gene from one parent. This terminology stems from a system of identifying genetic traits related to porcine stress susceptibility, which can greatly affect the health and meat quality of pigs.

When a pig is labeled "Nn," it indicates that one of its alleles is the "N" allele, which denotes the normal, non-stress gene, while the other allele is the "n" allele, signifying the presence of the stress gene. This genetic condition can have implications for the pig’s response to stressors, such as handling or environmental changes, which could result in issues like PSS (Porcine Stress Syndrome).

Understanding the genetic makeup like "Nn" helps breeders make informed decisions regarding breeding programs aimed at reducing stress-related issues in pigs, ultimately improving the welfare and productivity of the animals.