Management of inbreeding and coancestry to target short-term and long-term genetic gains

Inbreeding is not heritable. This means that breeding for low inbreeding generally has a transient and non-accumulating impact over generations. This is a bit like selecting for a trait that has a heritability of zero. However, coancestry (taken as the mean coancestry between an individual and the rest of the selected population) is heritable. Breeding for low coancestry in any one generation has a lasting impact over generations to increase genetic diversity and decrease the population mean inbreeding level. These issues have been poorly understood in some industries. Appropriate management of both coancestry and inbreeding is required to optimise the balance between short-term and long-term genetic gains, as well as to maintain genetic diversity. This paper tests and illustrates the implementation of such strategies. Management of coancestry is critical, whereas management of progeny inbreeding is of some transient value.