Heritability of semen characteristics in dogs.

Retrospective analysis was performed on semen collected from 24 dogs (parents: 14 Labrador retrievers and 10 Golden retrievers) aged between 16 and 28 months of age. The dogs were part of a large breeding programme but lived in the homes of volunteer families. The semen was subjected to a standardised examination procedure including assessment of: percentage normal motility, sperm concentration, total sperm output, percentage of live normal sperm, and total number of live normal sperm. Semen was subsequently collected from one son of each of the parents when the offspring were aged between 16 and 28 mo (offspring: 14 Labrador retrievers and 10 Golden retrievers), and was subjected to the same examination procedures conducted by the same technician. Examination of breeding records demonstrated that each of the 48 dogs achieved at least one pregnancy within a period of 3 months before to 3 months after the semen collection. There was a weak correlation between parents and offspring for each of the 5 semen parameters, although none of these were statistically significant. Narrow sense heritability measures were low for all parameters except for the heritability of high sperm motility (rN2 = 0.57) and the heritability of low total sperm output (rN2 = 0.57). It is plausible that breeding selection procedures may be useful in dog breeding programmes in an attempt to improve semen quality, although any impact upon fertility is yet to be proven.