October 27, 2017

Direct genetic, maternal and litter effects on behavior in German shepherd dogs in Sweden

Direct heritability traits in German Shepherds were measured by a series of tests, and it was concluded that the litter has a greater effect on the behavior than maternal effect.

Most puppies live with their mother and their siblings for the first 8 weeks of their lives, which is when a development of some of their “adult” behaviors is developed. A study was conducted, using data from 1989-2001 to examine genetic variation of behavioral traits in German Shepherd Dogs, and to determine whether there is a maternal or litter influence on these traits. 5959 cases were used in the Swedish Dog Mentality Assessment (DMA). The DMA was a test devised to help breeders in controlling the genetic material of German Shepherd Dogs (in addition to other breeds), as help for future training.

In the tests, each German Shepherd Dog was exposed to five different test situations. The first test was “Play”, testing the dog’s interest to play. The second test was “Chase”, testing the dog’s reaction to a small object moving away fast from the dog. The third test was “Sudden Appearance”, testing the dog’s reaction to a dummy that suddenly appears in front of the dog. The fourth test was “Metallic noise”, testing the dog’s reaction to the rattling sound of a metal chain pulled over a sheet of metal. The fifth test was “Ghost”, testing the dog’s reaction to two people covered in white sheets slowly approaching the dog. In each, 15 behavioral variables were scored 1 to 5 by a judge. Based on these variables, 4 traits were created: playfulness, chase-proneness, curiosity/fearlessness, and aggressiveness.

The results of the experiment indicated that effects of sex, test year, test month, and age were significant in most cases. For example, playfulness, curiosity/fearlessness, and chase-proneness increased slightly with age while aggressiveness decreased. Males were more prone to play, more curious, and slightly more aggressive and bolder than females.

It was concluded that direct heritability of traits in German Shepherd Dogs was highest for playfulness and curiosity/fearlessness. Maternal heritability of all traits were low, however, if the maternal genetic effects were included. Genetic correlations within the litter with regards to playfulness, curiosity/fearlessness, and chase-proneness were much higher than genetic correlations with aggressiveness. The study indicated that when there is substantial genetic variation, the mother has little influence (genetically and environmentally), and the litter has a larger influence than the mother.

A few ideas were suggested due to these findings. It is speculated that the maternal influence was not as significant because perhaps the data was not large enough or the structure was not sufficient. Additionally, between the 8 weeks of age and the testing time (at 1-2 years old), other influences may have contradicted the effect of the mother.

 

Reference: Strandberg, E., Jacobsson, J., Saetre, P., 2004. Direct genetic, maternal and litter effects on behavior in German shepherd dogs in Sweden. Livestock Production Science. Volume 93, Issue 1: 33-42.

Reviewed by Sadie Scott.

http://www.sciencedirect.com/science/article/pii/S0301622604002210