Heritability of longevity in the Icelandic sheep breed and the reproduction factors affecting it

Abstract

In recent years higher focus has been put on increasing welfare and decreasing negative environmental effects of animal production. One way to access this is increasing and understanding the factors affecting the animal’s longevity. Longevity is a complicated trait that can normally only be recorded after the animal’s death and creates a biased data for younger animals in the heard (Iversen et al., 2020). A new way of estimating the trait with a linear model when animals are assigned 0 for years where they live another year and 1 for their last year has been created and has given good results for heritability estimations at an early age.

This study estimated the heritability of longevity in the Icelandic sheep system based on the 1-0 model run as a simple sire model, sire model with the environmental effect of the dam and sire-dam model. Longevity was recorded a heritable trait giving heritability between h2 0.019-0,031 for annual basis record and h2 0.86-0.14 when estimated for average lifetime records of 5.28 years. The sire-dam model gave the strongest heritability when the sire and dam were given equal values but otherwise gave a low heritability for sires and high for dams. The simple sire model gave the lowest explanation out of the models.

Longevity increases with higher age at first lambing and if the ewe had any years without lambs during her lifetime. Ewe effect of EWE_REARED, EWE_BORN and DAM_AGE had low effect on longevity while litter effect L_REARED and L_BORN and HAD_MIN had higher effect on the trait.