FACTORS ASSOCIATED WITH INBREEDING IN CHAROLLAISLAMBS

Inbreeding within sheep populations is a relatively understudied area due to limited pedigree information. This study assessed the level of inbreeding within a Charollais sheep population. Data were obtained from35,220 Charollais lambs between the years2000 to 2018 from performance-recorded flocks in the UK. Differences among flocks, study years, lamb eight-week body weight categories and if embryo transfer lambs were assessed. Mean inbreeding value for Charollaislambswas2.8% (s.e. ± 0.1), with a range of 0% to 31%. While the proportion of lambs with an inbreeding value of >7% has been relatively stable at 0.1 or less since 2006, the general trend is an increasing mean inbreeding coefficient for the population in recent years. After adjusting lamb inbreeding coefficient for fixed and random effects, the average inbreeding coefficient was found to be lower for lambs in the heavier eight-week body weight category (>32kg), for certain flocks (mean ranged from 0.4% to 14.6%), and for embryo transfer lambs. Monitoring of inbreeding and approaches used for genetic selection in flocks can help minimise poor lamb performance(i.e. potentially lower growth and body weight) associated with inbreeding.