Heritability of crib-biting in Chilean horses

Abstract

Chilean horse has been a breed of closed registry for more than 85 years. Crib-biting is an oral stereotypy with a history of genetic predisposition that affects the Chilean horse. This study was aimed to estimate the heritability of crib-biting in Chilean horses. Data were collected from a total of 2098 Chilean horses registered in the Agricultural National Society Stud Book, which have been stabled for at least one year during their life. Horse owners provided for: name of the horse, name of the breeding farm, number of registration in the Agricultural National Society Stud Book, year of birth, gender (male or female), years of stabling and whether or not the horse presented crib-biting. Web way, the online Agricultural National Society Stud Book was accessed to create a database with information of the name and registration numbers of the sire and dam of each horse (n = 2098). Additionally, antecedents for all the ancestors available in the Chilean Horse Stud Book for all crib-biters (n = 84) were included, as well as a random sample of non-crib-biters (n = 215). The genealogical database was made up by a total of 7,187 individuals with the average inbreeding coefficient of 1.63%. The prevalence of crib-biting was 4%, being more frequent in males (P<0.0001). The heritability of crib-biting found in the present study (h2=0.229±0.058) suggest that this is a hereditary condition that follows a quantitative model of inheritance, where the influence of additive genetic factors is moderate to low.