The intake of a sufficient amount of colostrum during the first few hours post partum is essential for new born calves. Brown Swiss calves show an absence of a healthy sucking behavior more frequently than other dairy breeds. In an earlier study low to moderate heritabilities were estimated for sucking reflex in Italian Brown Swiss calves. In our study phenotypes of 9,307 South-German Brown Swiss calves were recorded post partum with sucking reflex encoded in 4 categories (no reflex, weak reflex, normal reflex and strong reflex). 50K SNP chip genotypes were collected from 3,072 calves.777K SNP chip genotype data from 192 calves was available and was used for imputation of 50K SNP chip genotypes. Variance components were estimated using sire threshold models and genome-wide association analyses (GWAS) were carried out with high-density genotype data using single-marker models or Bayesian multi-marker models. Low heritabilites were estimated between 0.08 and 0.12, depending on the trait coding. GWAS results of single-marker models showed significant SNPs on BTA 1, 6, 7, 9, 10, 11, 13, 16, 19, 22 and 26, pointing to a polygenic nature of sucking reflex. Possible candidate genes could be found on BTA 6, 19 and 22. Bayesian GWAS results identified a window on BTA 19 explaining 10 % of the genetic variance. Keywords: Brown Swiss, sucking reflex, genetic parameters, GWAS

Clarissa Dreher, Patrick Stratz, Robin Wellmann, Siegfried Preuß, Henning Hamann, Jörn Bennewitz

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume Biology - Growth and Development, , 105, 2018
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