Estimation of Genetic and Phenotypic Parameters for Udder Morphology Traits in Different Dairy Sheep Genotypes

Abstract

Knowledge of genetic parameters is the basis of sound livestock improvement programmes. Genetic parameters have been estimated for linear udder traits: Udder depth (UD), Cistern depth (CD), Teat position (TP), Teat size (TS) and external udder measurements: Rear udder depth (RUD), Cistern depth (CDe), Teat length (TL) and Teat angle (TA) – 1275 linear assessments (381 ewes) and 1185 external udder measurements (355 ewes) were included in the analysis for each character of 9 genotypes. Nine breeds and genotypes were included in these experiments: purebred Improved Valachian (IV), Tsigai (T), Lacaune (LC) ewes, and IV and T crosses with genetic portion of Lacaune and East Friesian (EF) – 25 %, 50 % and 75 %. Primary data were processed using restricted maximum likelihood (REML) methodology and the multiple‑trait animal model, using programs REMLF90 and VCE 4.0. High genetic correlations were found between UD and RUD (0.86), CD and CD(e) (0.93), TP and TA (0.90), TS and TL (0.94). The highest heritabilities were estimated for exact measurements of TL and CD (0.35–0.39) and subjectively assessed TA and TS (0.32 – 0.33).

Keywords

• ewes
• genetic and phenotypic correlations
• heritability
• udder