Genetic parameters for the external udder morphology in commercial farms of Istrian sheep from Croatia

Abstract

Istrian sheep is a local breed with superior milk yield and composition. Excellent udder shape of this breed needs to be preserved in future, since it’s economic value resides within the artisanal cheese production. Genetic parameters for the teat angle (Alpha) and the height of the cisternal part below the teat orifice (Cis) were estimated in order to evaluate the possibility for conservation of udder traits amiable for machine milking. Udder morphometry of the 240 registered Istrian ewes was measured from digital photographs of the posterior view of the udder on 10 commercial farms three times during lactation. Original pedigree records were trimmed to four recent generations. Heritabilities were estimated using single trait animal model. The stage of the lactation, interaction of lactation number, month of lambing and the farm were fixed effects, and the additive genetic value of the individual and permanent environment of the individual were random effects. Estimated heritability was 0.05 for Alpha and 0.71 for Cis mid-lactation measurements. Measurements of Cis during lactation did not result in a significant additive effect. The result shows potential in estimating genetic parameters of important udder traits in small commercial dairy ewe populations, using the digital measurements, given the reduction of non-genetic variability in the sample.

Keywords

• animal model
• digital morphometry
• genetic parameters
• udder shape