Genetic analysis of udder score and milk traits in test day records of Sfakia dairy ewes

M Volanis,A Kominakis,E Rogdakis

doi:10.5194/aab-45-69-2002

M Volanis, A Kominakis + Show 1 more

Open Access

https://doi.org/10.5194/aab-45-69-2002

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Abstract

Abstract. A total of 4466 monthly test day records of 555 Greek Sfakia dairy ewes were used to estimate heritabilities as well as genetic and phenotypic correlations for udder score (US), average daily milk yield (MY), fat percentage (FC) and protein percentage (PC) of milk. Genetic parameters were estimated with a multitrait animal model with correlated residuals. Heritabilities were between 0.17 and 0.24, 0.41 and 0.47, 0.32 and 0.52 and 0.44 and 0.55, for test day US, MY, FC and PC, respectively. Within traits, genetic correlations between test days were between 0.54 and 0.57, 0.71 and 0.96, 0.79 and 0.99 and 0.85 and 0.99 for US, MY, FC and PC, respectively. Genetic correlations between milk traits and US were negative and of very low magnitude (−0.04 to −0.06). Genetic correlations between MY – FC and MY – PC were negative and of varying magnitude, from −0.37 to −0.52 and from −0.44 to −0.50, in the four test days, respectively. Fat and protein percentages were found to be highly, positively, correlated.

Highlights

Findings of the late Minoan period (1600 – 1450 BC), currently on display at the Archaeological Museum of Iraklion (Crete), represent a sheep showing clearly the typical characteristics of the Zackel type
No significant differences were found in milk yield (MY) and fat percentage (FC) between udders of type II and III (Table 2)
Given the high genetic correlations between test day MYs, selection on early records is expected to result in increased lactation milk yield for Sfakia ewes

Summary

Introduction

Findings of the late Minoan period (1600 – 1450 BC), currently on display at the Archaeological Museum of Iraklion (Crete), represent a sheep showing clearly the typical characteristics of the Zackel type. The most stable and homogenous type is a sheep kept in the wider area of Sfakia on the White Mountains and in the lower area of the Apokoroniou district. This sheep is known under the name Sfakia sheep. Data analysis of 2942 lactations, spanning years 1982 to 1990, showed that the average milk yield and the length of the milking period is 109.8 ± 40.8 kg and 156.5 ± 29.3 days, respectively (VOLANIS and TZERAKIS, 1997c). Aim of the present study was the estimation of genetic parameters for udder score and milk traits, i.e. milk yield, fat percentage, protein percentage, in an attempt to appraise the possibility of genetic improvement of the Sfakia dairy breed

Methods

Results

Conclusion