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

Abstract

SummaryA 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.

Genetic and environmental dispersion parameter estimationby test interval method in dairy sheep

“…The estimates for PC were in accordance with those in Manchega sheep breed reported by Serrano et al (2001), only that their heritability estimates arised in the early lactation and they declined after that. Much higher heritability estimates for PC were shown by Volanis et al (2002) in Sfakia sheep breed, which were 0.44 in the first and 0.55 in the forth month of lactation. Furthermore, Meyer et al (1989) obtained higher heritabilities for PC in dairy cows with the highest value in the middle of lactation (0.49) and lower (0.23) at the beginning and at the end of lactation.…”

“…It increased almost two times to the last month (up to 0.18). Much higher heritability estimates for FC were shown by Volanis et al (2002) in Sfakia sheep breed, which were in the range from 0.32 in the first to 0.52 in the forth month of lactation. Our estimates were lower compared to the estimates in Slovenian dairy goats by Andonov et al (1998), where the heritability increased from the third (0.16) to the fifth month (0.29) of lactation, and it reduced thereafter.…”

“…Higher estimates for DMY compared to our results were found by Serrano et al (2001) in Latxa (0.20 to 0.33) and Manchega sheep (0.17 to 0.26) who divided lactation period into four months. Especially high heritabilities (0.41 to 0.47) were reported by Volanis et al (2002) in Sfakia breed. A similar trend of heritability estimates for DMY compared to our results was reported by Andonov et al (1998) in Slovenian dairy goats.…”

“…The effect is usually found in the fixed part of the model (Wilmink, 1987, Meyer et al, 1989. As seen from the literature, most authors treated only the additive genetic effect in the random part of the model in dairy cattle (Danell, 1982, Wilmink, 1987, Meyer et al, 1989 as well as in dairy sheep (Baro et al, 1994, Serrano et al, 2001, Volanis et al, 2002. Some of them (Swalve, 1995, Kominakis et al, 2001, Ilatsia et al, 2006, Tonhati et al, 2008 included the permanent environment effect over lactations in the random part as we did.…”

Effect of restricted suckling time on milk components and sucking behavior of lambs

“…This conclusion is in agreement with the observation in same breed that the fat content of sheep milk reaches peak level at the start of lactation then decline until 3rd weeks (CETIN et al 2007). The highest level of milk fat is usually observed in ruminants at the beginning of the lactation (WOJTOWSKI et al 2001, HORSTICK and DISTL 2002, VOLANIS et al 2002. The milk protein curves were greatest point in first week, lowest in second week for both groups ( Figure 5).…”