Future perspectives in breeding the indigenous local Stara Zagora sheep and improving the phenotypic and genetic parameters of the breed

Abstract

One of the most phenotypically attractive breeds in Bulgaria is the local Stara Zagora sheep. It is a local - indigenous breed specialized in dairy direction. In recent years, this valuable genetic resource is on the verge of being lost as the breed is threatened with extinction. The aim of the study is to monitor the genetic and phenotypic parameters of the main reproductive and productive traits in local Stara Zagora sheep.The research includes a total of 9495 ewes of the local Stara Zagora breed reared in 15 farms, produced during the period from 2011 to 2020 including. The studied traits were: fertility - biological of the first, second and third lambing, milk yield for a 120-day period of first, second and third standard lactation and live weight of different age categories. The statistical model that we used was based on the model of animal /Animal model/, using the software product PEST and VCE (Groeneveld), SYSTST 13 and SPSS for Descripive statistics. The average phenotypic values of the traits: are respectively - fertility of 1st - 113%, 2nd - 125% and 3rd - 129% lambing; live weight of weaning - 29.79 kg, at 18 months - 63.87 kg, and at 2.5 years 72.92 kg; milk yield of the 1st - 98.37 l; 2nd - 104.60 l and 3rd - 108.80 l. lactation. Heritability (h?) in the main selection traits milk yield of the first, second and third lactation is characterized by moderate values - 0.191; 0.225 and 0.184, respectively, and we report from low to moderate values of h? on the fertility in all three studied groups - fertility in the 1st - 0.183; 2nd - 0.149 and 3rd lambing 0.137. Milk yield is in high positive correlation and with a high statistical significance at different stages of lactation, between the 1st and 2nd - 0.849, between the 2nd and 3rd - 0.628 and between the 1st and 3rd - 0.447.