INFLUENCE OF SOME NON-GENETIC FACTORS AFFECTING THE FERTILITY RATE OF EWES FROM PLEVEN BLACKHEAD BREED

G. Ganchev, M. Simeonov, N. Todorov, K. Nedelkov

Abstract: The aim of the present study was to estimate the influence of some non-genetic factors on the fertility rate in 1801 ewes from the Pleven Blackhead breed. The results show that ewes inseminated in 2011 and lambed in 2012 had a higher fertility rate (P<0.01) in comparison with the ewes lambed in 2011 and 2013, which indicated that the year had a great influence over the fertility rate. Four years old ewes had a significantly higher fertility rate than the ewes at 2 and 3 years of age (P<0.01). The fertility rate of ewes with BCS from 2.6 to 3.5 at the beginning of the breeding period was significantly higher as compared to ewes with BCS over 3.6 (P<0.01), indicating that the fertility rate was directly connected with the body condition of ewes at the insemination. The ewes weighing 56 and 65 kg had a higher fertility rate in comparison with the ewes with live weight under 56 kg and over 66 kg (P<0.01). The standard deviation of the studied parameters pointed out a wide variation of the traits, regardless of the body condition and live weight of ewes at the insemination. The analysis of the factors shows that the factors like year, age of ewes, flock, nutrition, live weight and body condition score of ewes have an average degree of impact over the fertility rate (P<0.05 and P<0.01). The interaction between the factors -year х age and age х flock, had a significant influence (P <0.01) on fertility rate.

Keywords: age; body condition score; fertility rate; live weight; non-genetic factors; sheep; year

Date published: 2017-03-15