Effect of different sources of specific variance on the weight development and wool production of the Karnobat sheep breed

Genoveva Staykova and Margarit Iliev

Abstract: Subject of the study were 279 ewes of the Karnobat sheep breed, ownership of Institute of Agriculture – Karnobat, born in the period between 2010 and 2015. The live weight traits at weaning (100 days), at 9 months, at 1.5 years, at 2.5 years and the wool production at 1.5 years, 2.5 years and 3.5 years were studied. The information was extracted from the pedigree book of the breed for the three line groups. The data was obtained in conformity with the standard methods and guidelines in the Instruction Codex for Breeding for Preservation of the Local (Indigenous) Sheep Breeds in Bulgaria (2003). Analysis of variance per each age was conducted on the basis of multi-factor linear models (Harvey, 1990). The estimation of heritability coefficients were under Becker (1968). The differences among levels of studied factors were established on the basis of the Student’s distribution (Hayter, 1984). It was established that the average live weight of the Karnobat ewes was 23.289 kg at 100 days, 32.463 kg at 9 months, 41.840 kg at 1.5 years and 43.575 kg at 2.5 years. The average wool yield per ewe was 3.923 kg from first shearing, 2.858 at 2.5 years and 2.778 at 3.5 years. Lineage did not have significant effect on the phenotypic expression of the traits live weight and wool production of the ewes from the Karnobat breed. Year of birth had reliable influence on the live weight and wool production of the ewes from the Karnobat breed at all studied ages (P < 0.001). The coefficients of heritability of the trait live weight are low at 100-day and 9-month age (h2 = 0.092, h2 = 0.194,), and moderate at 1.5 and 2.5 years (h2 = 0.303, h2 = 0.399). The heritability estimates of wool yield are low at all studied ages (h2 = 0.076 to h2 = 0.141).

Keywords: breed; breeding lines; heritability; Karnobat sheep; live weight; wool yield

Date published: 2020-04-30