Genetic variance of the prolificacy trait in sheep from North- East Bulgarian Merino breed

Nevyana Stancheva, Petya Slavova, Georgi Kalaydzhiev, Jivko Krastanov, Stayka Laleva

Abstract: The aim of the study was to analyze the overall genetic variance and effects for the prolificacy trait
in North-East Bulgarian Merino sheep breed, with distinct participation of the Australian Merino and
Booroola breeds in its genotype. The study included 584 pedigrees and 1123 prolificacy records. An
animal model was used and the following factors were included in the statistical analysis: year of each
lambing, consecutive lambing, year of birth of the animal, regression effect of age in days to the date
of lambing. The average value for the prolificacy trait was 1.114 lambs per ewe with typical for the
phenotypic variation trait (29.0%). The genetic tendency for prolificacy was negative, depending on
the year of birth, and positive on subsequent rearing. Analysis of the variance indicated that the major
part of the genetic variance have been described, by the individual characteristics of the animals
(0.034 at 0.001 caused by heterosis). The proportion of genetic variance resulting from different breed
combination in the genotype was extremely low relative to the individual genetic varians (0.257),
which reflected the overall genetic variation. Estimates of additive and non-additive effects by genetic
groups did not establish clear distinguishable differences.

Keywords: additive and non-additive effects; animal model; genetic variance; North-East Bulgarian Merino Sheep; prolificacy

Date published: 2020-10-31