Analysis of the live weight of Thracian merino lambs depending on the lambing season and type of birth

Stanimira Slavova, Petya Slavova

Abstract: The aim of the present study was to establish the effect of lambing season and birth type on the
weight development of Thracian merino lambs. Research was conducted at the experimental farm
of the Agricultural Institute – Stara Zagora. Ewes of the Thracian merino breed were divided into 2
groups: group I /experimental/ – 102 ewes mated in anestral season /April–May/ after application of
vaginal tampons for estrous synchronization and hormonal treatment for inducing superovulation;
group II /control/ – 123 ewes mated in the estral season /July–August/, without being hormonally
treated. Progeny was divided respectively into 2 groups: group I – lambs of hormonally treated ewes
and group II – lambs of untreated ewes. The live weight of male and female lambs at birth, 10, 30,
70 days and at weaning, and of ewe lambs at 9 months of age were investigated, and the influence of
season and type of birth on the level of the trait was established. Data were processed using program
STATISTICA for Windows. It was found that the factors season and type of birth affected to a different
extent the live weight of lambs from birth to weaning (and at 9 months for the females). The effect of
season was weak and marked no definite tendency, while the birth type gave a significant advantage
to singles over twins. Therefore, it could be summarized that the weight development of lambs was
not so strongly influenced by the season as by the type of birth of lambs.

Keywords: lambing season; live weigh; prolificacy; Thracian merino ewes; type of birth

Date published: 2022-08-29