Effect of year, lambing season, sex and birth type on early performance in MIS lambs

Considering the fact that sheep production has an important role in agriculture of Serbia, lamb performance is essential. Objective of the study was to investigate effect of year, lambing season, sex and birth type on growth performances in lambs of MIS breed. Animal data (birth date, birth type, sex, birth weight -BW0, body weight after 30 days - BW30 and body weight after 60 days ? BW60) are gained from control of productive parameters maintained from 2011 to 2020. Research was conducted on the sample of 1592 lambs. Average daily gain from birth to 30 days (ADG1), from 30 to 60 days (ADG2), and from birth until 60 days (ADG3), were calculated and included in analysis. Calendar year was divided in four seasons, each season consists from 3 months: winter, spring, summer and autumn. Average body weights (? standard deviation) at birth, after 30 and 60 days were 4.41 kg (? 0.99), 14.11 kg (? 2.80), 24.05 kg (? 3.86), respectively. Average daily gains were 319.87 g (? 74.97), 329.84 g (? 70.90) and 324.99 g (? 55.48) for ADG1, ADG2 and ADG3, respectively. Lambing type and sex of the lambs affected all of the observed traits very significantly (p < 0.01). Lambing year had very significant effect (p < 0.01) on BW30, on ADG1 and ADG2, while lambing season significantly (p < 0.05) affected BW60, ADG2 and ADG3.Based on the results it can be concluded that birth type and sex had strongest effects in early productive parameters of lambs.