Publisher: Institute for Animal Husbandry, Belgrade-Zemun UDC 636.082.1 EFFECT OF ENVIRONMENTAL AND PARAGENETIC FACTORS ON BIRTH MASS VARIABILITY OF MIS SHEEP POPULATIONS

Original scientific paper Abstract: The aim of the study was to determine effect of environmental and paragenetic factors on body mass of lambs at birth. Investigation was realised on experimental sheep farm of Institute for Animal Husbandry, Belgrade-Zemun. Animal included in this research were representatives of Mis sheep population. The results of the research confirm that values of the birth mass range from 4.43 kg to 4,58 kg observed by years and 4.48 kg to 4.55 kg depending on the lambing season. Statistical analysis showed that the existing differences still significant on the level (P <0.05). Variations of body mass in lambs depending on the mother's age range in the interval from 4.29 kg to 4.52 kg kg and statistically very significant(P<0.01). Type of birth has also expressed a significant effect on the body mass of lambs at birth and variations range from 4.31 kg (twins) to 4.59 kg (single). Existing differences was statistically very significant (P<0.01). Average body mass in lambs depending on sex of lamb were almost the same, 4.54 kg male and 4.52 kg female, and the difference is not statistically significant (P> 0.05). Key words: lamb, season, birth mass, environmental and paragenetic factor