Live weight peculiarities of the Tsigai breed young sheep during the suckling period in connection with the terms of sheep ewes’ gestation

The correlation of the Tsigai breed ewes’ gestation period with the patterns of growth and development of the sheep growing stock during the suckling period was explored in the article. The dates of inseminations and calvings were selected for analysis to calculate the duration of ewes' gestation and indicators of live weight of young animals at birth and at weaning with subsequent calculation of correlations between these traits. The average duration of the ewes’ gestation period is 157.76 ± 0.61 days (Cv=7.6%). The single-born ewe lambs of the No. 01684 line were higher in live weight by 6.9% (р ≤ 0.001), and higher in average daily gain by 6.0% (р ≤ 0.001) than the sample averages at weaning. The single-born ram lambs the No. 80077 line have a significant advantage in terms of live weight at weaning by 9.1% (р ≤ 0.01), and in terms of average daily gains by 11.8% (р ≤ 0.05). Single-born ram lambs of the No. 01684 and No. 66796 lines with a reduced live weight at birth grow more intensively: a significant advantage in terms of live weight at weaning and average daily growth, respectively, is 12.1% (р ≤ 0.001) and 9.6 % (р ≤ 0.01) higher in comparison with the average sample values. Twin ewe lambs of the No. 80077 line with a lower live weight at birth by 0.2% and an increased weight at birth by 0.4, the difference of which is also not reliable, nevertheless have a significant advantage in average daily growth compared to the average – by 9.1% (р ≤ 0.001), while the twin ram lambs have no significant difference in the indicators of the suckling period. Milkiness is negatively associated with the duration of pregnancy of ewes and positively with the lambs live weight at weaning period. In order to establish a line for increased multiplicity, it is necessary to select ewe lambs to be used in the replacement stock from twin litters in the line No. 80077. The increased live weight of young animals from single litters is formed by the parent livestock of No. 01684, 20832, 65204 and 80077 lines. The advantage of twin ram lambs in terms of live weight over the average values has not been proven.