Ecological and physiological mechanisms of adaptation of young sheep in the conditions of Transbaikal

Abstract

The results of studying the adaptive abilities of young sheep depending on their origin and their relationship with productivity are presented. Temperature, velocity and humidity at birth of lambs (April) were 4.7 °C, 4.2 m/s and 17.7%, at the age of 6 months (October) - 1.0 °C below zero, 4.9 m/s and 33.7% respectively. The best indicators of live weight up to 6 months of age are shown by medium-wool young Aginskaya breed. Young rams at the age of 6 months had an advantage over their fine-wool counterparts of Transbaikal breed by 3.7% in terms of average live weight, and the gimmers by 6.3% (p > 0.05). The rams of the Transbaikal breed had the best height measurements of the body by 0.4 cm at the withers and by 1.3 cm in the height at hips. The Aginskaya breed peers were distinguished by better volume and latitude measurements, including oblique torso length and chest depth. The Aginskaya breed has longer ears (23,2-23,8%), neck (9,7-17,5%) and head (1,2- 2,5%), narrower forehead (11,5-17,6%) and less voluminous neck (5,1-7,2%) than their fine-wool counterparts. Clinical and hematological parameters were within the physiological norm. The lowest body temperature on the skin surface of the experimental youngsters at birth and at 6 months of age was noted in the ear area (25.2-26.0 °С), the highest - on the central part of the abdomen (29.3- 33.4 °С). In terms of skin thickness, depending on the origin of the sheep, the greatest difference was noted in the SCP, MR-12, and SCP areas. In fine-wool individuals, it is 28.0-39.1% thicker in the SCP, 9.7-46.2% thicker in the MR-12, and 25.0-43.5% thicker in the SCP. In test specimens a positive correlation of live weight with the height at hips (0.591-0.906), with the girth of the metacarpel (0.133-0.240), and with the width of the forehead (0.173-0.590) was detected. There was a correlation between live weight and head and neck length in medium-wool breed individuals (0.060- 0.463 and 0.147-0.394), as well as a weak correlation with skin thickness on MR-12. In fine-wool counterparts, there is a medium correlation between live weight and neck girth (0.490-0.553) and skin thickness in the SCP area (0.469-0.755).