DESCRIPTION OF EMBRYOGENESIS AND ESTIMATI ON OF OFFSPRING STATE IN SAIGA-TATARICA

In Kalmykia development and growth of Saiga tatarica foetus were inves tigated from 40-day-old embryos with 5-10 days intervals up to the sta ge of new-borns. Rates of the foetus growth and development are shown to vary during embryogenesis. The lowest growth rate was observed at t he age of 55 days, the maximal one was registered at the age of 75-100 days, stabilization of growth taking place at the age of 125-150 days when differentiation of external morphological characters intensified . The 125-day-old embryos reached differentiation similar to that of n ew-borns. Low average daily increments during the last month before bi rth were accompanied by a decrease of weight and viability of new-born s. the differences in the foetus age among the females collected at th e same date reflected variation in the time of copulation but did not influence the foetus differentiation and growth. The new-borns of redu ced weight (less 2600 g) were characterized by low viability, had neit her defensive reactions nor sucking reflex and died soon after birth. Birth of the inviable offspring was related to bad foraging and unsuff icient nutrition of females during the last period of pregnance starti ng from the time when the age of foetus was 125 days.