EVALUATIONS OF THE GROWTH OF HEIFERS BORN FROM EMBRYO-TRANSFER

In a group of 615 calves of the Czech Pied breed, of which 211 were fr om embryo transfer, and 59 Holstein calves, of which 22 were from embr yo transfer, we studied the progressing weight increase. In 90-day-old Czech Pied breed the weight of ET heifers was statistically highly si gnificantly lower ((x) over bar = 102.3 kg, s(x) = +/-0.7 kg) than tha t of their herd mates ((x) over bar = 104.8 kg, s(x) = +/-0.6 kg). The statistical significance of this difference in live weight was still maintained at the age of 180, 270 and 360 days in favour of the herd m ates. At the age of 540 days the live weight of the ET heifers ((x) ov er bar = 398.9 kg, s(x) = +/-5.3 kg) balanced that of their herd mates . The variability in both groups up to the age of 540 days was similar . In the Holstein breed, no statistically significant differences in w eight growth were found between the ET heifers and their herd mates. H owever, the growth curves were similar to the growth curves of the Cze ch Pied breed. Using analysis of variance we further studied the effec t of ET and the effect of the herds on the growth of Czech Pied heifer s (H a r v e y, 1977). The highly significant effect of the herds over the entire period of growth was confirmed. The effect of ET on the li ve weight of heifers was highly significant at the age of 90 days (mu + t(j) = 99.1 kg, and/or mu + t(j) = 101.4 kg) and statistically signi ficant at the age of 180, 270 and 360 days. In the second year of age, the differences in the estimated mean values of live weights of ET he ifers and herd mates were not significant. The effect of fathers on po stnatal growth of their daughters was highly significant both in heife rs born after ET and in heifers born after insemination. The effect of the season of birth of the heifers on growth was not univocally confi rmed.