Acta Universitatis Agriculturae Et Silviculturae Mendelianae Brunensis Sborník Mendelovy Zemědělské a Lesnické Univerzity V Brně

hEGEDŰŠOVá, Z., říHA, J.: The influence of season and sire on the results of superovulation and embryo transfer. Acta univ. agric. et silvic. Mendel. Brun., 2006, LIV, No. 5, pp. 25–36 The aim of the study was evaluate the influence of season and sires on profit and quality of embryos after superovulated treatment. Next we evaluated the conception rate after transfer of fresh and frozen embryos. In 1991–2004 there were used the beef cattle. Into the basic statistic evaluation it was involved 487 realised embryo recoveries and 2008 realised transfers in 1991–2004. Data for database were obtaining from ETprotocols – ET team Research Institute for Cattle Breeding, Ltd., Rapotin, prof. říha. The data processing was carried out by means of the common variation-statistical methods. The best results were achieved in summer (suitable 3.68 ± 3.65; the ratio of the suitable and total: 59.3%) and in autumn (suitable 3.54 ± 3.80; the ratio: 54.48%) and the good results, little different from the summer and autumn results, were achieved in spring. The average number of the recovered ova of the chosen breeds sires were variable (from 6.60 ± 6.17 in Blonde d ́Aquitaine to 17.16 ± 6.66 in Charolais). The most of the suitable embryos was recovered in the donors inseminated by the Hereford breed sires (7.15 ± 6.42). It was evaluated the above-average conception in the Simmental breed (63.43 %). beef cattle breeds, donors, recipients, superovulation, embryo transfer, conception rate, sire, season The embryo transfer in cattle and the following pregnancy ability of the dams is still the subject of the interest of the research sphere, especially of the breeders. With respect to the ascendant number of the transfers in the world-wide scale the attention is focused on the ET quality and on the aspects that have an influence on ET. We have paid our attention on the study of the influence of the year and the season on the embryo transfer efficiency in the chosen beef cattle breeds. The aim of this work was to evaluate the influence of the year, the season on the embryos gain and their quality after the superovulatory treatment. Furthermore, it was evaluated the conception rate after the transfer of the fresh and the thawed embryos in the monitored years and the influence of the season on the conception of the recipients. The utilisation of the embryo transfer method in the beef cattle breeding has its restrictions by reason of the seasonal character of the reproduction. The basic reproduction functions (the pregnancy and the birth, checking of the accessing of the first sexual activity and its functions, the synchronizing and superovulatory treatment, the recovery of embryos and the embryo transfer) is necessary to master in the short time during 60 and 90 days, the best including the next donors gravidity (říHA, 1995,1996). Better knowledge about the season influence on 26 Z. Hegedűšová, J. Říha the superovulation is for the dairy cows breeding than for the beef cattle breeding; in case of the beef cattle breeding the season is valuated foremost from the viewpoint of the breeding technology. KNEISSL (1990) mentions that the influence of the year on the embryo transfer was statistically significant; between particular years there were differences above all in the average numbers of the transferred embryos. In major part of the studies about the embryo transfer the influence of the year is not considered – KNEISSL (1990). říHA et al. (1998, 1999) were engaged in the evaluation of the influences on the embryos survival or on the donors conception, respectively, and of the influences affecting the gain and the quality of embryos in the beef cattle. It concerned mainly season influences on the embryos gain and its quality. The donors were divided into three groups according to the body skeleton character. The obtained data were analysed in relation to the season of the year. The satisfactory results were obtained for all groups in spring, summer and autumn season. On the basis of the results published in the authors works (říHA et al., 1988; říHA et al., 1990) it is possible to carry out the superovulation, the recovery of embryos and the embryo transfer during the whole year. The opinions on the season influence on the superovulation efficiency are various. VANĚK (1997) studied the influence on the gain and the embryos quality in the beef cattle. He ascertained the highest number of the suitable embryos in summer and in autumn. The most of the authors was engaged in the monitoring of the season influence on the gain and the embryos quality after the superovulatory treatment in the dairy cattle breeds. Only few literary resources is concerned with this issue in the beef cattle breeds. říHA (1990) ascertained the statistically significant differences in the conception rate of the donors according to the sire utilized for the insemination, i. e. according to the sires. After 12 sires it was obtained the conception rate more than 70%, on the contrary after 5 sires it was lower than 20%. In the other work of říHA (1999) there were ascertained only insignificant differences in the average number of the obtained ova and also of the suitable embryos. It was probably by reason of the high variability of the results. By means of the multifactor analysis it was in this work ascertained the influence of the dam and the sire on the gain of the ova and the suitable embryos. Also KNEISSL (1990) ascertained the highly significant influence of the sires on the embryos survival after the transfer in the range from 37.7% (REA 75) to 65.1% (ME 84). říHA et al. (1996) ascertained the significant influence of the sires on the conception rate in the heifers after the transfer of the in vitro thawed embryos from the gravid dams in the range from 14.3% to 51.5%. MATERIALS AND METhODS