Using biotechnological methods in beef cattle herds

The aim of this dissertation consists in analysing the results of the biotechnological techniques (insemination, embryotransfer) for a selected herd of meat-type cattle raised in a foothills countryside dutiny 5 years (2002 {--} 2006) and their comparison with natural breeding. The results this obtained are presented in dependence on the breed, fater{\crq}s origin and calving month. The analysis involves 795 Charolais calves and 450 meat-type Siemental calves. In the Charolais group insemination gave 275 calves, while natural breeding gave 520 calves. In the case of meat-type Siemental group the corresponding numbers are 179 and 271, accordingly. After embryotranfer we have got 4 Charolais calves and 15 calves of the other breed. The work evaluates the influence of the technique of breeding on to the rate of calf grow, with this investigation being performed in dependence on the breed. The meat-type Siemental bulls have shown a significant difference (p {>} 0,05) in the live weight of the calves 120 and 365 days old. In this age bulls born after insemination have been heavier (183,9 kg, 527,9 kg) in comparison with bulls born after natural breeding (172,4 kg, 497,0 kg). Concerming Charolais bulls, no statistically significant difference in the live weight have been found. In addition, no significant influence of the mode of breeding on to the live weight has been found for heifers of both breeds. Concerning the effect of the calving month on the rate of grow, the meat-type Siemntal calves have shown a highly statistically significant (p {>} 0,001) difference in the live weight of calves born in March. The live weights of calves born in March and weighed at 120, 210 and 365 days have been 181,17 kg, 289,2 kg and 510,31 kg, these values being valid for calves after insemination. The corresponding values for natural breeding are lower, particularly 168,26 kg, 271,37 kg and 439,59 kg. In addition a statistically considerable difference (p {>} 0,01) in the live weight has been found for calves 120 days old if the calves were born in April. Insemination has led to a live weight of 194,5 kg, while natural breeding to 168,9 kg. In the group of Charolais calves a statistically significant difference (p {>} 0,01 {--} 0,05) has been found at the age of 365 days. Calves born after insemination had a higher live weight (462,85 kg) as compared to those born after natural breeding (432,85 kg). As concerns the parameters characterising fertility, the following ones have been analysed: the service period (SP), the birth-to-birth interval and the percentage of becoming pregnanat after the first insemination. For the whole period under investigation, the SP value for the Charolais calves (T 100) has been 89,19 days while for the meat-type Siemental calves (S 100) 80,04 days. As concerns the birth-to-birth period found for Charolais (381,32 days) and the meat-type Siemental (390,35 days), it may be stated that these results are satisfactory. The percentage of becoming pregnant after the first insemination has shown a downword trend for both breeds in the course of the years under study. Investigated paramentrs of growth and reproduction are markedly influenced by the breed