Thesis (Ph. D.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 80-88). Also available on the World Wide Web.

Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 50-52). Also available on the World Wide Web.

The work deals with the evaluation of selected effects on reproduction of Holstein cattle breeds. The aim of the study was to evaluate reproductive parameters (insemination index, insemination interval, period service, interim, pregnancy after the first insemination) in a selected group of dairy cows. These reproductive indicators were subsequently evaluated depending on genotype, performance level, lactation order and age at first calving and used synchronization methods. The evaluation took place at the Vřesce farm, belonging to company Rynagro a.s. 260 Holstein breed cows and their hybrids were included. The results showed that some reproductive indicators (insemination interval, service period and interim) of the monitored group of dairy cows were lower than the average of the Czech Republic. When evaluating the genotype effect on reproductive parameters, a highly significant effect (p<0.01) of genotype on insemination interval was found. Holstein breed cows had a 7-day higher insemination interval than other crosses. In evaluating the effect of daily milk yield was not proven statistically significant differences (p>0.05) in period servis and interim. Statistically significant differences (p<0.05) in insemination index, insemination interval and pregnancy after the first insemination were proven in the performance evaluation. The p-value of the global null hypothesis was close to 0.05 and no significant differences between the compared groups were demonstrated in the subsequent multiple comparison. The effect of the order of lactation on reproductive parameters was not proven (p>0.05). However, interesting results were found by the impact of age at first calving. There was a statistically highly significant difference (p<0.01) between the groups in the insemination interval and the interim and a statistically significant difference (p<0.05) between the groups in the service period. Cows with a first calving age 23 months had all of these indicators lowest, the highest values were found within cows with a first calving age of 28 months. After evaluating the correlation analysis, a significant effect of age at first calving on insemination interval (p<0.05; r=0.13), on interim (p<0.01; r=0.17) and period service (p<0.01; r=0.17). Synchronization methods were used in 125 cows and the overall success rate after this treatment was 47%. The most commonly used protocol was the Ovsynch method. The calculations based on the extension of the service period quantified the theoretical loss for the extended cycle of dairy cows. This loss is 7 030, - CZK per cow and takes into account the losses for milk and the unborn calf, not the cost of further insemination and treatment of cows.

Thesis (M.S.)--Mississippi State University. Department of Animal and Dairy Sciences. / Title from title screen. Includes bibliographical references.

Thesis (M.S.)--Mississippi State University. Department of Animal and Dairy Sciences. / Title from title screen. Includes bibliographical references.

Thesis (M.S.)--Mississippi State University. Department of Animal and Dairy Sciences. / Title from title screen. Includes bibliographical references.

Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 56-59). Also available on the World Wide Web.

Thesis (Ph.D.)--Mississippi State University. College of Veterinary Medicine. / Title from title screen. Includes bibliographical references.