The aim of the work was to elaborate a literary review of the characteristics, reproductive properties of Holstein cattle and influences affecting the reproduction of cattle. Another objective of the work was to evaluate the selected influences on their reproduction in a group of selected dairy cows from the monitored cattle herd. The data were processed and sorted by genotype, level of milk performance, parity, length of dry period, length of insemination interval, difficulty of calving, age of the first calving and synchronization of estrous (Ovsynch). In evaluating the effect of the genotype on reproductive parameters, there were no statistically significant differences between purebred Holstein cows (H100) and crosses (H50-88C). In addition, the effect of milk yield on lactation on reproductive performance was evaluated. The results showed that with increasing performance, the values of reproduction indicators (insemination index, insemination interval and period service) have increased. The statistically lowest insemination index (1.70) and insemination interval (96 days) were detected in cows with a yield up to 8,000 kg. The service period (122 days) was conclusively the lowest in a cow group with a yield of 8,001 to 10,000 kg lactating milk. In contrast, the highest conclusive values of the insemination index, interval and period service were detected in a group of dairy cows with a yield above 12,001 kg of milk. It is further evident from the results that the values of the pregnancy rate after the first insemination increased with the increasing level of milk performance. The lowest value (27.14%) was detected in the group with the highest milk yield (over 12,001 kg of milk). There were no significant differences between the different groups of dairy cows in the evaluation of the influence of parity on the reproduction indicators. Furthermore, the influence of length of dry period was evaluated. The average dry period in the monitored herd was 69 days. The pregnancy rate after the first insemination was better for the group with a dry period over 61 days (40.38%). On the other hand, periods of service and days open values were lower in dairy cows with a dry period less than 60 days (119 and 394 days respectively). The length of uterine involution was also monitored by the length of insemination interval. Most cows in the monitored group of dairy cows (25.29%) were first inseminated 66th - 87th day after calving. No statistically significant differences were detected in the assessment of the age of the 1st calving and the severity of births on reproductive parameters. The use of controlled reproduction methods (Ovsynch) was also monitored and applied only in the case of reproductive disorders of dairy cows. In the monitored period, Ovsynch was used in only 10 dairy cows and the average service period was 140 days.
| Identifer | oai:union.ndltd.org:nusl.cz/oai:invenio.nusl.cz:320572 |
| Date | January 2017 |
| Creators | KOZÁKOVÁ, Tereza |
| Source Sets | Czech ETDs |
| Language | Czech |
| Detected Language | English |
| Type | info:eu-repo/semantics/masterThesis |
| Rights | info:eu-repo/semantics/restrictedAccess |
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