The aim of the thesis was to evaluate the effect of selected factors on the reproductive characteristics of Montbeliard dairy cows. Hypothesis said that high milk production, poor health and high air temperatures have a negative effect on reproductive indicators of cows.
In the literature review, there were summarized knowledge about the factors affecting fertility, reproductive indicators and a description of the breed. Observation was carried out on the farm Osičky, which is one of the centers of the company Agrodružstvo Lhota pod Libčany. To assess the influence of milk yield and health were monitored all standard lactations of dairy cows, which were completed in the period from 1. 1. 2014 to 31. 12. 2015. This gave rise to a set of 632 lactations.
To evaluate the milk production was data set divided by the number of lactation, quarter of calving and the rate of milk production into three groups. As a disease with an expected negative impact on fertility, mastitis was selected. Besides air temperature, the relative humidity was assessed too. Indicators such as days open, days from calving to calving and services per conception were evaluated. In order to assess the impact of climate change on fertility data file was divided into 3 groups of air temperature, by quarter, according to the category of cows and by calendar year. Services per conception, pregnancy after the first insemination and pregnancy after all insemination, were assessed. Data could be obtained only from a whole herd of cows and heifers. For statistical evaluation has been used SAS 9.3 software (SAS / STAT 9.3, 2011).
Achieved an average length of days open was 98.07 days, days from calving to calving 380.62 days, services per conception was 1.94, pregnancy after the first insemination in heifers 54.28% and 48.43% in cows, yield per lactation was 8 407, 98 kg of milk with fat contents of 3.65 % and a protein contents of 3.53 %. Mastitis occurred only in 17.72 % of cases. The average monthly air temperature during the year 2014 ranged from 1.3 ° C to 21.2 ° C, in 2015 it was 1.5 ° C - 23.2 ° C.
From the results of the regression analysis, it was found that the milk production per lactation had a statistically significant effect on the length of the days open (r = 0.214; P <0.001), services per conception (r = 0.296; P <0.001) and days from calving to calving (r = 0.147; P < 0.01). Therefore we can talk about the significant influence of milk production per lactation. With the increasing amount of milk kg days open and days from calving to calving extended and services per conception also grew. Analysis of variance confirmed the effect of the amount of milk yield per lactation on days from calving to calving (P <0.05), days open (P <0.001) and services per conception (P <0.001). Furthermore, quarter of calving had a significant effect (P <0.05) on services per conception and days open and the effect of category on pregnancy after all insemination (P <0.01) and services per conception has been demonstrated (P <0.05). Heifers showed demonstrably better results of assessed reproductive characteristics compared to cows. There was no effect of the incidence of mastitis on days open, days from calving to calving and services per conception proven (P> 0.05). Effect of air temperature on services per conception, pregnancy after the first insemination and pregnancy after all insemination, was not statistically proven (P > 0.05). Furthermore it has been approved many correlations between different parameters at the levels of significance (P < 0.001, P < 0.05).
The hypothesis was confirmed only for the negative impact of high milk production, but the impact of poor health and high air temperatures on reproduction was not approved. The results indicate a healthy herd in terms of mastitis, good management of breeding, which minimizes heat stress and which is of relatively high milk yield and proven negative impact of high milk production to reproduction, achieved a good level of reproduction.
| Identifer | oai:union.ndltd.org:nusl.cz/oai:invenio.nusl.cz:258336 |
| Date | January 2016 |
| Creators | Šťásková, Michaela |
| Contributors | Toušová, Renata, Petr, Petr |
| Publisher | Česká zemědělská univerzita v Praze |
| 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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