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Hodnocení výživy a metabolismu dojnic na základě výsledků vyšetření bazénových a individuálních vzorků mléka
Dubová, Kateřina
The thesis objective was to evaluate the results of bulk milk samples and individual milk samples taken during the performance control of dairy cows over one year, correlation analysis of mutual relationships between milk examined parameters and correlation analysis of milk composition and the temperature values. Next objective was to compare results of performance control between first-calvers and the dairy cows on the second and higher lactation and also use of results of milk samples to determine dairy cow health problems. The evaluation of nutrition and metabolism from bulk milk samples and the individual milk samples for the period from 4/2016 to 3/2017 was conducted in the ZD Dušejov. There are 480 dairy cows of Holstein at present. Comparison of bulk and individual milk samples results revealed the most important difference in the number of somatic cells (12 %) and urea (18 %). The differences are minimal for the other parameters. Based on the statistical comparison of individual samples, the first-calvers lower milk yield (17.2 %), than the cows on the second and higher lactation (P < 0.001), was found. In the early stages of lactation of first-calvers, there were recorded lower milk fat and higher lactose concentrations. The fact that the first-calvers have a healthier mammary gland shows the difference (P < 0.001) in the number of somatic cells. From the correlation of components of individual milk samples the closest relationship between the fat and the lactose/fat ratio (r = 0.95) and the relationship of citric acid to acetone (r = 0.76) was found. The most significant negative correlation was found between the milk yield and the day of lactation (r = -0.65) and milk fat (r = -0.57). Monitoring showed that the temperature affected the fat, protein (r = -0.88) and lactose concentration (r = -0.80). By the temperature rises, the risk of ketoses increases. This is confirmed by the results of relationship between the temperature and acetone and bethahydroxybutyrate concentrations (r = 0.87 and 0.85). Based on the use of fat/protein ratio as a suitable indicator of the effect of nutrition on the metabolism, it has been found that nearly half of the herd is threatened by the rumen acidosis. The rising risk of acidosis increases the number of mastitis treatments (r = 0.72; P < 0,01) and the incidence of inflamation the hoof (r = 0.45), which isn 't conclusive for low number of variables. Ketosis, according to the results of individual samples, is risk for average of 5 % of the herd. The positive correlation between the occurrence of placental retention and ketosis (r = 0.82; P < 0.01), was found.
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