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Obsah zinku, mědi a jódu v mléce krav
JAKEŠOVÁ, Jitka
Milk and dairy products are one of the most important sources of essential trace elements in human nutrition. My thesis provides informations about the content of zinc, copper and iodine in milk during the lactation and also includes the impact of other factors on the content of elements. The experiment includes dairy cattle breedings from Hořepník and Chyšná which are located in the region Vysočina. Another breeding is from Haklovy Dvory. It is located in southern Bohemia. Milk samples were taken in the relation to performance monitoring. During the period 25 to 132 days of lactation were taken 90 samples of milk from the Hořepník breeding. From breeding Chyšná were taken 78 samples of milk in the period of 11 - 89 days of lactation and from breeding Haklovy Dvory 81 samples of milk during the period 23 to 244 days of lactation. Copper and zinc content in milk was determined by atomic absorption spektrometry. The iodine content in the milk was set by spectrometry after incineration alkaline by Sandell-Kolthoff. The average zinc content in the milk was 3.59 ? 1.15 mg-l-1. The average copper content in milk was 0.14 ? 0.12 mg-l-1and the average content of iodine in the milk was 0.18 ? 0 06 mg-l-1. The greatest variability in milk was proved to copper (V = 82,65%), the lowest zinc (V = 32,05%). The greatest effect of the duration of lactation was observed in breeding Hořepník (Zn: rxy = -0,430, Cu: rxy = -0,425, I: rxy = 0,326). The influence of the duration of lactation was insignifant in the breeding Haklovy Dvory and Chyšná. Cow's milk, according to our results, supply the iodine accounts from 19,2% for men and 52,4% for women. The milk supply the zinc accounts from 5,2 % for men and 7,2 % for women, and copper from 2,5% for both sex.
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Iodine content in milk and milk whey during lactation
JAKEŠOVÁ, Jitka
Milk is an important natural resource of iodine in human nutrition. The content of iodine in milk is an objective indicator of iodine saturation of cows. My work shows data about iodine content in milk and whey during lactation and other factors which affect the iodine contents. The experiment includes 12 milkers at the beginning of their lactation. This milkers are from breeding Haklovy Dvory, which is situated near České Budějovice. Samples of milk were collected with monitoring performance regularly once a month since August to November 2014. The iodine content was determined spectrometrically after alkaline burning of the sample. The average content of iodine in milk in August 2014 was 169.63 ? 70.39 g.l-1, in September 202.25 ? 65.08 g.l-1, at the beginning of November (substitute sampling for October) 183.91 ? 65, 31 g.l-1 and at the end of November 2014 216.56 ? 68.67 g.l-1. The average iodine content in whey in August could not be realized. The average iodine content in whey in September was 140.5 ? 55,3 g.l-1, at the beginning of November 131.5 ? 45,9 g.l-1 and at the end of November 2014 168.2 ? 77, 8 g.l-1. The iodine content in the milk whey corresponds with the range for the recommended daily ration of iodine.
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