Cattle mineral requirements

Nutrition. Zinc is essential to the proper functioning of plants and animals and, as zinc sulfate and oxide, it is used as a feed supplement (49—51) (see Mineral nutrients Feedsand feed additives). Most crops use less than a kilogram of zinc per 1000 m per year, so that zinc salts added at 1.3—4.5 kg/ha gradually build up the zinc reserve (52). Animals, including humans, store relatively Htde available zinc and, thus, require a constant supply in the diet. For instance, beef cattle require 10—30 mg/kg dry feed, dairy cattle 40 mg/kg, and breeding hens 65 mg/kg. Zinc from plants is considered less available to monogastric aminals than zinc from animal protein. 

Of the seven macro mineral elements required by dairy cattle, five can be considered fertilizer elements (potassium, calcium, phosphorus, magnesium, and sulfur), but sodium and chloride are both toxic lo plants at high concentrations and present practical problems in areas with saline soils. High salt intakes have also been shown lo increase udder edema in heifers. Because of the importance of chloride in nutrition and mclabolisni. research is needed to define the chloride requirements of lactating cows and clarify mineral relationships, especially between chloride and potassium plus sodium-... 

The iodation of mineral mixtures increased the iodine content of cow s milk in Thuringia from 17 to 81 iag/1. The iodine content of meat and offals also increased significantly. The iodation of packed cooking salt and of the mineral mixtures for cattle and pigs resulted in a mean improvement of the iodine intake of women and men from about 30 Mg/day to 45 - 51 and 57 - 61, resp. Although, it remained considerably below the calculated iodine requirements of adults (100 to 150 Ug/day), it led to the disappearance of Struma konnata and reduced the frequency of struma in children and young people. 

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