الفهرس 
Organic form of mineralsOnly 14 pages are availabe for public view
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Abstract
This study was conducted to investigate the influence of zinc sulfate and zinc methionine supplementation on the nutrients digestibility, nutritive values, nitrogen utilization, ruminalfer mentation,blood parameters,antioxidant enzymes activities, milk yield, milk constitutes of lactating cows,somatic cells count,feed and economic efficiency. Twenty cows were divided into five similar groups. Animals were fed concentrate feed mixture(CFM),corn silage and rice straw without zinc supplementation. The other four experimental groups supplemental with 30 or 60 mg of Zn/kg of DM from Zn sulfate or zinc methionine. Results indicated that zinc addition either as zinc sulfate or zinc methionine increased(P<0.05)the digestibility of all nutrients which were reflected on the nutritive values(as Total digestible nutrients(TDN)and Digestible crude protein(DCP)of diets.Addition of zinc sulfate or zinc methionine reduced ammonia-N and increased TVFA’s, rumen volume, rumen digesta and microbial protein synthesis with sheep. Moreover, zinc methionine treatment led to an increase in antioxidant enzymes activity. Milk yield and 4% fat corrected milk yield were increased by increasing supplemental zinc methionine levels. Zinc addition enhanced the blood parameters as a total protein, globulin and glucose levels. Economic efficiency was preferable with animals fed supplemented zinc compared with control group. So, Zn in the form of
sulfate or methionine can be recommended to supplement dairy cows at the rate of 60 mg/kg DM in order to get more milk and milk composition, less
somatic cells count and better feed and economic efficiency. However, Zn methionine proved to be more pronounced effect than Zn sulfate.