The seasonal study of serum zinc level of cross breed dairy cattle in Moghan province

In this study, during four seasons of year, the bleed accomplished by using venoject tubes from samples randomly, on 200 non pregnant, apparently healthy, cross breed dairy cows at Moghan province. The end of each season, the serum Zinc levels were measured by Randox biochemical kit and using the spectrophotometery method. According to the one-way variance analysis (ANOVA), there is a meaningful statistical difference at the level of Zn (P<0.01), in winter with other seasons. This clear reduction may be the result of excessive using hay in diet, and also the excessive cold weather in winter.Also, in order to evaluate the correlation between serum zinc rate and the age of cows, the samples were divided to four age groups: 2, 3, 4, and 5 and more years old. According to the one-way variance analysis, there is a meaningful statistical difference for the five and more years old group, with the others. So by increasing of age, the serum zinc rate would decrease.