Seasonal Study for Deficiency of Some Trace Elements in Sheep in Talesh Area in 2019-2020

Mineral elements required by the body of living organisms are divided into two categories: macroelements and microelements, which make up 2-5% of the body weight of animals. Minerals have vital role in the efficiency of growth, production and reproduction performances. General conditions for the deficiency of these minerals can be caused by a deficiency in food, a deficiency in the soil, or an imbalance between the amounts of minerals (Costabe et al 2017). Deficiency may be low and the appearance of the animal may not indicate anything, but all deficiencies will affect the animal sooner or later. Deficiency of some elements such as copper, selenium, zinc and magnesium is more common in areas with poor soil (Myers et al 2019). Talesh region is located in the north of Iran in the west of Gilan province and due to having large and extensive pastures in this area; it is very prosperous for sheep keeping. No complete study has been conducted on the status of rare and essential elements of livestock in this area. Therefore, this study was conducted to investigate the serum levels of some elements (magnesium, copper, zinc and selenium) and seasonal comparison in sheep in this area.

The study was conducted on 200 sheep in four geographical areas north, south, west and east of Talesh city (50 samples per season). In the middle of each season, after registering the livestock characteristics, serum samples were obtained at different ages under one year and one year (42 cases), two years (44 cases), three years (28 cases), four years (40 cases), five years (24 cases) and six years and above (22 cases). Sheep were in both sexes (30 cases) and females (170 cases). Sampling was done randomly. From each animal, 10 cc of blood was taken from jugular vein and the serum was separated and frozen. During the measurement, the samples were separated from the freezer and the serum values of copper, zinc and selenium were measured by atomic absorption method (model AA6300 made by SHIMADZU company of Japan) (Bye 1989) and magnesium serum was measured by Pars Azmoun biochemical kit. The results analyzed by ANOVA and Ttest to determine the difference between seasons, different groups of ages and sexes.

The mean serum magnesium level was higher in spring (2.81 ±0.35 mg/dl) than in other seasons and lower in winter (2.60 ± 0.35 mg/dl) than in others. The mean serum levels of copper in spring, summer, autumn and winter was 0.80 ±0.071, 0.94 ±0.091, 0.84 ±0.091 and 0.60 ± 0.092 mg/dl, respectively. These means were 65.11 ±2.11, 72.10 ±1.64, 72.00 ±1.64 and 64.91 ± 2.36 mg/dl, respectively for zinc. The mean serum selenium levels were higher in summer (0.042 ±0.006 mg/dl) and lower in winter (0.035 ±0.005 mg/dl) than in other seasons. The differences between the seasons were significant in all elements (P < 0.05). The means of magnesium, zinc and selenium in the serum in males were higher than females nonsignificantly. The mean of serum copper was higher in the females that this increasing was not significant, also. Serum magnesium levels were higher in the 3 years than in other ages, but the difference between mean serum magnesium levels was not significant at different ages. The mean serum copper in the 5 years and the serum zinc and selenium levels in the six years were higher than in other ages, significantly (p < /p>