Assessment of zinc, iron, copper status in serum and consuming diets of Industrial & semi-industrial dairy cattle in Isfahan city, Iran

This study was conducted to evaluate the copper (Cu), zinc (Zn) and Iron (Fe) status in the industrial (n=12) and semi-industrial (n=12) dairy cattle farms from Isfahan city. A factorial experiment in a completely randomized block design consisting four blocks (North, South, West and East) was used and effects of season in two levels (cold and warm), cow-rearing practices in two levels (industrial and semi-industrial), physiological status in two levels (pregnant and non-pregnant), milk production in five levels [1(40Kg ≤), 2(30 Kg ≤χ40 Kg), 3(20 Kg ≤χ30 Kg), 4(10 Kg ≤χ20 Kg) and 5 (≤10 Kg)] on Cu, Zn and Fe concentrations in blood serum of 240 Holstein lactating dairy cows (after second calving, after peak of milk production, averaging 610±50 Kg BW, 30Kg daily milk yield and 170±20 days milking period) were studied. Blood samples were collected from the jugular vein of 5 dairy cows in each farm. In industrial farms diet Samples were collected from total mixed rations (TMR) and in semi-industrial farms, samples were separately collected from forage and concentrates. To assess the Cu, Zn, Fe status in blood serum and diet, concentrations of the elements were determined by atomic absorption spectrophotometry (AAS).The mean concentrations of selected elements in serum were found to be similar in both season in industrial farms. The mean concentrations of Cu and Zn in Serum samples from semi-industrial farms in winter were higher than summer (P0.05). The mean concentrations of selected elements in serum were found to be similar in both dairy cattle farms in winter but in summer the mean concentrations of Cu and Zn in serum samples from industrial farms were higher than semi-industrial farms (P0.05). No significant difference were observed in mean concentrations of selected elements in serum of pregnant and non-pregnant dairy cattle from industrial farms but mean concentrations of Cu in serum of non-pregnant cattle were higher than pregnant cattle in semi-industrial farms (P0.05). The mean concentrations of selected elements in serum were found to be similar in five groups of milk production in semi-industrial farms. In industrial farms, the mean concentrations of Cu in serum in 2 group (30 Kg ≤χ40 Kg) were higher than 1 (40Kg ≤) and 5 (≤10 Kg) (P0.05). No significant differences were observed in mean concentrations of selected elements in diet of industrial and semi-industrial farms in both seasons. In winter mean concentrations of Zn in diets of industrial farms were higher than semi-industrial farms and in summer mean concentrations of Cu in diets of industrial farms were higher than semi-industrial farms (P0.05). No significant correlation was found between concentrations of Cu, Zn and Fe in serum and diet. Comparison between mean concentration values and critical levels of these microelements (in serum and diet) by t student test showed that none of the values were classified as deficiency and mean Cu concentration in blood serum were in marginal range (P0.05). In industrial farms, mean concentrations of Cu, Zn and Fe in serum were 0.540±0.008 µg/ml, 1.157±0.016 µg/ml and 2.817±0.119 µg/ml, respectively. Furthermore, 11% and 2% of copper and zinc concentrations in serum were below the critical levels, respectively. In semi-industrial farms, mean concentrations of Cu, Zn and Fe in serum were 0.496±0.014 µg/ml, 1.067±0.046 µg/ml and 2.877±0.174µg/ml, respectively. Furthermore 39% and 9% of copper and zinc concentrations in serum were below the critical levels, respectively. Mean concentrations of Fe in serum were higher than normal level in both farms. In industrial farms, mean concentrations of Cu, Zn and Fe in diet samples were 13.008±1.15 mg/Kg, 72.846±5.348 mg/Kg and 494.41±49.41 mg/Kg, respectively and in semi-industrial farms, mean concentrations of Cu, Zn and Fe in diet samples were 12.967±3.824 mg/Kg, 47.314±5.497 mg/Kg and 550.82±55.907 mg/Kg, respectively. Not only in industrial farms but also in semi-industrial farms the mean concentrations of Cu, Zn and Fe in diet were higher than recommended levels by NRC in dietary dry matter. General conclusion of this study indicated that mean concentrations of Cu, Zn and Fe in diet were sufficiently high, mean concentrations of Zn and Fe in serum were in normal ranges and mean concentrations of Cu in serum were in marginal range, this was probably because of high concentration of Fe in diets.