Effects of replacing inorganic forms of manganese, zinc, copper and selenium with their organic source on growth performance of suckling Holstein calves

Considering that trace elements play an important role in growth performance and immune system in livestock. Nowadays, inorganic forms (mineral salts) of these minerals are added to mineral supplements. Because of mineral interaction, inorganic forms have lower bioavailability in gastrointestinal tract. One of the ways to increase the availability of trace minerals in the digestive tract of livestock is to replace their organic form (chelate with peptides and amino acids) in mineral supplements. For this purpose, the effects of organic sources of trace minerals on livestock performance have been studied. The objective of this experiment was to investigate the effect of replacement of inorganic form of zinc, copper, manganese and selenium with organic source on starter intake and growth performance of Holstein suckling calves.

30 Holstein calves (42 ± 2 kg of birth weight) were equally assigned to two groups of 15 (5 male and 10 female) control and treatment. The experiment was conducted in a completely randomized design and lasted for 80 days. The experiment was started at 4 days of age and calves were weaned at 70 days of age and were kept up to 80 days in individual hutches. All calves were equally fed with same starter. Chelated copper, zinc, manganese and yeast selenium in treatment group and copper sulfate, manganese oxide, zinc oxide and sodium selenite in control group were added to the starter. Weight and starter intake of calves were measured weekly and daily, respectively. Blood parameters and serum levels of zinc, copper, manganese, and glutathione peroxidase and superoxide dismutase enzymes were measured at the start of experiment and at the time of weaning. Calf feces were collected at the end of the experiment and after preparing the samples by wet ash method (AOAC, 984.27); fecal excretion of copper, zinc and manganese elements was analyzed.

Results showed that starter intake and feed efficiency increased significantly by 85.6g and 6.44% respectively in treatment group. Calves were fed with organic form showed higher average daily gain (p < 0.001). No significant difference was found in blood parameters, serum levels of copper and zinc. However, level of manganese in blood serum was significantly higher in treatment group. It was not found significant changes in level of glutathione peroxidase, superoxide dismutase, β hydroxybutyrate and immunoglobulin G in both groups (P≥0.05). In this study, Fecal excretion of manganese, zinc, and copper decreased significantly by 25%, 16%, and 22% respectively for calves were fed the organic form (P≤0.01).

This study showed that replacing inorganic forms of manganese, zinc, copper and selenium with their organic source had positive effects on growth performance and feed efficiency of suckling Holstein calves. Therefore, total replacement of copper, manganese, zinc and selenium with their organic form in mineral supplements of calf starter is recommended.