Organic supplementation of Cu and Se in the diets of Normande dairy cows

Objective. To evaluate the effects of organic and inorganic copper (Cu) and selenium (Se) on milk production, milk quality and reproductive parameters of Normande dairy cows. Materials and methods. 36 multiparous cows (BW = 600 ± 32 kg) were used, distributed in completely randomized blocks. Treatments were: Control: without mineral supplementation, IS: inorganic mineral supplementation with Cu and Se, IS+OS: 50% Inorganic supplementation + 50% organic supplementation, with an experimental period of 150 days (30 days before calving and 120 days of lactation). The variables evaluated were milk production and quality (total solids, protein, fat, somatic cells and MUN), blood metabolites (glucose, betahydroxybutyrate and BUN) and reproductive parameters (open days, days to first service and services per conception). Results. No differences were observed in milk production and quality (p>0.05). However, open days and services per conception were shorter when cows were supplemented with organic minerals (p<0.05). Conclusions.In this study milk production, milk quality and blood metabolites were not affected by supplementation with Se and Cu. However, the reproductive parameters of the cows improved when supplemented with organic Se and Cu.