Red clover increases micronutrient concentrations in forage mixtures

Forage crops provide micronutrients as well as energy, protein and fibre to ruminants. However, themicronutrient concentrations of forage plant species differ, legumes generally having higher concentra-tions than grasses. In addition to that there are also strong effects of soil type. Typically, the concentrationsof one or several micronutrients in forage are too low to meet the nutritional requirement of dairy cows.We hypothesized that the overall micronutrient (Co, Cu, Fe, Mn, Mo, Zn) concentrations of forage mixturesare affected by the red clover dry matter (DM) proportion and site effects. This hypothesis was testedat three contrasting sites. The results showed that increased red clover proportion increased the overallconcentrations of several micronutrients in the mixtures at all sites. At the site with the widest rangeof red clover proportion (0–70%) in the mixture, the Co, Cu and Fe concentrations more than doubledbetween the lowest and highest red clover DM proportion. At the other two sites a smaller increase inred clover proportion (from 10% to 25% or from 25% to 50%) also increased the overall concentrations ofCo by up to 80% but less for other micronutrients. One of the sites generally had higher micronutrientconcentrations in the crop and removed larger amounts of micronutrients with the harvested biomasscompared to the other two sites. This could be explained by differences in pH and micronutrient con-centrations of the soils at the sites. We conclude that increased red clover proportion in the sward hasthe potential to increase the overall micronutrient concentrations but that the effect of the soil is also acontrolling factor.© 2014 Elsevier B.V. All rights reserved.