Micronutrient concentrations in relation to phenological development of red clover (Trifolium pratense L.), perennial ryegrass (Lolium perenne L.) and timothy (Phleum pratense L.)



The main aim of this study was to examine how concentrations of the micronutrients cobalt, copper, iron, manganese, molybdenum, nickel and zinc change with phenological development in red clover, perennial ryegrass and timothy. An additional aim was to investigate micronutrient concentrations and the dry matter (DM) proportions of the leaves, stems and flowers at the flowering stage. The plants were harvested at five phenological stages, ranging from stem elongation to flowering, in a greenhouse pot experiment. The results show that micronutrient concentrations generally decreased with phenological development of the grasses, but that the reduction was larger in timothy than in perennial ryegrass. Concentrations of cobalt, iron, manganese and nickel were more constant in red clover than in the other species. Flowers and leaves had higher concentrations than stems. The generally low concentrations found in timothy were largely due to the high DM proportion of micronutrient-poor stems. Our results suggest that harvest at an early phenological stage is not only preferred due to high digestibility but also with regard to micronutrient concentrations. They also highlight the importance of considering phenological development and DM harvested when comparing forage species with regard to micronutrient concentrations.