Malate content of forage varieties commonly fed to cattle

The objective of this study was to determine the concentration of malate in forage varieties at different stages of maturity. Five alfalfa varieties (Alfagraze, Apollo Supreme, Cimarron, Crockett, and Magnum III) and three bermudagrass varieties (Coastal, Tifton-78, and Tifton-85) were collected at different stages of maturity. Samples were collected from replicate plots (n = 3) of each alfalfa variety at 9, 18, 28, 35, and 42 d of maturity; bermudagrass hay samples were composited from six bales of each variety from two cuttings staged to be harvested at 27 and 41 d of maturity. Malate was extracted from the samples and quantitated by high performance liquid chromatography using an organic acid column. As maturity increased, the concentration of malate declined in both plant species. Concentrations of malate were numerically higher in two alfalfa varieties (Crockett and Magnum III) at 35 and 42 d of maturity than in all other alfalfa varieties. Concentrations of malate in bermudagrass at 41 d of maturity were lower than concentrations of malate in all alfalfa varieties at 42 d of maturity. Malate declined as maturity increased in the Coastal and Tifton-78 varieties. Because malate stimulates the utilization of lactate by the predominant ruminal bacterium Selenomonas ruminantium, some of the benefits associated with alfalfa in the diets of dairy cattle may be due to the malate in this forage.