Nutritive Value and Herbage Accumulation Rates of Pastures Sown to Grass, Legume, and Chicory Mixtures

Abstract

Planting forage mixtures may benefit pasture herbage production; however, changes in botanical composition could cause variable (unstable) nutritive value. A grazing study was conducted to compare forage mixtures for variation in herbage nutritive value with time and herbage accumulation rate. In August 2001, four mixtures (two, three, six, and nine species of grasses, legumes and chicory, Cichorium intybus L) were established in replicated 1‐ha pastures (eight total) in central Pennsylvania. Pastures were grazed by dairy cattle (Bos taurus) from April to September of 2002 and 2003 and sampled frequently for nutritive value and herbage accumulation rate in April, July, and September each year. The intra‐annual variation (across all sampling periods within years) in fiber and digestibility was similar among mixtures; however, variation in crude protein (CP) was greater for the six‐species mixture than others in 2003. Concentration of CP (range of 155–250 g kg−1 dry matter) seemed to be controlled by herbage legume proportion (Pearson r of 0.33–0.90), whereas fiber (range of 278–506 g kg−1) and digestibility (range of 740–895 g kg−1) were controlled by the grass proportion (Pearson r of 0.54–0.88). The three‐, six‐, and nine‐species mixtures (all with chicory) had greater herbage accumulation rates than the orchardgrass (Dactylis glomerata L.)‐white clover (Trifolium repens L.) mixture in 2002, a dry year. Accumulation rates were similar among mixtures (avg of 62 kg ha−1d−1 in spring and 47 kg ha−1d−1 in summer) in 2003 with more rainfall. Complex forage mixtures were not inherently unstable in herbage nutritive value.