Improved Nutritive Value of Kura Clover– and Birdsfoot Trefoil–Grass Mixtures Compared with Grass Monocultures

Abstract

Improved dry matter (DM) production of cool‐season grass monocultures may result from either N fertilization or the addition of legumes such as kura clover (Trifolium ambiguum M. Bieb.) or birdsfoot trefoil (Lotus corniculatus L.). Such improvements could affect forage nutritive value and potential milk production from dairy cattle (Bos taurus). Laboratory estimates of forage nutritive value as well as potential milk production per unit mass and area were compared for six levels of N fertilizer on Kentucky bluegrass (KBG; Poa pratensis L.), smooth bromegrass (SBG; Bromus inermis Leyss.), and orchardgrass (OG; Dactylis glomerata L.) in monoculture or with either kura clover or birdsfoot trefoil in binary mixture with each grass. Experiments managed in a three‐harvest system were conducted from 1994 through 1996 near Arlington and Lancaster, WI. Either legume reduced neutral detergent fiber and acid detergent fiber and increased crude protein when added to grass. These effects increased with greater mixture legume DM proportions. Compared with grass monocultures averaged across years and locations and for any N rate, mixtures had greater potential milk production per megagram of DM and followed KBG > SBG > OG. Similarly, potential milk production per hectare for kura clover–grass mixtures exceeded that of monocultures by at least 49% for KBG and 12% for SBG while birdsfoot trefoil–grass mixtures were greater by at least 28% for KBG and 20% for SBG. Orchardgrass required maximum N rates to match milk production per hectare of the mixtures. Adding either kura clover or birdsfoot trefoil will improve potential milk production of these grasses while reducing reliance on fertilizer N in the North‐Central USA.