Interseeding cool-season forages into corn to increase yield and quality of residue grazed in the fall

Abstract

Six forage species/mixtures were interseeded into irrigated grain corn to evaluate their yield and nutritional quality as a means of improving diets for beef cattle grazing cornstalks during the fall. Species evaluated included annual ryegrass (Lolium multiflorum), crimson clover (Trifolium incarnatum), Fridge winter triticale (X Triticosecale), a mixture of annual ryegrass plus crimson clover, a brassica mixture (Barkant turnip [Brassicas rapa], Barnapoli rape [Brassica napus], Groundhog radish [Raphanus sativus var.oleifer Strokes], and Pasja hybrid [Chinese cabbage {Brassica rapa L. chinensis} x Turnip hybrid]), and a mixture of winter triticale plus the brassica mix. The cool-season forages were interseeded at the V6 growth stage of corn on June 30, 2014. DM yield (p=0.0013), CP (p=0.0149), aNDF (p=0.0001), and in-vitro true digestibility (IVTD, p=0.0027) differed among the interseeded forages. Annual ryegrass and the brassica mix had the highest yields (596 and 790 kg ha-1, respectively). The CP content of all treatments was higher than that of cornstalks (5.2% vs. 18.3-26.1%) and had the potential to provide supplemental protein for beef cattle grazing corn residue. The fiber content of the interseeded cool-season forages was lower than cornstalks (73.5% vs. 23.4-44.2%), being particularly low in the brassica mix and the brassica mix plus winter triticale. Except for crimson clover (77.7%), all treatments had high IVTD values (89.492.1%), with all forages having higher values than cornstalks (57.7%). The cost per kg of DM and kg of CP of the interseeded forages varied widely because of differences in seeding rates, seed cost, DM yield, and CP content. Annual ryegrass and the brassica mix were the treatments with the lowest costs ($0.18 and $0.17 kg-1 of DM and $0.96 and $0.72 kg-1 of CP; respectively), having values similar to good quality alfalfa hay with a current market price of $154 t-1. Interseeding cool-season forages can increase the quality of biomass offered to beef cattle grazing cornstalks during the fall. This should be combined with strip grazing to maximize utilization of the high quality cool-season forages that can grow during the fall. This practice can reduce supplementation costs for producers while improving nutrient cycling through a more even spread of manure across the field.