191 Yield and nutritive quality of summer annual forage mixtures

Abstract

Abstract Summer annual forage mixtures are both high yielding and contain a high nutritive quality. They provide a summer forage option for maintaining stockers, forage-finished beef, and replacement heifers on with little to no external inputs needed. Recently, sugarcane aphid infestations have limited production of sorghum × sudangrass (Sorghum bicolor var. bicolor*bicolor var. sudanese; S). This study investigated mono-, bi-, and tri- cultures of S, cowpea (Vigna unguiculata; C), and crabgrass (Digitaria ciliaris; R). Forage yield, CP, NDF, ADF, ADL, and sugarcane aphid counts were determined for each treatment. Sugarcane aphid counts were conducted on a weekly basis during the study and forage samples were harvested twice during each season. A forage subsample was taken for determination of CP, NDF, ADF, and ADL using wet chemistry. Data were analyzed using Proc Glimmix of SAS 9.4 (SAS inst., Cary, NC). During Year 1, the only difference in yield among treatments was observed in R, which was lower than other plots (949 and 1,259 kg/ha, respectively; P < 0.05). Neutral detergent fiber was greatest (P < 0.0001) in treatments containing S, whereas C and C+R had the least NDF (64.6%, 55.1%, and 56.6%, respectively; P < 0.02). Sugarcane aphids were greater (P < 0.0001) in S+C compared to S+R and SI on July 12 (33.5, 21.1, and 22.4 aphid days/ two leaf sample, respectively). During Year 2, there were no differences in yield among plots (996 kg/ ha, P > 0.9); NDF was greatest in S and lowest in plots containing C and C+R (63%, 46%, and 45.6%, P < 0.0001). While there appeared to be no reduction in sugarcane aphid pressure in the mono- and mixed- cultures of S, C+R showed promise as a summer annual mixture with similar yield and higher quality to that of S and S mixtures.