Effects of Annual and Perennial Forage Systems on Forage Biomass and Quality, Grazing Animal Performance, and Enteric Methane Emissions

Abstract The effects of perennial and annual forage systems on forage biomass and quality, grazing animal performance, and enteric methane emissions were evaluated over two summer grazing seasons in 2020 and 2021. Forage systems (treatments) included (1) AC Success hybrid bromegrass (Bromus riparius Rehm. × Bromus inermis Leyss.) + PS30006 alfalfa (Medicago sativa L.) (HBG-ALF), (2) AC Armada meadow bromegrass (Bromus riparius Rehm.) + AAC Mountainview sainfoin (Onobrychis viciifolia Scop.) (MBG-SF), (3) AC Hazlet fall rye (Secale cereale L.) + Frosty berseem clover (Trifolium alexandrinum L.) (FR-CLOV) and (4) Winfred forage brassica (Brassica oleracea L.× Brassica rapa L.) + Gorilla forage brassica (Brassica napus L.) + 4010 pea (Pisum sativum L.) + CDC Austenson barley (Hordeum vulgare L.) (BAR-PEA-BRASS). Yearling beef steers (n=156, body weight = 364 ± 14 kg) were randomly allocated to 1 of 4 replicated (n=3) forage systems for an average of 54 d grazing period each year. Dry matter yield (DMY) was greatest (P=0.006) for HBG-ALF (3036 kg/ha) and lowest for FR-CLOV (993 kg/ha) (P=0.005). Dry matter yield of BAR-PEA-BRASS (2123 kg/ha) and MBG-SF (1950 kg/ha) was similar (P=0.57). Total digestible nutrients (TDN) of BAR-PEA-BRASS (63.0%) and FR-CLOV (62.0%) was greater (P=0.001) than HBG-ALF (53.8%) and MBG-SF (54.7%). Crude protein (CP) was greatest (P=0.001) in FR-CLOV (13%). Crude protein of BAR-PEA-BRASS (9.6%) was greater (P=0.003) than HBG-ALF (6.6%) and MBG-SF (5.3%). Steer performance was greatest (P=0.03) on HBG-ALF (124 kg/ha). Steer performance on FR-CLOV (82 kg/ha), MBG-SF (76 kg/ha) and BAR-PEA-BRASS (74 kg/ha) was similar (P=0.92). Enteric methane emissions from beef steers did not differ between forage treatments (P=0.08). In summary, HBG-ALF forage system provided greater DMY, and grazing animal performance compared to the other forage systems, however TDN and CP content was lower than other forage systems and enteric methane emissions did not differ among treatments.