108 Forage Mass and Nutritive Value of Stockpiled Alfalfa-bermudagrass Systems

Abstract

Abstract The development of newer alfalfa cultivars with improved adaptation to local growing conditions and dual-purpose applications has increased alfalfa incorporation into grass systems in the southern United States. The complementary growth of both species helps to extend the forage production season length, decreasing producer reliance on supplementation. The objective was to determine forage mass (FM) and nutritive value, botanical composition, and structural responses of alfalfa-bermudagrass systems managed under five stockpiling strategies (6-, 8-, 10-, 12- and 14-weeks of accumulation) in Shorter, AL. A randomized complete block design with eight replications was used. Harvested forage samples were manually separated into individual components and placed into 60° C until constant weight, then weighed. Measurements of ground cover, and alfalfa density and persistence were taken prior to plot harvest. There was a treatment × year interaction (P= 0.009) and greater FM was observed for 10- and 12-wks of regrowth (4,279 and 4244 kg DM/ha, respectively) in Year 2. This response was associated with greater (P < 0.001) bermudagrass percentage in the mixture in Year 2 than 1 (averaged 57 vs 23%, respectively). Weeds remained below 4% in both years. There was a direct relationship between increased regrowth period length with leaf shattering and lodging. Over 10-wks of regrowth, percentage of lodging was >30% and rate of leaf shattering doubled. This response directly affected leaf area index observed for the alfalfa-bermudagrass mixtures at 14-wk with a reduction of 30% when compared to 6-wks regrowth (2.6 vs 3.9, respectively). Greater (P < 0.001) digestibility was associated with shorter regrowth period (6-wk), although the values observed ranged from 62 to 87% which represents high nutritive value forage that can meet higher animal requirements. Based on results, stockpiling alfalfa-bermudagrass mixtures using varying accumulation period lengths may be a viable system to provide high quality feed and extend the grazing season length into the fall and winter. This can also be an important strategy aiming to increase diversity and sustainability in forage-based livestock systems.