Animal Preference, Nutritive Attributes, and Yield of Pennisetum flaccidum and P. orientale1

Abstract

AbstractWarm‐season perennial grasses can make an important contribution to animal enterprises by providing forage for summer grazing. In the transitional belt, however, where cool and warm‐season grasses are used during the grazing season; both are hampered by periods of belownormal growth and frequently only the warm‐season species are available during midsummer. Six Pennisetum accessions initiated growth earlier in the spring in North Carolina than traditional warm‐season grasses, and continued growing through summer and into the fall until killed by frost. The objectives of this study were to evaluate these accessions for acceptance by free‐grazing animals, nutritive attributes, dry matter yield, and persistence. Plantings were made on a loam soil (Typic Hapludult, in the Clayey, Kaolinitic, Thermic family). Five accessions of Pennisetum orientale Rich (from India) and one selection of Pennisetum flaccidum Griseb. (from Afghanistan) were evaluated in one experiment (2 year study) for animal preference and associated nutritive value. Animals grazed all selections (each time forage reached 46 to 61 cm) but consistently preferred (P ≤ 0.01) P. flaccidum. In vitro dry matter disappearance (IVDMD) differed significantly among selections, but rank was not consistent from year to year. IVDMD ranged between 63.1 and 70.4%. Ranges for neutral detergent fiber (NDF) were: 55.0 to 57.9%; for acid detergent fiber (ADF), 28.5 to 34.1%; for lignin, 2.66 to 4.48%, and for N 2.95 to 3.78%. In a separate trial, dry matter yields (3‐year avg.) of the five P. orientale selections under a “short cut” regime (46 to 74 cm high cut to a 15‐cm stubble) were 7,948 kg/ha and for “tall cut” regime (76 to 102 cm tall cut to a 15‐cm stub ble) 12,393 kg/ha. P. flaccidum averaged 8,958 and 12,003 kg/ha for short cut and tall cut, respectively. Yields exceeded 15,700 kg/ha for several of the P. orientale selections managed under the tall cut regime. P. flaccidum produced more of its seasonal yield earlier (91% by 25 July) than did the P. orientale selections (only 77% by 25 July). The nutritive attributes of these forages were appreciably reduced by maturity. Mean values for the five P. orientale selections for the short and tall cut regimes and for P. flaccidum for each harvest regime respectively, were as follows: IVDMD 48.4, 44.0 and 54.7, 54.5%; NDF 61.4, 65.4 and 60.5, 61.1%; ADF 32.8, 35.8 and 33.9, 32.9%; lignin 3.07, 3.84 and 3.67, 3.30%; and N 2.39, 1.77 and 2.44, 2.13%. The Pennisetum accessions evaluated have potential as forage species in the southeastern U.S. In addition to their long growing season and high yield potential, their NDF concentrations were low compared with Coastal bermudagrass (Cynodon dactylon L.). This was especially noticeable in the more mature harvests. Such low fiber concentrations may contribute to an increased dry matter intake by grazing animals.