Effects of nitrogen fertilization and harvest date on yield, digestibility, fiber, and protein fractions of tropical grasses

摘要: To evaluate the response of three tropical forage species to varying rates nitrogen (N) fertilization [0, 39, 78, 118, 157 kg N/(ha x cutting)] and five summer harvests, DM mass nutritive value were evaluated in a randomized complete block design with split-split plot arrangement treatments. Plots (n = 60) established 1996, harvests conducted every 28 d from June through September 1997 1998, fertilizer applications occuring after each harvest. Fertilization 78 cutting) increased these grasses by 129% (P < 0.01) compared no N fertilization. Additional did not result further increases mass. Bermudagrass (Cynodon dactylon) produced more [P 0.01; 1,536 +/- 43 kg/(ha than stargrass [Cynodon nlemfuensis; 1,403 or bahiagrass [Paspalum notatum; 1,297 cutting)]. Peak for all occurred late July. In vitro organic matter digestibility (IVOMD) linearly A quadratic was noted IVOMD bermudagrass, whereas affected. digestible (57.5 0.4) (54.6 (51.9 0.4%). As level increased, NDF decreased forages. Total concentration as highest (2.4%, basis) bermudagrass (2.2%) (2.0%). depressed forages July 0.01). 0.05) (% DM) protein fractions. August, nonprotein reduced 11.8% 0.01), ADIN Bahiagrass had less cell contents but greater associated wall. Managerial factors, including harvest dates, can have profound effects on nutritional forage. An understanding is imperative improve supplementation programs ruminants.