Effect of Harvesting Dates on Biomass Yield and Nutritive Value of Improved Desho Grass (Pennisetum glucifolium) Varieties in Central Highlands of Ethiopia

The study was conducted to evaluate the agronomic performance of desho grass varieties and to evaluate the effect of harvesting date on growth performance, biomass yield, nutritive value and chemical composition of desho grass varieties. A factorial arrangement was employed using a randomized complete block design with 3 harvesting date (90, 120 and 150) and 3 desho grass varieties (Areka-DZF590, Kindo Koysha-DZF591 and Kulumsa-DZF592). The morphological and yield data collected were plant height (PH), leaf length (LL), leaf width (LW), number of tillers per plant (NTPP), number of leaves per tillers (NLPT), number of leaves per plant (NLPP) and dry matter (DM) yield t/ha. Chemical composition such as dry matter (DM), ash, crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF) and acid detergent lignin (ADL) were analyzed. Moreover, metabolizable energy (ME) and in-vitro organic matter digestibility (IVODM) were quantified. Results showed that all morphological parameters except LW were significantly (P<0.05) affected by the main effect of harvesting date. The highest value of PH (38.79 cm), LL (33.24 cm), NTPP (172.59), NLPT (6.22), NLPP (1088.50) and DMY (10.37 t/ha) were obtained from 150 days of harvesting date. Which increased with increasing harvesting date. The only morphological parameter significantly (P<0.05) affected by the interaction of variety and harvesting date, was PH. The highest value of plant height (40 cm) was measured from Areka-DZF590 variety at later stage of harvesting. All quality parameter of the experimental varieties were significantly (P<0.05) affected by harvesting date. The highest value of DM (91.53%), NDF (68.73%), ADF (34.37%), and ADL (3.69%) were recorded from 150 days of harvesting. Which increased with increasing age. On the other hand, the highest value of Ash (14.11%), CP (12.23%), ME (8.54 MJ/Kg) and IVOMD (60.80%) were obtained from 90 days of harvesting date, which declined with age. The result revealed that only CP significantly (P<0.05) affected by the main effect of variety. The highest value of CP (12.34%) were recorded from Areka-DZF590 variety. Based on the current findings, Areka DZF590 variety with 120 harvesting date could be recommended for the study area and similar agroecology to get a better yield and quality forages.