Effect of cultivar, top cutting height and harvest interval on leaf silage quality and fresh tuber yield of cassava

Abstract

Cassava leaves are categorized as high-protein herbage, and it is interesting as feed for animal. This study aimed to determine the effect of cultivar, top cutting height, and harvest interval on forage yield, leaf silage quality, and fresh tuber yield components of cassava. The experiment was arranged by using a split-split plot in a randomized complete block design with 4 replications. Two cassava cultivars (CC) were in the main plot, including Kasetsart 50 and Rayong 72. The sub plot has two top cutting heights (TCH), including 30 and 50 cm above the ground. Four top harvest intervals (THI) were sub-sub plotted, including 3-, 4-, and 6-month harvest intervals, and only harvested at 12 months after planting (MAP) (a control treatment). A tuber yield was harvested at 12 MAP. This experiment was conducted in Kamphang Saen district, Nakhon Pathom province, during May 2015 and June 2016. The results showed that CC and TCH did not affect the yield and quality of leaf silage as well as tuber yield components. In contrast, THI affected canopy height, dry matter (DM) yields of stem, petiole, leaf blade, and fresh tuber yield, but not tuber number or starch content. Increasing THI from a 3-month interval to 12 MAP decreased leaf blade DM from 426.5 to 24.2 kg/rai/year, but increased tuber yield from 1,046.7 to 1,710.2 kg/rai. However, CC, TCH, and THI did not affect neutral detergent fiber and acid detergent fiber contents, whereas the acid detergent lignin, ash, and crude protein contents of leaf silage obviously decreased with increasing THI. As a result, this study suggests that a 6-month harvest interval resulted in higher yield and protein content of leaf silage than a single harvest at 12 MAP (a normal practice), but had no effect on tuber yield components or starch content.