Ensiling Characteristics of Tropical Grasses as Influenced by Stage of Growth, Additives and Chopping Length

Abstract

Three trials were conducted in Sri Lanka to study the effects of growth stage, chopping length and additives on ensiling characteristics of Guinea-‘A’ (Panicum maximum, Jacq-Ecotype ‘A’) and NB-21 (Pennisetum purpureum, Schumac × Pennisetum americanum, L.). In the first trial, the grasses were harvested 1, 2 and 3 wk after clipping, chopped and ensiled in small laboratory silos (3-liter cardboard cylinders, double-lined with polyethylene bags) alone or with addition of either cassava (Manihot esculenta, Crantz), tuber meal (5%, wet basis), coconut (Cocos nucifera, L.) oil meal (5%, wet basis) or formic acid (3%, dry basis). Guinea-‘A’ grass contained an average of 2.3% N and 70.6% neutral detergent fiber (NDF); NB-21 contained 3.8% N and 65.9% NDF. Acetic acid concentration of silage was lowest when grasses were harvested after 1 wk of growth. Addition of cassava tuber meal or coconut oil meal decreased pH (P<.05) and increased lactic acid concentration (P<.05) of the silages. Generally, the effects were greater for cassava tuber meal. Addition of formic acid had no substantial effect on ensiling characteristics, compared with the control. In a second trial, Guinea-‘A’ grass was harvested 3 wk after clipping, chopped in three lengths (1.5, 7.5 and 15 cm), and ensiled in small silos. Lactic and acetic acid concentrations of silages increased (P<.01), whereas dry matter loss and pH decreased (P<.05) with fineness of chop. In a third trial, 2- and 3-wk growth of Guinea-‘A’ were harvested and ensiled in 210-liter metal drums, double-lined with polyethylene, chopped (1.5 cm) or unchopped. Cutting grass at 2 wk decreased (P<.01) pH and increased (P<.01) lactic acid concentration, compared with cutting at 3 wk. Dry matter loss was lower (P<.01) for chopped silage. Chopping decreased (P<.05) pH and increased (P<.05) lactic acid concentration of silage.

Tropics, Forage, Silage, Panicum maximum, Pennisetum purpureum × Pennisetum americanum, Silage Additives

© American Society of Animal Science 1986