Evaluation of Black-liquor treated N fortified bagomolasses silages in vitro and in vivo

Abstract

Black-liquor (10·48 g NaOH per liter), an effluent from the paper industry, was used to improve the biodegradability of bagasse. Ten kilograms of molasses was added to 100 kg of fresh bagasse to obtain bagomolasses. Four silages were prepared: untreated bagomolasses (S-1); black-liquor treated (4 liters) bagomolasses, without nitrogen fortification (S-2); (S-2) fortified with urea at 1·5% DMB (S-3) or dried poultry excreta at 26% DMB (S-4). Black-liquor treatment (equivalent to 4 g NaOH per 100 g) decreased NDF, hemicellulose and cellulose contents and increased lignin. An increase of about 14 percentage units in IVDMD or IVOMD and a two-fold increase in effective in situ DM degradability due to black-liquor treatment with or without supplemental N was observed. Four isonitrogenous complete diets were blended using silages 1 to 4, maize and groundnut cake in a roughage to concentrate ratio of 40:60 on DMB. The digestibilities of the complete diets were evaluated in a metabolism trial using a 4 × 4 latin square design with Nellore rams. Black-liquor treatment of bagomolasses followed by urea or DPE fortification during ensiling increased the hemicellulose digestibility and N retention expressed as a percentage of intake or of absorbed. A 91-day trial with yearling Nellore ewes showed that black-liquor treatment of bagomolasses followed by urea or DPE fortification increased ADG. Black-liquor treatment alone did not show a beneficial effect as the level of silage was only 40% on DMB of the complete diet.