Effect of ensiling on the nutritive value of low quality roughage rice hulls. II. Chemical studies

Abstract

The sequence of the effects of delayed and immediate sealed silos as well as the role of nutrient additives such as molasses and/or urea in the ensiling process of rice hulls and the subsequent nutritive value of the product has been shown. There were considerable variations in the chemical constituents during the ensiling of rice hulls among the different treatments under both delayed and immediate sealed silos. In at1 cases, when compared with the controls, the crude protein, soluble sugars, lactic acid, and fat contents were markedly increased, while the carbohydrate polymers and silica contents were significantly decreased.I t was concluded that the treatment of rice hulls + 2% molasses for two months ensiling period under anaerobic conditions can be considered as the optimum conditions for the production of good quality silage from the low grade roughages rice hulls. Changes in pH values also confirmed the improving effect of the combination of molasses addition and the immediate sealing of the silos.Acta Biotechnologica 12 (1992) 2 after filling. Four treatments were applied: (a) rice hulls alone (control), (b) rice hulls + 2% molasses, (c) rice hulls + 0.5% urea, and (d) rice hulls + 2% molasses + 0.5% urea, MaterialRice hulls were used as silage material, and ensiled after being thoroughly mixed with additives.Silos 350-ml glass tightly-cap bottles (6 x I2 cm, 0.2 mm thickness) were used as laboratory silos, Ensiling Procedure and SamplingThe quantity of rice hulls ensiled per silo was 50 g. The amount of water required to raise the rice hulls moisture to 60% W.H.C. was calculated. For the treatments requiring molasses or urea or both molasses and urea, the calculated amounts of the additives to give the required percentages were diluted with the previous calculated amounts of tap water, before being added to the rice hulls. Thoroughly mixed with the rice hulls using a wooden rod, the prepared material was tightly packed to the bottle brim as evenly as possible, and either sealing was delayed for a period of three days (Experiment 1) or sealed immediately after filling (Experiment 2). 22 silos for each treatment were prepared and examinations, made in duplicate, were carried out by taking two bottles at random at the beginning and after 3, 7, 14,21,30, 60,90, 120, 160 and 180 days, respectively, after ensiling. The bottles were kept in a closed cupboard at room temperature for 180 days. The average room temperatures ("C) were 16, 17, 18, 19, 22, Specimens were prepared for the SEM by a modified method of AKIN and AMOS 1161. The samples were observed by SEM from JEOL model JSM T-20, at accelerating voltage 20KV, magnification 35 -10.000 x . PHThe pH values were determined by using EIL pH meter model 7020 in 1 : 2.5 silage: water (C0,-free) suspension after standing for two hours (RICHARDS, [ 171).