Ground Rice Hulls Research Articles

Evaluation of Fungal Cellulases in Rice Hull Base Diets for Ruminants

Ground rice hulls were treated with a preparation of fungal cellulolytic enzymes having a specific gravity of 1.4 kg/liter at 0, 125, 250, 375, 500, 625, 750, 875, 1000, 1125, and 1250mg enzyme preparation per kilogram. In vitro dry matter digestibility (30.6%) was highest when 375mg enzyme preparation were added to 1kg rice hulls. The preparation of fungal cellulolytic enzymes was added to a diet with 50% ground rice hull base at 0, 250, 375, 500, 750, 1000, and 2000mg of enzyme preparation per kilogram. Six Holstein steers, averaging 132kg body weight, were used per treatment in digestion trials with total fecal collection to determine the apparently digestible dry matter, energy, and protein of diets treated with the preparation of fungal cellulolytic enzymes. Diets treated with 250, 375, 1000, and 2000mg of enzyme preparation per kilogram had higher digestibilities of dry matter and energy than those diets treated with other amounts of the fungal cellulolytic enzyme preparation. Protein digestibility was greater when 250, 500, or 2000mg of the fungal cellulolytic enzyme preparation were added to the diet. Thus, the addition of a preparation of fungal cellulolytic enzymes added in small amounts (250mg of enzyme preparation per kilogram diet) enhanced digestibilities of dry matter, energy, and protein of a 50% rice hull base diet.

Studies on forage cell walls

SummaryResults of a 13-week group feeding study (Expt 1) and a 16-day digestion and mineral, nitrogen and water balance study (Expt 2) in which alkali-treated rice hulls were fed to young Border-Leicester × Merino sheep of 24-kg body weight are reported.Five pelletized diets comprising a 1:1 mixture of ground lucerne and alkali-treated ground rice hulls (Expt 1) or these five diets supplemented with biuret plus one diet of 100% lucerne pellet (Expt 2) were examined.Sodium hydroxide at levels of 0, 2·5, 5, 10 and 15% (w/w) was applied to rice hulls for 12 h and neutralized with acid. Sheep fed the 5% NaOH treatment level or greater maintained or increased body weight: those fed the 0 and 2·5% level lost body weight. Daily food organic matter intakes were: 5% alkali, 1025 g, 0% alkali, 765 g; 100% lucerne, 1195 g.Organic matter digestibility was highest (52%) for the diet containing rice hulls treated at the 15% alkali level and this digestion coefficient was significantly greater (P < 0·05) than for the control diet (nil alkali) (42%) but not significantly greater than for diets with 2·5, 5 and 10% levels of alkali.It'is indicated that cell wall organic matter of rice hulls treated with 15% alkali was digested to an extent of 62% whereas cell wall organic matter in the control diet (0% alkali) was digested to an extent of 13%.Cellulose digestion (52%) of the rice hull component of diets was not increased by alkali treatment suggesting the alkali to have freed hemicellulose components of the cell wall for digestive attack. Digestibility of lignin of the rice hull component of diets was not significantly increased by alkali treatment.Animals tolerated the salt contents of diets containing rice hulls treated at high levels of alkali, were able to clear the excess salt from their bodies without significant alteration of their blood haematocrit ratios, and drank significantly more water. All sheep fed diets containing rice hulls had appreciable amounts of soluble silica in their blood plasma (> 100/μg/l) and urine (> 25 μg/l).It is concluded that alkali beneficiation of rice hulls offers a means of enhancing their nutrient worth to ruminants and that the process requires further study.

Attempts to Control Body Weight Gains of Growing Broiler Breeder Females with High Fiber Diets

Free-choice feeding of high-fiber growing diets has been proposed by some as a means of limiting weight gains of broiler breeder pullets. Such a system would eliminate problems with weighing and distributing feed. A study was conducted in which a grower diet normally fed in limited quantity was diluted with ground rice hulls on an 80:20, 70:30, 60:40 and 50:50 basis and fed ad libitum to growing broiler breeder pullets from 6 to 22 weeks of age. None of these dilutions was sufficient to result in body weight limitation within the range suggested by the primary breeder.

Ground Rice-Hull Ash as a Filler for Rubber

Abstract A ground rice hull ash prepared by a new burning process has been found to be a moderately reinforcing filler for rubber. This filler, 85-90% amorphous silica and 10-15% carbon, is made by a controlled incineration process in which the bulk of the organic components of the rice hulls is removed, leaving the skeletal silica structure of the hull intact and in the amorphous state. The resultant ash is easily ground to produce fine particles, generally in the range of 0.1-2.0 μm. This filler does not adversely affect either the vulcanization characteristics or the aging of SBR, natural rubber, nitrile rubber, butyl rubber, neoprene, EPDM, and propylene oxide rubber compounds. As it is predominantly silica, it responds effectively to silane coupling agents in improving properties of the rubber compounds. It is concluded that RHA filler is a satisfactory substitute for MT black and that, in blends with blacks, it can be effectively used as a partial replacement for finer and more reinforcing blacks.