UTILIZATION OF RICE BRAN IN DIETS FOR DOMESTIC-FOWL AND DUCKLINGS

Rice bran constitutes about 10% of brown rice and is used as an animal feed. There are 40-45 million tonnes of rice bran produced annually, mainly in the Far East and South-east Asia. In these areas hull adulte ration can occur, reducting the quality of the bran. This can now be d etected by a simple colormetric method. Rancidity is a major problem d ue to the high oil content of the bran. Rapid hydrolysis of the oil is followed by oxidation with the changes being accelerated in warm, hum id conditions. The effects on nutritive value and acceptability are un clear. An analysis of Australian produced rice bran (on a dry matter b asis) gives a mean crude protein concentration of 150 g/kg, ether extr act of 220 g/kg and neutral detergent fibre of 220 g/kg. The amino aci d profile is generally superior to that of cereal grains. Digestibilit y of the oil is much less in young chickens than in adult birds result ing in a 28-35% lower metabolizable energy (ME) depending on cultivar. Equations for predicting the ME of rice bran for birds at different a ges, and chemical components from rice hull content of rice bran are g iven. Digestibility of amino acids in rice bran is also lower for youn g chickens than adult birds. Inclusion of rice bran in chicken diets i n excess of 20% frequently depresses growth, but higher levels can be tolerated by ducklings. Results with ducklings suggest that the compos ition of the basal diet to some extent influences the response of bird s when rice bran is included in the diet. The inclusion of animal prot ein elicits an improved performance compared with that of an all-veget able based diet. Defatted rice bran (DFRB) gives the same performance as full fat bran when equalized for ME. Laying birds can tolerate high levels of rice bran. Although some reports indicate successful inclus ion of well above 600 g/kg, a practical upper limit of 450 g/kg seems to be accepted. Defatted rice bran at 250 g/kg diet resulted in leg pr oblems, increased mortality and reduced egg output. Shell grit allevia ted the problem. So far, attempts to improve the nutritive value of ri ce bran through addition of feed enzymes have had limited success. Fee d phytase has been successful in releasing phosphorus from phytate in rice bran which is present at up to 50 g/kg dry matter. Improving the nutritional value of rice bran by heat treatment is probably not econo mical, although extrusion cooking will stabilize the oil before extrac tion and is used to stabilize rice bran for human food. Feed enzymes m ay be effective when a suitable combination is found.