The illuminance and spectral power distribution in 19 duckling and 16 turkey poult houses in the UK were sampled. Illuminance was highly variable within duckling houses and to a lesser extent in housing for turkey poults. In a free choice experiment, the preferences of commercial ducklings and turkey poults for four incandescent illuminances (<I, 6, 20 and 200 Ix; Osram, 60 W, Pearl) were tested at 2 and 6 weeks of age. Four replicate flocks of 12 birds were given continuous access to four compartments illuminated with each illuminance for six days. The illuminances were changed daily between the compartments. After two days of conditioning, the birds’ location and behaviour was recorded at 10 min intervals over 22 h. Nine and 12 defined behavioural categories were recorded for the ducklings and poults respectively. Ducklings spent significantly more time occupying the three brightest light environments both at 2 and 6 weeks of age, and the least time in the dimmest. Illuminance had a significant effect on the partition of behaviours amongst the light environments. At 2 weeks of age, locomotion and environmentally directed pecking occurred most often in 6, 20 and 200 lx, whereas at 6 weeks, preening and feeding also occurred more often in these light environments. At 6 weeks of age, resting, standing and drinking occurred significantly more often in 6 lx than in the dimmest environment. Turkeys spent most time in the brightest environment at 2 weeks of age, but in 20 and 200 Ix at 6 weeks. This change in overall preference was reflected in the partition of different behaviours between the light environments. At 2 weeks of age, all behaviours were observed to occur most often in 200 lx. At 6 weeks, resting and perching were observed least often in <I lx, whereas all other activities were observed more in the two brightest light environments. These results show that ducklings and turkey poults have significant but differing preferences for illuminance, and imply that some spatial or temporal variation in the ambient illuminance of housing would be consistent with their preferences.

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 adulteration can occur, reducing the quality of the bran. This can now be detected by a simple colormetric method. Rancidity is a major problem due to the high oil content of the bran. Rapid hydrolysis of the oil is followed by oxidation with the changes being accelerated in warm, humid conditions. The effects on nutritive value and acceptability are unclear. An analysis of Australian produced rice bran (on a dry matter basis) gives a mean crude protein concentration of 150 g/kg, ether extract of 220 g/kg and neutral detergent fibre of 220 g/kg. The amino acid profile is generally superior to that of cereal grains. Digestibility of the oil is much less in young chickens than in adult birds resulting in a 28–35% lower metabolizable energy (ME) depending on cultivar. Equations for predicting the ME of rice bran for birds at different ages, and chemical components from rice hull content of rice bran are given. Digestibility of amino acids in rice bran is also lower for young chickens than adult birds. Inclusion of rice bran in chicken diets in excess of 20% frequently depresses growth, but higher levels can be tolerated by ducklings. Results with ducklings suggest that the composition of the basal diet to some extent influences the response of birds when rice bran is included in the diet. The inclusion of animal protein elicits an improved performance compared with that of an all-vegetable 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 inclusion 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 problems, increased mortality and reduced egg output. Shell grit alleviated the problem. So far, attempts to improve the nutritive value of rice bran through addition of feed enzymes have had limited success. Feed 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 economical, although extrusion cooking will stabilize the oil before extraction and is used to stabilize rice bran for human food. Feed enzymes may be effective when a suitable combination is found.