Effects of dehulled, crushed and untreated whole-grain paddy rice on growth performance in broiler chickens

Experiments were conducted to determine the effects of different types of paddy rice (dehulled, crushed and untreated whole-grain forms) on growth performance in broiler chickens. In Experiment 1, a control diet containing 41.6% corn (control), and three experimental diets containing 40.7% dehulled, 43% crushed or 43% whole-grain paddy rice, were formulated to be iso-caloric (3,100 kcal/kg ME) and iso-nitrogenous (20% crude protein), but to contain different levels of fat (6%, 5.6%, 10.7%, 10.7%, respectively). Groups of 0-day-old chickens were the fed experimental diets ad libitum for 28 d. The average final body weight of groups fed the crushed and untreated whole-grain paddy rice was significantly lower (P<0.05) than that of the control group, but that of dehulled rice-fed group was slightly higher than the control group. This finding implies that the growth retardation seen with crushed or untreated whole rice could be caused by the feed intake-reduction due to the fat addition to the experimental diets. In Experiment 2, the control diet containing corn and the experimental diets containing dehulled and untreated whole-grain paddy rice were formulated to contain similar levels of fat (5.6-6%) and to be iso-nitrogenous (20%), but not to be iso-caloric. As a result, the average body weight gain of the whole-grain rice-fed chickens showed a considerable increase compared with the control diet-fed chickens even though the energy content of the former diet was only about 90% that of the control diet. It is concluded that whole-grain paddy rice could serve as a valuable constituent of broiler chicken feed, but that excess fat in the diet to maintain the ME content (3,100 kcal/g) could have a negative effect on growth performance.