Nutrition and skeletal problems in poultry

Several excellent reviews regarding nutrition and skeletal disorders have a ppeared in the last 20 yr. This review will cover several areas of vitamin D research, the area of feed deprivation, and bone abnormalities, because t here has been considerable interest in these areas during the past 10 yr. S tudies indicate that the quantitative requirement for cholecalciferol (D-3) for broiler chickens is much greater than previously thought. Ascorbic aci d may play a role in stimulating 1-hydroxylation of 25-hydroxycholecalcifer ol [25-(OH)D-3], but the evidence is not clear under exactly what condition s this relationship is important in practical prevention of tibial dyschond roplasia. Studies indicate that dietary supplementation with 1,25-dihydroxy cholecalciferol [1,25(OH)(2)D-3] Will reduce the incidence of tibial dyscho ndroplasia in three different strains of broilers bred to develop a high in cidence of the disease. But it did not prevent the disease totally in the s trains, unless high enough levels of 1,25-(OH)(2)D-3 were fed to reduce gro wth rate. These studies indicate that these high tibial dyschondroplasia st rains have a defect(s) in vitamin D metabolism. Studies continue to elucida te the role of ultraviolet light in preventing leg abnormalities. Only a fe w studies have been conducted on the efficacy of various vitamin D-3 deriva tives to prevent tibial dyschondroplasia. Feed deprivation continues to be an intriguing method of preventing tibial dyschondroplasia, and examination of exactly how this prevents the bone abnormality could open avenues for e xplaining the disease.