肉鸡日粮中1α-羟基维生素D_3与1,25-二羟基维生素D_3的生物学效价比较

Comparison of bioavailability of 1α-hydroxycholecalciferol and 1α, 25-dihydroxycholecalciferol in broiler chickens

试验旨在研究以骨骼矿化指标评估142日龄肉鸡日粮中1α-羟基维生素D3（1α-OH-D3）和1,25-二羟基维生素D3[1,25-（OH）2-D3]的相对生物学效价。将300只1日龄罗斯308肉鸡母雏随机分为6个处理,每个处理5个重复,每个重复10只。设计6种饲粮,在基础饲粮（钙Ca 0.50%,非植酸磷NPP 0.25%,无维生素D3）中分别添加3个水平1α-OH-D3（1.25、2.5、5.0μg/kg）和3个水平1,25-（OH）2-D3（1.25、2.5、5.0μg/kg）。结果表明:以42日龄肉鸡胫骨强度、重量、长度、直径和灰分重量为评价指标,1α-OH-D3生物学效价分别是1,25-（OH）2-D3的0.78、0.77、0.93、0.91倍和0.78倍;以42日龄肉鸡股骨强度、重量、长度、直径和灰分重量为评价指标,1α-OH-D3生物学效价分别是1,25-（OH）2-D3的0.76、0.84、0.95、0.88倍和0.80倍;以42日龄肉鸡跖骨重量、长度和灰分重量为评价指标,1α-OH-D3生物学效价分别是1,25-（OH）2-D3的0.82、0.96倍和0.83倍。结果提示:以42日龄肉鸡骨骼矿化指标评价,1α-OH-D3的生物学效价约为1,25-（OH）2-D3的0.85倍。

The present study was to compare the relative bioavailability(RBV) of 1α-hydroxycholecal-ciferol(1α-OH-D_3) to 1α,25-dihydroxycholecalciferol [1,25-(OH)_2-D_3] in 1- to 42-day-old broilerchicks. On the day of hatch, 300 Ross 308 broilers were allotted to 6 treatments with 5 replicateseach. The basal diet contained 0.50% calcium(Ca), 0.25% non-phytate phosphorus(NPP), and wasnot supplemented with vitamin D_3. 1α-OH-D_3 was fed at 1.25, 2.5, and 5.0 μg/kg and 1,25-(OH)_2-D_3 was fed at 1.25, 2.5, and 5.0 μg/kg. The relative bioavailability(RBV) of 1α-OH-D_3 to 1,25-(OH)_2-D_3 was determined by the slope ratio method. Using tibia breaking-strength(BS), weight(W), length(L), diameter(D), and ash weight(AW) as the criteria, the RBV of 1α-OH-D_3 to 1,25-(OH)_2-D_3 were0.78, 0.77, 0.93, 0.91, and 0.78, respectively. Using femur breaking-strength, weight, length, diameter,and ash weight as the criteria, the RBV of 1α-OH-D_3 to 1,25-(OH)_2-D_3 were 0.76, 0.84, 0.95, 0.88 and 0.80. Using metatarsus weight, length, and ash weight as the criteria, the RBV of 1α-OH-D_3 to1,25-(OH)_2-D_3 were 0.82, 0.96 and 0.83. Thosedata indicate that the relative bioavailability of1α-OH-D_3 to 1,25-(OH)_2-D_3 is 0.85 in promot-ing bone mineralization of broiler chickens from1 to 42 d of age.