Effects of Substituting 25-Hydroxy vitamin D3 for Vitamin D3 on Performance,Egg Quality and Calcium and Phosphorus Metabolism of Laying Hens in Late Laying Period
This experiment was conducted to investigate the effects of dietary 25-hydroxyvitamin D3(25-OHD3)as a substitute for vitamin D3(VD3)on performance,egg quality,calcium and phosphorus me-tabolism,intestinal morphology and tibia quality of laying hens in late laying period.A total of 270 Hy-Line brown laying hens aged at 55 weeks with normal feeding and similar body weight(uniformity＞90％)were randomly divided into 3 groups with 6 replicates per group and 15 hens per replicate.The hens in the control group were fed a basal diet supplemented with 4 000 IU/kg VD3,the hens in experimental group 1 were fed a diet supplemented with 50 μg/kg 25-OHD3 and 2 000 IU/kg VD3,and the hens in experimental group 2 were fed a diet supplemented with 100 μg/kg 25-OHD3.The pre-trial period was 1 week and the experimental peri-od was 12 weeks.The results showed as follows:1)compared with the control group,the laying rate in exper-imental group 1 in weeks 5 to 8 was significantly increased(P＜0.05),and the laying rate in experimental groups 1 and 2 in weeks 9 to 12 was significantly increased(P＜0.05).2)Compared with the control group,the eggshell strength in experimental groups 1 and 2 at weeks 4 and 12 and in experimental group 1 at weeks 8 was significantly increased(P＜0.05);the albumen height in experimental group 1 at week 8 and in experi-mental group 2 at week 12 was significantly increased(P＜0.05);the Haugh unit in experimental groups 1 and 2 at each stage was significantly increased(P＜0.05).3)Compared with the control group,the contents of calcium and phosphorus in serum and calcium content in tibia in experimental groups 1 and 2 were significantly increased(P＜0.05).4)Compared with the control group,the activities of superoxide dismutase(SOD),glutathione peroxidase(GSH-Px)and catalase(CAT)as well as the superoxide anion scavenging ability and hydroxyl radical scavenging ability in serum in experimental groups 1 and 2 were significantly increased(P＜0.05),and the malondialdehyde(MDA)content in serum was significantly decreased(P＜0.05);the total antioxidant capacity(T-AOC)in serum in experimental group 1 was significantly increased(P＜0.05).Com-pared with the control group,the contents of carbonic anhydrase(CA)and parathyroid hormone(PTH)in se-rum in experimental group 1 were significantly increased(P＜0.05),and the diamine oxidase(DAO)content in serum was significantly decreased(P＜0.05);the bone Gla protein(BGP)content in serum in experimental groups 1 and 2 was significantly decreased(P＜0.05);the calcitonin(CT)content in serum in experimental group 2 was significantly decreased(P＜0.05).5)Compared with the control group,the villus height of jeju-num in experimental group 1 was significantly increased(P＜0.05),the crypt depth of jejunum in experimental group 2 was significantly decreased(P＜0.05),and the villus height to crypt depth ratio of jejunum in experi-mental groups 1 and 2 were significantly increased(P＜0.05).6)Compared with the control group,the tibia strength,trabecular number and trabecular area in experimental group 2 were significantly increased(P＜0.05),and the tibia ash content in experimental group 1 was significantly increased(P＜0.05).In conclusion,compared with dietary VD3 only,dietary 25-OHD3 can improve performance and egg quality,enhance antioxi-dant capacity,maintain intestinal morphology,promote the absorption and deposition of calcium and phosphor-us in serum and tibia,and improve tibia quality of laying hens in late laying period.[Chinese Journal of Ani-mal Nutrition,2024,36(5):2992-3002]
25-hydroxyvitamin D3laying hens in late laying periodperformanceegg qualitycalcium and phosphorus metabolismtibial quality
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