›› 2019, Vol. 46 ›› Issue (6): 1660-1667.doi: 10.16431/j.cnki.1671-7236.2019.06.012

• Animal Nutrition and Feed Science • Previous Articles     Next Articles

Effects of Excess Vitamin A on Metabolism of Calcium and Phosphorous of Broilers During Early Growth Period

GUO Xiaoyu, YAN Sumei, SHI Binlin, LI Yinhao, HAN Junying, ZHAO Yanli   

  1. College of Animal Science, Inner Mongolia Agricultural University, Hohhot 010018, China
  • Received:2018-11-02 Online:2019-06-20 Published:2019-06-19

Abstract:

The study was carried out to evaluate the effects of excess vitamin A (VA) on biochemical indexes of bone formation and the relative expression of alkaline phoshatase (ALP) and bone gla-protein (BGP) mRNA in small intestine,tibia and liver of broilers during early growth,and provide theoretical basis for further demonstrating the negative effects of excessive VA on calcium and phosphorus deposition in broiler chickens.The completely randomized design was used in this experiment.225 male and 225 female one-day-old AA broilers with similar body weight were divided into five treatment groups with six replicates of fifteen chicks each.The broilers were fed the basal diets supplemented with 3 000,6 000,15 000,30 000 or 60 000 IU/kg VA,respectively.The trial lasted for 28 d.At the age of 14,28 d,one bird from each replicate of each treatment was randomly selected and blood sample was obtained from the wing vein.The same birds used to obtain blood samples were killed,and liver,duodenum,jejunum,ileum and tibia samples were quickly removed and stored at -80℃.The regression analysis results showed that the contents of BGP,activities of ALP and BAP in serum,the relative expressions of ALP and BGP mRNA in the tibia,liver and small intestine of broilers during early growth significantly decreased (P<0.05) or tended to significantly decrease (P<0.10) linearly or quadratically with the increase of dietary VA.And the relative expressions of ALP mRNA in the tibia and liver and the relative expressions of BGP mRNA in the liver of broilers on the day 14 of experiment,ALP activity in serum and the relative expressions of ALP mRNA in the liver and the relative expressions of BGP mRNA in the tibia and ileum of broilers on the day 28 of experiment were the lowest when VA supplemental level was 42 766 to 47 185 IU/kg.These results implied that the dietary VA could reduce the serum BAP activity of broilers during early growth in linear and regulated the contents of BGP and ALP activity in serum,the relative expressions of the ALP and BGP mRNA in the tibia,liver and small intestine of broilers in a dose-dependent manner during early growth,and diets supplemented with 42 766 to 47 185 IU/kg VA had stronger inhibition effect on above indexes.These results implied that excess VA suppressed biochemical markers of bone formation and reduced the ALP and BGP mRNA in the tibia,liver and small intestine of broilers during early growth.

Key words: vitamin A; broiler; early growth period; bone; alkaline phosphatase(ALP); bone gla-protein(BGP)

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