Influences of Phosphorus Level in Diet of Parent Pigeons on Biochemical Index,Untargeted Metabolomics Profile of Serum,and Gene Expression of Phosphate Transporters in Squabs
[Objective]The aim of this study was to investigate the effects of different levels of inorganic phosphorus(P)on serum biochemical parameters,non-targeted metabolites,and expression of phosphate transporter genes in the small intestine and kidney of pigeon,so as to provide a theoretical basis for the regulation of phosphorus nutrition in pigeon during the period of rapid growth.[Method]A total of 192 pairs of parental Silver King pigeons(40 weeks of age)were randomly allocated to four treatment groups,each consisting of eight replicates of 6 pairs per replicate.The study lasted for 46 days including the phases of egg-hatching and squab-rearing.Dietary treatments included the basal diet(containing 0.3％of P),the basal diet supplemented with 0.2％,0.4％,or 0.8％inorganic P.The calcium(Ca)content in diets of parent birds were kept at 1.40％in every group.The levels of Ca,P,PTH and ALP activity in serum of 7,14 and 21 d old squabs were determined,and the content of Ca and P in crop milk were analyzed.The gene expression of Pi transporters(NaPi-Ⅱb,PiT-1,and PiT-2)in small intestine(duodenum and jejunum),and Pi transporters(NaPi-Ⅱa,PiT-1,and PiT-2)in kidney of squabs were determined.Serum metabolome profiles of 14 and 21 d old squabs in the groups of control,0.4％and 0.8％P-supplemented were analyzed.[Result](1)The P contents in crop milk sampled from squabs were very significantly(P＜0.01)increased by P supplementation in diets of parent pigeons.(2)No significant effect of P supplementation in diet of parent birds on serum P level,ALP activity and PTH level of squabs were observed in this study.However,the serum Ca content in birds of 0.8％P supplemental group decreased very significantly(P＜0.01).The serum ALP and PTH level of squabs significantly decreased with increased age(P＜0.05).(3)There was a tendency of increased gene expression of NaPi-Ⅱb in small intestine of squabs with dietary P levels of breeding birds,however,the difference was not significant(P＞0.05).The expression profile of PiT-1 and PiT-2 in kidney of squabs at the age of 7 and 14 d were very significantly higher(P＜0.01)than those in duodenum and jejunum.However,the difference of the mRNA expression level of PiT-1 and PiT-2 between kidney and intestine was not observed at the age of 21 d,and the PiT-1 value of kidney samples was even lower than that of jejunum.The mRNA expression levels of PiT-1 of 7 and 14 d old squabs were significantly increased by dietary P levels of breeding birds.The mRNA expression of PiT-2 in the group of dietary 0.4％P supplementation was significantly higher(P＜0.05)than that of 0.8％group when the squabs were 7 and 21 d old.The interaction of tissue and dietary P levels was significant(P＜0.05)on PiT-1 mRNA level of 7 and 14 d,and PiT-2 mRNA level of 21 d old birds.The mRNA expression level of NaPi-Ⅱa in kidney of 14 d squabs significantly decreased in the group of 0.8％P supplementation,compared with the control and 0.4％group.(4)At the age of 14 and 21 d,about half of the significantly different metabolites among the control and P-added groups were included in the category of lipids and lipid-like molecules,organic acids and derivatives was the second,and benzenoids next.The biological pathways involved in the metabolism of differentially expressed metabolites were mainly carbohydrate metabolism,metabolism of protein and amino acids,translation and lipid metabolism etc.[Conclusion](1)There was a significant effect of P supplementation in the diet of parent pigeons on P content in crop milk fed to squabs.The values of serum P of young birds were stable.However,the serum Ca of squabs in the group of highest dietary P treatment decreased,which might indicate that pigeons were intolerant to high dietary P level.(2)The expression levels of P transporters(PiT-1 and PiT-2)mRNA in the kidney mostly increased with dietary P supplementation.The regulation mechanisms of P reabsorption in pigeons need to be studied further.(3)The serum metabolome profiles of squabs indicated that P was involved in many important metabolic processes,such as lipid metabolism and bone mineralization etc.
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万方数据
维普
