Effects Of Dietary Copper Sources And Levels On Copper Transport In Growing Pigs

Copper is one of the necessary trace elements with manifold biological functions in animals. It is the component of metalloenzyme, and acts as electron acceptor or donor in various vital physiological and biochemical reactions. Therefore, maintaining the stability of internal environment copper has significant effects on the metabolic balance of copper in vivo. The intake, absorption, transportation and excretion of copper is a very complicated process, and is affected by dietary copper source and the level. This experiment was designed to study the effects of dietary copper source and level on the liver injury and copper transportation in growing pig, which elucidates the relationship between dietary copper resource and level and liver copper transportation, and further consummate the theory that high level copper can promote growth.This experiment adopted 2 * 2 factorial design, sixty 45 d ternary hybrid healthy piglets(with similar genetic background and parity, initial body weight of14.00±0.30 kg, male female half) were used, and the animals were randomly diveded into four group(fifteen in each group) to study the effects of dietary copper resource(copper sulphate, amino acid copper) and level(150,300 mg/kg) on liver copper transportation in growing piglet.Experiment I The effects of dietary copper resource and level on liver injury1. The level of copper in serum, liver, kidney and faece were significantly increased with the increase of dietary copper level(p<0.01), and there was no difference between the groups supplied with copper(p>0.05); the level of copper in muscle has significant difference between copper sulfate and amino acid copper with different supply level(p<0.05).2. The level of copper in liver organelles was significantly increased with the increase of dietary copper level(p<0.01). The level of copper in mitochondria was significantly different due to the dietary copper level(p<0.01),while there was no difference between the groups supplied with copper(p>0.05); and the change of copper level in lysosomes and cytoplasm was similar to the change in mitochondria. The activity of Acid Phosphatase(ACP), beta glucose glycosidic(β-glucosidase) enzyme and Cathepsin D(CTSD) in cytoplasm was significantly increased with the increased copper level(p<0.01).while there was no difference in lysosomal CTSD. The change of microenvironment would lead to the change of pH, and the permeability increased, allowing ACP and CTSD into the cytoplasm, ATP was needed for this process to increase the activity of ACP and CTSD. There was no significant difference to the activity of ACP, CTSD and β-glucosidase found in groups supplied with copper.ExperimentⅡThe effects of dietary copper resource and level on mRNA expression of copper transporter gene in liver of growing pigReal Time PCR(RT-PCR) was used to detect the effects of different dietary copper resource(copper sulfate and copper amino acids) and level(150 mg/kg and 300 mg/kg) on mRNA expression of copper transporter gene(CTR1, ATP7 A and ATP7B) in liver of growing pig. mRNA of CTR1, ATP7 A and ATP7 B were significantly expressed in each treatment group, and the expression of TR1 and ATP7 B mRNA were the highest when copper was supplied with 150mg/kg, however, and the expression of ATP7 A had no significant difference in groups supplied with copper sulfate and amino acids copper(p>0.05).The expression of CTR1 and ATP7 B mRNA were significantly decreased when supplied with 300 mg/kg dietary copper(p<0.01). The expression of ATP7 A in groups supplied with 300 mg/kg copper sulfate and amino acids copper had no significant difference(p > 0.05).In conclusion, with the increasing of the level of dietary copper, the level of copper in liver, serum, liver organelles and the activity of β-glucosidase in lysosome and cytoplasm were significantly increased. The activity of ACP and CTSD did not increase significantly, while the activity of ACP, CTSD and β-glucosidase did. There was no significant difference in groups supplied with copper. The high dietary copper leads to the significant increase of liver copper and the lysosome copper. The change of microenvironment and pH in lysosome may cause the decreased lysosome membrane stability and the increased membrane permeability, which results in the released ACP and CTSD into cytoplasm, and the activity of ACP and CTSD is increased significantly, causing the injury of liver. The destruction of normal function in liver promotes the excretion of copper leading to the increase of copper in kidney and manure.The mRNA expression of Ctr1 and ATP7 B was the highest in groups supplied with 150mg/kg copper, and was restrained in another group added by 300mg/kg copper. There was no significant difference on the mRNA expression of Ctr1 and ATP7 B in groups supplied with copper.when the copper was supplied with 150mg/kg, and the mRNA expression of Ctr1 and ATP7 B was restrained when the copper was supplied with 300mg/kg, and there was no significant difference on the mRNA expression of Ctr1 and ATP7 B in groups supplied with copper.