Effect Of Copper In Pig Feces On Content Of Copper And Protein In Leaves Of Maize

Copper is currently used as a growth promoter for pigs throughout the world.However, digestibility of dietary copper supplements with high levels is low to pigs,Lots of Cu excreted in pigs feces.In China and throughout the world,pig manure is disposed of an organic fertilizer to soils.Extensive evaluations are needed on transformation and translocation of copper in manure of pigs receiving high dietary copper doses to ensure environmental quality and health of the ecosystem.Results of such studies provide theoretical and technical guide for adequate management of copper supplementation for the pork industry and for development of regulatory standards by government agencies to protect public health.This dissertation systematically evaluate the environmental and ecological implications of pig manure with elevated copper levels.A pot experiment was used.maize(Zea mays L.) was grown in pots filled with 2.7-kg soil.Pig feces in the treatment groups were from those pigs fed with basal dietary supplement 250mg/kg Cu from CuSO₄,Cu-AA and TBCC,and three different amounts—100g,200g,300g were added into each treatment.Pig feces of controlling group were from those only fed with basal dietary,with 300g used in each pot.It was conducted to study the effects of different sources and levels of copper in pig feces on growing and Cu accumulation, Protein content in leaves.The results are as follows:â‘ At 40 days after planting(DAT),Cu concentrations in maize tissue were directly correlated to the amounts of Cu applied into the soil(p＜0.05).With a single application of 300 g manure/pot, soil Cu was found to be 111-113 mg Cu/kg,which exceeded the national soil quality standard of 100 mg/kg for Cu.Experimental manure applications at 100 and 200 g/pot increased soil Cu contents,but did not raise soil Cu levels beyond the national soil quality standard of 100 mg/kg.â‘¡Copper accumulation coefficient of root biomass was greater than that of aboveground biomass for each Cu application rate examined.Copper concentrations in the roots were linearly related to soil Cu,which may be described by this linear equation:Y=0.42X+22.98(r²=0.9032).â‘¢At 40 DAT,total fresh maize biomass decreased as Cu application rates increased(p＜0.05). Results seemed to suggest that plant roots and abovcground biomass exhibited different Cu toxicity tolerance threshold levels.Significant aboveground biomass reduction occurred at the 200 mg/pot manure application rate;whereas root biomass reduction was observed at 100 mg/pot manure application rate.Results appeared to suggest that the roots were more sensitive to Cu toxicity;root inhibition preceded aboveground biomass reduction. â‘£From 10 DAT-20 DAT,leaf soluble protein and total free amino acids increased significantly as Cu application rates increased(p＜0.05).Between 20 DAT and 40 DAT,however,leaf soluble protein and total free amino acids gradually decreased as Cu concentrations increased(p＜0.05), which may have resulted in a decrease in stress resistance of maize.Free leaf proline during the entire 40-day study period increased significantly as Cu application rates increased(p＜0.05).Free leaf proline increased the most with 300 g/pot manure application.Under the condition of experiment,the copper content of the discharging amount in the pig feces increased as the copper level become higher.The copper content in the soil became higher with the increasing of the concentration of the copper in pig feces.From 10 DAT-20 DAT,the copper in the pig feces promote compound of the protein of the leaves.30-40 days later,due to the increase of the concentration of the copper in pig feces,the copper became richer in maize crop,which prevented the combination of the protein.In order to be sure the copper content in pig tissues is under the limited sanitation standard of our country(10mg/kg),the copper content in soil should be below(Cu＜100 mg/kg).It is the most appropriate way for us to use the low does of copper in the additive so as to maintain the good circulation of our ecological environment.There was no significant difference on soil copper content and growing of maize with different copper sources.3 copper sources could be used.