Study On Physiological Influences Of Pig-maize By Copper In Feedstuff And Its System Ecological Effects

Copper is currently used as a growth promoter for pigs throughout the world.Extensive studies have been conducted on the performance of growing pigs and residual copper content in tissue to dietary copper supplements.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 physiological effects of high levels dietary supplemental copper to pigs,and the environmental and ecological implications of pig manure with elevated copper levels.Feeding and digestive studies along with a pot experiment were conducted.The main results are as follows.1.Three sources of copper,CuSO₄(cupric sulfate),Cu-AA(Cu-Amino acid complex),and TBCC (tribasic cupric chloride),were chosen as dietary supplements to pig feed at three Cu levels,10, 150,and 250 mg Cu/kg.Growing pigs of LandracexYorkshirexDuroc hybrid variety,50%male and 50%female,were used for the feeding study.Effects of copper from three kinds of sources at 3 levels on performance,blood biochemical traits and tissue copper contents of the growing pigs were conducted.Results showed that there was no significant difference in average daily gain(ADG)or feed to ADG ratio for the three Cu sources at the three Cu levels tested(P>0.05). Residual Cu in both the liver and the kidney increased as daily dietary supplemental Cu levels increased(p<0.01).At 250 mg Cu/kg,Residual Cu was 22.1-24.7 mg/kg and 17.0-18.1 mg/kg in the liver and kidney,respectively.The greatest residual Cu was found in the liver,followed by the kidney,muscle,and the heart in decreasing order.BUN(Blood serum urea nitrogen)of pigs with 150 mg/kg and 250 mg/kg Cu decreased by 17.2%and 10.2%,respectively compared with that of pigs receiving the 10 mg/kg Cu supplementation(p<0.01).SOD(Serum superoxide dismutase)activity differed among daily dietary supplemental Cu levels.SOD activity at 150 mg/kg Cu levels was 25.8%and 35.2%higher than that at the 10 mg/kg and 250 mg/kg(p< 0.05). CP(Serum ceruloplasmin)activity was significantly greater with high daily dietary supplemental Cu levels(p< 0.05).No significant differences were observed in ALB(serum albumin)and serum TP(total protein)for the three Cu levels examined(p>0.05).Cu-AA source caused 20.27%and 19.09%increasing of CP activity compared with CuSO₄ and TBCC respectively.Cu-AA source caused 21.47%and 16.15%decreasing of serum SUN content compared with CuSO₄ and TBCC sources respectively.2.The treatment dietary was supplemented with 10,150,250 mg/kg copper from CuSO₄,TBCC and Cu- AA in the basic dietary respectively.The effects of three kinds of copper sources in different levels on pig digestibility of copper and total feces were collected to analysis copper speciation.Results showed that No significant difference in Cu digestibility for the three Cu sources(p>0.05).Copper digestibility was 14.5%-15.6%,12.3%-14.2%,and 6.3%-8.7%for the 10,150,250 mg/kg Cu supplementation levels,respectively(p<0.05).Copper concentrations in pig feces increased as dietary Cu levels were raised(p< 0.05).The amount of Cu excreted in pigs with 250 mg/kg supplemental Cu was 7.6 times of that of pigs supplemented with only 10 mg/kg of Cu.Of the three Cu sources tested,available Cu in pig feces from CuSO₄ was the highest and significantly different(p<0.05)from the other two Cu sources,Cu-AA and TBCC, where no significant difference was found between the two sources(p>0.05).Potential availability of Cu was significantly lower for TBCC than that of either Cu-AA or CuSO₄ (P<0.05);no significant difference in potential availability of Cu existed between Cu-AA and CuSO₄(p>0.05).Copper was least available for TBCC compared with the other two Cu sources(p<0.05).3.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,photosynthetic characteristics,Protein content in leaves,protective enzyme activity and the membrane lipid peroxide of maize.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 aboveground 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‘£Copper appeared to promote photosynthesis of maize at 10 and 20 DAT(p<0.05).As Cu application rates were raised,increases in net photosynthetic rate,intercellular CO₂ concentration, stomatal conductivity,rate of transpiration,and chlorophyll content of leaves were observed (p<0.05).However,at 30 and 40 DAT,the trend appeared to be reversed.Leaf chlorophyll contents seemed to decrease with the increase of Cu application rates.When application rates of pig manure increased from 200g/pot to 300g/pot,significant decreases in photosynthesis,net photosynthetic rate,stomatal conductance,intercellular CO₂ concentration,transpiration rate of leaves were observed(p<0.05).Photosynthesis of maize differed among three sources feces,photosynthesis of maize was less promotion with TBCC source feces than with sources feces of CuSO₄ and Cu-AA at prophase of experiment,photosynthesis of maize was the most restraint with CuSO₄ source feces at anaphase of experiment.⑤From 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.â‘¥Between 10 DAT and 20 DAT,electric conductivity,malondialdehyde contents,and activities of SOD,peroxidase(POD)and catalase(CAT)in maize leaves increased as the Cu application rates increased(p<0.05).These physiological changes may have helped alleviate plant injury from harmful oxygen radicals.However,from 30 DAT to 40DAT,electric conductivity rate and MDA contents in leaves kept increasing as Cu concentrations increased,which resulted in significant decreases in activities of SOD,CAT and POD(p<0.05).Under the condition of experiment,different copper sources and levels had no significant influence on ADG and feed to ADG ratio.The copper content of the pig tissue and 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 the photosynthesis of the maize,the compound of the protein of the leaves and activity of the protection enzyme as well. 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 influenced the photosynthesis parameter of the maize, prevented the combination of the protein,decreased the enzyme activity,destroyed the elimination system of the oxygen and made the enzyme system out of balance.Combining the experiments of pig feeding,digesting and soil potted plant 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 were significant differences on some physiological indices with different copper sources,But there was no significant difference on growing of pigs and maize with different copper sources.3 copper sources could be used.