| To assess the environmental impact of high-dose Zn and Cu in the pig feed systematically, several studies were conducted in this paper as follows:1. Metabolic experiments for pigs fed diets supplemented with high-dose Zn and CuThree groups of six pigs (Duroc×Landrace × Yorkshire) with average body weight of 15± 1 kg (Group I ), 45± 1 kg (Group II) and 80± 1 kg (Group III) had been fed diets added with Cu 230mg/kg, Zn 250mg/kg; Cu 200mg/kg, Zn 100mg/kg; Cu 200mg/kg, Zn 80mg/kg respectively. Feces and urine were collected for seven 24-h periods.The experiments showed that only 0.13%~0.18% of total Cu intake were excreted in urine while total Cu excreted in feces and urine were 96.13% 87.86% and 88.02% for Group I Group II and Group III respectively. Total Zn excretion rate was 98.11% for Group I added with 2500mg/kg Zn while total Zn excretion rate were 92.26% and 87.18% for Group II and Group III,which were supplemented with Zn based on normal requirement. The results indicated that most of Zn intake excreted in feces and very little Zn excreted in urine.The Cu excretion rate is higher in piglets than that of growing and finishing pigs, the Zn excretion decreased as the Zn addition to the diets decreased.The concentration of Cu in air-dried feces is 1150.6mg/kg ~1211.9mg/kg, and the concentration of Zn in feces of piglet is 12921.3mg/kg.2. Assessment of pollution of Cu and Zn in the pigs' feces on soilIn Chenguang Pig Farm, Zhanjiang, Guangdong Province, in the place lm or 3m away from the manure pool, Cu and Zn in the soil was significantly higher than that of control group, while in the place 5m away, Cu and Zn in the soil was not significantly different from the control group. In Aotuo Pig Farm, Jinhua, Zhejiang Province, in the place lm or 2m away from the manure pool, Cu and Zn in the soil was significantly higher than that of control group, while in the place 4m away, Cu and Zn in the soil was not significantly different from that of control group. In Qianjin Pig Farm, Chongming, Shanghai, in the place 6m away from the manure pool, Cu and Zn in the soil was significantly higher than that of control group, while in the place 8m away, Cu and Zn in the soil was notsignificantly different from that of control group. It is evident that the radius of Cu and Zn contamination was larger than that of former Pig Farms.In Chenguang Pig Farm, after 5 years continuous fertilization of high Cu and Zn pig manure, Cu in the soil of the cassava field was 136.75% higher than that of control group while Zn in the soil was 133.87% higher that of control group. Cu in the soil of the sugarcane field was 157.16% higher than that of control group while Zn in the soil was 144.02% higher that of control group. In Jinhua, after 11 years continuous fertilization, Cu in the soil of vegetable fields and tea garden were 384.60%~2022.22% higher than that of control group while Zn in the soil were 66.42%~448.37% higher that of control group. In Qianjin Farm, after 5 years continuous fertilization, Cu in the soil of paddy field was 148.75% higher than that of control group while Zn in the soil was 67.22% higher that of control group. After 13 years continuous fertilization, Cu in the soil of the vegetable fields were 125.76%~1848.20% higher than that of control group while Zn in the soil were 61.62%~1097.62% higher that of control group. It is suggested that Cu and Zn in the soil significantly increase after fertilization of pig manure with high Cu and Zn.Fertilization of pig manure with high Cu and Zn resulted in Cu and Zn in soil to exceed the State Environmental Quality Standard of Soil to some extent. In Jinhua vegetable fields, in which hot peppers and cowpeas were planted, Cu and Zn in the soil samples exceeded the first and second grade State Environmental Quality Standard of Soil by 100%. In Chongming Peanut Field, Shanghai, Cu and Zn in the soil samples exceeded the first, second and third grade State Environmental Quality Standard of Soil by 100%. According to the comprehensive pollution index, the pollution of manure-fertilized fi...
|
PDF Full Text Request