【作者】 祝丹；

【导师】 陈代文； 余冰；

【作者基本信息】 四川农业大学 ， 动物营养与饲料科学， 2009， 硕士

【摘要】 本试验旨在研究日粮中添加铜对断奶仔猪采食量的影响以及探索铜调节断奶仔猪采食量的机理。实验选用100头28日龄健康DLY断奶仔猪,随机分为4个处理,每个处N5个重复,每个重复5头猪。4个处理分别饲喂含10、100、175、250mg/kg铜的日粮。实验期为21天,记录采食量和日增重,在试验的第21天从每个重复随机选取一头猪进行屠宰,采集前腔静脉血液和下丘脑样品待测。试验结果表明,随着铜添加剂量的增加,平均日采食量表现为增加的趋势,与10mg/kg铜添加组相比,100、175、250mg/kg铜添加组仔猪的平均日采食量分别提高了23%、31.8%和54.6%,当添加量达到250mg/kg时差异达到显著水平(P＜0.05);平均日增重同样随着铜添加剂量的增加而增加,与10mg/kg铜添加组相比,100、175、250mg/kg硫酸铜添加组仔猪的平均日增重分别提高了41%、60.7%和81.5%,当添加量达到175和250mg/kg时差异达到显著水平(P＜0.05);同时,175和250mg/kg硫酸铜添加组饲料转化效率分别提高了20.1%(P＜0.05)和16.4%(P＞0.05)。各组下丘脑铜、锌、铁含量差异均不显著,250mg/kg硫酸铜添加组仔猪下丘脑铜的含量有提高的趋势(P=0.053)。添加250mg/kg硫酸铜显著提高了断奶仔猪下丘脑NPY的mRNA丰度(P＜0.05);POMC的mRNA丰度随着铜的添加剂量增加而降低,当添加量达到175和250mg/kg时差异达到显著水平(P＜0.05);100、175、250mg/kg铜添加组下丘脑瘦素长型受体的mRNA的丰度均低于10mg/kg铜添加组,差异极显著(P＜0.01)。AMPKa2、MC4R、Orexin、OrexinR2的mRNA丰度无显著差异(P＞0.05)。各组血浆瘦素水平和胰岛素水平均高于10mg/kg铜添加组,但是差异不显著(P＞0.05)。以上结果表明,高铜能提高断奶仔猪采食量,促进生长。同时,高铜对采食量的调节可能与降低下丘脑瘦素长型受体的表达,影响下丘脑NPY神经元细胞和POMC神经元细胞的神经内分泌活动有关。更多还原

【Abstract】 The current study evaluated gene expression of appetite regulators in hypothalamus and levels of appetite regulating hormones in plasma in response to copper supplementation to investgate the effects of high dietary copper on the feed intake of weanling pigs and the underlying mechanism.100 crossbred pigs were randomly assigned to one of four groups with five replicates,based on body weight and gender.Cu was supplemented at the levels of 10,100,175 and 250 mg/kg in form of CuSO₄.Feed intake and weight gain were determined.On d 21 of the experiment 1 pig from each replicate was slaughtered and the hypothalami was collected for determining mRNA expression levels of appetite-regulating genes.Blood samples were also collected for determination of hormone levels.The results showed that average daily feed intake（ADFI） and average daily gain （ADG） were higher（P＜0.05） in 250 and 175,250 mg/kg copper-supplemented groups than in the control group.Feed:gain（F:G） ratio was lower in pigs fed the diets with 250 mg/kg copper（P＜0.05） than in the control group.250 mg/kg copper supplemention tended to increase copper concentration in the hypothalamus （P=0.053）,while the concentration of zinc and iron were not affected（P＞0.05）. Furthermore,The abundance of NPY mRNA in hypothalamus was higher in 250 mg/kg copper-supplemented group（P＜0.05）,whereas the abundances of POMC and long-form Leptin receptor mRNA were significantly reduced in 175,250 mg/kg and 100,175,250 mg/kg copper-supplemented groups respectively（P＜0.05）.No differences were found for AMPKα2 subunit,melanocortin-4 receptor（MC4R）,orexin, type 2 orexin receptor mRNA expression（P＞0.05）.Both Leptin and insulin levels in the plasma were numerically elevated by copper supplementation（P＞0.05）.These data suggest that copper has a stimulative effect on feed intake of weanling pigs which plays a pivotal role to elevate growth performance.Furthermore,the down-regulation of long-form Leptin receptor mRNA expression might contribute to the stimulation of high dietary copper supplementation via regulation of NPY and POMC mRNA expression.更多还原