三价铬对肥育猪生长激素分泌及垂体mRNA表达的影响

Effect of trivalent chromium on growth hormone secretion and pituitary mRNA expression in finishing pigs

将96头体质量约65 kg的杜长大三元杂交猪,按体质量相近、公母各半的原则随机分成4组,每组3个重复。试验猪1组设为对照,饲喂基础饲粮,其余3组为试验组,分别饲喂在基础饲粮基础上添加来源于氯化铬、吡啶羧酸铬,纳米铬的含200μg/kg铬试验饲粮。试验猪充分饲喂,自由饮水,试验为期40 d。饲养试验结束前1 d,从每组中选择6头猪,间隔15 min颈静脉采血1次,连续3 h,制备血清用于生长激素动态分泌模式研究。饲养试验结束后,按体质量相近原则从每组中选择8头猪进行屠宰,测定背膘厚和背最长肌面积;并各采取3头猪的脑垂体,RT-PCR法测定生长激素mRNA水平。结果表明,饲粮中添加200μg/kg三价纳米铬使肥育猪日增重提高了6.31%(P<0.05),料重比降低了4.61%(P<0.05),背膘厚降低了24.32%(P<0.05),背最长肌面积提高了20.22%(P<0.05)。生长激素动态模式分析结果显示,纳米铬组试验猪生长激素总体水平、最低值、峰值和峰持续时间分别提高了42.62%(P<0.05)、87.94%(P<0.05)、26.60%(P<0.05)和17.19%(P<0.05),吡啶羧酸铬组试验猪生长激素总体水平、峰值分别提高了36.58%(P<0.05)和27.18%(P<0.05)。垂体生长激素基因RT-PCR分析结果显示,纳米铬组试验猪垂体生长激素mRNA水平提高了27.63%(P<0.05)。研究结果提示,三价纳米铬可提高肥育猪垂体生长激素mRNA水平,促进机体生长激素分泌,从而促进生长和改善胴体特性。

The study was conducted to investigate the effect of different forms of trivalent chromium on growth hormone （GH） secretion and pituitary mRNA expression in finishing pigs. A total of 96 finishing pigs with an initial average body weight 65 kg were blocked by body weight and randomly assigned to four treatments with three replicates. Pigs were offered one of four diets including a control diet or the control diet supplemented with 200μg/kg chromium from either chromium chloride （CrCl3）, chromium picolinate （CrPic） or Chromium nanocomposite （Cr-Nano） for 40 days. During the trial,all pigs were given free access to feed and water. At the end of the feeding trial, blood samples were taken via auriculares at 15 min intervals for 3 hours. Eight pigs from each treatment were slaughtered for backfat thickness and longissimus muscle area （LMA）, and three pituitaries were collected to determine GH mRNA level. The results showed that average daily gain of pigs fed supplemental CrNano was increased by 6.31 （P〈0.05）, feed gain ratio was decreased by 4.61% （P〈0.05）, backfat thickness was decreased by 24.32% （P〈 0. 05） ,and LMA was increased by 20. 22% （P〈0. 05）. The results of GH dynamic secretion showed that supplemental CrNano increased the mean level,lowest value,peak value and peak duration of GH by 42.62% （P〈0.05）, 87.94% （P〈0.05） ,26.60% （P〈0.05） ,and 17.19% （P〈0.05） ,respectively. The mean level and peak value of GH in pigs fed Supplemental CrPic was increased by 36. 58% （P〈 0.05）, 27. 18% （P 〈 0. 05）, respectively. Pituitary mRNA expression of GH in pigs fed diet containing chromium from CrNano was increased by 27.63% （P〈0.05）. These results indicated that chromium nanocomposite increased GH mRNA expression and secretion in finishing pigs,through which growth was promoted and carcass characteristic was improved.