冷季补饲对藏羊小肠形态发育及营养物质转运载体基因表达量的影响

Effects of Supplementation in Cold Season on Morphological Development of Small Intestine and the Expression of Nutrient Transporter Gene

本试验旨在研究冷季补饲精料或尿素-糖蜜型舔砖对藏羊小肠组织形态发育及营养物质转运载体基因表达量的影响。选择1.5岁、体重((29.4±1.79)kg)相近的健康藏系绵羊母羊18头,随机分为对照组(CON组)、尿素-糖蜜型舔砖补饲组(BS组)和精料补饲组(CS组)。CON组自由采食燕麦干草,BS组在CON组基础上自由舔食尿素-糖蜜型舔砖,CS组在CON组基础上补饲精料200g·只-1·d-1。进行60d的饲养试验后,对全部试验藏羊进行屠宰,采集小肠各段组织,通过制作组织切片及荧光定量PCR,测定小肠组织形态发育和营养物质转运载体基因表达量。结果表明:(1)补饲精料或舔砖均显著提高了藏羊消化能和粗蛋白质摄入量(P<0.05),且CS组显著高于BS组(P<0.05);(2)补饲精料或舔砖均显著提高了藏羊十二指肠、空肠及回肠绒毛宽度(P<0.05),且CS组均显著大于BS组(P<0.05),补饲精料还显著提高了十二指肠和回肠绒毛高度(P<0.05),显著降低了空肠和回肠隐窝深度(P<0.05);(3)胰岛素样生长因子结合蛋白5(Insulin-like growth factor binding protein,IGFBP5)mRNA表达量在十二指肠和空肠黏膜中CS和BS组均显著高于CON组(P<0.05),且CS组显著高于BS组(P<0.05),在回肠黏膜中CS组显著高于BS和CON组(P<0.05);(4)十二指肠黏膜中L型氨基酸转运载体1(L-type amino acid transporter 1,LAT1)、阳离子氨基酸转运载体1(Cationic amino acid transporters 1,CAT1)、小肽转运载体1(Peptides transporter 1,pepT1)、钠依赖型葡萄糖转运载体1(Na+-dependent glucose co-transporter 1,SGLT1)及促葡萄糖转运载体2(Facilitative glucose transporter 2,GLUT2)mRNA表达量CS组显著高于BS和CON组(P<0.05),空肠黏膜中CAT1、pepT1mRNA表达量和回肠黏膜中CAT1、LAT1、SGLT1及GLUT2mRNA表达量,BS组显著高于CS和CON组(P<0.05)。以上结果表明,冷季补饲精料或尿素-糖蜜型舔砖均增加了藏羊对能量和蛋白质等营养物质的摄入量,促进了小肠组织形态发育,补饲精料提高了十二指肠黏膜中氨基酸、小肽及葡萄糖转运载体基因mRNA的表达量,而补饲尿素-糖蜜型舔砖提高了其在空肠和回肠黏膜中的表达量。

The objective of this study was to investigate the effect of supplement urea-molasses lick block or concentrate on morphological development of small intestine and the expression of nutri-ent transporter gene.Eighteen healthy,1.5-year-old Tibetan sheep ewes（（29.4±1.79）kg）were selected and randomly assigned into control group（CON group）,urea-molasses lick block supplementation group（BS group）or concentrate supplementation group（CS group）.The CON group were provided with oat hay ad libitum,the BS group were provided with oat hay ad libitum and supplemented with lick block ad libitum,the CS group were provided with oat hay ad libitum and supplemented with concentrate（200g/sheep/day）,during 60 days feeding experiment period.All ewes were slaughtered after the feeding trial.Sampled each segment of the small intestine,and then,the morphological development and nutrient transporter gene expression of small intestine were measured through making sections of small intestine tissue and fluorescence quantitative PCR.The results showed as follows：（1）Supplementation with concentrate or lick block significantly increased the intake of digestible energy and crude protein of Tibetan sheep（P0.05）,and the CS group was significantly higher than the BS group（P0.05）;（2）Supplementation with concentrate or lick block significantly enhanced the villus width of duodenum,jejunum and ileum of Tibetan sheep（P0.05）,and the CS group was significantly higher than the BS group（P0.05）,and the villus height of duodenum and ileum were significantly enhanced and the crypt depth of jejunum and ileum were significantly reduced in the CS group compared with the CON group（P0.05）;（3）The relative expression of insulin-like growth factor binding protein 5（IGFBP5）mRNA in both of the duodenum and jejunum mucosa were significantly enhanced in both of the CS and BS groups compared with the CON group（P0.05）,and the CS group was significantly higher than the BS group（P0.05）,and in the ileum mucosa the CS group was significantly higher than both of the BS and CON groups（P0.05）;（4）The CS group had the higher relative expression levels of cationic amino acid transporters 1（CAT1）,Ltype amino acid transporter 1（LAT1）,peptides transporter 1（pepT1）,Na＋-dependent glucose co-transporter 1（SGLT1）and facilitative glucose transporter 2（GLUT2）mRNA in duodenum mucosa compared with the BS and CON groups（P0.05）.The CAT1,pepT1 mRNA relative expression in jejunum mucosa and the CAT1,LAT1,SGLT1 and GLUT2mRNA relative expression in the ileum mucosa in the BS group were significantly higher than both of the CS and CON groups（P0.05）.We concluded that supplementation with urea-molasses lick block or concentrate increased the intake of energy and protein of Tibetan sheep in cold season,and promoted the morphological development of small intestine,and the expression of transporter gene mRNA of amino acids,peptides and glucose were enhanced in duodenum mucosa by supplementation with concentrate and they were enhanced in both of the jejunum and ileum mucosa by supplementation with urea-molasses lick block.