生长激素释放肽-2对猪生长性能、背膘及氮利用率的影响

Effects of Growth Hormone-releasing Peptide-2 Administration on the Growth Performance and Nitrogen Utilization in Swine

选择体重(33±2)kg的DLY猪20头,随机分成4组,每组5头,分别以0、3、9、27μg/kgBW的剂量每日肌肉注射GHRP-228d。在试验的第3周进行4d的代谢试验;在第4周末测量活体背膘和眼肌厚度。结果表明:在第1周末随着剂量的增加,猪的日增重在处理组较对照组分别提高了10.51%、12.06%、16.21%(P<0.05);28d的平均日增重在处理组分别提高了4.5%、1.27%、8.99%(p<0.05)。饲料氮在第3周的消化率各组分别为82.92%、81.29%、82.3%、85.15%;代谢率52.59%6、51.8%、53.20%、56.67%。GHRP-2处理组有减少背膘和增加眼肌厚度的趋势。在试验条件下,以27μg/kgBW的剂量每日肌肉注射GHRP-22周可显著提高生长猪日增重,采食量在整个试验期处理组间无差异;连续处理的第3周出现生长抑制现象,其机理有待于进一步研究。

Twenty crossbred pigs（Duroc×Landrace×York） at （33±2.0）kg BW were allotted to four treatments of five pigs per treatment, and were injected once daily i.m.with GHRP-2 for 28 days. Treatments were T1, noninjeeted control; T2,GHRP- 2（3.0 μ/kg BW）; T3,GHRP-2（9.0 μg/kg BW）; T4, GHRP-2（27.0μg/kg BW）. Metabolism experiment was conducted at the third week, and at the end of the trial, live baekfat and longissimus muscle thickness were determined. The results indicated that average daily gain was significantly increased by 10.51%, 12.06%, 16.21% during the first week, and by 8.7%, 7.2%, 37.38%（P 〉 0.05） during the second week, respectively. No difference were observed in feed intake. Feed/gain ratio tended to be decreased for the fast two weeks. But in the third week growth inhibition was observed with the administration of GHRP-2,while no response to feed intake. Average daily gain was similar to control group at the last week, and feed intake was not different among treatments. However, overall average daily gain was improved by 4.5%, 1.27% ,8.99%（P 〈 0.05） with GHRP-2 injection, respectively. Nitrogen digestibility of the four treatments were 82.92%, 81.29%, 82.3% and 85.15%; and the utilization rate were 52.59%, 51.8%, 53.20%, 56.67%, respectively. Administration of GHRP-2 tended to reduce back fat thickness and in return increase longissimus muscle thickness. The present study demonstrated that average daily gain was markedly improved by exogenous GHRP-2 administration （27 μg/kgBW/d） in the first two weeks of treatment, while feed intake was not affected. Continuous GHRP-2 administration caused growth inhibition in the third week. The mechanism should be further studied.