肥育安格斯阉牛血清瘦素与剩余采食量、生长性能和脂代谢指标的表型关系

Phenotypic Relationships between Serum Leptin and Residual Feed Intake,Growth Performance and Lipid Metabolism Indices of Fattening Angus Steers

本试验旨在探究肥育安格斯阉牛血清瘦素与剩余采食量(RFI)、生长性能、瘤胃发酵参数和脂代谢指标之间的表型关系。选取60头体况良好、健康的640~720日龄安格斯肥育阉牛[(634.4±53.35)kg],进行预试期14 d、正试期63 d的饲养试验,采用采食量自动记录系统测定每头牛每日的实际干物质采食量(DMI),并测定平均日增重(ADG),以确定其RFI。然后分别选择9头低剩余采食量(LRFI)和12头高剩余采食量(HRFI)肉牛,在第64天通过口腔胃管采集瘤胃液和通过尾根静脉采集血液以测定血清瘦素含量及脂肪沉积和蛋白质代谢相关指标、血清生化指标及瘤胃发酵参数等,并通过B型超声测定背膘厚度和眼肌面积。结果表明:1)与HRFI肉牛相比,LRFI肉牛RFI和DMI极显著降低(P<0.01),增重饲料比(G/F)极显著提高(P<0.01)。2)与HRFI肉牛相比,LRFI肉牛血清瘦素含量和眼肌面积显著提高(P<0.05),背膘厚度以及血清低密度脂蛋白(LDL)和极低密度脂蛋白(VLDL)含量极显著降低(P<0.01)。3)与HRFI肉牛相比,LRFI肉牛瘤胃微生物蛋白(MCP)含量显著提高(P<0.05)。4)RFI与DMI、背膘厚度以及血清LDL和VLDL含量呈显著正相关(P<0.05),与G/F、血清瘦素含量、眼肌面积以及瘤胃MCP含量呈显著负相关(P<0.05);血清瘦素含量与RFI、背膘厚度以及血清VLDL含量呈显著负相关(P<0.05),与G/F呈显著正相关(P<0.05)。综上所述,LRFI肉牛血清瘦素含量更高,且血清瘦素含量与脂肪沉积呈负相关,血清瘦素可成为筛选LRFI反刍动物的潜在生物标志物。

The aim of this experiment was to investigate the phenotypic relationships between serum leptin and residual feed intake(RFI),growth performance,rumen fermentation parameters and lipid metabolism indices of fattening Angus steers.Sixty healthy 640 to 720-day-old Angus finishing steers of(634.4±53.35)kg were selected and fed for 14 days in a pre-trial period and 63 days in a trial period,and the actual daily dry matter intake(DMI)and average daily gain(ADG)of each cattle were measured by an automatic feed intake recording system to determine their RFI.Then 9 low residual feed intake(LRFI)and 12 high residual feed intake(HRFI)cattle were selected to collect rumen fluid through oral gastric tube and blood through tail root vein on day 64 to determine the serum leptin content,fat deposition and protein metabolism related indices,serum biochemical indices and rumen fermentation parameters,etc.,and the backfat thickness and loin muscle area were measured by B-mode ultrasound.The results showed as follows:1)compared with HRFI beef cattle,RFI and DMI of LRFI beef cattle were extremely significantly decreased(P<0.01),and the ratio of weight gain to feed(G/F)of LRFI beef cattle was extremely significantly increased(P<0.01).2)Compared with HRFI beef cattle,the serum leptin content and loin muscle area of LRFI beef cattle were significantly increased(P<0.05),and the backfat thickness and serum contents of low-density lipoprotein(LDL)and very low-density lipoprotein(VLDL)were extremely significantly decreased(P<0.01).3)Compared with HRFI beef cattle,the rumen microbial protein(MCP)content of LRFI beef cattle was significantly increased(P<0.05).4)RFI was positively correlated with DMI,backfat thickness and serum contents of LDL and VLDL(P<0.05),and negatively correlated with G/F,serum leptin content,loin muscle area and rumen MCP content(P<0.05);the serum leptin content was negatively correlated with RFI,backfat thickness and serum VLDL content(P<0.05),and positively correlated with G/F(P<0.05).In summary,the serum leptin content of LRFI beef cattle is higher,and the serum leptin content is negatively correlated with fat deposition,which means the serum leptin can be a potential biomarker for screening LRFI ruminants.