| The present study was conducted to investigate the effects of different energy levels on the growth and slaughter,meat quality,rumen environment and flora structure,serum biochemistry and antioxidant indexes of grazing beach sheep,in order to provide some theoretical support for the selection of local Tan sheep production methods,improve production performance and reduce production cost.In this experiment,24 3-month-old de-stemmed male beach goats,healthy and free of disease,with similar body weight(23.38±0.70 kg),were randomly divided into 4 groups of 6 goats each.Low energy group(G),medium energy group(S),high energy group(Z)and grazing group(W).The pre-feeding period were 12 days and the normal test periods were 90 days.The results of growth performance,slaughter performance and meat quality of Tan sheep showed that:(1)the final weight and daily gain of medium energy group(S)and high energy group(Z)were significantly higher than those of low energy group(G)and grazing group(W)(P<0.05).(2)The carcass weight of groups S and Z was significantly higher than that of groups G and W(P<0.05),and the slaughter rate of groups S and Z was significantly higher than that of group W(P<0.05).(3)The fat in groups S and Z was significantly higher than that in groups G and W(P<0.05).With the increase of energy level,water loss rate and cooked meat rate were increased,and the highest values were reached in group W(P<0.05).There were no significant differences in protein,shear force,pH,pH after 24h,flesh color L,flesh color a and flesh color b among all groups(P>0.05).(4)The highest net income per sheep was 258.76 yuan in group S,while the lowest was 174.61 yuan in group W.The results of rumen environment,flora structure and rumen morphology of Tan sheep showed as follows:(1)Rumen fluid pH of group W was significantly higher than that of the other three groups(P<0.05).With the increase of energy level,acetic acid,propionic acid,isobutyric acid,butyric acid,valerate and isovalerate increased(P<0.05).Acetic acid/propionate in group S was significantly higher than that in the other three groups(P<0.05),and acetic acid/propionate in group G was significantly lower than that in the other three groups(P<0.05).(2)There was no significant effect on α diversity in the 4 groups(P>0.05).The total number of OTUs in the 4 groups was 5745,of which 3442,3600,3083 and 3213 were in group G,S,Z and W,respectively.The number of unique OTUs was 393,600,468 and 604,accounting for 6.84%,10.44%,8.15%and 10.51%of the total number of OTUs,respectively.There were 1442 OTUs in the 4 groups,accounting for 25.10%of the total OTUs.(3)At the phylum level,Bacteroidetes,Proteobacteria and Firmicutes were predominant.The proportion of Bacteroidetes in groups G,S,Z and W was 22.13%,55.58%,45.06%and 57.05%,respectively,and the S and W groups were significantly higher than those in groups G and Z(P<0.05).The proportion of Proteobacteria in group G,S,Z and W was 15.07%,2.65%,13.41%and 3.89%,respectively.The percentages of firmicutes in groups G,S,Z and W were 40.47%,34.44%,32.11%and 31.39%,respectively.The unconfirmed phylum in group G was significantly higher than that in other groups(P<0.05).There were no significant differences among other groups(P>0.05).At the genus level,Prevotella was the dominant bacteria in the four groups,with Group G,S,Z and W accounting for 11.41%,31.09%,23.26%and 21.90%,respectively.The proportion of Candida in groups G,S,Z and W was 15.07%,0.94%,0.53%and 0.56%,respectively.Candida in group G was significantly higher than that in the other three groups(P<0.05).Group G,group S,group Z and group W accounted for 3.38%,4.71%,3.10%and 11.83%,respectively.The RC9 intestinal group of group W was significantly higher than that of the other three groups(P<0.05).The rumen cocci in groups G,S,Z and W accounted for 7.70%,1.22%,0.92%and 0.87%,respectively,and the rumen cocci in group G was significantly higher than that in the other three groups(P<0.05).There were no significant differences among the other bacteria groups(P>0.05).(4)Rumen papillae height increased with the increase of energy level(P<0.05).There were no significant effects on other indexes among the 4 groups(P>0.05).The results of blood biochemical indexes and antioxidant indexes of Tan sheep showed that:(1)serum albumin,serum total cholesterol,serum triglycerides,serum creatinine,fasting glucose,serum αhydroxybutyrate dehydrogenase,serum aspartate aminotransferase,lactate dehydrogenase,high density lipoprotein and low density lipoprotein increased with increasing energy level(P<0.05).free fatty acids in group Z were significantly lower than those in groups S group and W group(P<0.05).There was no significant difference between the four groups in other indexes(P>0.05).(2)Malondialdehyde,catalase and superoxide dismutase showed an increasing trend in groups G,S and Z(P>0.05).glutathione peroxidase was the highest in group W(499.47 U/mL),which was significantly higher than the other three groups(P<0.05).There was no significant difference in the total antioxidant capacity of the groups(P>0.05).The results of extensive targeted metabolomic analysis of the blood of Tan sheep showed that a total of 765 metabolites were detected from the plasma of beach goats,and the KEGG annotation and pathway analysis of the differential metabolites revealed that 16 metabolites with corresponding KEGG annotation were screened in group W compared with G,28 metabolites with corresponding KEGG annotation were screened in group W compared with S,and 33 metabolites with corresponding KEGG annotation were screened in group W compared with Z.A total of 33 metabolites with corresponding KEGG annotations were screened in group S compared with G.A total of 20 metabolites with corresponding KEGG annotations were screened in group Z compared with G.A total of 9 metabolites with corresponding KEGG annotations were screened in group Z compared with S.The main metabolic pathways involved were purine metabolism,nucleotide metabolism,bile secretion,and linoleic acid metabolism.In conclusion,a certain energy level diet can improve the performance and reduce the cost of Tan sheep.Proper supplementation of grazing Tan sheep has no significant effect on the rumen microbial structure,and can improve the antioxidant capacity of Tan sheep.The plasma metabolism of grazing Tan sheep was affected by different energy levels. |
