Effects Of Essential Oil On Growth And The Rumen Microbial Community Structure In Weaned Goats

Essential oil(EO)is a volatile aromatic substance originally extracted from plants such as garlic,ginger and tea tree.Today,this substance can be synthesized and has been widely used in the fields of food and medicine.Because it has the characteristics of a high efficiency,safety,and cost-effectiveness,there is growing interest to investigate the use of EO in livestock industry.Based on a single factor experimental design,in this study,we investigated the effects of EO on growth,feed intake,serum indices,and the composition and diversity of the ruminal bacterial and archaeal communities in Nanjiang Yellow goats.A total of 60 weaned lambs were selected and were randomly assigned to four groups: the control group,the low-dosage group(50 mg/d),the medium-dosage group(100 mg/d)and the high-dosage group(150 mg/d)).The main results were as follows:The statistical analysis the mean daily gain and body weight on last day of treatment in the Nanjiang Yellow goats showed that there was no significant difference between the experimental groups(P > 0.05).The average daily dry matter intake of the group H and group M on day 41-60 was significantly higher than that of group L and group C,respectively(P < 0.05).There was no significant difference in the rumen p H between the groups(P > 0.05),while there was very significant difference in ammonia-nitrogen concentration between the groups(P < 0.01).The statistical analysis of serum indexes in Nanjiang Yellow goats showed that there were no significant differences in serum total protein,albumin,white bulb ratio,triglyceride,total bile acid,and glutamic-pyruvic transaminase(P > 0.05),respectively.The statistical analysis of the bacterial community structure in the rumen fluid in the Nanjiang Yellow goats displayed that there was no significant difference in Alpha diversity between the groups(P > 0.05)..The analysis of the unweighted Unifrac distance showed that there were significant differences between groups H and L(P < 0.05).At the phylum level,on day 60 of the experiment,the predominant phyla were Bacteroidetes(42.15%),Firmicutes(40.48%),and Proteobacteria(13.80%),with no significant difference(P > 0.05).At the genus level,moreover,the relative abundance of Bacteroidales F082 in group H(2.18%)was significantly higher than that in group C(0.66%)(P < 0.05).The relative abundance of Ruminococcus 2 in group H was 1.32%,which was significantly lower than that in group C(4.47%)(P < 0.05).The statistical analysis of the archaea community structure in the rumen fluid in the Nanjiang Yellow goats showed that Observed OTUs in group H was significantly lower than the other groups on the day 60 of the experiment(P < 0.05).Additionally,Faith’s PD in group H was significantly lower than that in group C and L(P < 0.05).At the phylum level,the predominant phylum was Euryarchaeota,of which he relative abundance was 94.19%.At the genus level,Methanobrevibacter Balch and Wolfe represented the highest relative abundances on day 60,and there was no significant difference in relative abundance among the four experimental groups(P > 0.05).The relative abundance of Methanococcus Kluyer and vam Niel in group H was 0.57% and was significantly lower than that in group L(2.17%)(P < 0.05).Taken together,the essential oil could increase feed intake in weaned lambs,but it did not significantly affect the serum total protein,albumin,triglyceride,total bile acid,and alanine transaminase.Furthermore,it could improve the rumen environment in weaned goats,promote the development of rumen microbial colonies,and improve the rumen digestion ability of the goat.Finally,it could inhibit the quantity and species of Methanogenus,reduce energy loss and greenhouse gas emission.