| Photoperiod is the key factor affecting the seasonal estrus of buffalo.Previous studies in our laboratory has shown that the types and abundances of rumen microorganisms in buffalo have seasonal fluctuations,and their metabolites（such as fatty acids）must be different.The effect of such differences on the reproductive physiological function of buffalo and the mechanism of action of follicle development are unknown.Melatonin is one of the key hormones in regulating biological rhythm,and its secretion is affected by light.Some studies have found that melatonin has a certain regulatory effect on animal reproduction,but whether melatonin has a regulatory effect on the seasonal fluctuations of rumen microorganisms and nutrient metabolism of buffalo has not been reported.This study collected rumen contents and serum of buffalo in different seaso ns from March 2022 to February 2023,and analyzed the relationship between melatonin and the seasonal changes of rumen microorganisms and reproductive hormones of buffalo through 16S r DNA high-throughput sequencing and other methods,in order to provide scientific parameters for improving the reproductive efficiency of buffalo and accelerating the reproductive improvement process.The main results are as follows:1.The relationship between melatonin and rumen microorganisms:The changes of melatonin concentration in rumen and serum of buffalo in different seasons were similar,and all of them were related to rumen microorganisms.The bacteria genera related to melatonin in rumen fluid mainly included:CAG 35,Candidatus＿Saccharimonas,Saccharofermentans,Lachnospiraceae AC2044 group;The bacteria genera related to serum melatonin mainly include:CAG-352,Chri stensenellaceae＿R-7＿group,Ruminococcus,Chujaibacter,Prevotellaceae＿UCG-00,Candidatus＿Arthromitus,NK4A214＿group,Prevotella.2.Relationship between reproductive hormones and rumen microorganisms:The rumen microorganisms were mainly related to reproductive hormones in rumen fluid at the generic level,including CAG 352,Candidatus＿Arthromitus,Chujaibacter,Succinivibrionaceae UCG-002;The main rumen microorganisms associated with serum reproductive hormones at the genus level included:CAG 352,Ruminobacter,Chujaibacter,Prevotellaceae UCG-001 and RF39.3.The relationship between melatonin and reproduction:There were significant differences in rumen and serum melatonin in spring,summer and autumn and winter.Some rumen microorganisms related to reproductive hormone were also correlated with melatonin.At the gate level,rumen microorganism Spirochaetota was positively correlated with serum melatonin and E2.Chloroflexi and WPS-2 were negatively correlated with serum melatonin and positively correlated with LH.At the generic level,CAG 352 was positively correlated with rumen and serum melatonin,and positively correlated with E2.Chujaibacter was negatively correlated with rumen and serum melatonin,and positively correlated with FSH.In summary,melatonin levels in rumen and serum were significantly correlated with rumen microorganisms:rumen microorganisms such as Chujaibacter were negatively correlated with melatonin levels in rumen and serum,while CAC-352 were positively correlated with melatonin levels in rumen and serum at the genus level.Rumen microorganisms related to reproductive hormones are also related to melatonin,Melatonin may regulate the seasonal reproductive rhythm of buffalo by interacting with rumen-related microorganisms. |
