In vitro microbial metabolism of progesterone and its effect on rumen fermentation characteristics of a maize-rich feed

摘要

IntroductionWhendairy cow become pregnant,serum progesterone (P4)concentration of the cow,unlike other ruminant animals,maintain at high level until parturition (Bedfordet al.,1972;Smith et al.,1973).Circulating concentration of P4 is determined by a balance between P4 production primarily by corpus luteum,and P4 metabolism primarily by liver (Wiltbank,Souza et al.,2012).Until recently,P4 can enter the reticulo-rumenthrough the wall of forestomach and saliva reproductive cycle (Borisenkov et al.,2003;Borisenkov et al.,2006).Until now,there is no clear evidence whether the P4,entered into rumen through the wall of forestomach and saliva reproductive cycle,could affect microbial digestion and metabolism in the rumen fermentation.Fonken et al.