Safety Analysis And Potential Hazard Point Control On Inputs Of Stall-feeding Yak

To understand the current security status of stall-feeding yak in northwest Sichuan alpine and gorge region,and find out potential hazard points during the breeding process,we selected eight stall-feeding yak farm at Aba prefecture of Sichuan as the research object,respectively collected the farm environment soil samples,drinking water,fodder and yak slaughtering tissues,a total of 42 hazard index such as physics,chemistry,toxicology and bacteriological index according to relevant standard.With methods of single factor pollution index and potential ecological risk assessment,those hazard index also were evaluated.Besides,we also studied the diet AFB1 content at the 0ug/kg,40ug/kg and 60ug/kg level on the influence of yak rumen microbial community composition and diversity by metagenomics sequencing.On this basis,according to the potential hazard control points we founded,the HACCP control scheme and measures are put forward.The results will provide reference for yak breeding safety of Aba prefecture,as well provide a scientific basis for reducing potential hazards of barn feeding inputs and producing clean animal by-products.The research results are as follows:(1)The eight stall-feeding yak farm soil heavy metals content of As?Pb?Cd?Cr?Cu and Ni in soil environment did not exceed national industry environmental evaluation standard of livestock and poultry breeding(HJ 568-2010).Moreover,the “ShenYuan” farm soil heavy metal potential ecological risk index RI is 307.84,indicating a considerable potential ecological risk,while other farm the level of potential ecological risk is moderate.The farm RI sorting as ShenYuan >XuSheng>QingLin>FaXin>MinChi>MaXin>XiShang>LeWu.(2)Overall the heavy metal content of eight barn feeding farm drinking water is far lower than the standard.However,except for “MinChi” and “XiShang” the number of total coliform group are 33MPN/100 ml and 12MPN/100 ml,respectively,which are exceeds the national pollution-free food of livestock and poultry industry calves breeding water quality standard(NY5027-2008),the rest of the farms of various indexes in safe range.(3)The farm feed bacteria and AFB1 content exceeds the national feed hygiene standards(GB 13078-2001),indicating a potential hazard risk;The heavy metal Cr content of the concentrated feed,corn straw and vinasse are exceeded the national standard,indicating a potential hazard risk and the risk ranking for concentrate feed>vinasse>maize straw.(4)Individual farms yak tissue heavy metal Pb content are higher than the value of national green food of meat standard(NY/T 2799-2015).And the Cd contents of yak liver and kidney for each farms are exceeded the national industry standard,which exist a big potential hazard risk.(5)The correlation analysis showed that the farm soil Pb,Cd,Cr,Cu and Ni has certain homology;The feed As,Pb and Ni are homology;Muscle tissue Pb,Cd,Cr,Ni and Cu elements has certain homology;In the liver and kidneys,Pb,As,Cr and Ni element are certain homologous;The same heavy metal element content in soil and yak tissue sample no significant correlation between;Feed As and Cu content have a certain relationship with the content of yak liver and kidney As and Cu.(6)With metagenomics sequencing,we identified eight microbial groups in yak rumen,the category are Proteobacteria,Firmicutes,Bacteroidetes,Euryarchaeota,Actinobacteria,Apicomplexa,Ascomycota and Deinococcus-Thermus,respectively;The research shows that the rumen microbial relative abundance index,evenness index and dominance index can be reduced when add 40ug/kg AFB1 into yak daily ration,besides,when the AFB1 addictive amount reaches 60ug/kg,can significantly reduce the Shannon-Weiner index(P<0.05),which showed that aflatoxin can decrease the yak rumen microbial diversity.(7)After analysis the source,harm and influence factors of potential hazard points at yak farm soil environment and the main feeding inputs,we aimed at those potential hazard points put forward a series of control measures,and formulate the HACCP safety management plan for stall-feeding yak breeding.To sum up,at present,the yak farm soil environmental,drinking water and feed as well as the hazard indexes of yak meat overall in the scope of security level,but a few indicators such as Cd,Cr and AFB1 exist hazard risk and need arise our attention.