Effects Of Methionine Hydroxy Analogue On Intestinal Redox Status And Bone Development Of Broilers

Intestinal and bone are important organs for digestion, absorption and pillar, It is crucial tomaintain their healthy and steady-state. Methionine(MET) is an essential amino acid, itsalternative source including2-hydroxy-4-methylthiobutanoic acid (HMTBA) and2-hydroxy-4-methylthiobutyric acid calcium salt(HMTB-Ca). Due to their structuraldifferences, compared to DL-methionine(DLM), HMTBA and HMTB-Ca may have strongantioxidant activity to play a positive role in intestinal oxidation and bone growth. Theantioxidant activity of DLM, HMTBA and HMTB-Ca in vitro was compared; Broilers werechosen as the object for their short growth cycle and high metabolic, the effect of differentlevels of methionine sources on growth performance, nutrient digestion and absorption,intestinal oxidation status and bone development were study, and its possible antioxidantmechanism was explored.In vitro: the differences of clearance rate of the three met sources on O-2· free radical andthe liver lipid peroxidation inhibition were examined; In vivo:2101-day-old male rosebroilers were randomly divided into7groups: control group (no exogenous methionine add),and other groups added with DLM, HMTBA, HMTB-Ca, and with0.2%/0.3%(first stage),0.1%/o.2%(last stage). At21and46day, growth performance, nutrient digestibility, digestiveenzyme activities, intestinal morphology, intestinal redox state, and bone developmentindicators and mRNA expression levels of intestinal and bone by RT-PCR were measured.The main results of the paper are as follows:(1)In vitro: O-2·scavenging capacity:HMTBA>DLM>HMTB-Ca; liver lipid peroxidation inhibition rate: HMTBA>HMTB-Ca>DLM.(2)At21day and46day, daily gain and feed intake were improved in chicks fed threemethionine sources and were positively correlated with the dose; Compared with the DLM,daily gain and feed intake at21day and daily gain at46day were significantly improved inbroilers fed HMTBA and HMTB-Ca (P<0.05), the high level of HMTBA and HMTB-Cagroups are of the most significant.(3)Compared with the DLM group, the intestinal amylaseand lipase activity were significantly enhanced in the high level of HMTBA and HMTB-Cagroups, the substance apparent digestibility were significantly enhanced in HMTB-Ca group,the ratio of villus length/crypt depth in duodenum and jejunum were significantly increased inbroilers fed high dose of HMTBA and HMTB-Ca (P<0.05), somatostatin (SS) was reduced at46day.(4)The GSH/GSSG ratio and CAT activities were significantly increased in broilersfed HMTBA and HMTB-Ca(P<0.05), MDA levels were decreased in duodenum andjejunum(P<0.05); Antioxidant genes NRF1, SOD1, SOD2, GST, PGC-1α, MT1mRNAexpression levels were raised in duodenum and jejunum.(5)Compared with the DLM, tibiaand femur bone strength and bone index were significantly improved in chicks fed high dosesof HMTBA and HMTB-Ca(P<0.05), calcium and phosphorus content in tibia and femurwere significantly improved, key genes of bone decomposition MMP2, MMP9mRNAexpression levels were significantly lowered in broilers fed HMTB-Ca(P<0.05).