Effects Of Dihydropyridine On Growth Performance, Meat Quality And Residue In Finishing Pigs

Three experiments were aimed to evaluate the effects of dihydropyridine (DHP) on growth performance, carcass traits, meat quality, blood indexs and the residue in finishing pigs.Exp.1:Study on Metabolites and Metabolic Kineticsof DHP in PigsThis study was aimed to evaluate the metabolic mechanism of dihydropyridine (DHP) in pigs by measuring the metabolic product in blood and urine when feed diet with DHP. Ten Duroc×Landrace× Yorkshire (DLY) pigs (120kg body weight) were randomly distributed into 2 treatments:control group (three replications, each with one pig) and experimental group (seven replications, each with one pig). Pigs in control group were fed the basal diet all the time and the experimental group were fed the basal diet supplemented with DHP (400mg/kg of diet) for 20min, then the diet was replaced by basal diet without DHP. At the time of 0.5,1,1.5,2,3,4,6,7,12,24, and 48h after diet replacement, a volume of 20mL blood sample was collected from jugular vein with each pig (seven pigs in experiment group, three pigs in control group); urine samples of each pig was collected every 4 hours for 6 days. DHP in blood and urine was analyzed with HPLC-MS/MS, and the metabolites of DHP in blood and urine was analyzed with HPLC-QTOF/MS/MS.The results showed that after DLY pigs were fed diets with 200mg/kg DHP one-time, 2,6-dimethyl-3-carboxy-5-ethyl pyridine was been detected which was the metabolite of DHP.Exp.2:The Effects of DHP on Growth performance, Carcass traits and Meat quality in finishing pigsThis experiment was conducted to investigate the effects of DHP on growth performance, carcass traits and meat quality in finishing pigs. A total of 12 healthy castrated DLY finishing pigs with an average body weight of about 150 kg were randomly allotted to 2 groups with 6 replicates (1 pig per replicate).The control group was fed basal diet and the experiment group was fed basal diet with 200 mg/kg DHP of diet. The experimental period was 28 days.The results showed that adding 200mg/kg DHP for 28d in the diet there was no significant difference in growth performance, carcass traits meat quality, but significantly reducding long straight.Exp.3:The Effectsof DHP on Growth performance, Meat quality and Residuein Growing-finishing pigsThis experiment was conducted to investigate the effects of DHP on growth performance, carcass traits, meat quality and tissue DHP residue in growing-finishing pigs.A total of 72 healthy castrated DLY pigs with an average body weight of about 60 kg were randomly allotted to 3 groups with 4 pigs per replicate. Pigs in each treatment group were fed diets containing DHP 0、200、 400 mg/kg of diets, respectively.The results showed as fllows:(1) Compared with the control group, the ADG of 200 mg/kg DHP group and 400 mg/kg DHP group were significantly increased (P<0.05), and the F/G was also improved significantly by supplementing 200 mg/kg DHP (P<0.05) or 400 mg/kg DHP (P<0.01).(2) Supplementation of DHP (200 or 400 mg/kg of diet) markedly reduced the average backfat thickness (P<0.01).With DHP supplementation (400 mg/kg), meat pH at 24h postmortem was significantly increased (P<0.01), rate of cooked meat and a* valueswere significantly higher (P<0.01), b* values and shear forces were significantly lower (P<0.01) when compared to the control group.(3) At 56d of the experiment, the ALT of 200 mg/kg DHP group was significantly increased (P<0.01). The T3 and GH concentrations of 400 mg/kg DHP group were markedly higher than that of the control group (P<0.01). The activities of SOD and CAT of 200 mg/kg DHP were extremely significantly increased (P<0.01), and GSH-Px activity was significantly increased (P<0.05).(4) No DHP was detected in urine, tissues or blood of pigs fed 200 mg/kg DHP or 400 mg/kg DHP.In conclusion, after DLY pigs were fed diets with DHP one-time or long-term, DHP was not detected in urine, blood or tissues, but in blood 2,6-dimethyl-3-carboxy-5-ethyl pyridine was detected which was the metabolite of DHP. Adding DHP in the diet of finishing pigs (BW> 150kg) had no significant improvement in growth performance, carcass traits and meat quality. ADFI was slightly reduced while ADG and F/G were slightly increased. Feeding DHP to grower-finishing pigs(60kg～120kg) for 56 days,200 mg/kg DHP group could significantly increase ADG and decrease F/G, and 400 mg/kg DHP group improved the carcass traits and meat quality.DHP for finishing pigs was not harmful to health.