Effects Of Dietary Apple Polyphenols Supplementation On Antioxidant Capacity,Lipid Metabolism And Meat Quality In Pigs

In recent years,with the increasing demand of consumers for high-quality pork,the pig industry has begun to pursue safer,healthier and higher quality pork.Studies have shown that antioxidant capacity and lipid metabolism are closely related to animal carcass traits and meat quality.Apple polyphenols（APs）have strong antioxidant and antibacterial activity and are widely used as natural preservative for meat products.However,there are few reports on the effects of dietary APs supplementation on the meat quality of livestock and poultry.Therefore,this paper studied the effects of dietary apple polyphenols on antioxidative capacity,lipid metabolism and meat quality in pigs to provide a theoretical support for application of apple polyphenols on pork production.Exp.1 Effects of dietary apple polyphenols supplementation on the antioxidant capacity and lipid metabolism in weaned pigletsA total of 54 castrated“Duroc×Landrace×Yorkshire”（DLY）weaned piglets（half of the male and female）with initial body weight of 7.04±0.37 kg were selected and randomly assigned to 3 groups（control groups,0.04%APs group and 0.08%APs group）with 6replicates per group and 3 piglets per replicate,the feeding period lasted for 42 d.The results showed that:（1）There were no differences on growth performance between APs treated groups and control group（P>0.05）.（2）The content of serum MDA was reduced by 0.04%and 0.08%APs（P<0.05）.The activities of hepatic T-AOC and CAT were increased by 0.04%APs（P<0.05）,and serum T-AOC activity was remarkably enhanced by 0.08%APs（P<0.05）.The hepatic Nrf2 m RNA level was upregulated by 0.04%APs（P<0.05）,and the m RNA expressions of hepatic SOD1,CAT and GST were notably increased by 0.08%APs（P<0.05）.（3）Compared to the control group,the contents of serum TG,hepatic TG and T-CHO were decreased by 0.04%APs,while HDL-C content was increased（P<0.05）.The contents of serum TG,T-CHO,LDL-C and hepatic TG were reduced by 0.08%APs（P<0.05）.The m RNA level of HMG-Co AR in liver was decreased by 0.04%and 0.08%APs,while the m RNA levels of LDL-R were up-regulated by 0.04%APs（P<0.05）.The hepatic CPT1b m RNA expression was increased by 0.08%APs（P<0.05）.The m RNA level of ACC in LD muscle was down-regulated by 0.04%and 0.08%APs,while the m RNA levels of CPT1b and PPARαwere up-regulated（P<0.05）.The m RNA level of HSL in LD muscle was up-regulated by 0.08%APs（P<0.05）.（4）Compared to the control group,the proportions of C14:1 and C16:1,Δ9-18desaturase activity in liver were decreased by 0.04%and 0.08%APs（P<0.05）.The proportion of C14:0 was decreased by 0.04%APs（P<0.05）.The proportions of C18:1n9,MUFA andΔ9-16 desaturase activity were decreased by 0.08%APs（P<0.05）,while the proportions of C20:3n6,C20:5n3 and C22:1n9 were increased（P<0.05）.Exp.2 Effects of dietary apple polyphenols supplementation on the antioxidant capacity,lipid metabolism and meat quality in finishing pigsA total of 36 castrated DLY finishing pigs with initial body weight of 71.25±2.40 kg were selected and randomly assigned to 3 groups（control group,0.04%APs group and 0.08%APs group）with 6 replicates per group and 2 pigs per replicate,and the feeding period lasted for 49 d.The results showed that:（1）Compared with the control group,dietary 0.04%and 0.08%APs supplementation had no effect on production performance（P>0.05）.（2）The activity of T-AOC in serum was increased by 0.04%APs,while the level of MDA in liver was decreased（P<0.05）.The activities of T-AOC,CAT in serum,GSH-Px in liver were enhanced by 0.08%APs（P<0.05）.Compared to the control group,the m RNA levels of SOD1,GPX1,CAT and Nrf2 in liver were up-regulated by 0.04%and 0.08%APs（P<0.05）,while the Keap1 m RNA level in liver were down-regulated（P<0.05）.In addition,the m RNA level of GST in liver was increased by 0.08%APs（P<0.05）.（3）Compared to the control group,the contents of serum TG,hepatic TG and T-CHO were reduced by 0.04%and 0.08%APs（P<0.05）,and the content of serum T-CHO was reduced by 0.04%APs（P<0.05）.The m RNA levels of HSL,CPT1b in liver were increased by 0.04%APs and 0.08%APs（P<0.05）.In addition,the m RNA levels of PPARαand LDL-R in liver were up-regulated by 0.08%APs（P<0.05）.The m RNA level of ACC in LD muscle was reduced by 0.04%and 0.08%APs（P<0.05）,while the m RNA levels of HSL and CPT1b were notably upregulated（P<0.05）.The m RNA level of FAS in LD muscle was decreased by 0.04%APs（P<0.05）.（4）Compared to the control group,the proportions of hepatic ether extract（EE）,C16:0and C20:4n6 in liver were decreased by 0.04%APs（P<0.05）,and the proportions of C16:0,C20:4n6 andΔ9-18 desaturase activity were decreased by 0.08%APs（P<0.05）.（5）Compared to the control group,the backfat depth at last lumbar vertebra was decreased by 0.04%APs（P<0.05）.The first rib,last lumbar vertebra and average backfat depth were decreased by 0.08%APs,as well as the abdominal adipose tissue index（P<0.05）.Compared to the control group,/there were no significant differences for dressing percentage,carcass length,backfat depth at the last rib and longissimus dorsi muscle area of finishing pigs in all the APs treated groups（P>0.05）.Carcass characteristics were not remarkably different between the 0.04%and 0.08%APs treated groups（P>0.05）.（6）Compared to the control group,the values of a*_{45 min}and b*_{45 min} in LD muscle were decreased by 0.04%APs（P<0.05）,and the values of L*_{45 min} and b*_{45 min} were decreased by0.08%APs（P<0.05）.Dietary 0.04%and 0.08%APs supplementation had no marked differences for p H values(p H_{45 min}and p H_{24 h}),drip loss,cook loss,marble score and shear force（P>0.05）.There were no remarkably difference on meat quality traits between the 0.04%and 0.08%APs treated groups except for the a*_{45 min} value（P>0.05）.（7）Compared to the control group,the proportions of His and Glu in LD muscle were increased by 0.04%APs（P<0.05）.In addition,the proportions of His,Glu,Lys,Ile,Arg,Asp,total EAA,TAA,the sum of flavor amino acids and the value of EAA/NEAA in LD muscle were remarkably increased by 0.08%APs（P<0.05）.（8）Compared to the control group,the m RNA levels of SLC7A1 and SLC1A2 were increased by 0.04%APs（P<0.05）.In addition,the m RNA levels of SLC7A1,SLC1A2,SLC7A7 and SLC7A2 in LD muscle were significantly increased by 0.08%APs（P<0.05）.（9）Compared to the control group,the proportions of C18:3n3,C22:6n3,the sum of PUFA,total EFA,the radio of PUFA to SFA in LD muscle were increased by 0.04%APs（P<0.05）.（10）Compared to the control group,the contents of T-CHO in LD muscle and blood urine nitrogen（BUN）in serum were decreased by 0.04%and 0.08%APs（P<0.05）,while the content of inosinic acid was increased（P<0.05）.In addition,the fat content in LD muscle was remarkably decreased by 0.04%APs（P<0.05）,and muscle crude protein was significantly increased by 0.08%APs（P<0.05）.Taken together,dietary 0.04%and 0.08%APs supplementation could increase the antioxidative capacity of weaned piglets and finishing pigs,improve lipid levels in serum and liver through regulating lipid and cholesterol metabolism.In addition,apple polyphenols administration could increase the carcass quality through decreasing backfat,and improve meat quality through decreasing the values of L*_{45 min},b*_{45 min} and increasing nutritional value and flavor.