| The study was to investigate the effects of extraneous antioxidants lipoic acid (ALA), Acetyl-L-carnitine (ALC) and carnosine on antioxidative capabilities, postmortem muscle condition and mTOR signaling path way of finishing pigs.In Exp.l, the experiment was conducted to evaluate the effects of dietary alpha-lipoic acid (ALA), acetyl-L-carnitine (ALC) and sex on growth performance, carcass characteristics, breast and thigh muscle meat quality, anti-oxidative ability, energy and lipid metabolism in broilers.A total of972one-day-old broilers with equal sex were randomly assigned in a3x3factorial design using3ALA and3ALC levels (6replications,9birds/replication). The ALA and ALC levels were0,50, and100mg/kg, respectively.Results showed that ALA or ALC significantly decreased the daily weight gain (ADG) and daily feed intake (ADFI)(P<0.05). In ALA or ALC treated broiler chickens, a decrease in the percentage of eviscerated yield, abdominal fat percentange and liver weight were found (P<0.05). ALC administration increased breast muscle pecentange (P<0.05). Breast and thigh musle L value were decrased in dietary complementation of ALA or ALC in broilers (P<0.05). LA treated group increased the24h pH in breast and thigh muscle(P<0.05).Increased LA or ALC resulted in increased total antioxidant capacity, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) activities and decreased levels of malondialdehyde (MDA) in serum and liver of birds (P<0.05). In addition, with increasing addition of LA or ALC, increased levels of insulin (INS), as well as decreased (P<0.05) levels of glucose and glucagon (PG) were observed in serum of broilers. Total cholesterol, triglyceride (TG) levels decreased (P<0.05) and nonesterified fatty acid, lipoprotein lipase, lipase levels increased (P<0.05) in serum with increased administration of ALA or ALC. Moreover, a significant (P<0;05) interaction of ALA x ALC was observed for daily feed intake, percentage of eviscerated yield,serum and liver SOD, serum GSH-Px, glucose and TG levels. Birds fed diets containing50mg/kg of ALA and50mg/kg of ALC had higher serum and liver SOD activities, lower serum glucose and TG levels than those fed diets containing100mg/kg of ALA or ALC alone. Overall, present data indicate that50mg/kg ALA and50mg/kg ALC did not influence growth performance of broilers. Besides, ALA and/orALC supplementation at low levels (50or100mg/kg) improved carcass characteristics,meat quality,anti-oxidative ability, energy metabolism and lipid metabolism in broilers, and synergistic effects by the combined supplementation of ALA and ALC were indicated by serum and liver SOD activities, serum glucose and TG levels. Addition of ALA and ALC was suggested in broiler diet, and the advice adding amount is50mg/kg.In Exp.2, the experiment was conducted to determine the effects of L-carnosine (LC) and/or ALA supplementation on growth performance, serum hormones and lipid profiles in finishing pigs. A total of40(LandracexYorkshire) pigs with an initial BW of57.93±3.14kg were assigned into completely random block design with four treatments. Four treatment groups received diets containing control diet (CON),0.1%LC,0.03%ALA, or0.1%LC+0.03%ALA. Growth performance, carcass traits, serum hormones and lipid profiles were measured at the2weeks after the trial and end of the experiment. The results showed that at the end of the experiment, the final live weight and average daily gain of the0.1%LC or0.1%LC+0.03%ALA groups were higher than those of the CON group (P<0.05), but no significantly difference in growth performance and carcass traits between0.03%ALA group and the CON group (P>0.05). Additionally,2weeks after the trial, serum T3,T4levels in the0.1%LC+0.03%ALA groups were higher than those in the CON groups (P<0.05).Serum IGF-1contents was significant increased in0.1%LC group than in the CON groups (P<0.05). Moreover, at the end of the experiment, serum T3, T4levels in the0.1%LC,0.03%ALA, and0.1%LC+0.03%ALA groups were higher than those in the CON groups (P<0.05) and the serum T3level in the0.1%LC+0.03%ALA group was the highest among all the groups (P<0.05).Serum TC and TG levels were significantly lower in the0.1%LC and0.1%LC+0.03%ALA groups than those in the CON group (P<0.05).Serum LDH, HDL-C,VLDL-C and BUN levels were not significant influence in this experiment (P>0.05). Serum LDL-Clevels were lower in the0.03%ALA and0.1%LC+0.03%ALA groups than that in the CON group at the2weeks after the trail and end of the experiment (P<0.05).0.1%LC, ALA, and0.1%LC+0.03%ALA groups resulted in increased SOD activities and decreased levels of MDA in serum at the end of the trail of finishing pigs (P<0.05). Serum GSH-Px was significantly higher in the0.1%LA and0.1%LC+0.03%ALA groups than those in the CON groups (P<0.05). This study suggestedthat dietary supplementation of LC and ALAimproved growth performance and positively modified serum lipid profiles.The growth promotion effect of LC and ALA may be partly related to the increased serum thyroid hormones in pigs.In Exp.3, this study was designed to evaluate the effect of LC and ALA on finishing pigs’ longissimus musle mTOR signaling pathway. On the basis of the second experiment, we determinatedthe expression of mTOR and its signaling moleculesin longissimus musle by Western immunoblotting (Western Blot). The results showed that ALA, LC and LC+ALA group were not significantlyin the expression of AKT/mTOR compared to CON group (P>0.05).ALA group, LC group and LC+ALA group significantly increased the AktSer473phosphorylation levels by33%,24%and37%compared with the control group (P<0.01).Addition of LC and LC+ALA significantly improved mTORSer2448phosphorylation levels by61%and93%than those in CON group (P<0.01).ALA group increased the mTORSer2448phosphorylation levels by22%, but the difference was not significant compared to CON group (P>0.05). ALA, LC and LC+ALA group were not significantlyin the expression of S6K and4EBP1compared to CON group (P>0.05). ALA group, LC group and LC+ALA group compared with the CON group significantly increased S6K phosphorylation levels by29%,32%and31%(P<0.05). Addition ofALA, LC and LC+ALA improved4EBP1Thr70phosphorylation levels by11%,21%and22%than those in CON group, but the difference was not significant (P>0.05). Moreover, ALA group, LC group and LC+ALA group all induced phosphorylation of S6K and4EBP1Thr70. S6K and4EBP1Thr70phosphorylation levels in LC group and LC+ALA group were slightly higher than ALA group, but the difference was not significant (P>0.05). |
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