Study On Antioxidant Activity Of Chestnut Tannins And Its Effect On Growth Performance Of Rabbits

This study included four experiments. Firstly, the effects of chestnut tannins (CT) on growth performance of rabbits reared in normal and high temperature were evaluated; In order to study the antioxidant mechanism of CT, the experiment was conducted to study the effects of CT on lipid oxidation, antioxidant status, and the gene expression of GSH-Px and Cu, Zn-SOD in rabbits; Moreover, the free radical-scavenging activities of CT were evaluated using free radical production in vitro systems.Exp 1.Effects of chestnut tannins on growing rabbit's performance, digestive enzymes activities, apparent digestibility of dietary nutrient, and nitrogen balancesThe aim of this study was to investigate the effects of chestnut tannins (CT) on the growth performance, digestive enzymes activities, apparent digestibility of dietary nutrient, and nitrogen balances of rabbits. The results showed that during the first 2 wk, the 1.0%CT group showed a significantly (P<0.05) higher average daily gain and lower average daily feed intake and feed conversion ratio than the control group, which showed a linear (P<0.05) response with increasing level of CT. Referring to the whole period of the trial, no significant differences were found in growth performance of rabbits among three groups. The CT diet enhancedα-amylase and protease activities of duodenum and jejunum contents of rabbits andα-amylase activities of ileum contents of rabbits. No significant effect was observed onα-amylase, protease and lipase activities of caecum contents of rabbits among three groups. No significant effect was observed on digestibility of dry matter, crude protein, crude fat, and crude fibre. Moreover, there was no difference on nitrogen balance of rabbits compared with control group.Exp 2.Effects of chestnut tannins on carcass characteristics, meat quality, lipid oxidation and fatty acid composition of rabbitsThe aim of this study was to investigate the effects of chestnut tannins (CT) on carcass characteristics, meat quality, lipid oxidation and fatty acid composition of rabbit. Results showed CT had no significant effect on live weight, hot carcass weight, dressing percentage, skin weight, pH, cooking losses, shear force and colour. The TBARS value was lower (P<0.05) in Longissimus thoracis et lumborum (LTL) muscle of rabbits fed 0.5% CT diet. Myristic acid (C14:0; P<0.01), palmitoleic acid (C16:1 cis-9; P<0.05) and pentadecanoic acid (C15:0; P<0.01) showed the lower content in LTL muscle of rabbits fed 1.0% CT diet, whereas the palmitic acid (C16:0) content was higher (P<0.05) in the rabbits of this group. Moreover, the rabbits fed with 0.5% CT diet had lower (P<0.01) levels of trans-vaccenic acid (C18:1 trans-11) compared to rabbits fed with control diet. No significant differences were observed in saturated (SFA), monounsaturated (MUFA), and polyunsaturated (PUFA) fatty acids.Exp 3.Effects of chestnut tannins on growth performance, redox status and gene expression of GSH-Px and Cu, Zn-SOD in rabbits reared in high temperatureThe study was conducted to determine the effects of CT on growth performance, redox status and gene expression of GSH-Px and Cu, Zn-SOD in rabbits reared in high temperature. Results showed that in the first week of the trial, CT supplementation increased (P<0.05) average daily gain (ADG). The CT 1.0% group showed a greater (P<0.05) average daily feed intake (ADFI) than the control group. The CT 0.5% reduced (P<0.05) feed conversion ratio (FCR). From 8 to 14 d of the trial, the CT 0.5% increased (P<0.05) ADG and reduced (P<0.05) FCR. In the last week, The CT 1.0% group showed a greater (P<0.05) ADG and lower (P<0.05) FCR than the control group. The CT 0.5% reduced (P<0.01) ADFI. For the overall period, CT supplementation had a significantly (P<0.05) positive effect on ADG and FCR. The final body weight of the CT 0.5% group was greater (P<0.05) than that of the control group. Furthermore, on 7 d, the inclusion of CT increased SOD (P<0.05), Cu, Zn-SOD (P<0.05) and reduced MDA (P<0.01). The rabbits fed CT 0.5% had significantly (P<0.05) lower cortisol and greater (P<0.05) T-AOC and GSH-Px than the control group. On 14 d, addition of CT increased T-AOC (P<0.01) and reduced MDA (P<0.01). The CT 0.5% group showed lower (P<0.05) cortisol and greater (P<0.05) GSH-Px than the control group. On 21 d, CT significantly (P<0.01) increased GSH-Px. The rabbits fed with the CT 1.0% diet had greater (P<0.05) SOD, Cu, Zn-SOD and lower (P<0.05) cortisol and MDA compared to rabbits fed with the control diet. On 21 d, Hepatic MDA was lower (P<0.01) with CT than without CT. Hepatic GSH-Px, SOD and Cu, Zn-SOD activity of rabbits fed with the CT 1.0% diet was greater (P<0.05) than that of control group. The mRNA expressions of hepatic GSH-Px and Cu, Zn-SOD in liver tissues of 1.0%CT-supplemented rabbits were 12.4 and 3.55 times higher than the levels in the control group, respectively.Exp 4.In vitro study on the antioxidant activity of chestnut tanninsFree radical-scavenging activities of chestnut tannins (CT) were analyzed using free radical production in vitro systems (1, 1-dipheyl-2-pic-rylhydrazyl radical, hydroxyl radical and superoxide anion radical). The results showed that the CT could scavenge free radical. The scavenging capacities of the CT against 1,1-dipheyl-2-pic-rylhydrazyl, hydroxyl radical and superoxide anion radical increased with the increasing of its concentrations. The concentrations of CT which were necessary to decrease the initial concentration (IC50) of 1, 1-dipheyl-2-pic-rylhydrazyl, hydroxyl radical and superoxide anion radical were higer than Vc.