| With the application and development of modern genetic and breeding theory,and the extensive use of antibiotics and chemical synthetic drug additives,the natural flavor of livestock and poultry products has changed greatly,and the pollution-free plant extract additives have attracted more and more attention.This study was aimed to investigate the effects of dietary garcinol on growth performance,antioxidant capacity of muscles and muscle fiber type composition of growing-finishing pigs.A total of 48 Duroc×Large White×Landrace ternary hybrid boars with healthy condition and similar weight?35.50±1.50?kg were randomly separated to four treatment groups with twelve pens per treatment and 1 pig per pen.The trial period was 90 days.During the experimental period of 90 days,the control group was fed the basal diet throughout the whole process;groups 1,2,and 3 were continuously fed with 400mg/kg of garcinol diet at 30,60,and 90 days before slaughter,respectively.At the end of the experiment,6 pigs were randomly selected from each group for slaughter.The samples of longissimus dorsi muscle?LDM?were collected and antioxidant index,enzyme activity,muscle fiber type composition,and the m RNA expression levels of muscle fiber types related genes were measured.To supply theoretical basis and experimental evidence for understanding the biological role of mangosteen and its potential as a functional feed additive,The main findings are as follows:?1?The results of growth performance showed that,compared with the control group,the treatment group had no significant effect on the average daily weight gain?ADG?,average daily feed intake?ADFI?and feed weight ratio?F/G?of the whole process of growing-finishing pigs?P>0.05?.?2?Carcass traits and meat quality index results show that:compared with control group,the treatment group had no significant effect on the carcass weight,dressing percentage,the area of the longissimus dorsi muscle and the last rib backfat?P>0.05?,but garcinol feeding for 60 days and 90 days significantly reduced the first ribs and last lumbar vertebra backfat depth?P<0.05?,and the difference between groups was significant?P<0.05?.No effect of dietary garcino supplementation was detected on p H 45 min,L*45 min,b*45 min,cooking loss?P>0.05?,but garcinol feeding for60 days and 90 days significantly increased the p H 24 h,a*45 min,a*24 h,b*24 h?P<0.05?,decreased the L*24 h,shear force,drip loss?P<0.05?,and indicators difference except for the a*24 hand b*24 hwere significantly?P<0.05?.The results showed that garcinol feeding for 60 days and 90 days significantly improved meat quality.?3?The results of muscle glycolysis potential and chemical composition-related indicators showed that:compared with the control group,each treatment group had no significant effect on the water content,crude protein,intramuscular fat,and glycogen content of longissimus dorsi muscle?P>0.05?,garcinol feeding for 60 days and 90days significantly increased the myoglobin content?P<0.05?,reduced glucose+6-phosphate glucose content,lactic acid content,and glycolytic potential?P<0.05?,and the difference between groups was significant?P<0.05?.Muscle-related glycolytic enzyme activity results showed that compared with the control group,garcinol feeding for 30 days had no significant effect on the glycolytic enzymes LDH,PFKFB3,GAPDH,PGK1 and other enzyme activities of LDM?P>0.05?,garcinol feeding for 60 days and 90 days significantly reduced related glycolytic enzyme activity?P<0.05?,but there was no significant difference between the groups?P>0.05?.The above results indicate that garcinol feeding for 60 days and 90 days can significantly inhibit muscle glycolysis.?4?The results of muscle antioxidant indexes showed that:compared with the control group,there was no significant difference in T-AOC in each treatment group?P>0.05?,but there was an increasing trend?0.05?P<0.10?.Compared with the control group,Garcinol feeding for 60 days and 90 days significantly increased the activity of T-SOD,GSH-Px,CAT?P<0.05?,and significantly decreased the MDA content of the LDM?P<0.05?.The above results showed that garcinol feeding for 60days and 90 days could significantly improve the antioxidant capacity of muscles.?5?The results of muscle fiber histology showed that garcinol feeding for 60days and 90 days significantly increased the proportion of I muscle fiber type of the LDM?P<0.05?,and significantly decreased the proportion of?muscle fiber type of the LDM?P<0.05?.Muscle fiber related gene expression results show that dietary garcinol supplementation had no effect on muscle My HC II x m RNA level?P>0.05?.But garcinol feeding for 60 days and 90 days resulted in greater muscle My HC?and My HC?a m RNA levels?P<0.05?,lower My HC?b m RNA level?P<0.05?.?6?Garcinol feeding for 60 days and 90 days significantly decreased p300acetyltransferase activity in the LDM?P<0.05?,and increased PGC-1?activity?P<0.05?.Above all:400 mg/kg garcinoll feeding for 60 days can significantly increase the muscle antioxidant capacity,reduce muscle glycolytic after slaughter,improve the meat quality from the aspects of metabolism.Garcinoll can promote muscle fiber types from?type to?type conversion of growing-finishing pigs,improve the meat quality from the aspects of histology.The possible mechanism is that garcinol can enhance activity of the p300-PGC-1?axis,which in turn affects muscle fiber classification. |
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