Effect Of Conjugated Linoleic Acid On Meat Quality And Its Mechanism In Chickens

Four experiments were conducted to study the effects of dietary conjugated linoleic acid mixture and trans-10, cis 12 CLA on chicken meat quality, carcass traits, lipid metabolism, MDH and lipoprotein lipase activity. Gene expression of A-FABP and H-FABP was also examined to discuss the different mechanism of between deposition of intramuscular fat and abdominal fat, and mechanism of between CLA mixture and t-10,c-12 CLA on growth performance and meat quality in chicks.Trial 1 was carried out to assess the effects of conjugated linoleic acid on meat quality, leptin and lipoprotein lipase in 126 days Old Beijingyou chickens. The results showed that dietary CLA significantly increased feed conversation rates and intramuscular fat of breast muscle (P <0.05), significantly decreased the percentage of abdominal fat, LPL activity and leptin content in serum (P < 0.05). However, percentages of intramuscular fat, pH and meat colour were not significantly affected (P >0.05) by dietary CLA. It was concluded that dietary CLA could increase feed conversion rates and lower abdominal fat rate, slightly improved meat quality. Mechanism of lower abdominal fat rates may be due to lower lipoprotein lipase activity and leptin content in serum.Trial 2 was conducted to study effect of supplemental trans-10, cis-12 conjugated linoleic acid on growth performance, meat quality and relative enzyme activities in broilers. The results showed that dietary t-10,c-12 CLA significantly increased ADG, feed conversion rates (P <0.05), also significantly decreased abdominal fat rate (P < 0.01), but percentage of breast muscle, thigh muscle and eviscerated yield were not significantly affected (P >0.05) by dietary CLA;dietary CLA had no significant impact on pH, colour L* value, a* value, but colour b* value and shear force (P<0.05);Sensory evaluation of breast muscle on flavour, taste, tenderness and acceptability are significantly increased by t-10,c-12 CLA (P <0.01), however, that of thigh muscle have no significant differences (P>0.05);Dietary CLA have significant effects on concentration of insulin and leptin in serum (P >0.05);MDH activity in many tissues had significantly difference (P <0.01);t-10,c-12 CLA significantly increased FABP expression, dietary trans10, cis12 CLA with 1.0% level significantly increased gene expression of H-FABP in liver, and A-FABP in abdominal mRNA levels (P <0.05). In conclusion, dietary t-10,c-12 CLA improved the feed conversion rate and ADG in broilers, and when dietary CLA was added more than 0.60%, ADG and ADFI has a downward trend;lower abdominal fat rates and higher intramuscular fat may be due to there are significant differences of serum leptin concentration and MDH activity among different tissues, meanwhile, dietary t-10,c-12 CLA significant increase A-FABP and H-FABP gene expression, which may result in lower abdominal fat and serum TG and higher intramuscular fat.Trial 3 investigated effect of trans-10, cis-12 conjugated linoleic acid by abdominal cavity injection on lipids metabolism in broilers. Results show that TG and leptin concentration in serum weresignificantly lower than control group (P <0.05) by dietary supplementation of t-10,c-12 CLA: MDH in liver and fat was significantly higher than the control (PO.01);Insulin in serum was significantly lower than the control (P< 0.05);Compared with control, trans-10, cis-12 CLA addition by injection CLA reduced serum and liver MUFA concentrations, but increased saturated fatty acid concentrations;T-10,c-12 CLA by abdominal cavity injection significantly increased H-FABP expression (PO.05), but did not affected the expression of A-FABP in abdominal fat (P >0.05). In conclusion, CLA by injection changed serum, liver, abdominal fat lipid metabolism and upregulated FABP gene expression.In conclusion, dietary trans-10, cis-12 CLA and CLA mixture have significant broilers' growth performance;Long-term addition of CLA increased intramuscular fat content and related traits of eating quality of chicken meat;dietary addition of CLA decreased serum lipoprotein lipase activity and leptin concentration, affected MDH activity in tissues, and no influence on insulin levels;dietary addition of CLA changed lipid metabolism of the muscle, serum, liver and abdominal, with linear increase of CLA isomers in muscle and other tissues. Dietary added trans 10, cisl2 CLA enhanced gene expression of both A-FABP and H-FABP. Conclusions: CLA could serve as a nutrient that regulate intramuscular fat and abdominal fat, and in comparison with the CLA mixture on growth performance and meat quality, et ai, trans-10, cis-12 CLA is more effective, but further study on more specific mechanisms are needed.