Effects Of Dietary Supplementation With Guanidinoacetic Acid And Complex Antioxidant On Meat Quality,Energy Metabolism And Antioxidant Capacity Of Broiler Chickens

Large-scale and intensive poultry breeding mode has promoted the production of livestock and poultry,but it has also brought a series of problems,such as high yield of heterogeneous meat and decline of meat quality.The meat quality of broilers is affected by many factors,among which the energy metabolism level and redox state are the most important factors.Guanidinoacetic acid（GAA）is the only precursor of creatine synthesis.Exogenous GAA could improve the energy metabolism level of the body,and then improve the meat quality.Complex antioxidant（CA）is a mixture of ethoxyquin（EQ）and propyl gallate（PG）.Studies have shown that EQ and PG could improve the antioxidant capacity of animals.Therefore,this experiment was conducted to investigate the effects of GAA or CA or their combination on growth performance,carcass traits,meat quality,energy metabolism and antioxidant capacity by adding GAA and CA to Ross 308 broiler diet.Experiment 1:Effects of guanidinoacetic acid and complex antioxidant diet on growth performance,carcass traits and meat quality of broiler chickens.In this study,a total of 192 Ross 308 broilers（25-day-old）were allocated into 4 groups,Control group:fed basal diet;GAA group:basal diet+600 mg/kg GAA;CA group:basal diet+150 mg/kg CA;GAA+CA group:basal diet+600 mg/kg GAA+150 mg/kg CA.Each treatment group had 6 replicates with 8 chickens per replicate.Body weight（BWG）and feed intake（FI）were recorded.At 42-d old,the breast and thigh muscles were sampled.The results were as follows:1)Dietary supplementation of GAA decreased the feed/gain radio（F/G）（P<0.05）;The F/G in GAA group,CA group and GAA+CA group was decreased by 7.02%,6.58%and 11.40%,respectively,compared with the control group.2)The eviscerated yield was increased by GAA supplementation（P<0.05）;GAA and CA had an interaction effect on breast muscle yield of broilers（P<0.05）.3)GAA inclusion increased p H_24hof breast（P<0.05）;CA inclusion increased a*value of breast（P<0.05）;GAA and CA had an interaction effect on p H_45minof breast muscle（P<0.05）.4)CA decreased the diameter of muscles fiber in breast and tight（P<0.05）,and tended to increase the density of muscle fiber（P>0.05）.In addition,compared with the control group,GAA group,CA group and GAA+CA group increased the muscle fiber density of breast muscle by 13.44%,18.55%and 23.18%,respectively,and CA group and GAA+CA group increased the muscle fiber density of tight muscle by 8.91%and 18.39%,respectively.The results showed that the GAA,CA or their combination supplementation had beneficial effects on growth performance,carcass traits,meat quality of broilers,and the combination of GAA and CA could exert a synergistic effect in improving the growth performance,meat quality and muscle fiber diameter and density of broilers.Experiment 2:Effects of guanidinoacetic acid and complex antioxidant supplementation on energy metabolism of broiler chickens.This trial design was the same with trial 1.The breast and thigh muscles were sampled.The results showed as follows:1)Dietary GAA supplementation increased the breast glycogen content（P<0.05）;Dietary CA supplementation decreased the lactate content and glycolytic potential in tight muscle（P<0.05）;.GAA and CA had an interaction effect on the breast glycogen content（P<0.05）.2)GAA supplementation significantly decreased the pyruvate kinase（PK）activity in tight muscle（P<0.05）;CA supplementation decreased the activity of breast PK,the activities of PK and lactate dehydrogenase（LDH）in tight muscle（P<0.05）;GAA and CA had an interaction effect on PK of tight muscle（P<0.05）.In addition,compared with the control group,PK activity of tight muscle in GAA group,CA group and GAA+CA group was decreased by 6.05%,19.59%and 40.78%,respectively,and the activity of LDH in tight muscle was decreased by 17.40%,35.17%and 43.64%,respectively.3)CA inclusion decreased the content of adenosine monophosphate（AMP）and the AMP/ATP ratio in breast muscle of broilers（P<0.05）;No interaction between GAA and CA was observed on adenosine triphosphate（ATP）,adenosine diphosphate（ADP）,AMP content in breast muscle of broilers（P>0.05）.The results of this study showed that the addition of GAA,CA or combination of GAA and CA could improve the energy metabolism level of the body,and their combination could exert a synergistic effect in improving the glycolytic enzyme activity.Experiment 3:Effects of dietary guanidinoacetic acid and complex antioxidant on antioxidant capacity of broilersThe experiment design was the same as experiment 1.The breast and thigh muscles from trial 2 were selected for measure.The results showed as follows:1)GAA supplementation increased the activity of glutathione peroxidase（GPX）in liver and the activity of catalase（CAT）in blood and reduced the reactive oxygen species（ROS）levels in breast muscle,tight muscle and liver,and reduced the malondialdehyde（MDA）content in breast muscle and blood of broilers（P<0.05）;CA diet increased the activity of CAT in blood,the GPX activity in breast and liver,and decreased ROS level in breast,tight muscle and liver,and decreased MDA content in breast,tight muscle and blood（P<0.05）.GAA and CA had interaction effects on MDA content,ROS level in breast muscle and the activity of CAT in blood,and GAA+CA group had the lowest ROS level,MDA content and the higest activity of CAT of broilers（P<0.05）.In addition,compared with the control group,the ROS level in tight muscle of GAA group,CA group and GAA+CA group was decreased by2.00%,13.00%and 21.00%,respectively;the ROS level in liver was decreased by14.00%,23.00%and 37.00%,respectively;and the MDA level in blood was decreased by18.00%,20.40%and 37.20%,respectively;2)Dietary CA increased the m RNA expressions of HO-1,NQO1 and GPX in breast muscle,and the m RNA expressions of Nrf2,HO-1 and GPX in tight muscle of broilers（P<0.05）.The results showed that the supplementation of GAA,CA or the combination of GAA and CA increased antioxidant enzyme activities,reduced the levels of ROS and MDA,and the combination of GAA and CA had the best effect.In conclusion,GAA,CA or combined with GAA and CA improved the growth performance,carcass traits,meat quality,energy metabolism,antioxidant capacity,and the combination of GAA and CA had the best effect.