| The aim of this study was to investigate the effect of creatine monohydrate (CMH) supplementation on carcass characteristics, meat quality and energy metabolism of postmortem muscle in duck and to knowledge for the further research and reasonable utilization in livestock and poultry industry. The study included two parts and the general results are presented as follows:In the first part, an experiment was designed to study the effect of CMH on carcass composition and meat quality of meat duck.360 healthy 26-d-old cherry valley ducks were randomly divided into 4 groups, with 3 replicates in each group and 30 ducks in each replicate. Experimental treatments were as follows:Ⅰ)the control diet;Ⅱ)the control diet with 0.4%CMH for 5 days before slaughter;Ⅲ)the control diet with 0.1%CMH for 10 days before slaughter;Ⅳ)the control diet with 0.4%CMH for 5 days followed by a control diet with 0.1%CMH for the next 5 days before slaughter. Carcass characteristics, serum biochemical parameter, the content of proximate nutrients in muscle and meat quality of cherry valley duck were determined after the trial period. Results showed that:CMH supplementation had no significant effects on carcass composition, but existed a trend of lean percentage increase and abdominal fat decrease in experimental groups compared with the control. Different volume of CMH supplementations have different effects on serum biochemical parameter of cherry valley duck. CMH supplementation had no significant effects on total protein. About the creatinine level in serum, groupⅡwas significantly different from the normal group. Meanwhile, the content of uric acid showed a downward trend and were significantly different with the normal group(P<0.05). Compared with the control group, the content of albumin of groupⅡ,Ⅲ,Ⅳwere decreased, and groupⅣ was siginificantly decreased(P<0.05). By analyzing the content of proximate nutrient s in pectoralis, leg muscle of cherry valley duck, we found that CMH supplementations have no siginificant effect on it. Through the analysis of pectoralis and leg muscle pH changes within 4 h postmortem, we found that the supplementation of CMH could delay the pH decline in postmortem muscle. No matter which dosing regimen, CMH supplementation improved the pH24h in breast and leg muscle, compared with the normal group. Breast pH24h in groupⅡ,Ⅲ,Ⅳincreased by0.01,0.03,0.04unit, respectively, and leg pH24h in groupⅡ,Ⅲ,Ⅳincreased by 0.01,0.03,0.04unit, respectively. pH24h in breast and leg muscle of group IV was significant diffefence(P<0.05). Compared to the normal group, the breast muscle L* in all the CMH supplementations were increased by 3.16%,5.31%,2.92% respectively, and groupⅢwas siginificantly increased(P<0.05); Different volume of CMH supplementations have no siginificant decreased on a*, but the breast muscle b* present a rising trend, especially groupⅢ,Ⅳwas significant difference between groupⅡand the control group(P<0.05). The leg muscle L* in groupⅣwas siginificant decreased by 7.12% compare to normal group, while groupⅡ,Ⅲdecreased by 3.81%, 4.15% respectively; the leg muscle a*, b* in groupⅡ,Ⅲ,Ⅳwere all increased, and there were significant difference between a*, b* in groupⅡand normal group(P<0.05), b* in groupⅢ(P<0.01), groupⅣ(P<0.05) and normal group. Different volume of CMH supplementations have no significant influence on the drop loss, cooking loss and shear force in breast muscle.In the second part, the experiment was designed to study the effects of different supplementation on the energy metabolism of postmortem muscle. Results showed that glycogen contents of breast and leg muscle in each of experimental groups were higher than those of the control, and the lactic acid showed a downward trend, while glycogen contents were not significantly affected. The lactic acid in breast and muscle in groupⅡ,Ⅲ,Ⅳwere significantly decreased by 30.67%(P<0.05),26.67%(P<0.05),21.33%(P<0.05) respectively, than that in the normal group. The content of the lactic acid in leg muscle of groupⅢandⅣwere significantly lower than that of groupⅡand the control group(P<0.05). CMH supplementation have no significant effect on creatine kinase activity and adenosine phosphate content of breast and leg muscle. The content of creatine, and the total creatine pool in breast and leg muscle were all higher than that of the control except the creatine level in breast muscle of groupⅢwas lower by 3.89%. Though the creatine level in breast muscle were not significantly increased, but the total creatine pool level were significantly increased than normal group (P<0.05). Compare to the normal group, the creatine level in leg muscle in groupⅢ, were significantly increased by 19.86%(P<0.05),19.16%(P<0.05), respectively, and the total creatine pool level in leg muscle of exeperiment groups were all significant increased (P<0.05). The content of phosphocreatine in leg muscle was not significantly different in different level of CMH supplementation, but the content of phosphocreatine in breast muscle of groupⅢ,Ⅳwere significantly increased compared with the normal group(P<0.05). The blood creatine level was improved by 9.76%,17.07% and 31.71%(P<0.05), respectively in groupⅡ,Ⅲ,Ⅳwith different CMH supplementation, and significant difference was found between groupⅣand the control.According to above results, CMH supplementation had no significant effect on the carcass characteristics of cherry valley duck, while it tend to increase of lean meat rate and the decrease of abdominal fat rate. Meanwhile it can decrease lactic acid accumulation and delay pH decline postmortem. Different volume of CMH supplementation have different effects on breast and leg muscle. As a whole, the adding protocol of groupⅣ(the control diet with 0.4%CMH for 5 days followed by a control diet with 0.1%CMH for the next 5 days before slaughter) was better than the others. |
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