| Creatine is an amino acid derivative with an important role in energy metabolism that has been largely used in livestock and poultry diet to improve growth performance in recent years.However,studies in fish are scarce.Based on this,in this study,we studied the effect of creatine added to low fish meal feed on the growth,energy metabolism and muscle quality of spotted seabass(Lateolabrax maculatus).The main research results are as follows:(1)Effects of creatine supplementation on growth and whole-body composition of spotted seabass fed low fishmeal level feedsUsing fish meal and soybean protein concentrate as the protein source and fish oil and soybean oil as the fat source,a test feed with a crude protein level of 45%and a crude fat level of 12%was prepared as a control group(containing 15%fish meal).Add 0.05%,0.1%.0.2%,0.4%creatine(marked as control group.0.05%Cr,0.1%Cr,0.2%Cr,0.4%Cr),and feed the initial body weight(4.4±0.7 g)spotted seabass.A total of 5 treatment groups were tested in the experiment,each treatment group was repeated 3 times,and the three groups of fish were fed the test diets for 8 weeks.During the feeding period,fish were fed twice times daily to satiation.In the end of experiment,samples are collected for analysis.The results showed that the growth of spotted seabass were significantly(p<0.05)influenced by the creatine of adding to the low fishmeal level feeds.In each treatment,the group offered 0.4%Cr diet had the highest weight gain rate,which was significantly higher than the control group.The addition of creatine to the feed had no significant(p<0.05)effect on the hepatosomatic index,viscero somatic index and condition factor of the spotted seabass.Whole-body composition analysis found that there was no significant difference in the total moisture,crude protein,crude fat,and crude ash content of the spotted seabass in each experimental group(p>0.05).According to the results of this experiment,the addition of creatine to the feed can promote the growth of spotted seabass through increase the weight gain rate.Taking the perch weight gain rate(WG)as the evaluation index,the appropriate addition amount of creatine in the feed is 0.31%.(2)Effects of creatine supplementation on energy metabolism of spotted seabass fed low fishmeal level feedsAs the level of creatine added in the feed increased,the content of lactic acid in the muscle was significantly increased,and the activity of lactate dehydrogenase and pyruvate kinase decreased significantly.Compared with the control group,the lactic acid content of the 0.1%Cr and 0.2%Cr test groups was significantly reduced(p<0.05);the lactate dehydrogenase activity in the 0.2%Cr and 0.4%Cr test groups was significantly lower than the control group(p<0.05).There was no significant difference among the remaining groups;pyruvate kinase activity was significantly lower in the 0.1%Cr,0.2%Cr and 0.4%Cr test groups(p<0.05).As the level of creatine added in the feed increased,the activity of creatine kinase in muscle showed an upward trend.Compared with the control group,the 0.1%Cr,0.2%Cr,and 0.4%Cr test groups was significantly higher(p<0.05).The content of glycogen in muscle does not produce a significant difference with the increase of creatine addition level(p>0.05).The relative expression levels of glycogen synthase and AMPKα2 in muscle showed an upward trend with the increase of creatine added in the feed.Compared with the control group,the relative expression levels of glycogen synthase in the 0.1%Cr,0.2%Cr and 0.4%Cr test group was significantly increased(p<0.05),and the relative expression level of AMPKα2 in the 0.2%Cr test group was significantly increased(p<0.05).The relative expression of glucose transporter 4 did not increase with the increase of creatine addition level,and there was no significant difference between the groups(p>0.05).The activity of alanine aminotransferase and aspartate aminotransferase in muscle and liver increased with the increase of creatine.Muscle alanine aminotransferase activity was significantly increased in the 0.2%Cr and 0.4%Cr test groups(p<0.05),and aspartate aminotransferase activity was significantly increased in the 0.1%Cr,0.2%Cr and 0.4%Cr test groups(p<0.05).Liver alanine aminotransferase activity was significantly higher in the 0.1%Cr and 0.4%Cr test groups than the control group(p<0.05),aspartate aminotransferase activity in each test group was significantly higher than the control group(p<0.05),but there was no significant difference between the other test groups(p>0.05).The content of creatine and ATP in muscle showed an upward trend with the increase of creatine in the feed,but there was no significant difference in ATP content between the groups(p>0.05).In the control group(p<0.05).The results of the study show that the addition of creatine to low fish meal feed can improve the energy metabolism of the spotted seabass.(3)Effects of creatine supplementation on muscle quality of spotted seabass fed low fishmeal level feedsThe addition of creatine to low fish meal feed had no significant effect on the pH value and centrifugal water loss rate of pike perch at 24h after slaughter(p>0.05),but significantly affected the pH value and cooking loss rate at 48h after slaughter(p<0.05).The pH value of 0.1%Cr was significantly higher than the control group(p<0.05),the cooking loss of 0.1%Cr and 0.2%Cr test group was significantly lower than the control group(p<0.05).Analysis of the gene expression in the muscles of spotted seabass shows that the addition of creatine to fish meal feed can significantly increase the relative expression levels of m-TOR and IGF-1.The 0.2%Cr test group was significantly increased(p<0.05),and the other groups were not significantly different from the control group(p>0.05).The relative expression of Myogenin,MEF2C,Myf5,Myod and Mstn all decreased first and then increased.The relative expression levels of Myogenin,MEF2C and Myf5 in the 0.2%Cr and 0.4%Cr test groups were significantly higher than the control group(p<0.05),and the relative expression levels of Myod were not significantly different between the test groups and the control group(p>0.05).The relative expression levels of Mstn in the 0.2%Cr and 0.4%Cr test groups were significantly higher than those in the other groups(p<0.05).Compared with the control group,the relative expression level of Caplainl in the muscle of spotted seabass was significantly increased in the 0.1%Cr,0.2%Cr and 0.4%Cr test groups(p<0.05),and the relative expression level of Caplain2 was in the 0.2%Cr and 0.4%Cr test groups Significantly increased(p<0.05);the relative expression of Cast showed a downward trend,and the relative expression of Cast in each test group was significantly lower than that of the control group(p<0.05). |
PDF Full Text Request