The Effects Of Different Peptide On The Growth,Muscle Tissue Structure,Amino Acid Metabolism Of Turbot

This study was conducted to investigate the effects of different peptide on the growth,muscle tissue structure,amino acid metabolism of turbot,in order to provide reference for the nutrition of turbot(Scophthalmus maximus L.).The results are summarized as follows.1.The effects of different peptide on growth and muscle tissue structure of turbot.This experiment was to investigate the effects of different peptide on growth and muscle tissue structure of turbot.Five isonitrogenous and isolipidic diets were formulated and fed to fish.Three free amino acids of the same amount of lysine,leucine and glycine were added to diet as the CAA group,the dipeptide Lys-Leu and free glycine were added to diet as the Lys-Leu group,the dipeptide Lys-Gly and free leucine were added to diet as the Lys-Gly group,the dipeptide Gly-Leu and free lysine were added to diet as the Gly-Leu group,peptides(fish protein hydrolysate)were added to diet as the FPH group,in order to meet the nutritional needs of the turbot for amino acids,amino acid account for 10.18%of diet mixture was added to diets of CAA,Lys-Leu,Lys-Gly and Gly-Leu groups.The results showed that the specific growth rate of CAA group were significantly lower than that of FPH group(P<0.05).The feed efficiency of Lys-Leu,Lys-Gly groups significantly higher than CAA group(P<0.05),while was no significant difference compared with Gly-Leu and FPH group(P>0.05).The trend of feed intake is opposite to feed efficiency.The protein efficiency of CAA group significantly lower than Lys-Leu group(P<0.05),while was no significant difference compared with Lys-Gly,Gly-Leu and FPH group(P>0.05).There were no significant differences in the body composition,the composition of amino acid and morphological structure of muscle fiber between five groups(P>0.05).The above results show that,Compared with free amino acids,fish protein hydrolysate significantly promoted the growth of turbot.Lys-Leu,Lys-Gly and Gly-Leu had no difference in the growth of turbot.Lys-Leu,Lys-Gly significantly improved feed utilization compared with free amino acids,and Lys-Leu group feed was superior to Lys-Gly group,while Lys-Leu,Lys-Gly,Gly-Leu and FPH had no difference in feed utilization.2.The effects of different peptide on changes in free amino acids in muscle and serum over time,amino acid and peptides transporter gene expression of turbot.This experiment was to investigate the effects of different peptide on changes in free amino acids in muscle and serum over time,amino acid and peptides transporter gene expression of turbot.Five isonitrogenous and isolipidic diets were formulated and fed to fish.Three free amino acids of the same amount of lysine,leucine and glycine were added to diet as the CAA group,the dipeptide Lys-Leu and free glycine were added to diet as the Lys-Leu group,the dipeptide Lys-Gly and free leucine were added to diet as the Lys-Gly group,the dipeptide Gly-Leu and free lysine were added to diet as the Gly-Leu group,peptides(fish protein hydrolysate)were added to diet as the FPH group.The results showed that free leucine content in serum was significantly higher in Gly-Leu group compared with CAA and FPH groups at 2h postfeeding,and Lys-Leu group were significantly higher than the FPH group(P<0.05).Free lysine content in serum was significantly higher in Lys-Gly group compared with CAA and Gly-Leu groups at 2h postfeeding(P<0.05).Free leucine content in muscle was significantly higher in Lys-Leu group compared with FPH group at 2h postfeeding(P<0.05).Free lysine content in muscle was significantly higher in Lys-Gly group compared with CAA and FPH groups at 2h postfeeding(P<0.05).Free leucine content in serum was significantly higher in CAA group compared with FPH group at 8h postfeeding(P<0.05).Free lysine content in serum was significantly higher in Gly-Leu group compared with FPH group at 8h postfeeding(P<0.05).Free leucine and lysine content in muscle was significantly higher in Lys-Gly group compared with FPH group at 8h postfeeding(P<0.05).Free leucine and lysine content in muscle and serum was no significant difference in all groups at 24h postfeeding(P>0.05).Fish fed Lys-Leu,Lys-Gly,Gly-Leu,FPH diets had significantly lower level of B~0AT1 and PAT1transcript in proximal intestine than that of fish fed CAA diet(P<0.05).Fish fed Lys-Leu,Lys-Gly,FPH diets had significantly lower level of y~+LAT2 transcript in proximal intestine than that of fish fed Gly-Leu diet(P<0.05),and CAA group significantly higher than FPH group(P<0.05).The expression of PepT1 significantly affected by experimental diets was also found in middle intestine(P<0.05).The expression of PepT1 in Lys-Leu,Lys-Gly group was significantly lower than that in Gly-Leu and FPH treatments(P<0.05),while was no significant difference compared with CAA group(P>0.05).The above results show that,the free leucine content of serum and muscle in the Lys-Leu and Gly-Leu groups increased compared with CAA,Lys-Gly and FPH groups at 2h postfeeding.The free lysine content of serum and muscle in the Lys-Leu and Lys-Gly groups increased compared with CAA,Gly-Leu and FPH groups at 2h postfeeding.The free lysine and leucine content of serum and muscle in the Lys-Leu,CAA,Gly-Leu and Lys-Gly groups no significant difference at 8h and 24h postfeeding,and FPH group was no significant difference compared with CAA,Lys-Leu,Gly-Leu and FPH groups at 24h postfeeding.The free lysine,leucine content in the serum and free leucine content in muscle of all groups decreased with time increased,while the free lysine content in muscle increased with time increased.CAA increases the expression of B~0AT1 and PAT1 in the proximal intestine.Gly-Leu and peptides(FPH)increase the expression of PepT1 in the middle intestine.3.The effects of fish protein hydrolysate on growth and muscle tissue structure of turbot.This experiment was to investigate the effects of fish protein hydrolysate on growth and muscle tissue structure of turbot.Six isonitrogenous and isolipidic diets were formulated and fed to fish.The experimental diets contained two control groups with no fish protein hydrolysate,positive control group included 44%fish meal,negative control group included 22%fish meal.Four experimental groups with different levels of fish protein hydrolysate and fish meal,PH4.5A group contained 22%fish meal and 4.5%fish protein hydrolysate,PH4.5B group contained 17%fish meal and 4.5%fish protein hydrolysate,PH18A group contained 22%fish meal and 18%fish protein hydrolysate,and PH18B group contained 0.5%fish meal and 18%fish protein hydrolysate.The results showed that the weight gain rate and specific growth rate of PH4.5A group andPH18B group were significantly higher than that of PH4.5B group and negative control group(P<0.05)and significantly lower than that of PH18A and positive control groups(P<0.05).The feed efficiency,protein efficiency and protein retention effiency of PH18A and positive control groups were significantly higher than that of PH18B,PH4.5A and negative control group(P<0.05).Contrary to feed efficiency,there were no significant differences in the feed intake among PH18A,PH18B and positive control groups(P>0.05),while these groups were significantly lower than that of PH4.5A,PH4.5B and negative control groups(P<0.05).There were no differences in the contents of crude protein and crude lipid between PH4.5B and negative control groups(P>0.05),while these groups were significantly lower than that of PH18A and positive control groups(P<0.05).There were no significant differences in total amino acids,essential amino acids and non-essential amino acids in the muscles among six groups(P>0.05).The muscle fiber cross-sectional area in PH18A group was significantly higher than that of PH18B,positive control,PH4.5A,negative control,PH4.5B groups(P<0.05),and PH18B group was significantly higher than PH4.5B group(P<0.05).The muscle fiber density of PH18A group and PH18B group was significantly lower than that of PH4.5B group(P<0.05).The above results show that,in terms of growth performance,both 18%and 4.5%fish protein hydrolysate added to high plant protein feeds can promote the growth of turbot and increase the feed efficiency and protein deposition rate of turbot,and growth and feed utilization in fish given 18%fish protein hydrolysate diet showed better than that of fish given 4.5%fish protein hydrolysate diets.For the morphological structure of muscle fiber,18%fish protein hydrolysate in diets can increase the cross-sectional area of muscle fiber and reduce the muscle fiber density,while 4.5%of the fish protein hydrolysate did not affect significantly the cross-sectional area of the muscle fiber and the fiber density.4.The effects of fish protein hydrolysate on changes in free amino acids in muscle and serum over time,amino acid and peptides transporter gene expression of turbot.This experiment was to investigate the effects of fish protein hydrolysate on changes in free amino acids in muscle and serum over time,amino acid and peptides transporter gene expression of turbot.Six isonitrogenous and isolipidic diets were formulated and fed to fish.The experimental diets contained two control groups with no fish protein hydrolysate,positive control group included 44%fish meal,negative control group included 22%fish meal.Four experimental groups with different levels of fish protein hydrolysate and fish meal,PH4.5A group contained 22%fish meal and 4.5%fish protein hydrolysate,PH4.5B group contained 17%fish meal and 4.5%fish protein hydrolysate,PH18A group contained 22%fish meal and 18%fish protein hydrolysate,and PH18B group contained 0.5%fish meal and 18%fish protein hydrolysate.The results showed that total amino acids content in serum was significantly higher in PH4.5A and PH18B groups compared with negative control group at 2h postfeeding(P<0.05),which were significantly lower than the PH18A group(P<0.05),and positive control group was significantly higher than PH4.5B and negative control group(P<0.05).There were similarity trend between essential amino acids and total amino acids.Total amino acids content in muscle was significantly higher in positive control,PH4.5A,PH4.5B,negative control groups compared with PH18A and PH18B groups at2h postfeeding(P<0.05),and the essential amino acids content of positive control and PH18A groups were significantly higher than the PH4.5A,PH4.5B and negative control groups(P<0.05).Total amino acids content in serum was significantly higher in PH18B group compared with PH4.5B group at 12h postfeeding(P<0.05),which were significantly lower than the PH18A group(P<0.05),and PH4.5A group was significantly lower than PH18A group(P<0.05),and positive control and PH18A groups were significantly higher than negative control group(P<0.05).Total amino acids content in muscle was significantly higher in PH4.5B and negative control groups compared with PH18A and PH18B groups at 12h postfeeding(P<0.05),which were significantly lower than positive control group(P<0.05),and the essential amino acids content of positive control and PH18A groups were significantly higher than the PH4.5A,PH4.5B and negative control groups(P<0.05).Total amino acids content in serum was significantly higher in positive control group compared with negative control group at 24h postfeeding(P<0.05).Total amino acids content in muscle was significantly higher in PH4.5A,PH4.5B and negative control groups compared with PH18B groups at 24h postfeeding(P<0.05),and PH18B and PH18A groups were significantly lower than positive control group(P<0.05),and the essential amino acids content of negative control,PH4.5A,PH4.5B and PH18A groups were significantly lower than the PH18A group(P<0.05),which was significantly lower than positive control(P<0.05).Fish fed negative control diet had significantly higher level of PepT2transcript in proximal intestine than that of fish fed other diets(P<0.05).Fish fed negative control diet had significantly higher level of y~+LAT2 transcript in proximal intestine than that of fish fed positive control,PH4.5A,PH4.5B,PH18B diets(P<0.05).Fish fed negative control diet had significantly higher level of CAT1 transcript in proximal intestine than that of fish fed positive control,PH4.5A diets(P<0.05).Fish fed PH4.5B diet had significantly higher level of B~0AT1 transcript in middle intestine than that of fish fed PH18B diet(P<0.05).The above results show that,the free amino acids in serum of turbot showed the same trend of growth in the fourth chapter at 2h and 12h postfeeding,while the free amino acids in serum were not significant differences in the six groups and tend to be stable at 24h postfeeding.With time increased,the free amino acids in the serum of the negative control group gradually increased,and the PH4.5B group decreased first and then increased.The PH18A group,the positive control group,the PH18B group and the PH4.5A group first increased and then decreased.As the level of fish protein hydrolysate added to the feed increased,free amino acids in the muscle gradually decreased.With time increasesed,free amino acids in the muscle gradually increased.