Study On Effects Of Different Resources And Levels Of Methionine In Diets On Gibel Carp (Carassius Auratus Gibelio)

Both of DL-methionine (DL-Met) and2-Hydroxy-4-(methylthio) Butyric Acid CalciumSalt(Methionine Hydroxy Analogue Calcium, MHA-Ca), are widely used feed additives ofmethionine. In this study, effects of different resources and levels of methionine in diets ongibel carp (Carassius auratus gibeilo) were investigated. Experimental fishes were reared inrecirculating system. Two8-week feeding trials were conducted to determine the effects ofdietary methionine level on gibel carp and the optimum dietary methionine requirement ofdifferent sizes of gibel carp. Biological values efficiency of MHA-Ca compared toDL-methionine in diets of gibel carp was also been studied. And the result were respectivelysummarized as follows:1Study on effects of different resources of methionine on dietary requirements ofmethionine and biological values efficiency of MHA-Ca compared to DL-Met in diets ofjuenile gibel carp (Carassius auratus gibeilo)This growth trail was conducted to determine the effects of different resources ofmethionine on the methionine requirement of juenile gibel carp (Carassius auratus gibeilo)with initial weight of2.60g based on practical diets. The relative biological effectivenessbetween MHA-Ca compared to DL-Met has also been studied. Eleven isonitrogenous (crudeprotein content:37.22%)and isoenergetic(gross energy:17.61KJ/kg)diets were formulatedwith graded inclusion levels of DL-methionine levels at0，0.08%，0.16%，0.24%，0.32%，0.40%of diets and MHA-Ca levels at0.095%，0.19%，0.285%，0.38%，0.475%, respectively.Fifty fishes were batch weighted and put into each tank and triplicates were designed for eachtreatment.All the experimental fishes were stocked in a flow-through system, fed four times aday. The results indicated that final body weight(FBW), specific growth rate (SGR), weightgain rate(WGR) and protein productive value(PPV) significantly increased with themethionine supplementation in diets (P <0.05) for gibel carps, which indicated that gibel carpcould utilize DL-Met and MHA-Ca efficiently. There were no differences on conditionfactor(CF) and hepaticsomatic index (HSI)(P>0.05). Methionine levels have no significant impact on fat and energy the whole fish body. The crude protein of whole body ofexperimental groups were higher than that of control group, while ash of control group lowerthan all experimental groups significantly.The methionine productive value (MPV) arereduced significantly（P<0.05）, while other essential amino acid productive values wereincreased with the higher methionine levels of diets. On the basis of SGR, the methioninerequirements of juvenile gibel carp were0.75%of diet, or as2.02%in terms of dietaryprotein with cystine level at0.38%of diet when DL-Met was supplemented. While MHA-Cawas supplemented, the methionine requirements of juvenile gibel carp were0.71%of diet, oras1.91%in terms of dietary protein with cystine level at0.38%of diet on the basis of SGR.The relative biological value of MHA-Ca(SGR) was106%as efficacious as DL-Met.2Study on effects of different resources of methionine on dietary requirements ofmethionine and biological values efficiency of MHA-Ca compared to DL-Met in diets oflarge size of gibel carp (Carassius auratus gibeilo)In this experiment, effects of different diets on growth performance, amino aciddeposition rate, blood indicators of gibel carp were studied, in order to explore the dietaryrequirements of methionine and biological values efficiency of MHA-Ca compared toDL-Met in diets of large size of gibel carp. Eleven isonitrogenous (crude proteincontent:36.13%)and isoenergetic(gross energy:19.47KJ/kg)diets were formulated with gradedinclusion levels of DL-methionine levels at0，0.1%，0.2%，0.3%，0.4%，0.5%of diets andMHA-Ca levels a0.119%，0.238%，0.357%，0.476%，0.595%, respectively. While the controlgroup fed neither DL-methionine nor MHA-Ca. Thirty fishes with initial weight of22.33gwere batch weighted and put into each tank and quadruplicates were designed for eachtreatment.All the experimental fishes were stocked in a flow-through system, fed four times aday. The results indicated that final body weight(FBW), specific growth rate (SGR), weightgain rate(WGR) and protein productive value(PPV) significantly increased with the MHA-Calevels in diets (P <0.05) for gibel carps, while the feed conversion rate was reduced. Thecrude protein content of whole body were significantly increased with increasing methioninelevels (P <0.05).The crude lipid and total energy of carcass were lower than the control group of that. There were no differences on condition factor(CF) and viscerasomatic index(VSI)(P>0.05). The methionine productive value (MPV) were reduced significantly（P<0.05）, while other essential amino acid productive values were increased with the highermethionine levels of diets. Both triglyceride and HDL-cholesterol were reduced significantlyas the supplement of methionine.On the basis of crude protein(CP) content of carcass, themethionine requirements of gibel carp were0.91%of diet, or as2.52%in terms of dietaryprotein with cystine level at0.36%of diet when DL-Met was supplemented. While MHA-Cawas supplemented, the methionine requirements of gibel carp were0.71%of diet, or as1.97%in terms of dietary protein with cystine level at0.36%of diet on the basis of SGR. Therelative biological value of MHA-Ca(CP) was101%as efficacious as DL-Met.In conclusion，the growth performance and crude protein content of whole body werereduced when the methionine of diet can not satisfy the methionine requirements of gibelcarp.Optimal supplementation of methinonine in diets could significantly improve growthperformance and carcass quality of gibel carp. The effect of supplement of MHA-Ca on dietsof gibel carp are better than DL-Met of that. The bio-effieacy of MHA-Ca compared toDL-Met in diets of juvenile gibel carp was higher than that of large size of gibel carp.