Preparation Of Coated Lysine And Its Effects On Growth Performance And Feed Utilization In Tilapia Nilotica And Approaching To Its Mechanism

In trial I, Lysine dissolubility of coated lysine hydrochloride in water and intestinal fluid were determined at different condition:(1) content of lysine hydrochloride was 30% or 40% or 50%, respectively. (2) proportion of stearic acid and glyceride was 20% vs 40%, or 30% vs 30%, or 40% vs 20%, respectively. (3) temperature of inlet air was 40'C or 50℃or 80℃, respectively. (4) velocity of coated materials was 1L/min or 2 L/min or 3 L/min, respectively.The result showed that at 5h:(1) lysine dissolubility achieved to 5.1%,8.4% and 40.6% in water, and to 60.3%,92.1% and 93.2% in intestinal fluid, for 30%,40%,50% of coated lysine hydrochloride content, respectively. (2) lysine dissolubility achieved to 36.3%, 11.2% and 6.7% in water, and to 91.3%,89.9%,72.7% in intestinal fluid, for 20% vs 40%, 30% vs 30%,40% vs 20% of proportion of stearic acid and glyceride, respectively. (3) lysine dissolubility achieved to 70.7%,65.4% and 12.6% in water, and to 88.3%,90.4% and 95.7% in intestinal fluid, for 40℃,50℃,80℃of inlet air temperature, respectively. (4) lysine dissolubility achieved to 25.6%,21.5% and 20.3% in water, and to 85.4%,91.5% and 90.3% in intestinal fluid, for 1 L/min,2 L/min,3 L/min of velocity of coated materials, respectively.Results above implicated that the suitable parameters of coated lysine were 40% of lysine hydrochloride,30% stearic acid vs 30% glyceride (coated materials),80℃of inlet air temperature, and 1 L/min of coated materials velocity.In trialⅡ, the research was conducted to evaluate the effects of coated lysine on growth performance, feed utilization, body figure, serum amino acids, serum biochemical parameters, nutrition of whole fish and its muscle, and approach to the mechanism by feeding experiment, dissection experiment and lab analysis of related samples.A total of 720 healthy Tilapia nilotica were divided into three groups, each of which included 8 replicates of 30 individuals each with initial weight 5.09±0.02g. The control group was fed basal diet which was lack of lysine (1.25% lysine). The other groups were supplemented with lysine of 0.32%(in the form of lysine hydrochloride) and 0.83%(in the form of coated lysine hydrochloride) respectively. The feeding experiment was done in tanks (240L) under the conditions of circulation, filtration, temperature 27.8±0.6℃, dissolved oxygen 6.20±0.6mg/L, pH 7.62±0.2. The fish were restricted fed twice per day, total feed weight per day was 6%-12% of fish biomass. Fish was weighed biweekly and the daily ration was adjusted accordingly. Fecal matter and uneaten diets were collected by siphoning from the tank after feeding for 40 minutes. The experiment lasted for 56 days while the preparing experiment was 14 days. During the experimental period, fish activity, feed intake and feces conditions were observed every day, feed intake and weight of the dead fish were recorded. At the end of rearing, the Tilapia nilotica were fasting for 24 hours. Then, the fish were weighed, and weight gain, feed intake and feed conversation ratio were calculated. Nine fish with the same size in each replicates were fetched to determine the length and weight, then, the serum was collected and the fish were dissected. Liver and muscle were collected and length of intestinal was measured. The fish left were fed again as usual, at 1,3,5,7 hours after fed, three fish per replicate were chosen and the serum was collected. Besides, three fish were collected per replicate before and after the experiment as whole fish samples. All samples were snap-frozen in liquid nitrogen for analysis.The results indicated that, dietary coated lysine supplementation had a significant effect (P<0.05) on growth performance, feed utilization, muscle composition, liver composition, body composition, transaminase activities in liver, ratio of intestinal length to body length, ratio of intestinal weight to body weight, biochemical compositions and serum free amino acids. Dietary supplement with lysine hydrochloride had no significant effects (P>0.05) comparing to control group. The highest WGR, SGR, PER, PRE, GPT, GOT, TP, CP and the lowest FCR, BUN, EE, ratio of intestinal length to body length and ratio of intestinal weight to body weight were observed in coated lysine-supplemented group. The WGR, SGR, PER, PRE, GPT, GOT,TP, CP,intestinal length index and intestinal weight index were relatively higher in coated lysine-supplemented group in comparison to the lysine hydrochloride supplemented group, while the FCR, BUN and EE showed the opposite trend. The highest serum free amino acids level occurred at 1h in control group and lysine hydrochloride group., while dietary coated lysine supplementation occurred at 3h.