Determination Of The Dietary Leucine And Ne Requirement For GIFT Strain Of Nile Tilapia(Oreochromis Niloticus)

This experiment took large size GIFT(about50g)as experimental object to study the effect of different groups on growth performance, digestive enzyme activity and non-specific immunity in order to ensure the requirement of Leucine and Isoleucine for GIFT. The studies include two parts:Experiment I, the requirement of Leucine for GIFT.A total of294fish with an average body weight of (53.65±0.05)g were randomly divided into7groups with3replicates in each group and14fish in each replicate. Casein-gelatin-peanut meal and coated amino acid mixture were used as dietary protein source and the dietary amino acid pattern, which was simulated the amino acid pattern found on the32%muscle protein of GIFT (The level of dietary leucine were1.11%,1.51%,1.90%,2.29%,2.69%,3.08%,3.48%). After56d feeding trial, the results showed that:Leucine levels of dietary could affect the growth performance, feed efficiency, digestion and absorption capacity, non-specific immune of GIFT. When the dietary leucine level was2.29%, the weight gain rate(WGR), specific growth rates(SGR) and protein efficiency ratio(PER) got the maximum, feed coefficient rate(FCR)got the minimum; When the dietary leucine level was2.29%, the crude protein and crude lipid of whole body got maximum, the crude protein and crude lipid of muscle got the maximum; the content of total amino acids, total essential amino acid, total non-essential amino acid and leucine of the muscle were maximum. When the dietary leucine level was2.29%,pepsin activity, intestinal amylase activity, intestinal protease activity, Na+-K+-ATPase activity got the maximum; when the dietary leucine level was2.29%,the activity of superoxide dismutase and lysozyme got the maximum; when the dietary leucine level was1.90%, the activity of alkaline phosphatase got the maximum. The above indices were increased firstly and then decreased, the feed coefficient was the first decline after rising trend. Taking WGR, SGR, FCR, PER as the observation index, dietary leucine requirement for GIFT was2.27%-2.33%of diet, or7.08%-7.27%of dietary protein.Experiment II, the requirement of Isoleucine for GIFT. A total of360fish with an average body weight of (49.12±0.13)g were randomly divided into6groups with3replicates in each group and20fish in each replicate. Casein-gelatin-peanut meal and coated amino acid mixture were used as dietary protein source and the dietary amino acid pattern, which was simulated the amino acid pattern found on the32%muscle protein of GIFT (The level of dietary leucine were0.57%,0.86%,1.16%,1.45%,1.75%,2.05%). After63d feeding trial, the results showed that, Isoleucine levels of dietary could affect the growth performance, feed efficiency, digestion and absorption capacity, non-specific immune of GIFT. When the dietary isoleucine level was1.45%, the protein efficiency ratio(PER) and protein deposition rate got the maximum, feed coefficient rate(FCR)got the minimum, When the dietary isoleucine level was1.45%, the crude protein and crude lipid of whole body, crude lipid of muscle, the content of total amino acids, total essential amino acid, total non-essential amino acid and leucine of the muscle were maximum. When the dietary isoleucine level was1.75%, the crude protein of muscle got the maximum; When the dietary isoleucine level was1.45%,pepsin activity, intestinal amylase activity, intestinal protease activity, Na+-K+-ATPase activity, the activity of superoxide dismutase and lysozyme got the maximum; when the dietary isoleucine level was1.75%,the activity of alkaline phosphatase got the maximum. The above indices were increased firstly and then decreased, the feed coefficient was the first decline after rising trend. Taking WGR, SGR, FCR, PER,PDR as the observation index, dietary isoleucine requirement for GIFT was1.43-1.47%of the diet. Under the condition of this experiment, or4.40-4.52%of dietary protein.In summery, dietary leucine requirement for GIFT was2.27%-2.33%of diet,(7.08%-7.27%of dietary protein), dietary isoleucine requirement for GIFT was1.43-1.47%of the diet(4.40-4.52%of dietary protein).