| Three 60 d feeding trials were conducted to examine the effects of different dietary arginine, phenylalanine, valine levels on growth performance、body composition、serum enzyme activities and biochemical indices of GIFT tilapia to detect the suitable requirement of folic acid, biotin and cholide in the diet. Dietary folic acid and biotin requirement experiment of GIFT tilapia was conducted in indoor culture system(Volume 500L). Dietary cholide requirement experiment of GIFT tilapia was conducted in pond cages(1m×1m×1.5m. Results of these studies are presented as follows:1. This experiment was conducted to determine the dietary arginine(Arg) requirement for genetically improved farmed tilapia(GIFT) strain of Nile tilapia, Oreochromis niloticus by formulating six isonitrogenous diets(30.21% crude protein, 17.77 MJ/kg general energy) containing Arg with increasing levels of 0.65%, 0.94%, 1.24%, 1.58%, 1.86% and 2.11%, respectively. Each experimental diet was fed to triplicate groups of 15 GIFT with initial body weight [(81.52±2.00) g] in freshwater floating net cages for 60 d. The results showed that with increasing of dietary Arg levels, the weight gains rate(WGR), the specific growth rates(SGR), the protein efficiency ratios(PER), and the protein deposition efficiencies(PDE) increased significantly(P<0.05) which reached their peaks(247.73%, 2.23%, 2.46% and 42.90%) in the 1.58% group, whereas the feed conversion ratios(FCR) decreased significantly(P<0.05) which reached the lowest value(1.34) in the same group. The hepatosomatic index(HSI) and the viscerosomatic index(VSI) of GIFT first decreased with increasing dietary Arg levels, but then increased, yet the condition factor(CF) had no significant differences(P>0.05). The tendency of ash content in muscle and crude lipid content in whole body was similar to FCR with increasing dietary Arg levels, but the tendency of crude lipid content in muscle was similar to WGR and SGR, while the crude protein in muscle and ash content in whole body first increased with increasing dietary Arg levels and then leveled off. And there were no significant differences of crude protein in whole body, moisture in whole body and muscle. With the increase of dietary Arg level, the tyrosine, glycine and alanine in muscle had no significant differences(P>0.05), while the other amino acids contents, gross of essential amino acid(∑EAA), gross of total amino acid(∑TAA) in muscle first decreased, then increased. The serum chemistry analysis showed that dietary Arg had significant effects on contents of aspartate transaminase(AST), alanine aminotransferase(ALT), total protein(TP), blood urea nitrogen(BUN), total cholesterol(T-CHO), glucose(GLU) and triglycerides(TG)(P<0.05). The activities of total Superoxide Dismutase(T-SOD), total nitric oxide synthase(T-NOS), lysozyme(LYZ) in GIFT liver increased with increasing level of dietary Arg but then decreased at further high level of Arg. With regarding the WGR, FCR and PER as the evaluation indicators, the quadratic regression analysis showed that the optimum dietary Arg levels of GIFT was 1.51% to 1.58% of diet or 4.99% to 5.25% dietary protein.2. There is a 60-day growth experiment was conducted to quantify the optimum dietary phenylalanine requirement of GIFT. Triplicate groups of experimental tilapia with initial body weight(52.70?1.80) g were cultured in freshwater floating net cages. Six isonitrogenous(30.10% crude protein) and isocaloric(17.73MJ/kg gross energy) diets to measured phenylalanine levels of the experimental diets were 0.78%, 0.95%, 1.09%, 1.34%, 1.51% and 1.72%, respectively. The results showed that with the increase of dietary phenylalanine levels, the weight gains rate, specific growth rates, protein efficiency ratios, and protein deposition efficiencies increased significantly(P<0.05) which reached their peaks in the 1.34% group, whereas the feed conversion ratios decreased significantly(P<0.05) which reached the lowest values in the 1.09% group. The hepatosomatic index, viscerosomatic index and condition factor of GIFT all increased significantly(P<0.05) as dietary phenylalanine levels increased from 0.78% to 1.34%, but they all decreased with further increasing phenylalanine levels. The highest whole body crude lipid and whole body ash contents were observed in GIFT fed 1.34% dietary phenylalanine, it was significantly(P<0.05) higher than that of GIFT fed 0.78% dietary phenylalanine. No significant difference(P>0.05) was found in whole body moisture, whole body crude protein, muscle moisture, muscle crude protein and muscle crude lipid contents and muscle amino acids contents among all the treatments. The muscle ash content of GIFT fed 0.98% dietary phenylalanine was significantly(P<0.05) lower than that of GIFT fed 1.72% dietary phenylalanine, but showed little difference(P>0.05) with that of the other treatments. The serum chemistry analysis showed that dietary phenylalnine had significant effect on contents glucose, total cholesterol, triglyceride and alanine aminotransferase(P<0.05), but no effect on aspartate aminotransferase contents(P>0.05). The dietary phenylalanine levels had significant effect on activities of intestinal protease, intestinal lipase and Na+-K+-ATPase(P<0.05), whereas the opposite was true for intestinal amylase activities. The quadratic regression analysis of WGR, FCR and PER showed that the optimum dietary phenylalanine requirement of GIFT was 1.17%~ 1.21% of diet or 3.89%~ 4.02% dietary proteins.3. A 10-week growth experiment was conducted to estimate the optimum requirement of dietary available valine for GIFT strain of Nile tilapia Oreochromis niloticus. Six isonitrogenous and isocaloric amino acid test diets were formulated to contain graded levels(0.55%, 0.88%, 1.12%, 1.38%, 1.62% and 1.96% dry diet) of available valine. The results showed that the content of dietary valine had a significant effect on weight gain rate, specific growth rate, feed conversion rate, protein efficiency ratio and protein deposition rate with the valine levels from 0.55% to 1.12% of GIFT(P<0.05). Whole body crude lipid and ash and muscle tissue ash content were affected by valine supplementation. Muscle tissue amino acids were not affected by valine supplementation. Not only dietary valine had affected the serum biochemical indicators, but also affected the serum, liver tissue and foregut tissue nonspecific immune indexes. The quadratic regression analysis of WGR, FCR and PER showed that the optimum dietary valine requirement of GIFT was 1.39%~ 1.43% of diet or 4.59%~ 4.72% dietary proteins. |
PDF Full Text Request