Effects Of Animal-plant Protein Ratio On Energy And Nitrogen Budgets Of Juvenile Soft-shelled Turtle

The effects of animal-plant protein ratio in expanded feed on feeding, growth, nutrient digestibility, nitrogen budgets and energy balance of juvenile soft-shelled turtle (Trionyx sinensis) (7.2-9.5g), were investigated in this experiment. Four expanded feeds (Feed 1-4) were formulated, with similar nutrient but different animal-plant protein ratio (Feedl, 1.5; Feed2, 3, Feed3, 5; Feed4, 7). The control feed was a commercial turtle powder one. The followings are the main results.1. The animal-plant protein ratio in expanded feeds has significant effects on feeding rate, protein efficiency ratio (PER) and feed coefficient (FCE). Too low animal-plant protein ratio leads to the increase in feeding rate and FCE, and the declining in PER.2. The specific growth rate (SGR) is not significantly affected by animal-plant protein ratio, but SGR has an increasing trend with the increase of animal-plant protein ratio.3. There aren't significant difference in body composition and morphological indexes of juvenile soft-shelled turtle among different animal-plant protein ratio groups.4. Carbohydrate digestibility increases significantly in responses to the rising of animal-plant protein ratio.5. There is a positive line correlation relationship between assimilation efficiency (y) and animal-plant protein ratio (x):y = 85.19 +0.9883 x6. The animal-plant protein ratio has significant effects on nitrogen budgets:animal-plant protein ratio =1.5:100CN = 7.69 FN + 70.56 UN + 21.75 GN animal-plant protein ratio=3:1000N = 6.85 FN + 64.15 UN + 29.00 GN7. There are significant differences in energy budgets among different animal-plant protein ratio groups, the ratio of growth energy to energy intakedecrease significantly owning to too low animal-plant protein ratio. The energy allocation models under different animal-plant protein ratio are following:animal-plant protein ratio is 1.5:100Ce= 13.63Fe + 7.11Ue + 10.87Ge + 68.40Meanimal-plant protein ratio is 3:100Ce= 11.61Fe +6.58Ue + 17.55Ge + 64.27Meanimal-plant protein ratio is 5:100Ce = 9.89 Fe + 6.75Ue + 15.93Ge + 67.42Meanimal-plant protein ratio is 7:100Ce = 8.19 Fc + 6.80UC + 18.13GC + 66.88Me8. Energy budgets are affected by processing techniques, expansion can increase the ratio of growth energy to energy intake.9. Processing techniques haven't significantly effects on body composition and morphological indexes of juvenile soft-shelled turtle.10. The PER and nutrient digestibility for expanded feed are significantly higher than those for powder feed, while the SGR and FCE for expanded feed are significantly lower than those for powder feed.From above results, some conclusions can be got:1. The protein utilization ability of juvenile soft-shelled turtle is similar to that offish, there are only 20% to 30% intake-protein being used to growth. Too much plant protein in feed can reduce the ratio of growth-protein to intake-protein.2 The proximate composition of feed affects the energy budget model. Higher concentrate of plant protein in feed leads to lower ability of energy absorption, and lower ratio of growth energy to energy intake.3 Comparison in feeding rate, SGR, PER, and nutrient digestibility among different expanded feed groups showed that, the optimum animal-plant protein ratio in expanded feed is 3.4 Expanded feed have many advantages, but too low feeding rate for it restrains the growth of juvenile turtle. So increasing the feeding rate is the pivot part for future work.