Effect Of Diet Quality And Ration Level On Growth And Activity Of Fishes With Different Feeding Habits

The present study included the experiments in groups and individual. By determining growth performance and monitoring the activity of the fishes fed diets with different qualities, effects of diet quality on the growth and feed utilization and its physiological ecological mechanism were investigated in different fishes of different feeding habits. The high quality diet (HQ diet) contained high dietary protein and the main protein source was fish meal while the low quality diet (LQ diet) contained low dietary protein and the main protein source was plant protein. During the experiment, growth rate, feed conversion efficiency, body composition and swimming speed and time were determined.In the experiment in groups, effect of dietary quality on growth and feed utilization was investigated in jian carp (Cyprimis carpio var. jian), gibel carp (Carassius auratus gibelio), hybrid carp ("Feng" carp)(Cypritnus carpio var. Xingguo Cyprimis carpiovar. mirror splitteredS ) and hybrid tilapia (Oreochromis niloticus O. aureus). Theresults are showed as the follows:1. For each diet, no significant difference between jian carp and gibel carp was found in specific growth rate of wet weight. But the mechanism of growth between strains was different. For LQ diet, in order to achieve similar growth rate, jian carp improved feed intake while gibel carp improved recovered protein and energy. For HQ diet, in order to achieve similar growth rate, jian carp improved feed conversion efficiency while gibel carp improved feed intake. When the diet quality was improved, jian carp achieved higher growth rate by higher feed conversion efficiency, recovered protein and energy, while gibel carp by higher feed intake and feed conversion efficiency. Compared to gibel carp, jian carp was more efficient in utilizing high diet and less efficient in utilizing poor diet. Under similar food situation, the growth difference in jian carp was mainly from the difference in feed conversion efficiency while the growth difference in gibel carp was from the combination of feed intake and feed conversion efficiency.2. For each diet, feed intake in dry matter, protein and energy were higher significantly in hybrid carp than that in hybrid tilapia. Hybrid carp showed significant lower specific growth rate of wet weight, protein and energy and significant lower feed conversion efficiency, recovered protein and energy than hybrid tilapia did. Feed intake of two fishes were unaffected by diet quality. Feed conversion efficiency, specific growth rate in wet weight, protein and energy of hybrid carp were significantly higher when fedLQ diet than those when fed HQ diet. Recovered protein and energy in hybrid carp was unaffected by diet quality in hybrid carp. Hybrid tilapia showed higher recovered energy when fed HQ diet. It can be concluded that hybrid tilapia was more efficient in utilizing both HQ diet and LQ diet than hybrid carp. Compared to hybrid tilapia, hybrid carp was more sensitive to diet quality.In the experiment in individual, growth trials were conducted to investigate effect of starvation and diet quality on growth and activity in grass carp (Mylopharyngodon piceus), bluntsnout bream (Megalobama amblycephala), gibel carp (Carassius auratus gibelio), common carp (Cyprinus carpio), black carp (Mylopharyngodon piceus) and spined catfish (Plelteobagrus fulvidracd). Growth trials were also conducted at 4 ration levels (starvation, 1/3 satiation, 2/3 satiation and satiation) to investigate the effect of ration size on the growth and activity of six fishes. The growth was determined by body weight change and the activity by swimming distance and time using image motion monitor system.The results are showed as the follows:1. Growth and feed utilization in six fishes were significantly affected by diet quality. The mechanism of growth was different for different fishes. For grass carp, black carp and spined catfish, feed intake was unaffected by diet quality, while specific growth rate in wet and dry weight was significant high...