A STUDY OF THE OPTIMUM DEMAND OF PROTEIN BY BLUNT-SNOUT BREAM (Megalobrama amblycephala)
| NACA/WP/88/68 | December 1988 |
| A STUDY OF THE OPTIMUM DEMAND OF PROTEIN BY BLUNT-SNOUT BREAM (Megalobrama amblycephala) |
Shi Wenlei, Shan Jian, Liu Meizhen, Yan Hai, Huang Fengqin
Zhou Xiaowei and Shen Ling
Freshwater Fisheries Research Centre of
Chinese Academy of Fisheries Sciences
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Blunt-snout (Megalobrama amblycephala), also called Wuchang fish in Chinese, is one of the major pond-culutred fish species. This paper gives a brief introduction on the studies on optimum demand of protein by bluntsnout bream.
MATERIALS AND METHOD
Protein gradient feeding method was adopted in this experiment. Specific composition of feeds used for the experiment is given in Table 1.
Table 1. Comparison of feeds used for the experiment Unit : %
| Item | Casein | Dextrin | Mixed inorganic salts | Various vitamins | Cod-liver oil | Cellulose | Gelatin |
| I | 6 | 75 | 4 | 1.5 | 4 | 9.5 | 2.5 |
| II | 12 | 69 | 4 | 1.5 | 4 | 9.5 | 2.5 |
| III | 18 | 63 | 4 | 1.5 | 4 | 9.5 | 2.5 |
| IV | 24 | 57 | 4 | 1.5 | 4 | 9.5 | 2.5 |
| V | 30 | 51 | 4 | 1.5 | 4 | 9.5 | 2.5 |
| VI | 36 | 45 | 4 | 1.5 | 4 | 9.5 | 2.5 |
| VII | 42 | 39 | 4 | 1.5 | 4 | 9.5 | 2.5 |
| VIII | 48 | 33 | 4 | 1.5 | 4 | 9.5 | 2.5 |
| IX | 54 | 27 | 4 | 1.5 | 4 | 9.5 | 2.5 |
| X | 60 | 21 | 4 | 1.5 | 4 | 9.5 | 2.5 |
RESULTS AND ANALYSIS
1. Optimum protein demand of the blunt-snout bream at 20°C water temperature.
The fingerlings with an average weight of 4.0 g were cultured for 29 days. See Table 2 and Figure 1 for the results.
Table 2. Percentage of protein in the diet and weight increase of bluntsnout bream fingerlings
| Feed | Protein (%) | Total weight (beginning) | Total weight (end) | Weight increase | Weight increase rate (%) | Feed coefficient |
| I | 7.02 | 57.53 | 58.07 | 0.54 | 0.94 | 71.30 |
| II | 10.19 | 53.13 | 62.38 | 9.25 | 17.41 | 4.16 |
| III | 15.11 | 58.35 | 66.29 | 7.25 | 13.61 | 4.85 |
| IV | 23.56 | 54.02 | 62.47 | 8.45 | 15.64 | 3.79 |
| V | 26.49 | 55.60 | 66.37 | 10.77 | 19.37 | 2.79 |
| VI | 33.45 | 59.59 | 71.51 | 11.92 | 20.00 | 2.50 |
| VII | 39.73 | 58.48 | 66.61 | 8.13 | 13.90 | 3.67 |
| VIII | 43.66 | 60.46 | 68.83 | 8.37 | 13.84 | 3.56 |
| IX | 50.38 | 56.16 | 62.37 | 6.21 | 11.05 | 4.11 |
| X | 54.32 | 55.81 | 59.60 | 3.79 | 6.79 | 6.73 |
Figure 1. Relationship between protein in feeds and weight increase.
Figure. 2. Relationship between protein in feeds and weight increase
Table 2 and Figure 1 show that when the water temperature is about 20°C, the range of optimum demand of protein in feeds by blunt-snout bream fingerlings is 27.04–30.39%.
2. Optimum protein demand of the blunt-snout bream at 25–30°C water temperature.
The fingerlings with an average weight of 37 g were cultured for 63 days. The results are given in Table 3, 4 and Figure 2.
When the water temperature is 25–30°C, the range of optimum demand of protein in the feeds of blunt-snout bream is 25.58 – 41.40%.
Table 3. Percentage of protein in the diet and the weight increase of blunt-snout bream
| Feed | Protein (%) | Total weight (beginning) | Total weight (end) | Weight increase | Weight increase rate (%) |
| I | 7.02 | 38.25 | 48.25 | 10.00 | 26.14 |
| II | 10.19 | 38.48 | 56.93 | 18.45 | 47.95 |
| III | 15.11 | 35.88 | 53.93 | 18.05 | 50.31 |
| IV | 23.56 | 35.95 | 56.21 | 20.26 | 51.91 |
| V | 26.49 | 37.15 | 57.05 | 19.96 | 53.57 |
| VI | 33.45 | 37.70 | 63.68 | 25.98 | 68.91 |
| VII | 39.73 | 37.23 | 68.33 | 31.10 | 83.85 |
| VIII | 43.66 | 35.23 | 53.80 | 18.57 | 52.39 |
| IX | 50.38 | 31.05 | 48.25 | 17.20 | 55.39 |
| X | 54.32 | 34.03 | 57.43 | 23.40 | 68.76 |
Table 4. Protein composition of feeds & its effects on the protein and fat composition of fish body and the biochemical index of blood
| Protein in feed (%) | Protein in fish (%) | Fat in fish (%) | Gutted fish weight rate (%) | Specific gravity of fish liver | Hemoglobin gram | Erythrocyte 1000/mm3 |
| 7.02 | 16.61 | 15.38 | 82.3 | 1.97 | 5.0 | 131 |
| 10.19 | 17.94 | 13.79 | 86.1 | 1.95 | 5.3 | 149 |
| 15.11 | 17.43 | 13.21 | 87.5 | 1.64 | 5.3 | 145 |
| 23.56 | 18.54 | 11.71 | 87.2 | 1.88 | 5.4 | 155 |
| 26.49 | 18.56 | 11.72 | 87.2 | 1.74 | 5.6 | 154 |
| 33.45 | 17.76 | 11.27 | 88.2 | 1.52 | 5.5 | 191 |
| 39.73 | 18.50 | 10.17 | 88.9 | 1.48 | 6.5 | 249 |
| 43.66 | 18.43 | 12.14 | 88.0 | 1.64 | 5.9 | 170 |
| 50.38 | 17.84 | 8.31 | 88.5 | 1.61 | 5.6 | 163 |
| 54.32 | 19.13 | 8.03 | 88.7 | 1.43 | 5.7 | 159 |
3. Effect of the protein composition of feeds on the protein and fat composition of fish flesh and the biochemical index of blood.
The relationship of the protein composition of feeds to the composition of protein and fat in fish body and to the specific gravity of fish liver is indicated in Figures 3, 4, 5, 6.
| Figure IV Relationship between protein in feeds and protein in fish body | Figure V Relationship between protein in feeds and fat in fish body |
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| Figure VI Relationship between protein in feeds and specific gravity of fish liver | Figure VII Relationship between dextrin content and fat in fish body |
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ACKNOWLEDGEMENT
Our thanks to Yuan Yongmin who assisted in drawing the figures.
