| This paper reported the results of experiments in which three rendered animal protein ingredients, poultry by-product meal (PBM), blood meal (BM), feather meal (FEM), were used in combination or alone to replace fish meal (FM) in diet formulation of malabar grouper. This study consisted of two experiments:(1) partial replacement of fish meal (FM) by the blend (the ratio is PBM:FEM:BM=7:2:1) in diet formulations for malabar grouper at two different protein levels, (2) partial replacement of fish meal (FM) with the blend used in the experiment (1) and P-PBM.The experimental design and process was as follows:1. In the experiment 1, a 2 X 4 design was established. The fish were fed eight isonitrogenous but non-isocaloric diets formulated to contain 19 MJ Kg-1 GE and 530 g Kg-1 or 490 g Kg-1 CP. The two control diets contained 50% steam dried herring meal, while in the other six diets,12.8%,25.6% or 38.3% the blend was combined to replace 30%,60% or 90% of the FM. A 10-week net pen experiment was carried out with one-year-old malabar grouper (initial body weight: 33.4g fish-1). During the experiment, the fish was hand fed to satiation at 08:00 and 14:00 h daily except the days when strong waves or typhoon attacked Shenao Bay. Water temperature and salinity were measured daily. At the end of the experiment, the fish in each pen was captured and bulk weighed. Three fish was sampled from each pen for the determination of final body composition, condition factor (CF) and hepatosomatic index (HSI).2. In the experiment 2, a 10-week net pen experiment was carried out with one-year old malabar grouper (initial body weight:33.4g fish-1). The control diet contained 50% steam dried herring meal, while in the other five diets,12.8%,25.6% or 38.3% the blend was combined to replace 30%,60% or 90% of the FM and 12.8% or 25.6% the T-PBM to replace 30% or 60% of the FM to compare the effect on the malabar grouper at the lower protein level. During the experiment, the fish were hand fed to satiation at 08:00 and 14:00 h daily except the days when strong waves or typhoon attacked Shenao Bay. At the end of the experiment, the fish in each pen was captured and bulk weighed. Three fish was sampled from each pen for the determination of final body composition, condition factor (CF) and hepatosomatic index (HSI).The study results were as follows:1. In the experiment 1, compared to the control of the two protein level, there were no significant differences in WG, FBW, FI, FCR, CF, HIS and chemical composition (moisture, crude protein, crude lipid and ash) of whole fish body between feeds containing 12.8% to 25.6% the blend and fish fed the control (replaced 30% to 60% of the FM). Fish fed the feed containing 38.3% the blend (replaced 90% of the FM) had lower WG, FBW than that of fish fed the control feed (P<0.05). There were no significant difference between the fore feeds at the higher protein level in protienases activity, but the feeds containing 12.8% to 25.6% the blend (replaced 30% to 60% of the FM) had lower proteinases activity than the control and the feeds containing 38.3% the blend (replaced 90% of the FM).2. In the experiment 2, no significant differences were found in FI, FBW, WG, FCR, FCR, CF, HIS and chemical composition (moisture, crude protein, crude lipid and ash) of whole fish body among fish fed the five test diets with the control. There was no siginificant difference between the control with the five test diets except the feeds containing 5% FM.On the basis of above experiments, we conclude that: the protein level can reduce to 49% CP for malabar grouper reared in net pen; fish meal in practical feeds for malabar grouper can be replaced 60% by the blend; the blend performed as good as the P-PBM at the lower protein level. |
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