Changes of growth performance and plasma biochemical parameters of hybrid grouper (Epinephelus lanceolatus ♂ × Epinephelus fuscoguttatus ♀) in response to substitution of dietary fishmeal with poultry by-product meal

Poultry by-product meal (PBM) has the good properties to replace fishmeal. Present study was conducted to assess the capability of PBM in substituting fishmeal in hybrid grouper (Epinephelus fuscoguttatus♀× Epinephelus lanceolatus♂). Six practical diets (52 % crude protein, 12.5 % crude lipid) were formulated with differently PBM replaced level: 0 % (control diet), 20 %, 40 %, 60 %, 80 % and 100 % (namely PBM0, PBM20, PBM40, PBM60, PBM80 and PBM100, respectively). Hybrid grouper with the initial body weight of 80.00 ± 0.02 g were fed different diets at the circulating water system for 8 weeks. Results presented that compared with the control diet (weight gain ratio: 308.83 ± 2.56 %, specific growth performance: 2.52 ± 0.01 %/d), significant differences were not found in the weight gain ratio (286.42 ± 3.65 %) and specific growth performance (2.42 ± 0.02 %/d) after 60 % fishmeal protein replaced by PBM. Higher inclusion of PBM in the diet had markedly decreased growth performance (P < 0.05). Fish fed with PBM40 diet made no significant effect on the feed, protein and lipid efficiency ratio (1.19±0.01, 2.29±0.01, 9.33±0.12) than the fish fed with PBM0 diet (1.24±0.01, 2.40±0.02, 9.80±0.07). However, the PBM60 diet decreased the feed, protein and lipid efficiency ratio (1.12±0.01, 2.15±0.02, 9.08±0.10) significantly than the control diet (P < 0.05). Moreover, dietary 60 % PBM inclusion level also had no significant effect on decreasing the whole body, muscle and plasma proximate nutrient contents and whole body amino acids, fatty acids contents compared to the control diet group. Based on the results, PBM could successfully replace 40 %–60 % protein from fishmeal in the formulated diets for the hybrid grouper. Present study proposed the supreme inclusion level of PBM in the diets which had important significance to aquafeeds industry.