* By Aquaculture Magazine Editorial Team
It is urgently needed to search for an alternative source for fish meal (FM) because the current production of FM is not sufficient to satisfy its increased demand for aquaculture production. This article presents the results of a study that aimed to assess the effect of replacing anchovy meal with chicken by-product meal (CBM) in juvenile abalone (Haliotis discus hannai) feed.
The total production of abalone accounts for only a far smaller proportion of aquaculture production compared to fish; however, it is considered as one of the most expensive seafoods for its scrumptious taste and nutritive value, particularly in China, Korea, and Japan.
Growing demand for abalone brings about a drop in wild stocks as well as an increase in cultured abalone production. China currently produces the largest quantity of abalone in the world, with 203,485 metric tons of abalone production in 2020, followed by Korea, with 20,059 metric tons in the same year (FAO, 2021).
The approach of using waste products to bring about a feed ingredient, as part of the circular economy, contributes to the reduction of the carbon footprint of ingredients utilized in aquafeed formulations. Especially, by-products derived from animals to replace fish meal FM in aquafeeds have recently received considerable attention.
Chicken by-product meal (CBM) mainly composed of chicken heads, bones, feathers, and feet is predominantly produced from chicken processing plants and considered as waste. CBM is inexpensive but contains an appreciable amount of crude protein and lipid. Here is presented research that evaluates the use of CBM as an ingredient replacer to FM as feed for juvenile abalone (Haliotis discus hannai) in terms of growth, survival, and carcass chemical composition.
Materials and Methods
This study aims to assess the effect of replacing anchovy meal with chicken by-product meal (CBM) in juvenile abalone (H. discus hannai) feed. Five diets were formulated to contain 0 (CBM0), 25 (CBM25), 50 (CBM 50), 75 (CBM75), and 100% (CBM100) CBM in replacement to 24% fish meal (FM) (Table 1).
Dried Saccharina japonica, which is the natural food for this species of abalone was also prepared. Each diet was fed to triplicate groups of abalone. 1,260 abalone assigned into eighteen cages were fed for 16 weeks. After the 16-week feeding trial, 30 abalones from each cage were exposed to air for 24 h, and survival was monitored for 7 days.
Results
The content of dry matter, crude protein, crude lipid, and ash in each diet was significantly (p < 0.0001) affected over time, and their significant (p < 0.0001) interaction was observed. The highest lost dry matter content was observed in the CBM100 diet among formulated diets throughout the 48-h observation period.
The highest lost crude protein content was observed in the CBM100 diet among formulated diets throughout the 48-h observation period. The highest lost crude lipid content was observed in the CBM100 diet among formulated diets within the same time measured.
The lost ash content of the CBM0 (5.8%, 7.1%, and 14.9%, respectively) diet was significantly (p < 0.05) lower than that of the CBM100 (7.8%, 9.9%, and 16.1%, respectively) diet and the S. japonica (14.7%, 21.0%, and 23.6%, respectively) throughout the 48-h observation period after seawater immersion. The highest lost ash content was observed in the CBM100 diet among formulated diets within the same time measured.
Survival of abalone ranging from 89.0% to 94.3% showed no significant (p > 0.2) difference among the experimental diets (Table 2). Weight gain and SGR of abalone fed the CBM0 (185.4 ± 12.83% and 0.93 ± 0.040%/ day, respectively) diet were significantly (p < 0.04 for both) higher than those of abalone fed the CBM100 diet (139.0 ± 6.36% and 0.78 ± 0.024%/day, respectively), but not significantly (p > 0.05) different from those of abalone fed the CBM25 (175.7 ± 5.41% and 0.91 ± 0.017%/day, respectively), CBM50 (162.1 ± 8.69% and 0.86 ± 0.030%/day, respectively), and CBM75 (158.4 ± 6.19% and 0.85 ± 0.021%/day, respectively) diets.
The survival of abalone fed all formulated diets showed no significant (p > 0.1 for Log Rank and Wilcoxon tests) difference throughout the 7-day post observation period after 24-h air exposure (Figure 1).
Discussion
It is urgently needed to search for an alternative source for FM because the current production of FM is not sufficient to satisfy its increased demand for aquaculture production (Wu, Yu, et al., 2022b; Yu et al., 2022). CBM containing relatively high crude protein, especially in essential amino acids including arginine, leucine, phenylalanine, and threonine (Ha et al., 2021) can be highly regarded as a good substitute for FM in an abalone diet as well.
Comparable weight gain and SGR of abalone fed the CBM75 diet to abalone fed the CBM0 diet in the present study might indicate that FM (anchovy meal) up to 75% could be replaced by CBM without compromising the growth performance of abalone. However, further increased replacement levels of FM with CBM in the CBM100 diet led to inferior weight gain and SGR of abalone compared to the CBM0 diet. Therefore, CBM seemed to be a sustainable and cost-effective protein replacer for FM in an abalone diet.
Similarly, Ha et al. (2021) reported that diets substituting FM up to 50% with CBM, which is the same CBM used in this study achieved comparable growth performance and feed utilization of olive flounder to fish fed a 65% FM-based diet when fish were fed with a 65% FM-based diet or one of the diets replacing 10%, 20%, 30%, 40%, and 50% FM with CBM for 8 weeks.
Growth performance of abalone fed all formulated diets outperformed abalone-fed S. japonica in this study, being consistent with the previous studies demonstrating that abalone fed a nutrition-balanced diet outperformed the growth of abalone fed macroalgae. This could be elucidated by the fact that poor nutrient content (crude protein: 11.5% and crude lipid: 1.1%) in the S. japonica restricted the growth of abalone because of relatively high dietary protein (25%–30%) (Mai et al., 1995b) and lipid (2%–5%) (Lee, 2004) needs for normal growth of abalone.
Inferior growth performance (weight gain and SGR) of abalone fed the CBM100 diet compared to abalone fed the CBM0 diet in the present study might indicate that an excessive amount of FM substitution with CBM in abalone feed may bring about reduced growth performance. Analogous results were also observed in other studies (Falaye et al., 2011; Kim et al., 2021; Wu, Zhang, et al., 2022) showing that high substitution level of FM with CBM in diets led to the reduced growth performance of fish.
Lower lost content of dry matter, crude protein, crude lipid, and ash throughout the 48-h observation period after seawater immersion in CBM0 diet compared to the CBM100 diet in the present study might suggest that CBM0 diet were more stable than the CBM100 diet. This can partially explain why abalone fed the CBM0 diet out performed the growth of abalone fed the CBM100 diet in the present study, being consistent with the previous study (Lee et al., 2017) demonstrating that abalone-fed diets with higher water stability could produce better growth performance.
Significantly longer shell lengths and wider shell widths of abalone fed the CBM0 diet compared to those of abalone fed the CBM75 and CBM100 diets were observed in this study. In considering combined growth and shell growth including shell length and width, FM up to 50% could be made with CBM in abalone diets without compromising growth performance.
Improved shell length and width of abalone fed the CBM0 diet compared to that of abalone fed the CBM75 and CBM100 diets appeared to be closely related to the growth rate of abalone, agreeing with other studies (Dai & Cho, 2022a; Lebata-Ramos et al., 2021; Luo et al., 2013; Zhao et al., 2018) explaining the positive relationship between shell growth and carcass weight versus growth rate of abalone.
Abalone subjected to air exposure lowered immune response, but increased vulnerability to bacterial infection, and subsequently led to decreased survival (Malham et al., 2003; You et al., 2018). Nevertheless, no remarkable difference in the survival of abalone during the 7-day post-observation period after the 24-h air exposure in the present study might indicate that substituting FM with CBM in diets did not cause any negative effect on the survival of abalone subjected to air exposure.
Conclusion
Chicken by-product meal success- fully substituted for fish meal (an- chovy meal) up to 50% in formulated abalone diets. It exhibited similar growth performance, shell length, and width, and survival response to juvenile abalone subjected to a 24-h air exposure after an experimental duration of 16 weeks.
This is a summarized version developed by the editorial team of Aquaculture Magazine based on the review article titled “CHICKEN BY-PRODUCT MEAL AS A REPLACEMENT TO FISH MEAL IN JUVENILE ABALONE (HALIOTIS DISCUS HANNAIINO 1952) FEED” developed by: DAI, Q. and HWOAN CHO, S. Korea Maritime and Ocean University. The original article was published, including tables and figures, on MARCH, 2023, through WORLD AQUACULTURE SOCIETY. The full version can be accessed online through this DOI: 10.1111/jwas.12973
