Turning Animal Waste into Fish Food: A Study on Two Fish Species

Jenn Hoskins
5th March, 2024

Turning Animal Waste into Fish Food: A Study on Two Fish Species

Image Source: Natural Science News, 2024

Key Findings

  • In India, a study tested whey fermented protein as a fishmeal alternative for two fish species
  • Optimal fishmeal replacement by this protein is 12.23% for carp and 40.02% for catfish
  • Catfish, with stomachs, better utilize the fermented protein than stomach-less carp
In the realm of aquaculture, the quest for sustainable and cost-effective fish feed is paramount. The industry has long relied on fishmeal as a primary feed ingredient, but its production is both environmentally taxing and costly. A recent study by WorldFish - India[1] has explored an innovative solution to this problem by utilizing whey fermented animal protein blend (WFAPB) as a potential fishmeal replacer in fish diets. The study focused on two species of fish with different digestive systems: the stomach-less carp fish Labeo rohita and the stomach-bearing catfish Mystus vittatus. The goal was to determine whether WFAPB could effectively replace fishmeal without compromising the fish's growth or the nutritional value of their muscle tissue. Researchers formulated five experimental feeds with varying levels of WFAPB replacing traditional fishmeal: from 0% up to 100%. Initial laboratory experiments spanned fifteen days and monitored the postprandial (after eating) absorption of amino acids—building blocks of proteins—in the fish's blood plasma. It was discovered that replacing more than half of the fishmeal with WFAPB led to an excess absorption of certain amino acids after 6 hours of feeding, with the catfish showing a higher absorption rate than the carp. To assess long-term effects, a 90-day trial was conducted in outdoor cement vats. The study measured the growth of the fish and the deposition of amino acids in their muscle tissue. By employing regression analysis and a two-phase fuzzy methodology, the researchers aimed to find the optimal level of fishmeal replacement that would support both growth and amino acid deposition. The results were enlightening. When considering growth parameters alone, the optimal fishmeal replacement levels were relatively low: 7.63% for L. rohita and 36.79% for M. vittatus. However, when the deposition of 15 amino acids was also factored in, the ideal replacement levels increased slightly to 12.23% for L. rohita and 40.02% for M. vittatus. This indicates that while both species can benefit from the fermented feed, the stomach-bearing catfish are more adept at utilizing the WFAPB. This research ties into the broader context of sustainable aquaculture practices. Previous studies have highlighted the importance of understanding digestive processes in fish to optimize feeding regimes[2], and the potential of using waste streams from the dairy and fisheries industries to create valuable products through fermentation[3]. The current study expands on these concepts by directly applying them to develop a practical feed alternative. Moreover, the study's findings contribute to the sustainable management of whey, a byproduct of the dairy industry that poses environmental challenges[4]. By fermenting whey to recycle animal protein, the research offers an eco-friendly solution that not only reduces waste but also creates a valuable resource for aquaculture. In conclusion, the study by WorldFish - India demonstrates that whey fermentation can be an effective method to produce a sustainable fishmeal alternative. While the replacement levels for optimal growth and nutrient deposition are species-specific, the research provides a foundation for tailoring feed formulations that could benefit various types of fish. The implications for the aquaculture industry are significant, offering a path towards more environmentally sustainable and cost-effective fish farming practices.

AgricultureSustainabilityAnimal Science

References

Main Study

1) Recycling of animal protein wastes in the formulation of feed for Labeo rohita and Mystus vittatus-a comparative evaluation.

Published 2nd March, 2024

https://doi.org/10.1007/s11250-024-03910-6

Related Studies

2) Postprandial pattern of digestive enzymes and protein turnover in meagre (Argyrosomus regius) juveniles.

https://doi.org/10.1016/j.cbpb.2023.110828

3) Characterization and Evaluation of Proteolysis Products during the Fermentation of Acid Whey and Fish Waste and Potential Applications.

https://doi.org/10.1021/acsfoodscitech.2c00157

4) Whey Utilization: Sustainable Uses and Environmental Approach.

https://doi.org/10.17113/ftb.59.02.21.6968


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