In Vitro Digestibility Study: Evaluating Plant Proteins Digestibility in Anabas testudineus and Channa punctata

Abstract

Protein is the most important component of any fish feed for its role in growth, especially during the larval stages, and its high cost. Fish meal continues to be a major source of protein in fish feed production. But its supply cannot keep pace with everexpanding aquaculture production, leading to its high cost. Plants are being considered as potential replacements in the search for new alternatives to fish meals. But their application depends significantly on their digestibility in target species. The present study aims to determine the protein content of four locally available plants Moringa oleifera, Ipomoea aquatica, Lemna minor and Salvinia natans, and test their digestibility in vitro by using the pH drop method in two important food fish Anabas testudineus and Channa punctata, of Assam, India. The crude protein in all plants ranged from 19-29%, and the highest crude protein was observed in Lemna minor (29.9 ± 2.34%). The in vitro digestibility was estimated by calculating the RPD% (relative protein digestibility) using casein as a standard reference. Digestibility of the plant proteins exhibited species-specific variations. The RPD% ranged from 50.39% to 75.39% in A. testudineus, and 41.38% to 54.02% in C. punctata compared to that of casein (100%). The highest RPD% was observed in I. aquatica (75.39%) for A. testudineus, and the lowest (50.39%) in L. minor whereas, in C. punctata, the highest RPD% was observed in L. minor (54.02%) and the lowest in I. aquatica (41.38%). The digestibility of all plant proteins was comparatively higher in A. testudineus than in C. punctata. Our results indicate that I. aquatica and L. minor may be a suitable replacement for animal protein in the diet of A. testudineus and C. punctata, respectively, because of their good protein content and high digestibility. Moringa may be considered for utilization in the fish feed as it recorded good protein and digestibility. This information may be useful in developing a cost-effective, plant-based protein diet for the two fish species for their mass production. Keywords: Anabas testudineus, Channa punctata, In vitro digestibility, Ipomoea aquatica, Plant proteins

Lemna minor: Unlocking the Value of This Duckweed for the Food and Feed Industry

“…Another study by Irabor et al [42] showed that up to 50% of fish feed replacement with L. minor is optimal, since above 60%, there is a decline in the growth of catfish (Clarias gariepinus). Another study carried out in India by Devi et al [43] with the objective of determining the protein content of locally available plants, including L. minor, tested the in vitro digestibility, simulating the digestion of two fishes Anabas testudineus and Channa punctata. The highest crude protein was observed in L. minor, above 30%, while showing better digestibility for C. punctata, around 54%.…”

“…Beyond being used as a staple diet for fish, L. minor can also be used as a dried food supplement [21,28,40,42,43] combined with soybeans [44], organic acids [45] and several other types of fishmeal combinations [41,42,46]. As other plants, L. minor also synthesizes metabolites from the plant's secondary metabolism, which for this species remains poorly understood.…”

“…The highest crude protein was observed for L. minor; highest digestibility for Channa punctata [43] Poultry Diet…”

Effect of partial replacement of Fish meal by Lemna minor on the growth and immune response of Heteropneustes fossilis

“…L. minor of the family Lemnaceae is one such floating aquatic plant widely available in India. Due to its high protein, amino acid and fatty acid content and low fibre (Chakrabarti et al, 2018), the plant has been widely tested in fish for the replacement of traditional fish meal (Sonta et al, 2019;Irabor et al, 2022;Goswami et al, 2022, Devi et al, 2022.…”