Dietary inclusion of tuna liquid hydrolysate: Effects on the Pacific white shrimp Penaeus vannamei performance and gut health

Abstract Objective The Pacific white shrimp Penaeus vannamei is of great relevance in the Americas and forms the prime aquaculture activity in Mexico. Novel feed additives like fish by-products increase production profitability and support shrimp health and performance. We aimed to study the effects of tuna liquid hydrolysate (TLH) on the performance of Pacific white shrimp reared in an intensive commercial system under brackish-water conditions, analyze the associated return on investment, and examine TLH-induced modulation of the gut microbiota. Methods We examined two dietary inclusion levels of TLH (2.0% [TLH 2.0] and 4.0% [TLH 4.0]) and their influence on shrimp performance and gut microbial modulation of juvenile Pacific white shrimp raised for 6 weeks in brackish water under intensive conditions. Results Tuna liquid hydrolysate 2.0 led to a higher final biomass, lower feed conversion ratio, and higher final yield than TLH 4.0. Additionally, TLH 2.0 displayed a higher return on investment than the control and TLH 4.0. Survival, final average weight, weight gain, and specific growth rate were unaffected by TLH dietary inclusion. Tuna liquid hydrolysate preserved microbial homeostasis. The phyla Proteobacteria, Firmicutes, Bacteroidetes, candidate phylum OD1 (Parcubacteria), and Fusobacteria were predominant in all experimental groups. Lactococcus, Cetobacterium, Exiguobacterium, Enterococcus, and Mycoplana were the most abundant genera in all experimental groups. The genus Sediminibacterium decreased in both TLH dietary treatments. The probiotic bacterial genus Bacillus was stimulated by the TLH 2.0 diet. The genera Enterococcus, Lactococcus, Cetobacterium, and Shewanella and the order Rhizobiales were part of the core microbiota in Pacific white shrimp. Conclusions Our study suggests that TLH can be included as a functional aquafeed for juvenile Pacific white shrimp, with a recommended dietary inclusion level of 2.0%. It supports optimum growth and survivorship, preserves gut health, and leads to a better return on investment.