Interactive effects of dietary protein and live bakery yeast, Saccharomyces cerevisiae on growth performance of Nile tilapia, Oreochromis niloticus (L.) fry and their challenge against Aeromonas hydrophila infection

Abstract

Yeasts used as a probiotic in fish diets could stimulate fish resistance against bacterial infection and could enhance the activities of digestive enzymes in fish guts. In addition to yeast importance, dietary protein is another important part in fish diets that should be carefully optimized to meet fish requirement. It is proposed that the yeast supplementation may enhance the dietary protein turnover and reduce the protein requirement for fish. Therefore, the interactive effects of dietary protein and yeast levels on the growth performance of Nile tilapia, Oreochromis niloticus (L.) fry and their challenge against Aeromonas hydrophila infection was evaluated. In the present study, ten experimental diets were formulated to contain either 35% or 45% crude protein (CP). For each protein level treatment, bakery yeast (Saccharomyces cerevisiae) was supplemented at 0.0, 0.50, 1.0, 2.0, or 5.0 g/kg diet. Fish (0.25-0.48 g) were distributed at a rate of 25 fish per 140-L aquarium. For each diet, triplicate aquaria were fed twice a day, 5 days a week for 12 weeks. Fish growth and feed utilization were significantly affected by either dietary protein or yeast levels alone, while no significant effect of their interaction was observed. The highest fish growth was obtained at 1.0-5.0 g yeast/kg diet at both protein levels; however, the fish performance at 45% CP was better than that fed on 35% CP diets. The optimum feed conversion ratio (FCR) was obtained when fish fed on 1.0-5.0 and 2.0-5.0 g yeast/kg diet at 35 and 45% CP, respectively. The cumulative fish mortality, after interperitoneal injection with A. hydrophila for 10 days, and bactericidal activity was significantly higher in fish fed 35% CP diets than those fed 45% CP diets. Both variables decreased significantly with the increase in yeast levels. The lowest bacterial count and bactericidal activity were obtained in fish fed 5.0 g yeast/kg diet irrespective to dietary protein levels. It could be concluded that the inclusion of live bakery yeast in practical diets could improve the growth performances, feed utilization, and physiological status of Nile tilapia fry and their challenge against A. hydrophila infection. Moreover, fish performance when fed 45% CP diet was better than those fed 35% CP diet. Based on these results, the most suitable yeast level for maximum Nile tilapia growth was determined to be 2.0 g yeast/kg diet with 45% CP diet; however, this level was recommended to stimulate their productive performance and enhances their resistance against A. hydrophila infection.

Effects of dietary baker’s yeast extract on the growth, blood indices and histology of Nile tilapia (Oreochromis niloticusL.) fingerlings

“…Generally, brewer's yeast is a particularly important natural bioproduct as it contains immune‐stimulating compounds such as β‐glucan, nucleotides, mannan oligosaccharides and chitin, and it has been proven to influence the immune response (Abdel‐Tawwab, ; Abdel‐Tawwab, Abdel‐Rahman, & Ismael, ; Bidhan, ; Li et al., ). The results of our study indicate that the diets supplemented with yeast extract improved growth and have beneficial effects on haematological and biochemical blood parameters, lipid profiles and the histological structure of liver and gut of Nile tilapia.…”

“…Fish diets should not only provide the essential nutrients that are required for normal physiological functioning, but also serve as the medium by which fish receive other components that affect their health (Goda et al., ; Li & Gatlin, ). Baker's yeast, or Saccharomyces cerevisiae yeast, is a particularly important natural bioproduct as it contains immune‐stimulating compounds such as nucleotides, β‐glucan, mannan oligosaccharides and chitin, and it has been proved to influence the fish immune response and to promote growth (Abdel‐Tawwab, ). On the other hand, commercial brewer's yeast is inactive yeast (dead yeast cells) that is a by‐product of brewing.…”

Aqualase®, a yeast-based in-feed probiotic, modulates intestinal microbiota, immunity and growth of rainbow troutOncorhynchus mykiss

“…Levucell SB20 ® ) or a subcellular component (e.g. MacroGard ® and Betagard A ® ), modulate the immune and antioxidant systems, enhance gut maturation and improve survival and growth (Reyes‐Becerril, Salinas, Cuesta, Meseguer, Tovar‐Ramirez, Ascencio‐Valle & Esteban ; Tovar‐Ramírez, Mazurais, Gatesoupe, Quazuguel, Cahu & Zambonino‐Infante ; Abdel‐Tawwab ; Navarrete & Tovar‐Ramírez ; Mohammadi, Mousavi, Ahmadmoradi, Zakeri & Jahedi ).…”

Saccharomyces Cerevisiae Used As Probiotic: Strains Characterization And Cell Viability

“…Abdel-Tawwab [12] evaluated Nile tilapia (Oreochromis niloticus) and observed the physiological variables were directed affected by the diet. Feed with protein levels more than 45 %and yeast added (2.0g Kg -1 ), better were the fish yield and decreased the mortality rate.…”