Abstract
The global criticism on the adverse effects of synthetic antibiotics including destabilization of gut microflora necessitated research into natural alternative like phytobiotics. Tamarind pulp is a phytobiotic known for its antimicrobial, growth-promoting and antioxidants properties, with little information on the mechanism of its growth promotion in fish. Therefore, this study investigated the effects of tamarind pulp (TP) meal as feed additives on the growth, gut microflora, and morphometry in Clarias gariepinus. The fish were fed with diets fortified with graded levels (0.0%, 0.5%, 1.0%, 1.5% or 2.0%) of TP or 0.2% oxytetracycline (OTC). Fish weight gain, feed conversion ratio (FCR), gut microflora and morphometry were determined. The weight gain of fish rose (P 0.05) with increasing levels of TP, while the FCR reduced significantly, compared to those fed the control diets. The total viable counts and enterobacteriaceae from the gut of fish fed OTC-fortified control diet was lower, compared the fish fed unfortified control (0.0% TP) diet and diets containing TP. Fish fed 1.0-2.0% TP-fortified diets had significantly higher yeast counts, compared to those fed other diets, while on the other hand higher (P0.05) Streptococcus sp was obtained from fish fed the control diets. The thickness of muscular lining of the base of villi, villi height and absorption area were higher (P ˂ 0.05) in fish fed OTC-fortified (C2) diet, compared to other treatments, while lower crypt depth were obtained in fish fed TP-fortified diets. The correlation analyses showed moderate negative (R = -0.539 at P 0.05) relationship between FCR and population of enterobacteriaceae while a very strong positive relationship (R = 0.848 at P 0.01) existed between FCR and population of haemolytic Streptococcus. The enhanced growth in fish fed TP-fortified diets could be accredited to the reduced crypt depth and colonization of yeast and reduced Streptococcus counts. Therefore the application of tamarind pulp meal at 2% is recommended for enhanced growth and healthy gut microflora composition.
Highlights
The composition and population of microflora in the gastrointestinal tract play an important role in the growth and health status of animals
The application of tamarind pulp meal at 2% is recommended for enhanced growth and healthy gut microflora composition
Inclusion of tamarind pulp in the diets of C. gariepinus enhanced (P
Summary
The composition and population of microflora in the gastrointestinal tract play an important role in the growth and health status of animals. Gut microflora play significant in digestion by stimulating the enterocytes to synthesize gut peptides which enhance secretion of digestive enzymes such as proteolytic, amylolitic, cellulolytic, and chitinolytic enzymes which are important for digestion of nutrients (Bairaji et al, 2002; Gutowska et al, 2004; Butt and Volkoff, 2019) and improve nutrient utilization and growth performance. Utilization of some phytobiotics has been reported to increase growth of gut beneficial microbiota such as Lactobacillus, Bacillus, yeast, proteolytic bacteria and / or reduction in E. coli, Aeromonas, Vibrios, and other potential pathogenic organisms in fish (Honghai et al, 2004; Giannenas et al, 2012; Ramesh et al, 2013). Clarias gariepinus is a commercial tropical farmed fish species and the most-cultured species in Nigeria, widely cultured intensively in other African countries, as well as in many parts of Europe and Asia due to its fast growth, high consumer acceptance and adaptability to a wide range of environmental conditions and high market value (Al-Dohail et al, 2009; Strauch et al, 2018; Adeniyi, 2020)
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