Effects of dietary supplementation with β-glucan-enriched complex and vitamin premix on the growth performance, organ integrity, and intestinal histomorphometric parameters of Nile tilapia

This study evaluated the effects of interactions between β-glucan-enriched complex and vitamin premix on the zootechnical performance and histological and histomorphological parameters of the gastrointestinal tract of juvenile Nile tilapia (Oreochromis niloticus). The diets were supplemented with a manufacturer-indicated dosage of vitamin Premix at 1.5 kg ton feed⁻¹ (Vit_1.5 treatment) and with a high level of vitamin Premix at 2.0 kg ton feed⁻¹ (Vit_2.0 treatment), with or without the β-glucan-enriched complex added at a concentration of 5.0 kg ton feed⁻¹. Thus, the fish were subjected to four treatments: Vit_1.5 (control group), which consisted of individuals supplemented with the indicated level of vitamin Premix; Vit_1.5 + β-glucan group, which consisted of individuals supplemented with Vit_1.5 + β-glucan-enriched complex; Vit_2.0 group, which consisted of individuals supplemented with a high level of vitamin; and Vit_2.0 + β-glucan group, which consisted of individuals supplemented with Vit_2.0 + β-glucan-enriched complex. Twenty-eight experimental units with 40 fish each were used, totaling 1120 juveniles (2.5 ± 0.10 g and 4.9 ± 0.10 cm) fed for 30 days, and the data were collected at the end of the experimental period. There was an improvement in the final weight, final weight gain, and specific growth rate, as well as hepatic sinusoidal congestion, a mononuclear infiltrate, a decrease in microsteatosis, pyknosis nuclei, and melanomacrophage centers, a mononuclear infiltrate, as well as congestion in the spleen and an increase in the number of goblet cells and villi in the intestine. The interaction between β-glucans and vitamin premix in artificial diets for tilapia has been shown to improve zootechnical parameters, albeit slightly, and has led to the development of tissue adaptations in the gastrointestinal tract to improve nutrient absorption. However, pathological conditions were observed in the liver and spleen, and we suggest future research with longer feeding times and subsequent exogenous challenges to confirm these alterations.