Combined effects of dietary bovine lactoferrin, Lactobacillus plantarum, and xylooligosaccharide on hemato-immunological and digestive enzymes of silvery-black porgy (Sparidentex hasta) fingerlings

A 6-week study was conducted to evaluate the effects of the following eight experimental diets, which varied in bovine lactoferrin (LF), xylooligosacharide (XOS), and Lactobacillus plantarum (LP) as probiotic silvery-black porgy (Sparidentex hasta) juveniles including control (diet 1), 400 mg kg⁻¹ LF + 5 g kg⁻¹ XOS (diet 2), 400 mg kg⁻¹ LF + 10 g kg⁻¹ XOS (diet 3), 400 mg kg⁻¹ LF + 1 × 10⁶ CFU g⁻¹ LP (diet 4), 800 mg kg⁻¹ LF + 5 g kg⁻¹ XOS (diet 5), 800 mg kg⁻¹ LF + 10 g kg⁻¹ XOS (diet 6), and 400 mg kg⁻¹ LF + 1 × 10⁶ CFU g⁻¹ LP (diet 7). Growth performance and humoral immune responses were not affected by different experimental groups (P > 0.05). Hematological parameters including red blood cell count, hemoglobin content, and hematocrit increased by supplementing diets with different combinations of immunostimulants (P < 0.05). Fish fed diet supplemented with 800 mg kg⁻¹ LF + 5 g kg⁻¹ XOS had highest total protease (1.0 ± 0.1 U mg protein⁻¹) and α-amylase (34.9 ± 2.3 mg protein⁻¹) activities (P < 0.05). Our results suggest that diets supplemented with selected levels of LF, XOS, and L. plantarum could not improve growth performance and humoral immunity, however improved hematological and digestive enzyme activities in S. hasta fingerlings.