Nutritional potential of marine and freshwater algae as dietary supplements for growing rabbits

The aim of this study was to investigate the effect of including marine and freshwater algae in rabbit diets on their performance, digestibility, carcass characteristics, and blood metabolites. One hundred growing male rabbits, aged 30 d and weighing 783.5 ± 2.01 g initial body weight, were randomly assigned to five treatment groups (n = 20 rabbits). Five comparable dietary groups were formulated as follows: the control diet was a basal diet without aquatic plants inclusion, while the diets for the other four treatments included the basal diet plus 4% of marine algae (U. lactuca and P. capillacea) or freshwater algae (S. polyrrhiza and C. aegagropila). Compared with the control group, final body weight, daily weight gain, and feed conversion ratio improved significantly in UL group; followed by those in PC and SP groups (p < .05). Total digestible nutrients and digestible crude protein increased significantly in UL, PC and SP groups. Rabbits in the CA group had lower nitrogen intake, N digested, and N balance decreased than the other groups (p < .05). The UL group had dressing weight and meat protein significant increases, but the SP and CA groups had significant increases in liver, kidney, and spleen weights (p < .05). Including marine and freshwater algae reduced (p < .05) total lipids, total bilirubin, triglycerides, and cholesterol especially in the UL and PC groups, and similarly, HDL and LDL levels were lower in the UL, PC, and SP groups compared to the CA and control groups. In conclusion, the responses in performance, digestibility, and blood metabolites suggest that aquatic plants (with the exception of CA) have the potential to be a sustainable feedstock for growing rabbits' diets.Highlights Ulva lactuca, Pterocladia capillacea and Spirodela polyrrhiza improve rabbits' performance. Marine and freshwater algae inclusion showed no signs of disease. Marine and freshwater algae reduced total lipids, triglycerides, and cholesterol.