Effect of different bacterial mixtures in the diet of growing New Zealand White rabbits on growth performance, carcass traits, blood parameters, meat quality, and gut microbial load

Abstract

This study examined the impact of dietary probiotics on the health, growth, and meat quality of New Zealand White rabbits. A total of 96 weaned rabbits were divided into three groups: one received a standard diet without probiotics, while the others were given diets containing different combinations of Lactococcus lactis and Bacillus velezensis for eight weeks. By the end of the trial, rabbits in the control and one of the probiotic groups showed greater weight gain, although feed efficiency remained consistent across all groups. Blood analysis revealed improved lipid profiles in the probiotic-fed rabbits, with higher HDL and reduced levels of LDL, cholesterol, and triglycerides. Kidney function markers, including urea and creatinine, also differed between groups, suggesting possible metabolic effects. Antioxidant status improved in the probiotic groups, as indicated by lower malondialdehyde and higher glutathione levels, pointing to reduced oxidative stress. Additionally, the immune response was enhanced, with higher levels of IgM detected. Meat from probiotic-fed rabbits demonstrated better water-holding capacity and greater pH stability, although colour remained unaffected. Notably, analysis of the gut microbiota showed a favourable shift, with an increase in beneficial Lactobacillus and a decrease in harmful bacteria such as E. coli, Clostridium, and coliforms. These findings suggest that incorporating probiotics into rabbit diets can support healthier growth, improve meat quality, and reduce reliance on antibiotics, offering a safer and more sustainable product for consumers.Highlights Probiotics (Bacillus velezensis, Lactococcus lactis subsp. lactis, and Lactococcus lactis subsp. cremoris) significantly affected growth performance in NZW rabbits. Supplementation of probiotics improved antioxidant status and immune response. Probiotic supplementation significantly altered caecal microbiota composition.