Dietary nano-encapsulated Nigella sativa oil and Lactobacillus acidophilus enhance performance, antioxidant status, and gut health in heat-stressed growing rabbits

The present study evaluated the effects of adding Lactobacillus acidophilus, Nano-encapsulated Nigella Sativa oil, or their combination to alleviate the influences of heat stress on the health and performance of growing rabbits. A total of one hundred and twenty male New Zealand White rabbits were randomly assigned to 4 experimental groups (six replicates, 35 days). Rabbits were fed a basal diet without supplements (first group, CON), whilst the other three groups were supplemented with L. acidophilus (LA, 10 × 108 CFU/kg of diet), nano-encapsulated Nigella Sativa oil (Nano-NS, 300 mg/kg), or their mixture (NSLA). Adding the NSLA mixture significantly enhanced body weight gain, improved feed conversion ratio, increased carcase weight, and reduced mortality rate. Additionally, the NSLA supplementation increased trypsin activity and improved nutrient digestibility, particularly of crude fibre and protein. Furthermore, dietary inclusion of the NSLA mixture decreased levels of malondialdehyde (MDA) and interleukin-6 (IL-6), besides increasing superoxide dismutase (SOD), immunoglobulins (IgA and IgG), interleukin-10 (IL-10), and triiodothyronine (T3) levels. Reduced counts of pathogenic bacteria, increased concentrations of volatile fatty acids (VFAs), and upregulated expression of mucin-2 (MUC-2), sodium-glucose cotransporter-1 (SGLT-1), and cationic amino acid transporter-1 (CAT-1) genes in rabbits fed NSLA mixture. We conclude that a dietary supplementation with a combination of nano-encapsulated Nigella Sativa oil and L. acidophilus can effectively mitigate the negative impacts of heat stress in growing rabbits.