Dietary Supplementation of Mixed Organic Acids Improves Growth Performance, Immunity, and Antioxidant Capacity and Maintains the Intestinal Barrier of Ira Rabbits

SIMPLE SUMMARY: Diarrhea in weaned rabbits is one of the most common problems in early weaned rabbits, which can lead to slow growth, decreased immunity, and even death. Against the background of a total ban on the use of antibiotics in feed, the development and utilization of antibiotic substitutes have become top priorities. Mixed organic acids (MOAs), as a residue-free green additive, have the ability to enhance immunity and intestinal digestion, regulate pH, and improve intestinal microbiota. Although there are more studies on MOAs, the current domestic and international studies on them mainly focus on pigs and chickens, and the effects on rabbits are less reported. Therefore, this experiment used weaned rabbits as the experimental object to explore the effects of the dietary addition of MOAs on the growth, immunity, and intestinal function of rabbits, to provide a theoretical basis for the application of MOAs in the production of meat rabbits. The results showed that MOAs could improve the growth performance, immunity, and antioxidant ability and maintain the intestinal barrier function of weaned rabbits, which has a promising application prospect in meat rabbit breeding. ABSTRACT: The aim of this study was to investigate the effects of mixed organic acids (MOAs) on growth performance, immunity, antioxidants, intestinal digestion, and barrier function in Ira rabbits. A total of 192 weaned male Ira rabbits at 35 days of age were randomly assigned to four groups with six replicates of eight rabbits each. The rabbits in the control group (CON) were fed a basal diet, and the antibiotic group (SAL) was fed a basal diet supplemented with 60 mg/kg salinomycin. The test groups were fed a basal diet supplemented with 1000 mg/kg and 2000 mg/kg MOAs (MOA1 and MOA2, respectively). The experiment lasted for 55 days. The results showed that the ADG of Ira rabbits in the SAL group and MOA1 group was higher than that in the CON group (p < 0.05). The serum IL-6 and liver MDA levels of Ira rabbits in the SAL group, MOA1 group, and MOA2 group were lower than those in the CON group (p < 0.05). In addition, sIgA levels in the jejunal mucosa of Ira rabbits in the SAL group and MOA1 group were increased compared with those in the CON group (p < 0.05). Compared with the CON group, the gene expression of IL-6 was decreased (p < 0.05) in the jejunal mucosa of Ira rabbits in the SAL, MOA1, and MOA2 groups, while the gene expression of IL-1β tended to decrease (p = 0.077) and the IL-10 content tended to increase (p = 0.062). Moreover, the gene expression of ZO-1 in the jejunal mucosa of Ira rabbits was elevated in the MOA1 group compared with the CON group (p < 0.05). In conclusion, dietary supplementation with MOAs can improve growth performance, enhance immune function and antioxidant capacity, and maintain the intestinal barrier in weaned Ira rabbits.