Oxidized β-carotene (OxBC), a phytochemical that occurs naturally in plants, is formed by the spontaneous reaction of β-carotene with ambient oxygen. Synthetic OxBC, obtained by full oxidation of β-carotene with air, shows considerable promise as an in-feed antimicrobial alternative additive that enhances health and performance in livestock. OxBC is predominantly composed of β-carotene-oxygen copolymers that have beneficial immune-modulating effects that occur within the innate immune system by priming it to face microbial challenges and by mitigating the inflammatory response. OxBC does not have any direct anti-bacterial activity. Further, unlike traditional immune stimulants, OxBC modulates but does not stimulate and utilize the animal’s energy stores unless directly stress-challenged. These immune effects occur by mechanisms distinct from the provitamin A or antioxidant pathways commonly proposed as explanations for β-carotene’s actions. Trials in poultry, swine, and dairy cows with low parts-per-million in-feed OxBC supplementation have shown performance benefits over and above those of feeds containing regular vitamin and mineral premixes. Through its ability to enhance immune function, health, and performance, OxBC has demonstrated utility not only as a viable alternative to in-feed antimicrobials but also in its ability to provide tangible health and performance benefits in applications where antimicrobial usage is precluded.

The effects of oxidized β-carotene (OxBC) were determined upon the growth performance of swine through their full growth cycle under commercial production conditions in Vietnam. Five hundred 28-day-old-weaned barrows and gilts were used in a 140-day complete wean-to-finish feeding trial. Animals were randomized by weight, and each pen contained 20 pigs with the same ratio of barrows to gilts. There were five dietary treatment groups with five replicate pens per treatment: Control basal diet, no antibiotics or OxBC; Basal diet with antibiotics; no OxBC; Basal diet supplemented with 2, 4, or 8 mg OxBC/kg of diet, no antibiotics. Growth performance parameters were calculated for each production stage (Starter: Days 1–28, Grower: Days 29–84, Finisher: Days 85–140) and for the overall study (Days 1–140). OxBC and antibiotics each improved growth rate, feed efficiency, and body weight compared to the unsupplemented control (p < 0.001). Animals receiving 4 and 8 mg/kg OxBC performed better than animals on antibiotics (p < 0.001). In Starter pigs, OxBC reduced the occurrence of diarrhea dose-dependently (2, 4, and 8 mg/kg) and more so than did antibiotics (p < 0.001). These findings support the concept that oxidized β-carotene can facilitate swine growth and health in the absence of in-feed antibiotics.

Clearance of apoptotic neutrophils (PMN) following infection is critical for the resolution of inflammation. Despite demonstrating immunomodulatory properties, the effects of retinoids in PMN in the context of an inflammatory response remain unknown. Objective: to evaluate the immunomodulatory properties of two retinoids, oxidatively‐transformed carotene‐β (OxC‐β) and retinoic acid (RA) in a model of Mannheimia haemolytica ‐induced bovine respiratory disease, which is characterized by severe inflammation. Results: in vitro , RA and OxC‐β induced caspase‐and time‐dependent apoptosis, but not necrosis, in bovine PMN, but not epithelial cells or fibroblasts. Neither RA nor OxC‐β affected PMN function. In M. haemolytica ‐infected calves (2×10 ⁷ CFU), animals that received a 28‐day dietary OxC‐β treatment (10 mg/kg) had elevated apoptotic leukocytes and reduced LTB ₄ levels in their lower airways 3h post‐infection vs infected‐untreated calves. Conclusion: RA and OxC‐β promote cell‐specific apoptosis and inhibit the production of pro‐inflammatory LTB ₄ , both mechanisms that promote the resolution of inflammation, thereby suggesting an anti‐inflammatory role for retinoid derivatives. Supported by NSERC and AIHS.