Effect of oxidized β-carotene on the growth and feed efficiency of broilers

Fully oxidized β-carotene (OxBC) containing β-carotene-oxygen copolymers is proposed as an alternative to antimicrobial growth promoters. Two trials were conducted to determine the efficacy of OxBC in enhancing growth and feed intake (FI) in male and female Ross × Ross 308 broilers in Ontario, Canada, and in Ross 308 male broilers in the United Kingdom. In the first trial, 0, 1, 2, or 5 ppm OxBC were added to diets in a 20% cornstarch premix, whereas in the second trial, 0, 2, or 5 ppm OxBC were added in a 1% cornstarch or 1% corncob grits premix. In trial 1, 2, and 5 ppm OxBC improved bird final body weights (BW) compared with the unsupplemented, nonmedicated (no bacitracin methylene disalicylate included), negative control birds after 39 d of feeding under commercial conditions (P < 0.05). All levels of OxBC improved feed conversion (FCR) during the finisher period (P < 0.05), whereas 2 and 5 ppm OxBC enhanced FCR relative to the negative control group during the full production cycle (P < 0.05). Average daily FI was not affected by OxBC, whereas 2 and 5 ppm OxBC increased broiler average daily gain (ADG) (P < 0.05). Oxidized β-carotene did not affect bird mortality. The optimal OxBC dose was 2 ppm under the conditions used. In trial 2, 2 or 5 ppm OxBC on cornstarch and 5 ppm OxBC on corncob grits improved ADG, BW, and FI when fed for 35 d, as compared with the negative, nonmedicated control (P < 0.05). Feed conversion was not improved in the OxBC groups compared with the control group (P > 0.05). There were no differences among the 3 OxBC groups (P > 0.05). When birds were fed 2 ppm OxBC on corncob grits, the overall ADG, BW, and FI were lower than the respective control values (P < 0.001). Overall bird mortality was higher than expected for all groups, including the control group, but no dose effect was evident. Cornstarch was the preferred carrier for OxBC, and 2 ppm OxBC was the optimal dose under the conditions used.