Effect of Oxidized Soybean Oils on Oxidative Status and Intestinal Barrier Function in Broiler Chickens

The objective of this study was to evaluate the effect of oxidized soybean oils on the growth performance, metabolic oxidative status and intestinal barrier function of broiler chickens. A total of 240 one-day-old female broiler chickens were assigned to four dietary treatments with six replicates (cages) of 10 birds each. The dietary treatments comprised of a basal diet supplemented with 4% of. non-oxidized (fresh) soybean oil (control treatment, SNX), lowly-oxidized soybean oil (SLX) (oil heated for 10h at 200 degrees C), moderately-oxidized soybean oil (SMX) (oil heated for 18h at 200 degrees C), or highly-oxidized soybean oil (SHX) (oil heated for 30h at 200 degrees C). Diets and water were offered ad libitum. The experiment was lasted 21 d.The growth performance of broilers, determined from 1 to 14 d and from 1 to 21 d of age, was not affected by the dietary treatments (p>0.05). Broilers fed oxidized soybean oils presented higher corticosterone serum levels compared with those fed non-oxidized oil (p<0.05). Higher malondialdehyde (MDA) levels onday14 and 21 (p<0.05), and lower total antioxidant capacity (T-AOC) and totalsuperoxide dismutase (T-SOD) values on day 21 were obtained in the liver of broiler fed oxidized oils relative to those fed the non-oxidized oil (p<0.05). Broilers fed the highly-oxidized soybean oil had higher (p<0.05) MDA levels in the jejunum on day 21 compared with those fed non-oxidized soybean oil. Chickens fed moderately- and highly-oxidized soybean oil presented lower (p<0.05) T-SOD activity inileal mucosa compared with those fed non-oxidized soybean oil. Ileal mRNA expression of claudin-1 tended to be down regulated by the dietary addition of oxidized oils (p=0.056). The mRNA expression of interleukin-22 (IL-22) of broilers fed moderately-oxidized and highly-oxidized soybean oil was higher (p<0.05), and the mRNA expression of occludin and catalase was lower (p<0.05) than those fed non-oxidized soybean oil. However, the morphology of the jejunal and ileal mucosa was not influenced (p>0.05) by the dietary oxidized oil treatments. It was concluded that oxidized oils may cause oxidative stress by reducing intestinal and liver antioxidant capacity, increase intestinal permeability by reducing mRNA expression levels of tight-junction proteins claudin-1 and occludin, and cause inflammation by increasing mRNA expression level of the inflammation-related factor IL-22.