ABSTRACT
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°C); moderately-oxidized soybean oil (SMX) (oil heated for 18h at 200°C); or highly-oxidized soybean oil (SHX) (oil heated for 30h at 200°C). Diets and water were offered ad libitum. The experiment was lasted 21d.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 21were 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.
Keywords:
Intestinal barrier function; inflammation-related factor; oxidative stress; heat-oxidized oil; broilers
