Acute change in environmental temperature may have negative impacts on the performance of broiler flocks. Additionally, cold stress may increase the susceptibility to respiratory diseases such as avian infectious bronchitis (IB). The supplementation of biofactors combined with antioxidants may help the animal to cope with early life stressors and improve growth performance. The objective of this study was to evaluate the dietary supplementation of Protected Biofactors and Antioxidants (P(BF+AOx)) on the growth performance, antioxidant activity, expression of immune-related genes, and immunometabolic phenotype of the jejunum and liver of broiler chickens submitted to early life stress.
The treatments were a nutritionally complete basal diet supplemented or not with P(BF+AOx) from 1 to 14 d of age. A total of 720 one-day old male Ross 308 chickens were placed into pens of 30 birds (12 replicates/treatment). The P(BF+AOx) is a complex of vitamins and fermentation extract (vitamin A, vitamin D3, vitamin E, menadione, thiamine, riboflavin, niacin, pantothenic acid, vitamin B6, biotin, folic acid, vitamin B12, L-tryptophan, and fermentation extract of dried Bacillus subtilis, Aspergillus niger and A. oryzae) microencapsulated in a matrix of triglycerides from hydrogenated vegetable oil. Birds were double-vaccinated against infectious bronchitis (IB) at the hatchery and submitted, on d 3, to an acute reduction on environmental temperature (from 32° C to 20°C) for 48 h. Feed intake (FI), body weight gain (BWG), and feed conversion ratio (FCR) were calculated weekly. On d 7 and 15, samples were collected for expression of immune-related genes and kinome array analysis, and serum to evaluate the antioxidant status.
From d 1 to 21 and d 1 to 28, the dietary supplementation of P(BF+AOx) significantly increased BWG (P < 0.05) by 3.6 and 3.8%, and improved FCR (P < 0.05) by 1.2 and 1.8%, respectively. From d 1 to 35, dietary supplementation enhanced BWG (P = 0.03) by 4%. Serum glutathione reductase activity on d 15 was higher in birds fed diets supplemented with P(BF+AOx) compared to the control diet-fed birds (P = 0.04). Dietary supplementation reduced the expression of IL-1ß (P = 0.03) in the lungs on d 7. On d 15, dietary supplementation increased the expression of IL-6 (P = 0.02) and IL-10 (P = 0.03) in the liver. It was observed that, via decreased phosphorylation, catalase was activated in the jejunum and liver, and the phosphorylation of immunoregulatory or proinflammatory proteins was decreased. Other important cellular signaling pathways were also changed in the liver and jejunum due to the supplementation.
The supplementation of P(BF+AOx) improved the growth performance of broiler chickens undergoing early life stress. Further analyses demonstrated that this novel feed additive was beneficial in modulating the immune and antioxidant defense systems of the birds. Overall, the kinome data functionally agreed with the gene expression and antioxidant results and indicates a general anti-inflammatory and antioxidant response in birds supplemented with P(BF+AOx).