The aim of this study was to investigate the effects of administration level of a dietary phytogenic premix (PP) characterized by carvacrol and thymol (Anco FIT – Poultry) on the gene expression profile of antioxidant enzymes (i.e. CAT, SOD, GPX2, GPX7) and transcription factor Nrf2 at intestinal level. In addition, broiler liver and meat lipid oxidation and total antioxidant capacity (TAC) were determined.
Depending on PP inclusion level (0, 750, 1000 and 2000 mg/kg diet) in a three stage feeding program formulated to meet Cobb 500 nutritional requirements, treatments were: PP-0, P-750, PP-1000 and PP-2000. Feed and water were available ad libitum. Each one of the 4 treatments had 125 broilers arranged in 5 replicates of 25 chickens each. At 42d, 2 birds per treatment replicate were analyzed for gene expression and 4 birds per treatment replicate were pooled for biochemical analyses.
Data were analyzed by ANOVA, taking the treatment as fixed effect. Statistical significant effects (P≤0.05) were further analyzed and means were compared using Tukey HSD test. In addition, polynomial contrasts tested the linear and quadratic effect of PP inclusion levels.
Gene expression of SOD was up-regulated in the duodenum (P=0.027), jejunum (P=0.026) and ceca (P=0.023) in PP-1000 and PP-750 compared to PP-0. Expression of GPX2 was up-regulated in the duodenum (P=0.032) and jejunum (P=0.013) in PP-1000 and in ceca (P=0.006) in PP-2000 compared to PP-0, respectively. In addition, Nrf2 was up-regulated in ceca (P=0.024) in PP-1000 compared to PP-0. Intestinal mucosa TAC was higher in duodenum (P=0.011) and ceca (P=0.050) in PP-1000 compared to PP-0.
Lipid oxidation was delayed in a linear pattern with increasing PP inclusion level in breast (PL=0.020) and liver (PL=0.046). Moreover, the PP inclusion level resulted in higher breast (P=0.005), thigh (P=0.002) and liver (P=0.040) TAC. In particular, breast and thigh TAC increased in a quadratic pattern reaching plateau at PP-1000, whereas liver TAC continued to increase linearly.
Overall, a consistent PP inclusion effect on meat, liver and intestinal antioxidant capacity has been shown with PP-1000 being the most effective.
Konstantinos C. Mountzouris, Vasileios Paraskeuas, Eirini Griela, George Papadomichelakis and Konstantinos Fegeros
Department of Nutritional Physiology and Feeding, Agricultural University of Athens, 118 55 Athens, Greece
Presented at the EPC 2018 in Dubrovnik, September 2018