Phytogenic Administration and Reduction of Dietary Energy and Protein Levels Affects Growth Performance, Nutrient Digestibility and Antioxidant Status of Broilers

Abstract

The aim of this study was to investigate the effect of reduced dietary energy (ME) and protein (CP) levels along with administration of a phytogenic feed additive (PFA) based on oregano, anise and citrus essential oils, on broiler growth performance, nutrient digestibility, meat and blood biochemical parameters and total antioxidant capacity (TAC).Depending on dietary ME and CP level down regulation compared to a corn-soybean meal basal diet A used as positive control, three diet types [A, B(＝A-3%) and C(＝A-6%)] were implemented. Depending on the inclusion or not of PFA at 125 mg/kg diet, 450 1-d old, male Cobb broilers were randomly allocated in six treatments according to a 3×2 factorial arrangement with 5 replicates of 15 broilers; A: diets formulated optimally to meet broiler nutrient requirements for maximizing protein content of meat for starter, grower and finisher growth periods; APh: A+PFA; B: suboptimal in ME and CP levels by 3%; BPh: B+PFA; C: suboptimal in ME and CP levels by 6%; CPh: C+PFA.Feed conversion ratio (FCR) was improved in birds fed diet A compared to diet C during the grower period (P D ＝ 0.021) and overall (P D ＝0.010). Phytogenic supplementation resulted in higher (P D×Ph ＝0.020) total tract apparent digestibility of fat in birds fed diet C compared to diet A. Birds fed diet A had higher (P D ＝0.001) plasma cholesterol, compared to birds fed diet C. In addition, birds fed diets A and B had higher (P D ＝0.002) breast protein content compared to C. Overall, PFA inclusion reduced cholesterol (P Ph ＝0.002) and increased plasma TAC (P Ph ＜0.001). Moreover, PFA increased breast (P Ph ＝0.001) and thigh (P Ph ＝0.01) TAC. In conclusion, a reduction in dietary ME and CP levels, adversely affected the FCR, whereas PFA supplementation tended (P Ph ＝0.089) to compensate these effects. Moreover, the addition of PFA reduced plasma cholesterol and improved plasma and meat TAC.

Effects of Diet and Phytogenic Inclusion on the Antioxidant Capacity of the Broiler Chicken Gut

“…In this study, overall BWG and FCR were better in chickens receiving diet type H compared to diet type L ( Table 2 ). These results were in line with previous studies regarding effects on performance and relevant biological responses [ 29 , 30 , 31 , 32 ]. However, the topic of energy and protein reduction on metabolic pathways related to cyto-protection via the Nrf2/ARE pathway is still scarce in broilers.…”

Research Note: Phytobiotics modulate the expression profile of circulating inflammasome and cyto(chemo)kine in whole blood of broilers exposed to cyclic heat stress

“…However, chronic HS exposure increased SOD activity in the liver, while lipid peroxides were decreased ( Lin et al., 2000 ). In the intestine, components of the antioxidant system are upregulated by various dietary PFA in broilers, although the magnitude of these changes, as well as impact on overall growth seem to vary based on the PFA studied, dose, and other stress challenges ( Botsoglou et al., 2002 ; Luna et al., 2010 ; Paraskeuas et al., 2016 ; Paraskeuas et al., 2017 ; Mountzouris et al., 2020 ).

Figure 1 Effect of PFA supplementation on circulating antioxidant markers in HS broilers.

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Priming of intestinal cytoprotective genes and antioxidant capacity by dietary phytogenic inclusion in broilers

“…Generally, there is good evidence that the PP constituents may enhance antioxidant capacity when administered in broiler diets. Relevant to literature examples include studies with ginger ( Zhang et al., 2009 ; Zidan et al., 2016 ), lemon balm ( Marcincakova et al., 2011 ), thyme or thymol and/or oregano or carvacrol alone ( Botsoglou et al., 2002 ; Luna et al., 2010 ; Hashemipour et al., 2013 ) or in combination with other phytogenics ( Paraskeuas et al., 2016 ). Furthermore, it has been recently shown that the PP inclusion used in this work improved liver, breast meat and thigh meat TAC ( Mountzouris et al., 2019 ).…”

“…In addition, activation of the Nrf2 pathway by dietary phytogenics such as curcumin and grape seed extract alleviated aflatoxin B1-induced immunotoxicity and oxidative stress in broilers ( Wang et al., 2018 ; Rajput et al., 2019 ). However, it is clear the magnitude of antioxidant and anti-inflammatory capacity of phytogenics will largely depend on the chemical properties of phytogenic constituents, their inclusion level in the diet, the absorptive and post-absorptive phytogenic kinetics and host digestive physiology ( Brenes and Roura, 2010 ; Mueller et al., 2012 ; Sahin et al., 2013 ; Stefanson and Bakovic, 2014 ; Paraskeuas et al., 2016 , 2017 ; Lee et al., 2017 ; Huang and Lee, 2018 ).…”