Effects of Graded Levels of Ethanolic Romanesco Cauliflower (Brassica oleracea var. botrytis) Leaf Extract in Drinking Water on Growth Performance and Functional and Sensory Meat Traits of Ross 308 Broilers under Cyclic Heat Stress

Abstract

The aim of this experiment was to determine the effect of ethanolic Romanesco cauliflower (Brassica oleracea var. botrytis) leaf extract when supplemented in drinking water on the negative effects of cyclic heat stress in Ross 308 broilers. The 240 one-day-old chicks were assigned to 4 treatments (0, 200, 400, 600 mg dry matter/L of drinking water) and five replicates of 12 chicks were used. The trial lasted 35 days. Birds were exposed to cyclic heat stress at 34 ± 1°C for 8 h/day for 13 consecutive days (days 22–34 of age), before sampling at day 35. The best results were obtained at 400 mg/L, at which final body weight increased from 2084 g to 2242 g, body weight gain increased from 2039 g to 2198 g, and feed conversion ratio improved from 1.66 to 1.56, while mortality decreased from 5.00 to 1.67%. The same treatment improved dressing percentage and breast yield, decreased cooking loss, shear force, and breast-meat lipid oxidation during frozen storage for 3 months at -18°C, and increased sensory acceptability. Romanesco extract further improved antioxidant status by enhancing antioxidant enzymes (superoxide dismutase, glutathione peroxidase, and catalase) and antioxidant metabolites (reduced glutathione and ferric reducing antioxidant power), while decreasing serum malondialdehyde, triglycerides, cholesterol, and liver- and kidney-function indices. The results suggest that ethanolic Romanesco leaf extract can be a useful phytogenic supplement for broilers exposed to cyclic heat stress by supporting growth performance, oxidative stability, and meat quality.