Comparison of Impacts of Essential Oils, Green Tea Powder, Betaine, Probiotics, and Other Dietary Supplements on Growth and Well-Being of Heat-Stressed White Pekin Ducks

Three experiments were conducted to compare different dietary supplements fed to mixed-run White Pekin ducks (<i>n</i> = 48 birds/treatment) reared for 35 d and exposed to ambient temperatures from d 0 to 35 or heat stress (32 °C-35 °C) for 12 h/d on d 20-35. The basal diet (CON) was supplemented with 0.5 kg/MT seaweed extract (SE), 2.0 kg/MT betaine (BET), or 1.25 kg/MT yeast fermentate (YF) in Experiment 1; with 0.25 kg/MT mannanoligosaccharide (MOS), 0.5 kg/MT green tea powder (GT), or 0.55 kg/MT Poultry Star synbiotic (PS) in Experiment 2; or with 0.09 kg/MT Essential Oil #1 (EO1), 0.5 kg/MT Essential Oil #2 (EO2), or 0.5 kg/MT Microsaf probiotic (MS) in Experiment 3. Heat stress reduced body weight and feed consumption (Exp. 1-3) and negatively affected measures of stress (Exp. 1 and 2) and at least one measure of intestinal health (Exp. 1-3). Intestinal morphology was improved in birds that were fed EO1, EO2, and MS, and some measures of stress susceptibility were improved in birds that were fed SE, YF, MOS, GT, BET, or PS. Essential oil supplementation may be best used in combination with another of the supplements tested to optimize health and welfare in Pekin ducks. Further research could clarify which combinations are ideal for supporting both intestinal health and stress susceptibility in ducks.