Stress-alleviating properties of dietary red grape pomace in Ross 308 broilers reared at a high stocking density

Abstract

Nutraceutical plant products such as red grape pomace (Vitis vinifera L. var. Shiraz) contain potent antioxidants that could mitigate stress caused by high stocking density. An experimental feeding trial was conducted using a total of 720 densely-stocked (30 birds/pen) Ross 308 broiler chickens (300.6 ± 9.30 g live weight) to evaluate their productive, physiological, and meat quality responses, as well as welfare indicators when supplemented with incremental levels of red grape pomace. The birds were randomly distributed to 24 pens, each with a floor space of 1.32 m2 (1 m length × 1.2 m width × 1.55 m height). The birds were raised on standard chicken diets supplemented with 0, 15, 30, and 50 g/kg of red grape pomace. Overall feed intake, overall body weight gain, and overall gain-to-feed ratio were not influenced by experimental diets. No quadratic or linear trends were observed for blood parameters, except for neutrophils and mean platelet volume. Linear decreases were observed in the weights of duodenum, ileum, cecum, and colon as red grape pomace levels increased. With regards to meat quality, water-holding capacity increased linearly, whereas cooking loss decreased linearly as dietary red grape pomace levels increased. Increasing red grape pomace levels did not affect temperature, yellowness, lightness, chroma, and shear force, but affected initial pH and 24-hour redness and hue angle of the breast meat. The use of red grape pomace did not improve productive performance, physiology, meat quality and welfare parameters, neither did it alleviate high stocking density-induced stress.