Dietary oyster mushroom fermented Vachellia erioloba pods enhance Boschveld chicken meat healthiness without altering its physicochemical quality, growth performance and physiology

Abstract

The high content of fibre and antinutritional phytochemicals limit the utilization of Vachellia erioloba tree pods as nutraceutical feed additive for indigenous chicken diets. The pods can however be solid-state fermented using oyster mushrooms to enhance the nutritional utility of their spent substrate for the nutrition of the native birds. Therefore, this study investigated the effects of dietary incorporation of V. erioloba pods oyster mushroom spent substrate (OMSS) on growth performance, carcass traits, visceral organs, haemato-biochemistry, and meat quality including its fatty acid composition in Boschveld chickens. In a completely randomized design, 250 4-week old mixed gender Boschveld chicks were randomly allotted to 25 pens in which they were offered treatment diets (0, 1.25, 2.5, 5 and 10% OMSS) each with 5 replicates of 10 for 12 weeks and then slaughtered. While there were neither linear nor quadratic effects of diet on overall feed intake (FI) (P > 0.05) and body weight gain (BWG) (P > 0.05), dietary incorporation of OMSS decreased overall feed conversion efficiency (FCE) (quadratic: P < 0.05) particularly in weeks 5 (linear: P < 0.05), 6 (quadratic: P < 0.01) and 11 (quadratic: P < 0.05) with no effects in subsequent weeks (P > 0.05). Also, OMSS induced no effects on all carcass characteristics, visceral organs, haemato-biochemistry and meat physico-chemical quality (P > 0.05) except for the increase in serum albumin (quadratic: P < 0.05) and bilirubin (quadratic: P < 0.05) as well as 24 h post-slaughter meat lightness (linear: P < 0.01), redness (quadratic: P < 0.05), yellowness (linear: P < 0.05), hue angle (quadratic: P < 0.05), and drip loss (quadratic: P < 0.05). Further, the spent substrate decreased meat myristic (linear: P < 0.01), palmitic (linear: P < 0.05), palmitoleic (linear: P < 0.01), and oleic (linear: P < 0.01) acids, as well as its total polyunsaturated fatty acids (PUFAs) (linear: P < 0.05), monounsaturated FAs (MUFAs) (quadratic: P < 0.01), and n-6 PUFAs (linear: P < 0.05). Furthermore, it decreased the meat n-6/n-3 PUFA ratio (quadratic: P < 0.01), with meat from birds fed diets incorporated with 2.5% OMSS eliciting the lowest ratio of 3.63. In contrast, dietary OMSS increased meat stearic (linear: P < 0.001), docosahexaenoic (quadratic: P < 0.01), and tricosanoic (linear: P < 0.001) acid concentrations as well as its total saturated FAs (SFAs) (linear: P < 0.01) and n-3 PUFAs (quadratic: P < 0.01). In conclusion, dietary feeding of V. erioloba pods-derived OMSS enhanced meat nutritional healthiness without majorly altering its physico-chemical quality as well as growth performance, carcass traits, and haemato-biochemistry in Boschveld indigenous chickens. It is recommended for inclusion in indigenous chicken diets at 2.5% level.