Incorporation of untreated or white-rot fungi treated cowpea stover on performance, digestibility, health and meat quality of growing rabbits

Legume stovers may be an important feedstuff resource for animals, especially in the Mediterranean production systems. However, these stovers contain antinutritional factors, such as lignin, that may affect the growth performance of the animals. Studies with white-rot fungi showed their ability to increase the nutritional value of several agricultural wastes through changes in lignin structure facilitating the access to structural polysaccharides that are potentially digestible. This contributes to a better utilization of the diet’s nutrients and, consequently, to a better animal performance and health. The present work aimed at evaluating the effect of cowpea stover (Vigna unguiculata), untreated (US) or treated (TS) with Pleurotus citrinopileatus, on performance, digestibility, health and meat quality of growing rabbits. The TS treatment resulted from the inoculation of cowpea stover with Pleurotus citrinopileatus mycelium under solid-state fermentation for 22 days. Five experimental diets incorporating 0 (C), 50 (US50) and 100 g/kg (US100) of US and 50 (TS50) and 100 g/kg (TS100) of TS were used. Trials were conducted using 80 rabbits with 35 days old. The animals were randomly assigned to one of the 5 treatments and were slaughtered at 63 days of age. The incorporation of cowpea stover did not affect animal growth performances (mean daily weight gain of 44.4 g/kg; mean feed intake of 154 g/day; mean feed conversion rate of 3.46) or digestibility (mean dry matter digestibility of 564.8 g/kg; mean neutral detergent fibre digestibility of 369.6 g/kg). The orthogonal contrasts showed that the animals fed with US had a final live weight 5.0% lower (P = 0.04) than the ones fed TS (2214 vs. 2323 g). The TS diet allowed a 17.4% reduction (P = 0.03) in blood cholesterol levels. No influence (P > 0.05) of treatments was detected for carcass traits (mean chilled dressing out percentage of 59%) and meat quality parameters. There was a decrease in the caecal microbiota similarity index (P = 0.01) between US and TS diets. The incorporation up to 100 g/kg of treated cowpea stover with Pleurotus citrinopileatus in the rabbits’ compound feed showed potential to overcome the detrimental effect that the incorporation of the US has on the final live weight of growing rabbits. Further research on the specific effect of TS diets on cholesterol blood levels and shifts on the microbial population of the gastrointestinal tract should be assessed.