A novel feedstuff: ensiling of cowpea (Vigna unguiculata L.) stover and apple (Malus domestica Borkh.) mixtures. Evaluation of the nutritive value, fermentation quality and aerobic stability

BACKGROUND: Agro-industrial by-products are of low economic value as foods for human consumption but may have potential value as animal feedstuffs. This study evaluated a novel feedstuff, ensiled discarded apple (85%) and cowpea stover (15%) mixtures with two different ensiling periods (45 and 60 days), regarding the nutritive value, fermentation quality and aerobic stability. RESULTS: Generally, no differences (P > 0.05) were observed between ensiling periods for nutritive value and fermentation characteristics. Silages were stable after ensiling, presenting high lactic acid (77.3 g kg(-1) dry matter (DM)) and acetic acid (54.7 g kg(-1) DM) and low ethanol (15.7 g kg(-1) DM) and NH3-N (105.6 g kg(-1) total N) concentrations. No butyric acid was detected in silages, and they were aerobically stable for up to 216 h. Lactic acid bacteria numbers were high at silo opening (7.14 log colony-forming units (CFU) g(-1)), while Enterobacteriaceae were not detected and yeasts/moulds were low (2.44 log CFU g(-1)). Yeast/mould and Enterobacteriaceae numbers grew considerably during 12 days of air exposure. CONCLUSION: A mixture of low calibre discarded apples with cowpea stover can be used as animal feed after the ensiling process owing to its nutritive value and long aerobic stability. (C) 2017 Society of Chemical Industry