Effect of applying formic acid, heterolactic bacteria or homolactic and heterolactic bacteria on the fermentation of bi-crops of peas and wheat

This work aimed to compare the effectiveness of bacterial inoculants or a chemical additive for preserving whole-crop silages made from wheat, two pea varieties (cv Magnus or Setchey) or intercrops of wheat and both pea varieties. The forages were harvested when the wheat and peas were at the late milk and yellow wrinkled stages respectively, and conserved in five replicate mini silos without treatment (control) or after treatment with 2.5 g kg(-1) of formic acid (FA) or 1 x 10(6) cfu g(-1) fresh forage of either of two bacterial inoculants (WholeCrop Gold (WCG) or WholeCrop Legume (WCL), Biotal Ltd, Cardiff, UK). WCG contained Lactobacillus buchneri, while WCL contained L buchneri, L plantarum and Pediococcus pentosaceus. Chemical composition, fermentation characteristics and in vitro digestibility were measured after 65 days of ensiling. Additive-treated bi-crops had lower (P < 0.05) concentrations of soluble N, ammonia N and lactic acid than the controls. Inoculant-treated bi-crops had higher (P < 0.001) acetic acid and lower (P < 0.001) residual water-soluble carbohydrate (WSC) concentrations than FA-treated bi-crops. WCL-treated bi-crops had similar residual WSC concentrations to and higher (P < 0.05) starch concentrations than WCG-treated bi-crops. Unlike Magnus pea bi-crops, Setchey pea bi-crops treated with WCL had lower concentrations of ammonia N (P < 0.01) and acetic acid (P < 0.001) and higher concentrations of starch (P < 0.001) and lactic acid (P < 0.05) than those treated with WCG. For both bi-crops, FA-treated bi-crops were more stable (P < 0.05) than inoculant-treated or untreated silages, and the stability of inoculant-treated and untreated silages was similar. Formic acid treatment was also the most effective at reducing WSC losses in the bi-crop and pea silages. Inoculant treatment reduced proteolysis in these forages but did not prevent spoilage in the bi-crops. Additive treatment reduced yeast counts but did not improve the fermentation in wheat silages. (C) 2004 Society of Chemical Industry.