Effect of cereal and pea monocultures and combinations and silage additives on whole-crop cereal silage nutritive and fermentation characteristics

Abstract

The efficient production and utilisation of home-grown feed is considered one of the key factors that underpins the profitability of dairy systems in southern Australia. The use of winter forage cereals for grazing and silage provides an opportunity to achieve high dry matter yields over the winter and spring period. However, questions remain on the nutritive value of whole-crop cereal silage and its subsequent use as a production feed in livestock systems. This experiment examined the nutritive characteristics of winter wheat, triticale, forage peas and bi-crops of cereals and peas sown at different proportions, cut for silage at the soft dough growth stage of the cereals and their subsequent silage nutritive characteristics and fermentation patterns when ensiled with and without bacterial inoculant additives over 2 consecutive years. The estimated metabolisable energy (ME) (Year 1) and crude protein (CP) (Years 1 and 2) concentrations of the forage pea before and after ensiling were higher (P < 0.05) than all other forages in both years. The cereal–pea mixes had similar estimated ME values to the cereal monocultures both before harvesting and as silage, although there were significant improvements in CP concentration at the higher rates of pea inclusion. All resultant silages were well fermented as indicated by low pH, low proportions of total N as ammonia-N and high lactic acid concentrations. There were marked differences in the proportions of lactic acid and acetic acid in the pea silages between years and this is likely a result of dry matter content differences at ensiling. There was no effect of silage additives on resultant silage nutritive characteristics or fermentation parameters indicating that well fermented silage can be achieved without the additional cost of using a silage additive. This study has indicated that forage peas can be ensiled with winter cereals and produce silages that have higher CP concentrations than cereal silage but with similar fermentation parameters. Furthermore, this experiment has highlighted the potential of growing a monoculture of forage peas for ensiling with the resulting silage having higher estimated ME and CP concentrations.