Whole-crop cereals for grazing and silage: balancing quality and quantity

Abstract

There has been a marked increase in the use of cereals for supplementary grazing and silage for the developing dairy industry in the South Island. Cereals provide high energy supplement in autumn/winter or can be used as a high fibre source in spring. Variation in yield potential in cultivar trials in Canterbury was assessed for autumn and spring-sown crops. The aim was to produce high quality cereal feeds with good yield potential by examining the variation among species and cultivar selections in well managed trials. Single-bite crops sown in early autumn in Canterbury provide up to 5.5 t/ha herbage DM yield with at least 17.5 % protein, 12% total soluble carbohydrate including starch (TSC) and metabolisable energy (ME) of 11.3 MJ/kg in mid-June. Multiple graze types (eg. Doubletake triticale) with similar winter productivity and quality to single-bite crops produced an additional 13.5 t/ha biomass for a silage crop. At ensiling, this cultivar had 9.3 MJ/kg ME with mean 19.5% total soluble carbohydrates. Spring-sown cereals for silage produced up to 20 t/ha. Harvest timing was a significant factor in the wide range in quality of herbage for ensiling. Cultivar means ranged from 7.0 - 12.8% DM for protein, 8.7- 31.6% DM for TSC and 8.3-10.5 MJ/kg DM for ME. More mature herbage had reduced organic matter digestibility and higher TSC but reduced ensilability at DM content in excess of 40%. Keywords: dairying, fibre, forage, herbage quality, metabolisable energy, near infrared reflectance spectroscopy, supplements