This paper reviews the use of maize silage in pastoral dairying systems in New Zealand. The evolution of dairying systems to make profitable use of maize silage and other supplementary feeds has occurred during the last decade in conjunction with an increased use of maize silage. When used within recommended levels of feeding, maize silage provides a low cost source of starch and fibre which complements pasture well for much of the year. Balancing dietary deficiencies in protein, minerals, and in some cases fibre, will optimise milksolids production at high levels of maize silage supplementation. Targets for good quality maize silage include a dry matter content of 28-35%, an energy content of 10.8 MJME/ kgDM, a protein content of 7-8%, and a pH of 3.8 to 4.5. Opportunities for further productivity gains exist through further intensification of dairying systems using high-yielding crops. Keywords: dairy cow, feed quality, maize silage, nutrition

This paper reviews the key factors that have led to the widespread adoption of maize silage in North Island and Canterbury dairying systems and explores current maize silage feeding strategies. Maize silage has proven to be a cost effective supplementary feed that allows farmers to achieve higher MS/ha production. The worldwide significance of maize ensures a large plant breeding and research input that has resulted in significant ongoing genetic gains. Current maize feeding systems are based around systems quantified and described by research at Waimate West Demonstration Farm. A number of new technologies using maize silage are being investigated. These centre on manipulating the feed value of the silage through both plant breeding mechanisms and harvest-management strategies. Keywords: maize silage, supplementary feed

Silage is an important supplement in New Zealand dairy systems, however quality can be variable. Challenges with pasture silage lie mainly in the fermentation process, while maize silages tend to have a better fermentation profile, but are prone to heating and spoilage at feed-out. A series of laboratory scale silo trials were used to investigate the effect of different silage inoculants on aerobic stability in maize silage (n=8) and fermentation quality in pasture silage (n=6). Inoculants affected aerobic stability in maize silage, and pH, fermentation losses, ammonia-N and fermentation acid profile in pasture silage, however products differed in their efficacy. Farmers can make better inoculant purchase decisions by choosing products that have supporting trial data as well as guaranteed bacteria numbers.

New Zealand dairy farmers are lifting stocking rates and increasing available feed through nitrogen (N) fertiliser applications to pasture, growing maize for silage and other supplementary crops for silage or grazing on-farm, and/or procuring feed supplements off-farm. This has raised concerns about the possibility of increased risk of nutrient losses to waterways and the atmosphere. This paper reviews NZ and overseas data on the integration of maize silage into dairy systems. Maize silage is a low protein forage which helps optimise animal protein intake and reduces N loss. Maize silage-supplemented dairy farms leached more nitrogen per hectare but less per kg milksolids (MS) than intensive all-grass systems. Feeding maize silage on a feedpad and spreading the resulting effluent uniformly over the farm further reduces N leaching. In the Resource Efficient Dairying (RED) trial, total emissions of nitrous oxide (N2O, a potent greenhouse gas) for the maize-supplemented farmlet was 14% lower on a per hectare basis and 22% lower on a kg MS basis than the all-grass system when both received 170 kg N/ha as urea. The increases in maize dry matter production in response to incremental additions of N and water, where production is constrained by these inputs, can be 2-3 times greater than that for pasture. Using a feed and stand-off pad and managing maize growing through minimising tillage effects, determining soil N status at planting and timing N applications appropriately further reduce the environmental impact of maize silage-based dairy systems. Keywords: all-grass, environment, greenhouse gases, intensive dairy systems, maize silage, nitrates

This study compared the yield and nutritive content of conventional and leafy maize silage hybrids, and the expected differences in milksolids (MS) production if fed to cows. A range of conventional and leafy hybrids were planted in paired strip trials (n=162) or small plot trials (n=132) during spring 1999, 2000, 2001, 2002, 2003, and 2004 in all of the main maize silage growing areas from Nor thland to Canterbury. Pair ed comparisons of short, medium, and long maturity conventional and leafy hybrids were made. On average, conventional hybrids yielded 1824 kg DM/ha (9%) more than leafy hybrids and had a marginally lower fibre digestibility (0.6 percentage units). Modelling using the Cornell Net Carbohydrate and Protein Systems (CNCPS) model showed that leafy hybrids had a similar metabolisable energy (ME) content and MS per cow and per tonne of maize silage were not different. For dairy farmers growing their own maize silage crop to feed to cows, the planting of conventional hybrids will result in more MS and profit/ ha of maize grown than will the planting of leafy hybrids. If maize silage is purchased on a cent/kg dry matter (DM) basis, the small differences in nutritive content of leafy and conventional hybrids will not affect MS production or profit. Keywords: dairy cows, leafy hybrids, maize silage yield, nutritive value