Int’l - Maize silage 'best option' for most dairy farms

“Maize silage remains the best summer-crop silage option for most NZ dairy farmers” says animal nutritionist Raewyn Densley. “As well as delivering higher yields, maize silage offers better nutritional quality, higher milksolids production and greater profits than for cereal silage.” While average New Zealand maize silage yields are in the range 20-25 tonnes of drymatter per hectare, top crops can yield more than 33 tonnes of drymatter per hectare. This far outweighs the yield potential of cereal crops such as wheat, oats, barley and triticale (a cross between wheat and rye). The high yields of maize silage mean that most farmers can grow it on farm for 15 cents per kilogram of drymatter making it a very cost effective feed source. “Local silage quality results show maize silage outperforms cereal silage,” says Densley. “Maize silage is also a more consistent product with much less variation between the average and the worst quality samples submitted for testing.” This is due to the fact that rapid lignin build-up in cereals after the boot stage results in a fast decline in digestibility whereas maize quality declines much more slowly. Achieving the optimal nutrient composition of cereal silage requires careful monitoring and timely harvest of the crop. Harvest delay caused by contractor breakdown or bad weather can have a very detrimental affect on the cereal silage quality. In the 2002 season, FeedTech, AgResearch in Palmerston North, tested cereal silage and maize silage samples. Maize silage had lower fibre levels and higher average soluble sugars and metabolisable energy content than the cereal silage (Table 1). “The high levels of soluble sugars and starch in maize make feeding it a very efficient way of putting condition onto cows. It is also an excellent complement to lush, high protein pasture”. Maize silage has been shown to outperform cereal silage in terms of milk production and animal growth rates. In a trial conducted at Ohio State University, cows were fed on diets containing either triticale silage or maize and lucerne silage. Drymatter intakes were higher for the maize and lucerne silage than for the triticale silage. Cows fed the triticale silage required more concentrate to be fed to achieve the same milk performance as that achieved on maize silage and lucerne silage diets. In two separate trials conducted by the British Milk Development Council and the Agricultural Research Institute of Northern Ireland, diets containing grass silage and maize silage were shown to give higher milksolids production than wheat and grass silage based diets. “Making the most profit from cropping in dairy systems is all about choosing the right crop for the right situation,” says Densley. “Cereal silage has a role as a winter crop following maize silage or as a summer crop alternative for farmers who are in high altitude areas or dairy districts in the lower South Island where maize silage does not grow as well. “The take home message is don’t grow cereal silage if you can grow maize silage, it yields less, and the resultant product is lower in quality than for maize silage.”