By Charl van Rooyen and Fredalette Uys
Silage is crucial for the success of dairy farms and large-scale livestock farming. Prof Robin Meeske, specialist scientist at the Western Cape Department of Agriculture’s Outeniqua Research Farm in George, provides advice on effective principles for making silage.
What new technology for making silage shows promising results?
The basic principles of successful ensiling remain the same. The silage crop must be ensiled at the correct stage with optimal moisture content (65% moisture for maize silage).
The material must be finely chopped (8-12 mm for maize silage) and tightly packed (240kg dry matter/m³ for maize silage). One of the biggest problems is spoilage losses in the bunker.
The losses can largely be limited by properly compacting the silage then placing a dense, thin oxygen barrier of plastic on the bunker before covering the silage with conventional silage sheets to seal the bunker.
In what ways can losses in silage making be limited?
By chopping, packing and sealing the silage well, and sealing a silage bunker in a shorter time. Once the bunker is opened, air is allowed in. Yeasts and moulds start to grow and the pH begins to rise.
Silage made from crops such as maize that contain sufficient sugars (water-soluble carbohydrates) tends to heat up more easily when exposed to air.
This is because it contains a significant amount of residual sugars as well as high levels of lactic acid. These sugars and lactic acid are nutrients used by yeasts and moulds.
The stability of silage can be improved by administering a heterofermentative lactic acid bacterial inoculant (which produces more than one product during fermentation) during ensiling, thus increasing the levels of acetic acid in silage. Acetic acid suppresses the growth of yeasts and moulds.
Which additives show good results?
Several lactic acid bacterial (Lactobacilli) inoculants are available and can be categorised as either homofermentative (producing a single product during fermentation) or heterofermentative inoculants.
Homofermentative lactic acid bacteria efficiently use sugars and primarily produce lactic acid. This type of inoculant is recommended for crops with low sugar content, such as tropical grasses, alfalfa and oats.
A heterofermentative lactic acid bacterial inoculant uses sugars less efficiently and produces lactic acid, propionic acid, acetic acid and carbon dioxide.
This inoculant is used for crops such as maize with high sugar content and should not be used for crops with low sugar content. It is suitable for improving the aerobic stability of maize silage.
Most companies involved in the silage industry offer options for this inoculant, and it is used in the production of maize silage.
How can farmers outside the dairy industry best use silage? Is it a profitable option for small livestock and beef farmers?
Maize silage is commonly used as roughage in finishing rations for beef cattle. Lambs can be effectively finished with maize silage as a base.
In a study, we found that lambs fed 60% maize silage and 40% concentrate grew at a rate of 255g per day. The costs associated with cultivating and making silage vary greatly – maize silage can cost up to R2,500/ton of dry matter.
The feed costs for beef herds must be kept as low as possible. They should preferably be kept on natural pasture and be supplemented to address nutritional deficiencies.
