MAKE GREAT QUALITY SILAGE

Grant Pringle, Lead Agronomist, Pannar Seed

Maize silage is an important source of feed for the dairy and feedlot industry.

Several characteristics of maize silage make it attractive to many livestock producers. Maize produces palatable feed with a relatively consistent quality as well as higher dry matter yields and energy content than most other types of feed. Silage has several advantages over hay as a mechanically harvested product. These include preserving more nutrients per hectare due to less waste, and it is also less exposed to damage due to weather conditions because the forage does not have to lie in the field to dry.

The main purpose of silage is to preserve the digestible fibre, protein and energy in the feed, and to maintain the protein in a form that can be efficiently used by ruminants. As with hay, the harvest date affects the quality of the forage preserved as silage. Higher yields and quality can be obtained when plants are more mature but ensiling a drier maize crop means more effort required to compact the bunker. Good maize silage is an integral part of feedlots, dairies and other intensive livestock production systems in South Africa. Pannar offers a complete package of maize silage hybrids, which meet all the requirements of these systems.

There are three major factors that affect the final yield and quality of the silage. The first is the climate and it is largely out of our control. This includes water/rainfall, sunlight, heat units, soil properties, pests and diseases. The second is hybrid selection; it is important to choose the hybrid that is best adapted to the given production region. The third factor is management, and it is management that often has the largest impact on the yield and quality of the silage. Management focuses on tillage practices, fertilisation practices, planting and establishment of the crop, the physiological age of the maize when the silage is cut, the length of the chop, crushing of plant material, and the process of filling and compacting of the bunker.

20% difference between the best and worst hybrids

No hybrid will reach its yield potential if it is not well adapted to a specific production region. The ARC national maize trials show that there can be up to 20% difference between the top performing and worst performing hybrids. Select hybrids with a good record of performance in your local geography and with stable yields over different seasons. Another aspect to consider is the growth class of a hybrid; it must produce the maximum yield in the available growing period. Constraints include the length of the available growing season, residual effect of herbicides, successional crops and other fodder-flow considerations.

The hybrid that produces the best grain yields in a particular area is probably the right choice for silage production.

The grain content of silage is of critical importance and determines up to 65% of the energy value of the silage. The best grain-producing hybrids in a particular area are usually the best adapted to local growing conditions, and therefore, are also usually the best choice if maize were to be planted for silage.

The following aspects should be considered when choosing a hybrid:

• the hybrids adaptability to the area
• the environment’s disease pressure
• planned cutting date
• will a contractor be used
• grain yield potential

Each of these factors affects the final yield and quality of the silage. Hybrids with thick woody lignified stems (usually those with excellent standability) should be used carefully for silage as a relatively large proportion of the dry matter may consist of indigestible lignin.

Pannar markets a range of maize hybrids that are ideally suited for making silage. The hybrids in the medium early and medium growth classes (5- and 6-series hybrids) usually make up the bulk of silage plantings. The reason for this is the consistency and reliability of the yield performance of this group of hybrids. Depending on an area’s heat units, the medium early hybrids are ready for the cutting of silage approximately 110-140 days after emergence. The medium early and medium growing season hybrids generally offer good disease tolerance and a longer cutting window of 10 to 20 days. A plant population of 10 to 30% higher than what is normally planted for grain production is recommended for silage production.

The primary advantage of hybrids in the quicker growing classes (ranging from 100-130 days from emergence to cutting) is the possible earlier establishment of follow-up crops such as ryegrass, winter cereals and wheat. In regions with sufficient heat units, two silage crops can be cut in a single season under irrigation by using ultra early hybrids.

The ultra early hybrids usually have excellent nutritional value due to a high grain to leaf and stem ratio. However, the hybrids are inherently more susceptible to diseases and in certain production areas this is an important consideration. They also have a limited cutting window due to their quicker drying rate. This is an additional risk factor as the timing for cutting the silage is important. The plant population recommendation for ultra early hybrids is usually around 40% higher than for the hybrids in the medium growth class. The reason for this is that ultra early hybrids have fewer leaves and a shorter plant type and need plant population to make up yield.

Choose hybrids from the range as categorised for your production region and consult your local Pannar representative.

Maximising the starch content

For the best quality silage, it is very important to cut and ensile the crop at the right time. The primary objective is to cut the crop when it reaches the maximum starch content. During the plant’s initial development stage, vegetative development takes place and the maize plant’s factory is established, namely the roots, stem and leaves. Thereafter, the reproductive phase begins when the tassel and silks appear, and pollination takes place. The important period of grain filling takes place over a period of approximately eight weeks. This is a critical period as the plant accumulates approximately 50% of its final dry matter mass, which is in the form of starch into the grain. During grain filling, the starch content increases as the plant becomes physiologically mature. As an approximation, the starch content increases by 0.6% for every 1% increase in DM. However, the neutral detergent fibre (NDF), which gives an indication of the digestibility and rate of digestion, remains relatively unchanged over this period. This means that if the maize is cut later, the starch content should be higher, to the benefit of the quality and quantity, and without impact on the digestibility of the fibre.

A rule of thumb for determining when maize is ready to be harvested for silage is to look at the milk line. The milk line, which is indicated by the colour difference between the soft and hard starch contained in the kernels, is visible on the maturing grain when a maize ear is broken in two. Maize is ready for ensiling once the milk-line is at least 50% down the kernel. If the maize is ensiled when the milk line reaches the two-thirds mark down the grain, the crop’s DM content is approximately 35-38% and the starch content has reached its maximum level. Studies in the Southern Cape have indicated that if the maize is cut when it reaches a DM-content of 35-38%, this results in a significantly higher starch content.

Harvesting silage at this stage is more demanding on management and equipment, even a short delay can result in the crop becoming too dry and posing challenges to compaction in the bunker. Making use of inoculants, particularly those with heterofermentative strains, is recommended if harvesting high DM material. Inoculants accelerate the fermentation and preservation process. Making silage of physiologically more mature maize requires the corn cracker within the forage harvester to break up the harder kernels. It is advisable to check this kernel processing regularly. Uncracked kernels pass through the animal’s digestive system undigested and are a waste of potentially good quality silage. During the fermentation process of the silage, the digestibility of the starch improves and reaches optimal digestibility after about six months.

Successful silage production is dependent on continuous attention to detail and management throughout the entire process of planting, growing, harvesting, and ensiling the crop. It is this effort that makes the difference between mediocre and excellent results.

Reduce volatility in productivity and profitability on your farm by choosing these stable performers. Add to this the agronomic knowledge and insight of Pannar's team, and you can confidently plant Pannar's cultivars knowing that you will reap the maximum yield on every bag.

For more information please contact your Pannar sales representative or agronomist or visit www.pannar.com.