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January 12 2021

The who’s who of the silage industry

As Published in Silage talk of Stockfarm Magazine January 2021

In the world of silage, as in all fields, there are people who tend to drive the industry forward. They work tirelessly to improve silage technology and techniques, yet they are less well known than some of the torchbearers in other industries.

I would therefore like to highlight a few experts – people whom I had the privilege of meeting or who had an impact on my silage knowledge – although they are not the only ones who deserve recognition. Here are some of the people who are taking the lead in the silage industry (in no particular order):

Silage storage and safety

Prof AI Virtanen of the University of Helsinki in Finland won the Nobel Prize for Chemistry in 1945 for his work on silage preservation. His research on the use of organic acids launched an international movement to find solutions for controlling silage storage capability. The university continues his legacy with active research into silage preservation. Dr Keith Bolsen of the Silage Safety Foundation in Texas in the United States (US) coined the term ‘silage safety’. An increasing number of accidents occur annually at large silage operations around the world. Through the awareness that his work created, human lives are spared. Dr Bolsen passed away in May last year,< but his long career, including his role as professor emeritus at the Department of Animal Sciences and Industry at Kansas State University, made a significant impact on the silage world.

Silage quality and ensiling

The following people are currently among the leading silage experts in the world. Their work covers various aspects of silage and has a direct impact on improving silage quality and the efficiency of silage making processes. On home soil Prof Robin Meeske of the Outeniqua Research Farm in George and the Western Cape Department of Agriculture, is a leader in the field of silage research. His work involves< improving silage efficiency with a specific focus on the commercial farming sector. He is also the mastermind behind the protocol used in Plaas Media’s Santam Agriculture National Silage Competition, which will be held for the eighth time this year. Retired Prof Richard E Muck of the American Dairy Forage Research Center in Wisconsin continues to consult in the industry and publish his research, which covers a wide range of topics. He documents silage losses, improves silage density, compares silage covers, enhances protein preservation during ensiling and studies the effects of silage additives. He is undoubtedly one of the most well-known silage researchers in the world. Prof JM Wilkinson, honorary professor at Nottingham University in the United Kingdom and a livestock consultant, has authored almost 400 publications, including 15 books on silage. His current research focuses on improving the nutritional value of silage, reducing nutrient losses during ensiling, and efficient feed utilisation in livestock production systems. Prof Giorgio Borreani, associate professor of agronomy and crop science at the University of Turin in Italy, has been involved in silage research since 1993. His research focuses on silage quality and the evaluation of new machinery and technology in the silage sector, as well as the management factors that influence crop preservation through ensiling. Another well-known silage specialist and speaker is Dr Limin Kung Jr from the Department of Animal and Food Sciences at the University of Delaware, US. He has numerous publications to his name and is respected in his field. He is perceived as someone who always makes time to help and advise young and future professionals.

Women in the industry

Women are also making their mark in the field of silage and recognition must be given to Dr Kirsten Weiss from Humboldt University in Berlin, Germany, and Dr Marketta Rinne from the Natural Resources Institute in Finland. While most of these names may not be familiar to many, they, along with numerous other silage experts in the world, are at the helm of silage research in the 21st century.

December 15 2020

Silage parameters (Part 4): The role of pH

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As Published in Silage talk of Stockfarm Magazine December 2020

The amount of silage-related problems that I encounter daily, compelled me to write a short series on silage parameters that require adherence. This is the last article in the series and deals with decreased levels of acidity (pH) triggered by fermentation.

Aspects of preservation

The effective preservation of silage for longterm storage is not determined by only one step, but by the successful amalgamation of all the key steps. This includes working within suitable moisture limits, creating an anaerobic (oxygen-free) environment as well as achieving a low-enough pH, noting that the ideal pH of each crop differs.

Mechanics behind a drop in pH

Anaerobic, homofermentative lactic acid organisms produce lactic acid from simple sugars, causing the pH to drop during primary fermentation. These organisms can either occur naturally or can be administered by adding bacterial silage inoculants. If no inoculant is added, it is up to naturally occurring organisms to drive fermentation. This poses several disadvantages, including producers not knowing how many suitable lactic acid organisms are present, how active they are and how many are present compared to spoilage bacteria. Spoilage organisms often compete for the same sugars but do not convert these sugars to lactic acid. Among others, these organisms form too much acetic or even butyric acid. At certain levels both these volatile fatty acids have a detrimental effect on intake. Silage inoculants are designed to add enough selected organisms to counteract the effects of spoilage organisms, leading to guaranteed fermentation. Yet this alone does not guarantee success – the other factors, as well as the silage’s limitations or parameters, must be considered.

What happens during preservation?

All the aforementioned organisms, as well as the yeasts and moulds that might be added, exhibit varying tolerance levels for fermentation factors. Some are eliminated when oxygen is absent and others when at a low pH, while all have a certain moisture level at which they’ll thrive. However, most spoilage organisms are only eliminated when all factors work together. The lactic acid bacteria we use are relatively oxygen tolerant, meaning that high oxygen levels will initially not harm them. However, they are not working at full speed yet! This only occurs a few days later when the storage format becomes highly anaerobic. This means that aerobic organisms such as enterobacteria are the first to start working, forming unnecessary levels of, for example, acetic acid before the necessary lactic acid is formed. This is one good reason why rapid oxygen removal is so crucial. If this step takes too long, producers are literally growing future problems for themselves! Other bacteria, for example certain Clostridia species, may be more active at a lower dry matter (DM) content. Although low oxygen levels after compaction limit their activity, the pH must drop even lower than usual to fully inhibit their negative impact in these moisture-rich conditions. This is rarely a problem in drier silage. Organisms such as naturally occurring yeasts are inactivated upon removal of oxygen, but the lowest pH achieved with high-sugar crops (approximately 3,6) is not low enough to kill them. The yeasts simply become dormant, waiting to do damage once the silage is opened.

Aerobic instability

If all the steps initially followed to achieve preservation come undone when opening the silage, then unstable silage is the result. Oxygen will reactivate the dormant organisms and heat will be generated in the process – this is the heat detected when removing silage. These organisms continue to utilise available nutrients – such as some yeasts that live on lactic acid – and this in turn raises the pH. A rise in the pH will compromise preservation and efficiency. The duration of preservation after opening is called aerobic stability and producers should always strive to extend this period for as long as possible to allow animals to efficiently ingest the silage before any silage-associated problems occur.

November 15 2020

Silage parameters (Part 3): Oxygen removal

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As Published in Silage talk of Stockfarm Magazine November 2020

The problems relating to silage that I encounter on a daily basis, compelled me to write a short series on silage parameters that have to be respected. This is the third article in the series.

Removal of oxygen

It is common knowledge that compaction has an enormous impact on successful silage making. Of course, this only applies to bunkers and buns. As I’ve mentioned on previous occasions, the removal of oxygen rather than compaction is the issue here. This is what makes silo bags such an excellent option. Although the compaction level when using silo bags may not be as high as that of a correctly compacted bunker, oxygen is removed faster and more efficiently. But let’s look at compaction, since most silage is still produced this way.

False perceptions

There is a perception that wet silage compacts better than dry silage. This is not the case, as the moisture in silage also takes up space. Wet silage might seem firm, which is interpreted as proper compaction, but oxygen removal is generally not sufficient. In addition, water carries oxygen and sustains numerous spoilage organisms. Wet silage is therefore usually not up to standard and leads to excessive losses. However, this does not mean that wet silage cannot be adequately compacted; producers often simply conclude the process too early. When it comes to compaction, there is an ongoing debate regarding single or dual-wheel tractors. However, this is irrelevant as the pressure a tractor exerts is the real measure. There are several dual-wheel tractors heavy enough to exert more pressure per square meter than what single-wheel tractors can achieve. However, the same principle applies across the board: A tractor with as much extra weight as possible will still achieve better compaction than one without it.

Bunkers

Sometimes the rate of cutting and transporting crops is so high, that compaction falls short. In this regard, time is a crucial factor – cutting must either be done at a slower pace or more time must be spent on bunkers. This can be accomplished by spending more hours per day on compaction, or by filling two or three bunkers at a time using additional equipment. In terms of dry silage, a combination of the stated strategies is sometimes necessary to achieve adequate compaction. With very dry silage, however, other options do exist.

Silo bags

Silo bags can be used to produce slightly drier silage (there are certain responsibilities). Keep in mind that the silage parameters must be respected to achieve optimal fermentation and preservation. With the correct strategy when using silo bags, you can successfully ensile at a dry matter (DM) level that is approximately 10% higher. The strategic use of silo bags will eliminate compaction from your management responsibilities and take care of oxygen removal on your behalf:

If higher DM silage works better in your system, you can ensile most crops at around 45% using silo bags. Certain conditions apply.
Some crops, such as maize silage, are better when it has a slightly higher DM as the plant has a chance to form enough starch.
Silo bags can be used in seasons when unforeseen factors such as untimely rain, mechanical breakdowns, or contractors running late force you to cut dry silage.
Remember, though, that drier crops are associated with higher fibre and lower digestibility. So, make informed decisions.

Just because drier silage can be produced in silo bags does not mean that hay stuffed into a bag can be called silage – always respect the parameters!

Oxygen management challenges

Oxygen management poses several other challenges, such as negative pressure in bunkers that can ‘suck’ in oxygen again. Likewise, carbon dioxide, which is the waste product of cell respiration and fermentation, helps to render silage anaerobic. This heavy gas, however, escapes from the bottom of bunkers and buns but remains inside silo bags, where it displaces oxygen. This is certainly not a simple process, but there is no denying that the success of silage depends on the removal of oxygen.