Richardt Venter

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July 15 2024

Silage for a drought-proof fodder bank.

Your priority as a livestock producer is to always have enough feed available for your animals. Recurring and sometimes ongoing drought conditions, such as that experienced all too often across large regions of our country, is a stark reminder of the need to have a fodder bank or feed stockpile of some kind.

In the worst situation the problem is not only the drastic increase in the cost of roughage, but also the availability thereof. So, the question should not be what it would cost to have a fodder bank – the question is whether you can afford not to have one?

More rather than less

Producers should therefore produce feed during the good years and store it for times of need. Although this is easier said than done, many a producer who stayed in business during the dry years will tell you it was mostly due to fodder flow planning and the availability of stored feed.

In contrast, those producers who had to cull some of their livestock due to a lack of feed, sometimes sacrificing years of herd-building and genetic progress, will tell you that they would have given anything to have a little more feed available.

How practical is hay?

The problem with hay is that it cannot be stored indefinitely. Even hay stored in sheds will lose a lot of nutritional value over time as oxygen remains present. A study in this regard showed that lucerne hay that was stored under sheets for only eight months lost almost 5% dry matter (DM), whereas unprotected hay lost around 11% DM.

Hay stacked directly on the ground can absorb moisture, increasing the bottom bales’ moisture level to more than 30%, effectively turning those bales into heaps of useless fodder. In bales stored fully exposed, the outer layer, which can easily represent one third of the bale, can lose as much as 48% of its digestibility.

Furthermore, hay that contains mould due to rain exposure and improper storage cannot be fed to animals because of the mycotoxin risk. Spotting contaminated bales is a huge challenge as mould is not always visible to the naked eye.

Hay quality is another sore point. Most grass hay is cut too late – we like to boast about the per-hectare performance parameter of bales, which is often pitiful considering the quality. Late cut hay contains far less crude protein and is less digestible, which means the effort and money producers put into cultivating the pasture have basically gone to waste.

Lucerne hay has the additional problem of leaf loss. No matter how good the process the producer employs to minimise losses during hay production, the loss will never be as low compared to when silage is made. Lucerne destined for ensiling is handled while wet, and although you do not necessarily pay for the leaves that were lost in the field when purchasing a ton of hay, you still gain more protein if you ensile it.

Silage as a feed source

There is no other long-term storage system for roughage that can deliver a more palatable, highly digestible, lower-storage-loss feed than silage. Provided that the plastic remains intact, silage can be stored indefinitely.

Wrapped bales can last in the sun unprotected for one year but will last much longer if covered by sheets or stored in a shed. Silo-bagged silage can last four years or longer based on the quality of the plastic used and the care given. Bunkers that are fully covered by an additional plastic layer (over and above the new silage film), and/ or by soil, can last more than a decade! This is all because of the exclusion of oxygen. Correctly made and stored silage has none of the oxygen-related challenges such as aerobic spoilage, microbial organism growth or oxidation.

Silage is clearly the better long-term option when it comes to preserving a fodder bank for difficult years. It is true that silage made from maize, for example, improves with age – starch degradability improves until around ten months, which means it is better to feed older than very fresh silage.

There are many farms on which fodder flow planning is underestimated and largely underutilised. When done properly, it will highlight the shortcomings in medium- and long-term feed storage requirements, and lead to improved planning and a drought-proof fodder bank.

July 15 2024

Mycotoxin occurrence in silage.

Richardt Venter Uncategorized

When it comes to managing mycotoxins in silage, prevention is always better than cure. However, treating this problem has limitations and there are several risk factors that can hamper your silage-making efforts.

From a ruminant point of view, grain and roughage, being the two main sources of animal nutrition, are always potential harbourers of mycotoxins. Silage is a key component in ruminant rations, especially in terms of quantity as it is a high-moisture roughage storage form and when not done correctly tends to support mould growth. Silage is therefore an important potential contributor to mycotoxin contamination of rations.

Moreover, maize silage combines the grain and roughage components, as a large quantity of the toxins that can potentially form in-field on grain can, among others, also end up in the silage.

A distinction must be made between field-derived and silage-derived mycotoxins. Field-derived mycotoxins that end up in your bunker are beyond your control. The presence of these mycotoxin producing moulds in the field depends on several factors, including climate, season, region, cultivar and the crop cultivated on the same field the previous season.

However, mycotoxin formation in silage is dependent on the producer’s management framework, because a lack of management combined with incorrect inputs afford these potentially dangerous moulds the opportunity to proliferate. Hence, it is preventable.

Deterioration and formation

The good news is that well-preserved silage that is fully anaerobic renders some toxins inactive, allowing them to deteriorate over time – they detoxify, as it were. Unfortunately, some species do survive this storage period of silage and play a negative role in ruminant nutrition.

It is worth noting that not all environments are conducive to mycotoxin formation. Mycotoxins are mould’s defense mechanism against its environment. During the aerobic growth of mould (when it is even visible to the naked eye), it is often not actively forming toxins; however, toxins are formed in the layer directly beneath this visible mould, where it has been activated by the remaining oxygen but is not actively multiplying.

Let’s take the silage bunker’s top layer for example – the spoilt, mould-ridden part of the top layer, which is typically removed first, is only the first layer of the problem. The silage directly underneath this visible spoilt layer can in some cases contain extremely high levels of mycotoxins, but because it is usually not discarded, it is fed to animals without the producer being aware of it.

Is removing the oxygen as quickly as possible enough to prevent mould growth and therefore mycotoxin formation in silage? Unfortunately, the answer is ‘no’; however, there are some misconceptions regarding this process. The oxygen removal rate is indeed an aspect of silage-making that prevents mould. This relates to the time oxygen is still available in the silage, potentially leading to microbial growth, including that of mould.

Most silage is eventually rendered anaerobic, but the last of the oxygen not removed by mechanical processes such as compaction can still serve as fuel for aerobic spoilage organisms, giving them a chance to multiply before entering dormancy in a preserved, anaerobic environment. If the rate of oxygen removal was slow, these spoilage organisms would have increased in number and when the silage is eventually opened for feed-out, they will have a major negative impact.

This problem typically presents itself when having to manage the silage bunker face. The number of oxygen-activated spoilage organisms is directly proportional to aerobic instability and subsequent deterioration of and losses occurring on the silage face.

Negative effects

Finally, some mycotoxins, when ingested, lead to major problems and suppress rumen function. Intake is the main driver of efficient livestock production and anything that suppresses intake will have a negative effect on production. This also pertains to impaired rumen function, as it causes substandard feed conversion and reduced immunity. Prevention therefore remains the preferred strategy.

July 15 2024

Factors affecting silage digestibility.

Richardt Venter Uncategorized

A strong relationship exists between the intake and digestibility of feed. In this month’s article the focus shifts from intake to factors that affect digestibility.

There is a direct link between the digestibility of feed and the traits of the ruminant. Digestion is a process in which the macromolecules of feed are converted into simple compounds that can be absorbed by the gastrointestinal tract (GIT).

In ruminant animals this process is especially complex, given the physiology of their stomachs. The reticulo-rumen is the first chamber of ruminants’ four-stomach setup, which breaks down feed particles through rumination and microbiological fermentation. This is followed by the rest of the GIT where feed is digested in a more similar way as in monogastric (single-stomached) animals.

In silage, like all other feedstuffs, various factors can affect digestibility. These factors occur throughout the silage making and utilisation process – from the growth conditions of the crop, harvesting, processing and storage, to the final preparations for feeding and the animal itself.

Impact of processing methods

Correct processing of forage for silage contributes to improving the digestibility of the final product. Cut length, for example, can affect intake and digestibility, which in turn affects milk production or average daily gain (ADG) in animals.

Where maize silage is concerned, mechanical processing using corn-crackers fitted to forage harvesting machinery results in improved utilisation of starch. The estimated average increase in starch digestibility of the ensiled plants is 4,2% more than the initial unprocessed digestibility.

Changes during fermentation

The yield of fermentation end-products in silage varies, depending primarily on the number of substrates and microbial populations, as well as the rate at which oxygen is removed. What is more, some silage may contain up to 200g/kg dry matter (DM) of fermentation end-products, especially lactic acid and other volatile fatty acids, which provide low energy to the rumen microorganisms.

Factors such as exposure to air and the use of additives can also influence digestibility, as it has a direct impact on the rate and efficiency of fermentation.

Degradability of nutrients

During the fermentation process of silage, a part of the nitrogen (N) fraction is degraded to soluble fractions such as peptides, amino acids and ammonia, which are rapidly degraded in the rumen with low microbial synthesis efficiency. High concentrations of ammonia can interfere with digestibility. It can also enter the N-recycling process and increase the cost of energy in the animal. As it has a negative impact on intake, the ammonia in well-prepared silage should always be kept as low as possible.

During the ensiling process, hemicellulose is broken down to provide additional substrate for fermentation – this is evident in the lower concentrations of neutral detergent fibre (NDF) in the silages than the original crops. The degradation of hemicellulose can also occur through hydrolysis by organic acids or certain additives.

Compared to the original plant material, NDF concentrations can be altered by breaking the nitrogen bound to NDF. However, an increase in the concentrations of NDF and acid detergent lignin in silage may occur due to relative DM losses or effluent losses of soluble nutrients.

Exposure of silages to air, although inevitable, also affects digestibility and can reduce it. This reduction can be avoided or minimised by adequate ensiling management procedures, from storage to removal.

A final thought

The ensiling process is complex and yields a variety of end-products of fermentation. These products may have a direct or indirect impact on the intake and digestibility of silage. Optimal control of fermentation is therefore essential to improve intake and digestibility. Various additives may contribute to increased intake and improved digestibility. To choose the ideal additive, it is necessary to understand the factors that may limit intake and digestibility.

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July 12 2024

Factors affecting silage intake.

Richardt Venter Uncategorized

Ensiling involves the conversion of water-soluble carbohydrates (WSC) to organic acids through the activity of lactic acid bacteria, a process that lowers the pH to preserve the forage. Ensiling has two main advantages: Large quantities of forage are preserved in a short period, and the process is less weather dependent than preserving hay, for instance, or feeding fresh forage daily.

In the past it was believed that ensiling had several disadvantages, including that the changes the crop underwent reduced its potential feeding value and intake as silage. Fact is, silage is a process of loss, and these losses must be managed every step of the way.

Palatability is that property of feed affecting its taste and smell, both of which animals are sensitive to. Palatability may thus be seen as the main culprit when intake-related problems emerge. I believe the correct application of management practices and technology will improve the palatability, digestibility and intake of silage.

Changes and its effect on ensiling
Changes in the nutritional value of forage can be attributed to production procedures, preservation, and postopening management. Forages undergo biochemical and microbiological changes which not only include the rather substantial conversion of WSC to mainly lactic acid, but also the partial breakdown of proteins.

These changes depend on the interaction between micro-organismsText content on the material to be ensiled, and the amount and type of substrate available.

The main factors that can interfere with the fermentation of silage is the dry matter (DM) content, WSC concentration, micro-organism populations present in the forage, and oxygen removal rate.

The fermentation of forages with a low DM and WSC content may be undesirable, while forages with an excessive WSC content may generate acidic silages, which can reduce silage intake.

Due to the fermentation process, many changes occur in the chemical traits of forage. Organic acid concentrations vary, and it is not only these values, but also the relative ratio of certain key organic acids that affect intake.

Some end-products of fermentation, such as high levels of acetic acid, butyric acid (even the smallest of amounts can cause problems), as well as abnormally high levels of ammonia, are associated with reduced silage intake. This is due to poorly fermented, and thus poorly preserved, silage.

Feeding value of silage
The feeding value of silage is usually determined by intake and digestibility, while the quality of silage and the nutrients available have a direct influence on animal performance.

It has long been believed, and often observed, that the intake of silage is generally lower than that of the same forage given fresh. This is attributed, in part, to the presence of toxic substances produced during fermentation.

Yet the validity of a blanket statement such as this should be questioned, as the variability introduced during the production of silage, and management factors during silage production and removal, has a much bigger influence on quality. Proper management can result in well preserved silage and in similar or even greater intakes compared to fresh forage. The correct usage of additives may also increase voluntary intake.

Intake of dry matter
The variation in DM intake has often been blamed on the crop offered to animals as silage. Most documented cases, however, makes very little or no mention of the fermentation traits, different end products of fermentation or management level applicable to each case.

It is not surprising that DM intake is often scrutinised, as it is the main driver of animal performance (60 to 90% of performance-related variations is associated with metabolisable energy intake, and only 10 to 40% with diet digestibility).

Additional benefits
It is sometimes easy to overlook the additional benefits of silage. The fact that an entire crop is harvested at its optimum stage, then fully processed and preserved for a relatively long period, ads to the value of silage when compared to the same crop offered fresh.

We can agree that the fermentation profile of silage can influence palatability, and therefore intake. More precisely, poor fermentation has a negative effect on animals’ intake. However, identifying the origin of the problem, be it the crop or lack of management remains crucial.

February 4 2021

Selecting the correct cultivar for maize silage

Richardt Venter Blog

As Published in Silage talk of Stockfarm Magazine, February 2021

What makes a good maize silage cultivar? Different opinions exist as to the general definition of a ‘good’ maize silage cultivar. Producers, nutritionists and even silage contractors apply various criteria, but the target animal to be fed remains one of the key factors in this definition.

In addition, the relative importance of quality versus quantity may lead to diverse interpretations, but the general rules/targets for making good-quality maize silage remain the following:

High quality per kilogram dry matter (DM).
High quantity per hectare (yield).
Efficiency, which includes cost.

The quality of cultivars

An easy way to define quality is to use the well-known parameter of total digestible nutrients (TDN). The TDN content of feed is calculated from the digestibility of crude protein, crude fat, as well as cell wall (neutral detergent fibre and other fibre fractions) and non-structural carbohydrates (including starch). A good (high) TDN value can typically be achieved with a low fibre, high starch content and high digestibility of all fractions.

TDN is especially useful as a comparative tool as it helps to predict the relative nutritional usability of different cultivars for silage making.

Yet quality on its own can be misleading as there is not much point in having a high-quality cultivar, but with a yield so low that it does not add up economically.

I would also exclude challenging years, which may be marked by drought, hail or frost damage, from the quality discussion. Having some feed available in difficult years, even if it is low quality, is still better than having none.

More does not mean better

For many producers, quantity usually means as many tons per hectare as possible. However, without sufficient quality, a high-yielding cultivar will only solve half the problem as far as on-farm fodder flow is concerned, as various nutrients will then have to be sourced from external sources. This is especially true for maize silage which has an inherent ability to produce starch, and the starch varies greatly in digestibility based on harvest stage.

Depending on the nutrient, the location and cost of logistics, the economy, and factors not in producers’ control (e.g. the exchange rate), this can be a very costly endeavour. Furthermore, yield should always be standardised at 35% DM, or presented on a full DM basis. Comparing silage yields on an as-is basis, and not on a 35% DM basis, is the most common mistake that producers, contractors and agronomists make.

Efficiency of cultivars

A useful efficiency parameter to link quality and quantity is the prediction of milk produced per hectare, which tries to combine the effects of good yield and good quality. In this instance we can estimate the milk produced per ton of DM silage and multiply that by the yield per hectare.

It does not have to be milk production only; any performance parameter can be applied. It connects the known value of the end-product to one of the major inputs. This is how the economics of it all, including input costs, is tied to the evaluation.

The variation introduced by the different cultivar growth classes (ultra-quick, quick, medium, or long growers) complicates this matter. A leading seed company recently evaluated their own hybrids for ensiling quality in South Africa. According to the data, it seems that the quicker growers generally perform better at higher populations and under irrigation, whereas slower growers tend to perform better at lower plant populations and under dryland conditions. However, there are exceptions in both groups.

A final thought

Overall silage efficiency and productivity is best evaluated using an efficiency parameter such as milk produced per hectare. This bridges the gap between what is planted for silage and what is consumed by the livestock, bearing in mind cost and relative production expectations.