Mould in the bale can cost you dearly

Sometimes mould forms in a bale. Feeding mouldy bales to the cows involves a potentially high risk. “A small patch of mould is not a big issue, you can cut it out of the bale. But if there are several mouldy patches, it’s best to cut your losses and get rid of the affected bale,” says Sjon de Leeuw, management and strategy consultant at PPP Agro Advies. “But prevention is better than cure.”

Homogeneous composition

There are various factors that can cause mould to form in bales. The main cause is air penetrating into the bale. Crude ash in the bales also creates a risk of mould. De Leeuw: “And when the composition of the bale is not homogeneous, for instance because wet and dry grass have been mixed, mould formation is inevitable.”

Measures to prevent mould start at harvesting. The mower must be set properly to avoid crude ash in the grass. The same applies to the tedder, rake and baler settings. “If a contractor does a good job and bales, binds and wraps the crop in the right way, any risk of mould formation is already reduced during an early stage of forage production,” says de Leeuw. “Subsequently, it is essential to ensure the bales are stacked in the right way in the right place. Measures taken to prevent air entering the bales through holes caused by birds, for example, will further reduce the risk of mould.”

Feeding mouldy bales is the same as feeding toxins

“In general, farmers have difficulty throwing feed away. But that is my advice if you find a mouldy bale. Should you decide to feed your animals a mouldy bale, what you are basically doing is feeding them harmful toxins. Those toxins can cause rumen acidification, reduce milk production and lead to issues with hoof health and weakened immunity. If you delay taking action until you have to cull cows, you are much too late. Prevention is better than cure.” advises de Leeuw.

De Leeuw: “Feed losses translate to a higher cost price. If something went wrong during the harvesting process or the bale was damaged during storage, there is a high risk of mould. On average, you can expect a €0.01 feed loss per kilogram of dry matter. So, as you can imagine, the damage caused by mould can be considerable. But my strong advice is, if you discover mould in the bales, accept your losses as the financial damage will always be less severe than having sick cows. If you feed poor quality rations that €0.01 per kilogram will soon multiply and cost you dearly. And that will make the cost price far too high.”

The ideal cutting height for the best regrowth

Harvesting each cut as cleanly as possible from the field, followed by optimal regrowth. The essence of cutting is determining the cutting height. The following applies: cutting slightly higher than needed ensures a cleaner cut of grass and encourages quick regrowth. 

As a rule, cutting the grass to around 5 centimetres above soil level is advised. “But applying that cutting height as standard is not always the best strategy,” says Sjon de Leeuw, Advisor Management and Strategy at the renowned Dutch consultancy PPP Agro Advies1. “Several factors influence how you determine the correct cutting height: the age of the grassland plays a role; and another determining factor is the moment of harvest. It’s important all year round to avoid cutting the growing point of the grass as this seriously affects the chances of good, rapid regrowth.”  

Cutting height and harvesting moment 

In spring the growing point of the grass is slightly closer to the soil level than the level in mid-summer. It then becomes closer to the soil again in autumn. “That explains why you can’t cut your grass at the same height all year round,” says de Leeuw. “The growing point changes during the season and if you are harvesting from grassland that is a little older, then the cutting level may need to be higher – whatever the situation, it is important to adapt your cutting height during the season.” When harvesting grass for silage, don’t just concentrate on the grass you are cutting now, but think about the next cut. “Cutting higher may reduce the yield slightly, but you will quickly recover that loss within a week thanks to good regrowth. And that gives you benefits in the second cut,” explains de Leeuw. “Assuming you can harvest five cuts in a season, and they are cut at the right height each time, good regrowth means you can realise about two weeks of extra growth days.”   

Minimal amount of crude ash in the grass

Once the correct cutting height has been determined, make sure all machines are correctly adjusted accordingly. “You can set the cutting height to 7 centimetres, but if the tedder, rake and pick-up of the silage chopper or loader wagon are not adjusted to that height, there is still a risk of crude ash in the grass. Adjust the machines accurately and always do a final check in the field. Drive a short distance, then get out and check the adjustment heights. Too high settings are not necessary but do make sure all the separate pieces of equipment are correctly aligned mutually for the best results.” 


Nutritional value – What is the optimum mowing and baling time? 

Harvesting the grass from the fields as well as possible and achieving the highest possible nutritional value. That is the whole purpose of using mowers, tedders and baler-wrapper combinations. There are two decisive factors: the crude protein percentage and the net energy for lactation.  

“First of all, make sure the grass does not start to head and flower. This means that proportionally the stem will account for too much of the grass and that will be at the expense of the net energy for lactation (MJ NEL) and the protein percentage,” says Gerard Abbink from consultancy Groeikracht BV. “To bale the best quality grass, make sure you cut it before it starts to head and produce flowering stems.” As the days grow longer, grass will head faster. From mid-May to mid-August, the day length is approximately 14 hours. This is sufficient for perennial ryegrass to start heading. Before that time, often at the time of the first cut, or during the autumn cuts, the grass will retain a high proportion of leafy growth. This naturally increases digestibility and means grass from these cuts has a higher nutritional value.  

Temperature influences time of harvesting 

The temperature especially can often postpone the moment of mowing the first cut. If there is not enough grass, it is not a problem to delay mowing for a week. “The only time absolutely not to delay mowing is once the days start to lengthen”, according to Abbink. “Regardless of the amount of grass after the first cut, I recommend mowing every four weeks. That might go against the farmer’s or contractor’s instincts, but a shorter mowing interval is better than waiting for longer for a larger volume.”  

Bale as soon as possible

The length of time the mowing process takes is crucial when it comes to the net energy for lactation. “Once the grass has been mown and dried to a dry matter percentage of 30-50%, the baler should come into action as soon as possible. This minimises quality losses in the silage. Research shows that mown grass left lying in the field loses 0.0069 MJ NEL every hour1. So, in the interval between mowing and baling some nutritional value will obviously be lost. But suppose you wait three days instead of two before baling, in that case the loss is 0.16 MJ NEL. Remember that a dairy cow that produces 30 kg of milk a day needs about 131.1 MJ NEL, of which 94,53 is directed to milk production. Every hour of waiting before baling and ensiling can therefore ultimately reduce production by around 700 grams. Grass usually needs about 48 hours to wilt and dry to a dry matter content of 40%. So, waiting an extra day for a dry matter content of 50% will cost you too much.”  

Groeikracht BV recently performed a study that measured how the method of preservation correlates to nutrient loss in silage. “If the grass is loaded into a clamp, dry matter will certainly be lost until the moment the clamp is covered with sheeting. This is an unavoidable process. It is therefore important to cover the clamp as soon as possible. In this respect, baling is a better way of storing grass, as it minimises the losses. Baling should also be done as soon as possible, as our research has shown that waiting longer before wrapping with film has a dramatic effect on the dry matter content. Every hour longer you wait before wrapping equates to a loss of dry matter of 1.5%.” 

Home-grown protein, make sure you feel the benefits!

The proportion of home-grown protein. In other words: the quantity of home-grown protein divided by the quantity of protein in the ration. Managing forage production effectively offers plenty of benefits to dairy farmers. “Poor management of the entire process, from producing the best first cut of silage grass to presenting the forage at the feed fence, can make a negative difference of around €7 euros per bale. Harvesting quickly and cleanly, then preservation in airtight conditions is vital,” says Sjon de Leeuw, management and strategy advisor at PPP Agro Advies.

A dairy farmer’s business model all depends on its farm management. De Leeuw: “Feed rations account for the biggest expense on a farm. Farmers feel the financial implications of buying minerals, concentrates and other ingredients. But one area they do have some control over is the production of protein.”

As much as possible from your own land

It is important to aim for the maximum protein yield from your own land, as this logically reduces the dependence on protein from external sources. Quantity and quality are both equally important here, as well as maintaining the right energy to protein balance in the ration. Too much protein can have a detrimental effect on the animals, so every farm aims for the optimum protein content in the bales or silage.

Influential factors on protein

“In practice, I regularly see wide variations in how much home-grown protein is produced on farms. In some cases, one farmer harvests less than 50 per cent protein from their own land while another farmer gets more than 65 per cent – even though the number of cows and hectares of grassland are the same. This suggests that farmers who produce more protein on their own land manage forage production and feeding far better,” says De Leeuw. According to the advisor, contributing factors include the harvesting method, the time of harvesting and the way of preserving. To ensure good preservation, the speed of harvesting and getting the grass wrapped airtight as quickly as possible are essential.

De Leeuw: “And bear in mind that the optimum dry matter content is around 40 per cent. You can work with percentages of 50 or higher, but that increases the risk of heating. But what makes this complicated is that the protein in drier grass is generally more rumen-resistant, i.e., of better quality. But the friction between drier grass increases the risk of heating.” One of the causes of heating is a higher dry matter content combined with inadequately sealed material. This effect can be amplified by a low face removal rate of the silage. The lower the removal rate, the longer the period that oxygen can enter the silage mass. And if oxygen is given free rein, heating will inevitably occur. Feeding bales uses up the forage faster, so the risk of heating in the bale is considerably lower than in silage.

Different bales for optimal rationing

The protein content of grass harvested in summer is often lower than in grass baled in autumn. The differences affect the ration and how the cow utilises that ration. De Leeuw: “To get an optimal percentage of protein from their own forage, it is important to mark the bales obtained from different harvests and have them analysed. This information means you know what you have and where it is stored. To keep the protein content at the same level, various bales can be mixed to create the ration. Autumn grass is best suited for dairy cattle. Provided it has been harvested properly, it is palatable and combined with a bale with an appropriately low protein content. A low-protein bale on its own is more versatile and can also be fed to pregnant or dry cows at any time.”