Dairy farmers are being encouraged to analyse forage regularly during feed-out this winter – to ensure rations meet performance targets and support rumen health.
This year’s silage could present a challenge for the rumen due to variable spring weather playing havoc with usual cutting practice, says Lientjie Colahan, technical sales support at feed experts Lallemand Animal Nutrition.
“It has been a tale of two halves this year,” says Ms Colahan. “Some were able to get their first cuts harvested very early and others had to wait much later than usual. As a result, we are faced with two likely scenarios.
“Farmers will have either early-cut ‘rocket fuel’ silages that are highly digestible and could impact rumen pH, or high neutral detergent fibre (NDF) silages that were cut late and are not as digestible as you’d want them to be.”
Where first-cut was later, silages will contain more lignin which cannot be digested by ruminants. As grass leys age the lignin content increases, lowering overall fibre quality and digestibility.
“For those who took cuts later than planned, this could be an issue,” says Mrs Colahan.
Farmers who cut early and made high quality silage, the problem will be the opposite. “These highly digestible silages will move through the rumen quickly and could increase the acidosis risk by challenging the stability of rumen pH.”
In either scenario, Ms Colahan says it will be important to analyse forage regularly and balance diets accordingly to maintain cow health and performance. Highly digestible silages could be balanced with a cereal whole-crop that has a high straw content, she says.
“This will slow down the passage rate through the rumen and maximise digestion of the rations fibre component.”
Farmers with stemmy forage high in NFF should ensure the chop length of the total mixed ration is as short as possible to decrease the particle size of the feed. This helps microbes break down the fibre more easily and will maintain good dry matter intake of the ration.
Mrs Colahan says including a rumen specific live yeast will prove beneficial in both situations. It can help good microbes outcompete bad microbes – and therefore establish a more favourable balance within the rumen.
“When it comes to high NDF silages, specific live yeast has a positive impact on the rumen fungi that work to break open the outer layer of the fibre particles. This allows rumen bacteria to break down the fibre further, making it more digestible.
“On the other hand, in a situation where acid load may be increased as a result of highly digestible forages, a live yeast promotes the bacteria that utilise lactic acid as a food source as-well as competing directly with the lactic acid producing bacteria for their food source.
“This regulates the rumen pH by reducing the amount of lactic acid present.” Regardless of the type of silage you have to work with, close attention to detail during feed-out will help you get the most out of the available forage and support productivity, says Ms Colahan.
Raise mower to ensure quality silage
Cutting grass crops at 9cm rather than 6cm or 3cm, will give the highest quality silage and allow quicker regrowth, according to trials carried out by specialists DLF seeds.
Visual assessments two weeks after cutting clearly showed 3cm plots of perennial ryegrass were still yellow and brown. But 6cm plots were returning to green and 9cm plots were lush and growing back well.
“Cutting low will undoubtedly produce more silage in the clamp but the feed quality will be compromised,” says David Rhodes technical manager for DLF Seeds. “This is because there will be a lot of stem as well as leaf included.
“Scalping grass plants will also mean they will struggle to photosynthesise because there are no green areas left to capture sunlight, so they will eventually die. Even cutting at 6cm will mean it takes longer for the crop to regrow for the next cut.”
Farmers using a contractor should highlight the importance of cutting height, added Mr Rhodes. Some contractors might prefer to cut low to increase tonnages cut rather than adjusting mower height to optimise regrowth.