12 minute read
VET’S VIEW
Irrespective of milk yield, herd size or system, all dairy herds have a degree of ketosis on-farm which, if not appropriately treated, will have a negative effect on health, fertility and milk production. Dairy Farmer reports. Prevalence of ketosis across the dairy sector
It is crucial that ketosis is not just seen as a problem among high yielding herds, but instead presents a threat to all dairy cows says Kate
Heller, ruminant technical consultant at Elanco.
She says a study in Ireland showed that grazing herds averaging 6,758litres had 27% incidence of ketosis, which is directly comparable to what is seen in higher yielding herds, with the figure for this category standing at 28.5%.
“Every cow will experience a negative energy gap in the run up to calving and consequently will be at risk of ketosis.
“However, there are outliers in the herd which will be far more likely to suffer from the condition,” Ms Heller explains. “To identify those most at risk, I would recommend pinpointing any sick, old, fat, thin or twin-bearing (SOFT) cows, as well as those which have pre-
Kate Heller says clinical ketosis is often just the tip of the iceberg where herd health is concerned.
In the field Sam Bowker, Exeter
JSam Bowker works on his Exeter-based family dairy farm and as a farm animal vet for Blackdown Farm Vets in Devon.
The farm runs 220 Irish Holstein cross cows on an autumn block calving system, with cows average 7,600 litres per cow over their lactation.
Since stepping back into a more active role on the farm, Mr Bowker has taken a keen interest in whole herd management, with a particular focus on the transition period.
This has delivered multiple improvements in production, health and fertility rates, including a 10% increase in conception across the herd.
“We try to breed all of our own replacements, so fertility is a key focus for us,” explains Mr Bowker.
“We have made a number of changes to how we handle the transition period, including introducing a specific TMR, and body condition scoring the whole herd.
“Far off dry cows are grazed on standing hay. Traditionally we just fed hay and dry cow rolls during the transition period but following work with our nutritionist, we now feed a transition specific TMR two to three weeks pre-calving to prime them for early lactation.
“The diet consists of mainly maize and chopped straw with some grass silage, treated wheat, soya and dry cow minerals. This more intensive diet helps to reduce the negative energy gap,” he says.
The Bowkers have also increased a focus on body condition scoring (BCS) both pre- and post-calving.
“All cows are scored at drying off with a target score of between 2.75 and 3. When they come in for transition, they are scored again before moving onto the TMR, which helps to reach our goal for a body score of 3 at calving,” he explains.
Sam Bowker
Track
“It is vital that we track all body scores to regulate cows that could be at risk of ketosis.
“When scoring the herd at transition, we also administer a monensin bolus to all cows that are at a heightened risk of the disease.
“This includes cows in their fourth lactation or older, any with a BCS 3.5 or over and any twin bearers, to assist with energy conversion.
Five key areas to address when looking to control ketosis on-farm
rNutrition: Ensure adequate dry matter is available and introduce a transition specific diet. rHerd environment: Avoid overcrowding or changing groups during the transition period. rPrevent cows from getting fat: Fat cows have are inclined to eat pre and during calving, resulting in increased fat mobilisation, speeding up the risk of ketosis. rKnow your herd status: Regularly monitor your herd throughout the transition period and address any issues or symptoms immediately. rTreat those at risk: Treat all at risk cows with a monensin bolus three to four weeks pre-calving.
Administering a bolus three to four weeks ahead of calving can reduce the incidence of ketosis by up to 74%.
The active ingredient, monensin, is released into the rumen over 95 days, stimulating glucose production, to decrease the energy gap that leads to ketosis
viously su ered from a post calving disease or a previous case of ketosis. ese cows should be prioritised for preventative treatment.”
When thinking about ketosis, Ms Heller says many immediately presume that looking out for a suppressed appetite, reduction in milk and poor rumen ll alongside a smell of pear drops are the key indicators.
Clinical
However, by the time these symptoms are visible, clinical ketosis has already taken hold.
“Clinical ketosis is o en just the tip of the iceberg and indicates there are many more cows within the herd with high levels of ketone in their blood.
“ is in return will be a ecting their health and performance, but is classi ed as sub-clinical ketosis, as no clinical signs are presented.
“By having a well-rounded, holistic approach to transition management, encompassing nutrition, herd management and environment, farmers can get ketosis under control and see the bene ts of this in yield and herd health”, explains Ms Heller.
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“The other key part of our transition management plan is conducting ketone tests on all fresh cows at 10 to 17 days in milk. This allows us to see any that may be at risk of high blood-ketone levels allowing us to react quickly to prevent ketosis.”
Tailored transition management has led to general increased herd health and better conception and fertility rates on the Bowkers’ farm.
“Since implementing an all-encompassing transition management plan we have seen a significant decrease in post-calving diseases with just one case of milk fever, one retained cleansing and no cases of displaced abomasum last year,” says Mr Bowker.
“Last year’s conception rates were 56% which is a huge increase on previous years.”
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Profit from our knowledge
Buoyant milk prices and high bought-in feed costs provide added reasons to do a great job of making maize silage this season.
Maize silage offers good opportunity with high prices
ith soaring
Wfeed costs it makes a lot of sense to maximise milk production from home-grown forage, says Volac silage scientist Dr Mark Leggett. Moreover, healthy milk prices add to this argument.
But there is another reason why it is important to retain as much feed value as possible when ensiling maize crops this season.
Higher fuel and fertiliser costs mean maize has cost more to grow this year. So any losses in dry matter (DM) and nutrient content which are allowed to occur will steal some of that extra investment, he adds.
Dr Leggett says: “With its high starch content, maize is an ideal source of home-grown metabolisable energy compared with buying-in energy from extra concentrate.
Maize is an ideal source of home-grown metabolisable energy, says Dr Mark Leggett.
“However, a key challenge is that maize plants play host to a lot of undesirable micro-organisms – in the form of bacteria, yeasts and moulds [see infographic, above right].
“If allowed to multiply in the clamp, these can cause signifi cant
feed value reductions, both during storage and when the resulting silage is fed out.”
Typical losses
Although diffi cult to quantify precisely, Dr Leggett says even typical losses in maize clamps equate to about one in every 10 trailer-loads of DM ensiled being lost, but they can be higher, for example two out of every 10 trailer loads if clamp management is not up to scratch.
When spoilage occurs in the vulnerable top and shoulders of the clamp, he says half the DM in these areas can go to waste, or more.
Dr Leggett says: “The other important point to stress is that it is the most digestible parts of the DM that undesirable microbes feed on fi rst – the sugars and starches.
Dr Mark Leggett’s tips for making better maize silage Potential sources of undesirable microbes (bacteria, yeasts and moulds) on maize plants which feed on
Maize tips Why do this? nutrients and interfere with preservation in the clamp
Clean the clamp To remove undesirable bacteria, yeasts and moulds before harvest surviving on old silage and in cracks Harvest maize To provide a balance of: promptly at 30-33% ● Starch content in cobs – for energy dry matter (DM) ● Foliage that is still green – for digestibility ● Crop still suffi ciently ‘soft’ for consolidation Leave at least 15cm Because the stem base is: of maize stubble ● Low in nutritional value ● At risk from soil bacteria that interfere with fermentation ● At risk from yeasts and moulds Chop to the So the maize is: optimum length ● Short enough to aid clamp consolidation (1.5-2cm) ● Long enough to perform in the rumen Treat with a ● To reduce fermentation losses (due to ineffi cient dual-acting additive fermentation bacteria naturally present on the crop) ● To target the yeasts and moulds that cause losses from heating Fill the clamp in ● To aid consolidation and keep air out: oxygen maximum 15cm trapped in silage allows yeasts and moulds to thrive layers, roll with (Typically, maize at 30% DM requires 25% of its suffi cient weight weight arriving at the clamp/hour to consolidate it. and sheet thoroughly So 100 tonnes/hour requires 25t rolling constantly) (side sheets, an O2 barrier fi lm and wellweighted top sheet)
Various fungal diseases living on the maize plant
Dead or dying leaves and stem tissue harbouring yeasts and moulds
Soil microbes and mould spores splashed up around the stem base, especially in muddy conditions Microbes on decaying tassels at the top of plant and on cobs
Dirt and decomposing crop debris e.g. shed tassels trapped in leaf joints – providing a breeding ground for ‘bad bugs’
“So not only is there less DM available to feed, but the DM that remains contains less energy for the cow.”
As an example, Dr Leggett says maize is notoriously prone to losses from aerobic spoilage (heating), caused by yeasts and moulds feeding on the silage in the presence of air.
But it is not just losses from heating which maize suffers from. Invisible losses from poor quality fermentations can account for as much as half the overall DM losses in maize clamps, he says.
So when planning how best to conserve maize, it is important to consider both problems.
Dual-acting
Dr Leggett says: “Preserving maize silage is not a single-step process. It requires a joined-up approach [see table, above]. This starts even before harvest by thoroughly cleaning the clamp to remove contamination from old silage.
“It doesn’t end until you can see the silage at feed-out is staying cool.
“Fortunately, some steps, such as achieving a good consolidation, can benefi t not only the fermentation but also help in reducing aerobic heating losses. An integral part is also to choose the correct type of additive. To target both sources of loss, I would advocate an additive which is dual-acting.
“The additive Ecocool, for example, contains two types of benefi cial bacteria. The fi rst, Lactobacillus plantarum MTD/1, which is also found in Ecosyl, is targeted at improving fermentation.
OTHER COSTS OF BAD MICROBES
MAIZE silage heating is a sign that dry matter (DM) and nutrients are being ‘burned up’ by yeasts and moulds.
But besides heating, bad microbes can cause other problems.
Dr Leggett says: “Palatability can also be reduced, resulting in lower DM intake and greater rejection, which will push up bought-in feed requirements.
“Additionally, moulds can cause mycotoxins, requiring remedial action. Both of these are added reasons to pay close attention to crop and clamp management and additive choice from the outset.
“Prevention is certainly better than cure.”
“But in Ecocool, MTD/1 is blended with a second bacterial strain, Lactobacillus buchneri PJB/1, which is included to inhibit yeast and mould growth. In trials, compared with untreated maize silage which contained 440 million colony-forming yeast units per gram after exposure to air, maize silage made with Ecocool contained less than 1,000.
“Ecocool has also been shown to keep maize silage cool and stable for more than 10 days after removal from the clamp.
“With a lot at stake with high feed and milk prices, an additive looks a worthwhile investment.”
For more information on Volac’s Cut to Clamp initiative, visit
