What is Ketosis?
Ketosis is essentially the cows response to a negative energy balance. In other words:
Energy used > energy taken in (eaten)
Ketosis can be divided into 2 categories:-
1. Primary ketosis - The cow is not obtaining the energy requirement that she needs from the diet that she is eating.
2. Secondary ketosis – A problem with the cow is stopping her from eating enough food to match her energy requirements e.g an LDA stops the cow eating but she still needs energy to move, produce milk etc.
What do cows need energy for?
Seems a simple question but cows use large amounts of energy just to exist. Energy is needed to:-
- Maintain body temperature
- Digest their food
- Produce milk
- Fight infections
You can appreciate how much heat a cow produces when you are stood in a milking parlour on a freezing winter morning – heats up pretty quickly doesn’t it.
Some people can smell a characteristic sweetness to the cows breath but not everyone can smell this. Your vet can usually make a tentative diagnosis using the clinical signs although blood, milk and urine tests are also available for conformation.
Individual animals are best treated as advised by your vet. Propylene glycol drenches or steroid injections can be used as can glucose injections into the vein. Groups – diet should be evaluated and problems corrected.
- Getting the dry period right is essential to correctly condition the cows to cope with the demands of lactation. Cows that are too fat won’t eat enough to meet their energy requirements and will be at risk of developing ketosis (along with LDAs, metritis, poor fertility etc). Aim for cows to calve at between condition score 2.5-3.0.
- Get a chart and regularly score and record your cows condition. This can seem tedious but time spent doing this can identify problems early before they become bigger problems.
- Prepare your dry cows well for the milking cow diet. Gradual slow exposure to the diet that the cows will be eating when they are milking allows the rumen bugs to adapt to the diet.This ensures they are able to utilise the diet as soon as the cow has calved. This has many benefits not just in preventing ketosis.
- Regular metabolic profiling with blood tests can identify potential problems. Edinburgh university run a good scheme with useful practical reports. The faster you can identify a problem the more effectively you can fix it and the less money it ends up costing you.
What Is SARA?
Sub-Acute Ruminal Acidosis. This is a recurrent low (acidic) rumen pH causing a hostile rumen environment to the good rumen bacteria therefore inhibiting digestion of food.
Why Does SARA Occur?
The bacteria in the rumen breakdown food to produce acids which are absorbed and utilized by the body. SARA occurs when the amount of acid produced by the bacteria in the rumen exceeds the amount that can be absorbed out of the rumen. This leads to a recurrent acidic environment in the rumen after feeding.
When does SARA occur?
Generally there are 2 separate groups of cows affected:-
- Transition cows (0-20 days of lactation)
- Peak yield cows (60-80 days of lactation)
There are many signs of SARA in a herd although all animals may not show the same symptoms. Generally the main symptoms include:-
• Faeces (loose or firm)
• Swishing tails
• Reduced cudding
• Cows dropping their cud
• Undigested food in faeces
• Reduced milk yield
• Reduced butterfat (10% of mid lactation cows have a butterfat of less than 2.5% or 10% of mid lactation cows have a butterfat less than the milk protein by 0.4% or more.
• Increased incidence of LDA
• Reduction of dry matter intake (DMI)
• Excessive condition loss in early lactation
• Reduced conception rates
• Increase in E.coli mastitis
SARA can cause subtle but significant losses that are often not noticed on the farm. Lost revenue through reduced milk yield, increased vet bills, increased culling, poor fertility not to mention the money wasted on feed due to a poor feed conversion efficiency. Clients often see a general improvement across their farm after correcting a SARA problem.
Your vet will need to take rumen fluid samples (either with a stomach tube or via rumen tap - a needle inserted through the body wall directly into the rumen) to test the pH (acididty). They may need to test up to 12 cows to get significant diagnosis (or have over 3 of the 12 with acid rumen fluid). Cows with a rumen fluid pH of under 5.5 are considered to be too acidic. Your vet will be able to measure the acidity of the fluid and may want to carry out some other tests too.
You could also become suspicious after looking at your milk records if 10% of mid lactation cows have a butterfat of less than 2.5% or 10% of mid lactation cows have a butterfat less than the milk protein by 0.4% or more.
Dietary management can be easily achieved after identifying where problem are likely to be occurring. It can be as simple as adding straw or hay to the rations to encourage chewing which in turn produces saliva which neutralises the acid. Supplements can be added to the diet to help neutralise acids. The best way is to prevent the problem from occurring in the first place – try not to feed too much concentrate at one go in the parlour – the use of TMR slows the intake of concentrate and dilutes the acidic effect. A cow consuming more than 10kg of concentrate a day is at an increased risk of developing SARA
Milk fever (or hypcalcaemia) is the result of a reduction of blood calcium in the early stages of lactation. This is due to the cow having a sudden, dramatically increased demand for calcium to produce milk. In the newly calved cow, this sudden need for calcium comes as a bit of a shock for the body and it can take several days for the normal mechanisms required to regulate calcium levels to begin working efficiently . It is during this transition period that cows are prone to classical milk fever.
Cows that are further into their lactation are better able to cope with the shortfall of calcium by absorbing it from their bones and also the mechanisms by which calcium is absorbed from the diet are working much more efficiently.
Cows can be affected by milk fever both clinically (with obvious signs) and subclinically (more subtle - often leads to other problems). The signs to watch out for include:-
- Subclinical; Retained cleansing, reduced appetite problems associated with reduced food intake (LDA in particular).Remember cows don’t necessarily have to be recumbent to be suffering from low grade milk fever.
- Clinical; Recumbency, 'S' shaped neck, dry faeces, cold, lack of cudding - eventually death. These are your classical cases. The cow is down and unless treated promptly can progress to death. The longer a cow is down, the more likely she will develop secondary problems such as muscle damage which can make her less likely to recover fully.
Diagnosis is generally based on clinical signs. Blood samples are often taken to analyse later if there has been no improvement – however, blood samples are not much good if taken if supplemental calcium has already been given as this will give confusing results.
Calcium is injected subcutaneously and/or intravenously. A COW NEEDS TO BE GIVEN BETWEEN 6-12G CALCIUM TO TREAT THE CONDITION. A 40% bottle of calcium contains 12g and a 20% bottle of calcium contains 6g. It is important that you are aware of how much calcium is in the bottles that you have on your farm. If in doubt ask your vet.
Take care not to overdose as this can cause heart failure. Always give intravenous calcium slowly and monitor the cow carefully and stop injecting if you have any concerns. The cow will tremble and may begin cudding if treatment is successful. Not all cows will get up straight away.
Be careful when giving multiple bottles of calcium under the skin and into the vein – there is a risk that this may actually raise the blood calcium to too high a level which can cause death in some cases. Giving magnesium under the skin (never directly into the vein) and a phosphorus injections can also help in some cases. Discuss with your vet the best treatment protocol for you on your farm.
The basic aim when preventing milk fever is to adequately prepare the cow for a the sudden increase in requirement of calcium when she calves and begins to lactate. Some suggestions on how to do this include:-
- Feed a low calcium diet in the transition during the last 3 weeks to encourage the calcium regulation mechanisms to kick start early. Ideally you need to be feeding a diet with less than 100g calcium a day which practically can be difficult to achieve. You are basically trying to trick the cow into believing that she is in a state of low calcium during a relatively safe period for her to be in this state (her calcium demands are low at this stage)
- Using a DCAB diet – This method slightly acidies the rumen which in turn produces an environment which supports optimum calcium absorption from the diet. This is effective but requires careful monitoring. Monitor urine pH to check the effectiveness of the diet. You need to supplement dietary calcium when using DCAB (not restrict it as is normally reccomended with other diets). Discuss with your vet or nutritionist if you are thinking about trying a DCAB diet.
- Check the magnesium status of your dry cows and supplement them if necessary – However, don’t over supplement as this can inhibit calcium absorption.
- Monitoring of the cows with blood samples during the dry period will help highlight some potential problems.
Milk fever problems can be a tricky to resolve and often requires dietary changes that can take weeks to show results (you just have to grin and bear it in the meantime). It is better to prevent a problem if at all possible.
What is an LDA?
Left displaced abomasums (LDA) have become a regular problem on UK dairy farms recently so what are they?
The abomasum is the fourth stomach of the cow. It is the equivalent of our stomach in that it contains all the stomach acids. It is very mobile but normally balances underneath the rumen which holds it in place due to its vast size.
What happens when it displaces?
I always imagine the abomasum to be like an inflated balloon in a tub of water. If you use the palm of your hand to hold it to the bottom it is quite easy due to the large surface area of your hand. If you try and keep it on the bottom with your fingertip it is more likely to roll out on one side or the other and float to the surface.
The same happens with the rumen. As long as the cow is eating and the rumen is full, the abomasum is held in place. If the rumen is smaller than it should be for any reason, the abomasum takes the opportunity to roll out from underneath it and “float” upwards. It depends on which way it rolls (left or right) as to whether it becomes an LDA or an RDA. It usually displaces to the left where the rumen traps it against the left body wall. If it displaces to the right there is more room for it to move and rotate which can cause more serious complications.
Cows with displaced abomasum typically present as recently calved cows with a sudden milk drop and decreased appetite. They may have a concurrent problem e.g. retained afterbirth, mastitis, lameness or they may have had milk fever.
Basically anything that can interferes with the cows appetite, a reduction in contractions of the rumen (you notice these as the cow won’t chew her cud) or physical factors (twins commonly squash the rumen and then leave a nice big space for the abomasum to displace into once they have been born. Dairy cows these days also tend to be bigger and deeper chested allowing much more room for the abomasum to float into).
Usually a run of LDAs on a farm suggests a problem with dry cow feeding or the management of them as they enter the milking herd. Your vet will be able to discuss possible improvements or take a series of blood tests to determine if your current diet is meeting the needs of your cows. Edinburgh university do a very good general nutrition profile and in my experience give very readable reports and practical information.
Displaced abomasums should be looked upon as indicators of a usually deeper problem on the farm. It is often makes economically better sense to investigate and correct the underlying factors than to continually throw money at fixing your cows as they develop the problem.
LDAs will always occur in modern dairy cows but keep a record of number of cases and send them to your vet. It is useful to have a rolling total over say 3 months as LDAs can be seasonal to some extent – Some farms see them more during the winter when the cattle are housed.>
Below are some targets
|LDA||<2 cows per 100 calving|
|RDA||<2 cows per 100 calving|
An LDA/RDA is easily diagnosed by your vet. They will flick the side of the cow whilst listening with a stethoscope. An LDA/RDA gives a characteristic pinging noise due to the gas trapped in the displaced abomasum. The vet may also push their fist into the cows abdomen whilst listening to hear a splashing (tinkle) noise caused by the fluid trapped in the abomasum.
There are many ways in which an LDA can be fixed. The way your vet uses tends to be based on what they have found works for them and no way is better or worse than any other method.
The most commonly encountered methods are
1. Roll the cow – The cow is rolled around the abomasum. The gas trapped in the abomasum makes it float to the highest point of the cow so, with a bit of encouragement, it can be floated back into position by rolling the cow. There is a high risk of the abomasum re-displacing if the cow does not fill her rumen up quickly as the space will still be there for it to move into.
2. Toggle – As with rolling the cow, the abomasum is encouraged to move up to its normal position and then with the cow on her back a large bore needle is inserted into the abomasum twice and 2 toggles are introduced and tied on the outside. This should anchor the abomasum in place. This is often a quicker and cheaper option although there is a risk of not toggling the right organ as it is performed blindly.
3. Operate - Several methods are available to operate – all are as good as each other and the one your vet will use comes down to their personal preference. Essentially all methods ensure the abomasum is back in position before anchoring it into place hopefully reducing the risk of a reoccurrence next year. Cows usually recover well but there is the risk of post surgical complications as with any surgical procedure.
4. Cull – Some cows are just beyond hope. Your vet will be able to advise if it makes more sense both economically and for the welfare of the cow to cull the animal.
The prognosis for surgically correcting an LDA is good if the condition is identified and treated rapidly. Unfortunately however, the cows production for that lactation is likely to be reduced in that she may produce a lower peak yield, have lower overall production and she may take longer to get back in calf in some cases. It is always better to take measures to prevent an LDA from occurring than it is to try and fix the problem after it has happened.
Due to the increasing size of the modern dairy cow it is unrealistic to expect never to have an LDA but you can certainly reduce the chances of one developing if you employ careful dry cow management.
The aim is to dry your cows off at condition score 2.5 and aim to calve at between condition score 2.5 and 3. It is important to allow the cows rumen to become used to the milking cow diet before calving – it can take several days for the rumen bugs to adjust to a new diet. If the rumen isn’t ready then the cow won’t eat and the rumen will remain small allowing the abomasums to displace. Get into the habit of regularly condition scoring your cows at various stages of the lactation. This way you will be able to identify trends if cows are losing too much condition which may indicate problems with the diet.
Increase concentrate rations gradually – a sudden increase will cause an acidosis and kill all the bugs in the rumen. The cow will then not eat and be a problem the whole lactation.
Decreasing milk fever (low calcium) also helps reduce the risk of an LDA. Whether the cow lies down and has a full blown case of milk fever or she experiences subclinical milk fever (low calcium but not low enough to cause classic symptoms) the low calcium changes the motility of the cows guts making a displacement more likely.
Reducing stress in the early stages of lactation is essential. If a cow has to cope with giving birth, suddenly producing 40+ litres of milk, moving into a new group where she has to find her place in the hierarchy and a change in accommodation then there is no wonder she doesn’t find time to eat as much as she should. If possible keep fresh calved cows in a separate group and milk them together. If you get a cow over the first week of lactation successfully then life should be alot easier for the rest of the lactation.
Record all cases of LDA/RDA and discuss numbers with your vet. They will be able to discuss with you sensible steps to reduce the risk of getting any more.
The root cause of any metabolic disease is dietary. This does not mean that the diet you are feeding your cow is necessarily wrong in the amount of energy/ nutrients provided but sometimes other reasons mean the cow is not able to utilise the diet as effectively as you would like.
When a farm has a problem with a metabolic disease the following will be considered as a cause:-
- Is the diet correct for all the cows needs? This is only really useful if we believe that everything that the diet contains is being utilised optimally. A cow is an animal, not a machine, and so doesn’t always read the textbook. Just because the diet information sheet says the diet is correct you shouldn’t automatically believe it. Management, environment etc all have an effect on how efficiently a cow utilises her diet.
- Has the rumen been prepared adequately for the diet that the cow is being fed? The rumen is a large fermentation vat – it contains millions of bacteria that break down the food the cow consumes and provide the energy. Just as the cow needs to be taken care of so do the rumen bugs. They don’t cope well with sudden changes to the diet, in fact they can take at least 2 weeks to adjust to a new diet and in the meantime the diet that you are feeding your cow is not fully utilised.
- Do the cows have an opportunity to eat the amount of food that they are supposed to? Is there enough trough space? Are cows walking long distances each day (whilst walking cows are not eating – they need to do this almost constantly to meet the energy requirements of a peak lactation milk yield)? Are cows getting bullied in the group they are in? – a cow on the lower end of the herd hierarchy needs to feel safe whilst eating or she won’t – it is essential to provide plenty of trough space and escape routes for the bullied cow. The list of questions is endless.
- Is the diet palatable? If the diet is not tasty then the cows won’t eat it no matter how nutritionally balanced it is!
- What are the condition scores of the cows. Overfat cows don’t eat as much as cows with a healthy condition score.
The list goes on, but as you can see, although the actual diet itself is important it is only a small component in the control of metabolic diseases.
An obvious way to check if metabolic disease is a problem on your farm is to identify and records individual cases of the diseases as they occur. However only doing this could potentially be overlooking a large chunk of the problem. Many metabolic diseases can be on the farm in a subclinical form – that is they may be affecting your herd without any obvious outward signs. It is often a good idea to monitor the effectiveness of the diet at different stages of the year, usually after a major change in the diet. Remember it is better to assess a diet after the cows have been eating it for a month (this allows the rumen bugs to be fully adapted to it and utilising it as best as possible. Edinburgh University Dairy Herd Health and Productivity Service (DHHPS) run a brilliant scheme allowing farmers to subscribe and have regular blood samples as required – these results are reported with easy to read practical suggestions and I have found them extremely helpful and in my opinion the most cost effective test any dairy farm could carry out.
Obviously there are the vet fees and drug costs to treat the individual cases which, in themselves, can be expensive. However, subclinical metabolic disease on a farm will probably cost a farm many thousands of pounds over a year in lost or sub optimal production and increased culling costs. It is worth monitoring them or at least being aware of the signs.
Individual diseases are discussed in more detail elsewhere . They are often easy to diagnose by their clinical signs or with a blood sample. However individual cases are often the tip of the iceberg and may indicate further problems throughout the herd. This should not be ignored and your vet will be able to advise you on a sensible monitoring protocol tailor made for your herd.
Again, this is covered in more detail elsewhere, but careful monitoring of the herd and discussing management of your herd (especially the dry cows and the early lactation cows) with your vet and nutritionist should help to identify any areas where you may be able to improve.