Milk fever is a disease that affects dairy cattle but can also occur in beef cattle, goats, or even dogs. It occurs when there is reduced blood calcium levels (hypocalcaemia) in cows a few days before or after calving. Some people call this condition postparturient hypocalcemia while others call it parturient paresis.
A positive diagnosis is given when the blood calcium level goes below 8.5 mg/dl (or 2 mmol/l). Incalf cows need to replenish the calcium that the fetus needs for growth, which is about 30 g per day. The cow should replenish this calcium through the feeds or by supplementation.
The coefficient for converting concentrations into mmol/L from mg/dl: mg/dl/mmol/l = 18. You can get this value as follows:
100 mg/dl = 100 mg/100 ml = 1000 mg/L
Molar mass of glucose is 180
Divide the concentration by the molar mass of glucose to get the concentration in mmol/l
1000/180 = 5.55 mmol/l.
The coefficient of concentration is (100 mg/dl)/(5.5 mmol/l) = 18
When the demand is not met through feeding, the calcium reserves in the skeletal muscles drop. After parturition, the cow needs even more calcium to replace what is lost through the colostrum. The cow loses plasma calcium through the udder to make the colostrum for the calf.
When the plasma calcium drainage is so severe that it affects the cow's neurotransmitter functions, the cow will exhibit the clinical signs of milk fever.
Causes and predisposing factors for milk fever
High producers have a higher risk to hypocalcaemia since the fall in their blood calcium level is greater. They may not be able to replenish the large volumes of calcium reserves that drain into the milk.
Heifers are rarely affected by milk fever since they have not fully realized their production potentials. Older dams that have calved multiple times have a higher productivity, hence higher susceptibility to milk fever.
The feeding regime during the closeup dry period has a great bearing as to whether a cow will suffer from milk fever or not. During this time, there is an increased demand for calcium, which the cow should replace from the feed.
However, you should be cautious when making the ratios so that you do not unnecessarily increase the alkalinity of the feed to an extent that calcium becomes non-bioavailable for the cow.
A highly alkaline environment hinders mobilization of calcium from the bones and absorption of calcium in the intestines. The imbalance increases the cow's risk to milk fever.
Cows that get milk fever before parturition are attributed to the rapid fetal growth, which demands a lot of calcium. If the cow cannot replenish the minerals through the feeds, it will have milk fever. Such cows should have a well-balanced diet that will supply all the needed nutrients.
The feeding program should continue until after parturition. You should incorporate as much calcium and clover-rich pastures as possible because the two will help prevent grass tetany (magnesium deficiency caused by feeding on lush grass).
- Fat cows with good body condition at parturition since they tend to produce more milk.
- Channel isle breeds, e.g. Jersey
- Cows with a history of milk fever
- High green feed diet during the dry period or feed with potash
Symptoms and different stages of milk fever
Milk fever affects about five percent of all lactating cows annually. Large herds may be more susceptible, especially if most of the animals are old or exhibit the risk factor listed above. The old stock may pass the undesirable traits to their calves, which compounds the problem in the farm.
You can diagnose milk fever in three distinct phases:
i) Phase 1
Cows are hypersensitive, restless, and may have body tremors. They shift body weight and have unbalanced gait, especially in the hind legs. This phase is tricky because you have only one hour window to detect and treat the cow. If you do not treat the cow at this stage, it progresses to phase 2
ii) Phase 2
This stage lasts a bit longer, ranging from one hour to half a day (12 hours). The cow has a clearly observable difficulty while moving around and is generally dull. Body temperature drops and the muzzle dries up. Heart rate increases to more than 100bpm. The strength of the heartbeat (tarchycardia) falls and may not be easily noticeable.
The cow loses ability to stand on her feet and lies down sternally. You may observe constipation and the cow will have difficulty defecating or urinating since the smooth muscles will have paralysis. The cow tucks the head in the flanks.
You still have a better chance of saving the cow. However, if you do not treat the cow, the condition will progress to phase 3.
iii) Phase 3
The cow has lost all the ability to stand, body temperature has dropped drastically and the heart rate has increased to over 120bpm. Cow exhibits lateral recumbency (lies on the side) and does not respond to stimuli. Tarchycardia is very weak and if you do not introduce an intravenous injection, the cow will slip into a coma and die after a few hours.
How to treat milk fever
Treat the affected cow as soon as possible because death is certain if you don't. Collect the animal's blood sample for further clinical analysis before you administer any treatment.
Depending on the stage of the condition, you may choose one of the three options available for administering the treatment.
a) Oral treatment
For animals that are still in the early stages of the condition, oral treatment is a viable option. The advantage of this option is that the calcium gets absorbed in the intestines.
However, some people may be reluctant to use this option because calcium gels ulcerate the oral cavity or the cow's intestines. Furthermore, the unpalatability of these gels will lead to reduced feed intake.
On the other hand, administering a liquid calcium solution increases the risk of pulmonary aspiration since the solution is very caustic. You can use 300 ml, or more, of a 40% solution of calcium gluconate.
Since a myriad of other minerals such as magnesium, phosphorus and glucose (for energy) may be in short supply at the same time, you can use a combined mineral solution that contains these minerals.
b) Subcutaneous administration
You inject calcium solution in the peripheral parts. Since the animal has a low pulse and an inefficient circulation, you should split the dose and administer it in different parts. This will facilitate a speedy uptake of the treatment into the system.
One problem with this method is that, there is a likelihood of the drug causing necrosis at the injection site. This is attributed to the poor circulation of blood in the peripheral tissues.
c) Intravenous injection
Administer 500 milliliters of 23 percent calcium gluconate intravenously. It will boost the blood calcium level, which is not only necessary but also critical in an emergency situation. IV injection provides a rapid increase in blood calcium and provides the desired result almost instantly.
Take caution while administering an IV treatment so that you do not end up killing the cow with a heart attack. Administer the dose slowly to boost the blood calcium levels slowly.
Take note that blood calcium will drop again after four hours, taking the cow back to a hypocalcaemic state. Administering large IV doses will not benefit a cow with milk fever much. Once the cow has regained strength, add oral treatment to reinforce the IV.
What other progressive treatment options for milk fever exist?
Always keep packets of calcium gluconate solution together with an injection kit for emergency situations. Ensure they are clean and sterile. If you do not know anything about animal health, keep your vet's number on speed dial. Always call your vet to do IV injections because you can easily kill your valuable cow.
When your cow has slipped to the later stages of phase two of milk fever and phase three and it is lying on the sides, prop it up before you start administering treatment. Propping the cow will help you expel the gas in the cow's stomach and reduce flatulence.
Feed the animal and give it plenty of clean water. Keep it as comfortable as possible.
Cows that have slipped into a coma may have inhaled rumen into their lungs. You can tell this if rumen content is present around the nose. If that is the case, administer antibiotics because your cow may die due to inhalation pneumonia.
Refrain from milking the cow for the next 24 hours to allow it extract as much calcium as possible. Gradually increase the amount of milk over the period of 48 - 72 hours.
Preventing milk fever episodes
i) Feeding management
Feeding plays a key role in preventing the occurrence of milk fever. Keep cows on low calcium diets to stimulate their body systems to mobilize calcium from the bones. This will help in maintaining a level concentration of calcium in the blood. It is easier for the cow to mobilize calcium from the bones than from the feeds.
Conduct mineral test for the feeds and check for availability of calcium, phosphorus, magnesium, potassium, sodium, sulfur, and chloride. Consult an animal nutritionist to help you develop an effective feeding plan that will take care of your cow's mineral needs and prevent incidences of milk fever.
Identify the animals that are at risk of developing milk fever and put them on dry matter feed for about three weeks before calving.
Limit the amount of grass and green pasture feeding to reduce the risk of grass tetany. Ensure that the feed has no mold or traces of mycotoxins (e.g. afflatoxin) in it.
Administer high energy low calcium feeds to improve productivity. Cereals have high energy and phosphorus as an added advantage. You can add about 100 grams of ammonium chloride to the feed if the cow's rumen has a high pH (test urine pH).
Begin administering this ration to the cow two days before parturition and continue until two days after parturition.
ii) Physical monitoring
When the cows are about to calve down, keep a closer watch over them to allow you detect milk fever early should such an incidence occur.
After parturition, gradually introduce calcium rich feeds and do not restrict the cow's feeding. You can even use calcium feed supplements.
iii) Vitamin supplementation
If you cannot find proper dietary management programs readily, you can inject the cow with vitamin D intravenously (co-factor for calcium absorption). Administer this before parturition (usually between two to seven days before calving).
If the cow does not calve down withing the projected window and the seven-day window elapses, repeat the treatment after 10 days (as necessary).
Supplement vitamin D intake for all the lactating animals. Peg the supplementation to 50,000 units per head per day for all the cows. This will help the cows to utilize calcium much better.
iv) Mineral supplementation
Some farmers prefer to take the precaution and inject the cow with calcium gluconate just before or after calving. This method is quite a success in preventing milk fever since the boost builds up calcium reservoir in the blood to make it readily available for making milk.
There should be a caveat here. IV administration of calcium will boost calcium level in the blood but the effect is likely to wear off after some time if the cow's biological calcium regulation system has not taken effect.
You can drench the cow with a calcium solution for two days before parturition. Since magnesium deficiency is almost always associated with milk fever, you can add magnesium into the drenching solution. Drenching after injecting the cow will prevent relapse of milk fever.
A solution of Epsom salt can help flush out toxins from the cow's gastrointestinal system. The cow will be able to stand up in two to four hours after administration. Do not give up before you try this option.
Make sure to contact your vet or animal health officer for guidance since every cow has a unique need.
Follow the manufacturer's instructions and directions carefully.