Down Cows – Get Them Up, Keep Them Up

Down Cows – Get Them Up, Keep Them Up

1 July 2020

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Dairy cows are the elite athletes of milk production. Over many generations they have been bred to provide an abundance of milk – in quantities far in excess of those required to rear a calf.

To achieve such a supply, cows must deliver a calf each year. In New Zealand, those births are seasonal, usually timed in the spring to gain advantage from the availability of the most nutrient-rich pasture.

Cows need to transition safely from being pregnant to non-pregnant, that is from a condition of non-lactating (dry) to lactating (milking), and from a low to a high level of feed intake – the transition period.

The transition period requires careful management to ensure cows achieve the recommended body condition at drying off, adequate nutrition through the dry period, careful transitioning of the diet during the calving period, and availability of minerals at appropriate times. If not achieved, the risk of metabolic disturbances increases, which can manifest as imbalances of minerals such as calcium (Ca) – milk fever; magnesium (Mg) – grass staggers; and phosphorus (P) – hypophosphataemia. Metabolic disturbances can also manifest as an excessive breakdown of body tissue to meet the demands of lactation (ketosis). There are associations between these metabolic conditions of the transition period and each other, with other disorders, including reduced reproductive performance, and lowered productivity.

The following metabolic disorders may occur during the transition period.

Milk Fever

(clinical hypocalcaemia)

What is it?

Hypocalcaemia is a sudden fall in blood Ca, which can be determined from the level of Ca in a blood sample. Milk fever often occurs within a few hours of calving due to the demands of milk production. At this critical time, inefficiency to mobilise Ca from bone stores, inability to efficiently absorb Ca from the gut, and poor control of Ca loss into urine, means the production demand may exceed the cow’s capacity to supply Ca.

What are the signs?

Early signs are weakness, unsteadiness, depression and glazed eyes. If untreated, recumbency will follow, there may be a S-shaped bend in the neck, dilated pupils, constipation, a low temperature, a fast but weak heart rate, and an inability to rise if approached.

What are the preventative measures?

Careful management of dry cow feeding and mineral intake can help to prevent hypocalcaemia. Administration of oral Ca products before cows have developed milk fever, i.e. administered at calving or shortly after, may also help. Examples of oral products are Oral-Cal or Oral-Max.

How do I treat it?

Hypocalcaemia can be treated by administering calcium borogluconate intravenously. Suitable products are CBG 37.5, Glucalmag, Glucalmax or Glucalphos. Be aware that for hypocalcaemia, a slow intravenous injection is preferred to administration under the skin. As a sole treatment, injections of Ca given under the skin take too long to be absorbed and may result in the cow’s condition deteriorating before the Ca has had time to be beneficial. When the cow has recovered its ability to rise and is able to swallow, intravenous Ca can be supported with oral Ca supplements like Oral-Cal and Oral-Max.

Grass staggers

(hypomagnesaemia)

What is it?

Hypomagnesaemia usually occurs within six weeks of calving and results from low Mg intake or absorption. Grass staggers is often precipitated by inclement weather and grazing of lush, fertilised pastures. Urgent attention is necessary as Mg is also important for maintaining the cow’s Ca balance. Low Mg increases the risk of hypocalcaemia.

What are the signs?

Grass staggers is dramatic and characterised by twitching of the ears, frothing at the mouth, bellowing, muscle tremors and aggression. These symptoms are followed by a spastic (stiff) gait, incoordination, muscle spasms, recumbency, paddling of the limbs, convulsions, coma and death. The heartbeat is strong and fast, and may be heard when standing close to the cow. Although many of these cases may die, early intervention and treatment can lead to complete recovery.

What are the preventative measures?

Dusting of pasture with magnesium oxide powder and provision of shelter during periods of inclement weather can help prevent grass staggers.

How do I treat it?

Magnesium sulphate 20 percent should only be administered under the skin to treat grass staggers. Glucalmag, Glucalphos or Glucalmax may also be administered, but intravenous injection of these products must be carried out very slowly to avoid heart failure. Once cows have recovered, they can be administered oral magnesium oxide or magnesium chloride.

Ketosis

What is it?

Ketosis (acetonaemia) occurs when the energy demands of lactation exceed what’s available from the cow’s diet. This may be the result of cows having reduced appetite due to suffering another disorder, being over-conditioned, or consuming a low energy diet. To make up for this, the cow breaks down body fat and muscle to meet the demands of lactation.

What are the signs?

Ketosis usually occurs within two to eight weeks after calving and in one of two forms; wasting ketosis (slow fever), or nervous ketosis. The wasting form is characterised by rapid loss of weight/condition, inappetence or preferentially eating of grass or silage over grain, a dull coat, firm faeces and glazed eyes. The nervous form may show similar signs to the wasting form plus signs of neurological disturbance including those of hyperexcitability, pica (aberrant feed selection) and aggression, making the nervous form hard to differentiate from grass staggers without testing blood samples.

What are the preventative measures?

Provision of adequate feed and feed space, a diet of sufficient energy density, and no over-condition cows at calving can help prevent ketosis.

How do I treat it?

Short-term reduction of milking frequency may help manage the drain on energy reserves. Daily drenching cows for three to four days with Ketol – an oral drench that provides a concentrated source of energy – helps support their blood glucose levels. Slow intravenous injectable metabolic products such as Glucalphos and Glucalmax can provide an immediate, short-term boost to blood glucose. Higher glucose concentration injectable metabolics are available from your veterinarian.

The above is not an exclusive list of metabolic conditions that can affect cows during the transition period. For example, low blood Ca (hypocalcaemia) can be linked to other conditions such as low blood P (hypophosphataemia). Such conditions may be identified from blood samples and may require administration of additional remedies from your veterinarian to aid in their correction.

If there is any doubt about the condition or treatment of cows, always seek immediate veterinary advice.

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