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Editorial Information

Carbohydrate Overload


Carbohydrate overload (ruminal lactic acidosis, grain overload, barley poisoning)

Causes

Acidosis results from the sudden unaccustomed ingestion of large quantities of carbohydrate-rich feeds, typically grain or concentrates and, much less commonly, potatoes and by-products such as bread and bakery waste.

 

Carbohydrate overload

The smaller the particle size, for example following milling, the more quickly fermentation occurs, and the more severe the clinical signs for a given amount ingested.

 

Carbohydrate overload

  • Sudden unaccustomed ingestion of large quantities of carbohydrate-rich feeds,
  • Typically grain or concentrates

Carbohydrate overload

Cattle may escape and gain access to feed stores causing barley poisoning

Clinical presentation

The severity of clinical signs depends upon the amount of grain ingested, whether the grain was rolled or whole and the rate of introduction of the dietary change. Colic signs may be observed soon after grain engorgement and cattle appear restless. Cattle are weak and may fall and experience difficulty rising. Tooth grinding is frequently heard. Cattle have a distended abdomen due to the enlarged static rumen; fluid also becomes sequestered within the intestines. There may be no diarrhoea for the first 12 to 24 hours after carbohydrate ingestion, thereafter there is profuse diarrhoea with a sweet-sour odour and may contain whole grains. The most severely affected cattle become recumbent and may die within 24-48 hours. Cattle that recover have a protracted convalescence.

Carbohydrate overload

There is profuse diarrhoea with a sweet-sour odour and may contain whole grains

Carbohydrate overload

Cattle are weak and experience difficulty rising.

 

Carbohydrate overload

The most severely affected cattle become recumbent and may die within 24-48 hours.

Clinical signs

  • Colic
  • Appear restless
  • Weak and may fall and experience difficulty rising
  • Tooth grinding
  • Distended abdomen
  • No diarrhoea for the first 12 to 24 hours
  • Thereafter there is profuse very fluid, foetid diarrhoea
  • Sweet-sour odour and may contain whole grains
  • Recumbency and death within 24-48 hours in severe cases

 

Differential diagnoses

Your veterinary surgeon may also consider:

  • Peracute toxaemic conditions such as metritis and coliform mastitis.
  • Salmonellosis
  • Hypocalcaemia in recumbent cows.

 

Diagnosis

Diagnosis is based upon the history and clinical findings, particularly once diarrhoea is evident.

Treatment

In most situations therapy is restricted to oral fluids, intravenous multivitamin preparations and antibiotic therapy. Proprietary antacid products (such as Agger's antacid) contain 220 g sodium bicarbonate, 110g magnesium oxide and 40 g yeast cell extract diluted in 20 litres for a cow.

Oral fluids,

Intravenous multivitamin preparations

Antibiotic therapy

Penicillin injections are given daily for up to 10 days in severely affected cattle to counter potential bacterial spread via the bloodstream.

Management/Prevention/Control measures

Grain/concentrate feeding must be gradually increased over a minimum of six weeks before ad-libitum feeding. Allow more than 10 per cent good quality roughage in the diet.

 

Carbohydrate overload

Barley straw as roughage and bedding.

 

Carbohydrate overload

Cattle select the best straw; the remainder acts as bedding.

 

  • Increase concentrates over a minimum of six weeks
  • Allow more than 10 per cent good quality roughage 

Fatty Liver Syndrome

This term is used to describe the mobilisation of fat that frequently occurs around calving and during the first month of lactation in high-yielding dairy cows. This is thought to be a "normal" occurrence in high-yielding dairy cattle, which may have up to 20% fat in the liver in the immediate peri-parturient period (normal cow has less than 5%). However, if the negative energy balance is severe and prolonged, then more than 20% fat may be deposited in the liver which can interfere with liver function and result in exacerbation of energy problems and the development of acetonaemia. This may lead to fat cow syndrome.

Carbohydrate overload

Inclusion of barley straw to dry cow ration to promote rumen function.

Clinical presentation

Fat dry cows (body condition score>4.0) lose too much body condition too rapidly during early lactation. Appetite is greatly reduced which further aggravates fat mobilisation and deposition within the liver, heart, and kidneys. Milk yield is greatly reduced. There is an increased prevalence of milk fever and clinical acetonaemia which may be refractory to conventional therapy. The incidence of toxic mastitis and retained foetal membranes/metritis is also increased. The mortality rate of clinical cases is high.

Clinical signs

  • Fat dry cows (body condition score>4.0)
  • Rapid weight loss
  • Poor appetite
  • Poor milk yield
  • Increased prevalence of milk fever - poor treatment response
  • Increased prevalence of acetonaemia - poor treatment response
  • More toxic mastitis cases
  • More cows with retained foetal membranes/metritis
  • Increased mortality rate

Carbohydrate overload

There is an increased prevalence of milk fever

 

Carbohydrate overload

Cows with fatty liver are more prone to toxic mastitis

Carbohydrate overload

There is an increased prevalence of retained placenta and metritis.

Diagnosis

Diagnosis is based upon history and clinical signs, in particular poor response to standard treatments for metabolic diseases such as ketosis. Typically, there is a large difference in body condition scores between dry cows and those cows calved one to two months.

Carbohydrate overload

Dairy cow calved six weeks which has lost a great deal of condition since calving.

There is biochemical evidence of severe negative energy balance during early lactation. Liver enzyme and bilirubin concentrations are greatly increased. Necropsy findings include extensive fatty infiltration of the liver which is grossly enlarged, pale, with rounded borders. There is increased fat infiltration of the kidneys and heart.

Carbohydrate overload

Necropsy findings include extensive fatty infiltration of the liver.

Clinical pathology

  • Large difference in body condition scores
  • Severe negative energy balance during early lactation
  • Liver damage
  • Extensive fatty infiltration of the liver at necropsy

Treatment

Symptomatic treatment may be attempted to enhance energy metabolism and promote liver function. Oral administration of glucose precursors such as propylene glycol (150g) or glycerine should be given twice daily by drench. Glucocorticoid therapy such as dexamethasone, stimulates glucose production and depresses milk yield thereby reducing energy requirements. Other therapies include vitamin B12 essential for the metabolism of propionate, and multivitamin injections.

  • Oral administration of glucose precursors
  • Glucocorticoid therapy such as dexamethasone
  • Vitamin B12
  • Multivitamin injections
  • Review ration

Euthanasia may be the best option for advanced cases which are recumbent.

Prevention/control measures

Correct dry cow management whereby cows calve in body condition score 2.5 - 3.0 avoiding excessive body condition. Review transitional cow management in the late dry period and ensure provision of suitable ration to cows in late dry period/early lactation including good quality forage. Maximise dry matter intake in the late dry period/early lactation. Ensure that protein and energy supply in the diet is balanced.

Carbohydrate overload

Avoid overcrowding and stress particularly in recently-calved cows.

Do not overestimate the energy contribution from forages especially that fed to high yielding, early lactation cows at pasture. Any dietary changes should be made gradually. Group cows according to their nutritional requirements. Avoid overcrowding and stress particularly in recently-calved cows. Do not overfeed concentrates. Regularly monitor nutritional status including body condition scoring of cows, faecal consistency, and metabolic profiles where appropriate.

Carbohydrate overload

Do not overestimate the energy contribution from forages especially high yielding early lactation cows at pasture.

Preventative measures

  • Calve in body condition score 2.5 - 3.0
  • Maximise dry matter intake in transition period
  • Ensure that protein and energy supply is balanced
  • Dietary changes should be made gradually
  • Group cows according to their nutritional requirements
  • Avoid overcrowding and stress
  • Do not overfeed concentrates
  • Regularly monitor nutritional body condition scores
  • Regularly monitor faecal consistency
  • Metabolic profiles where appropriate.

 

Carbohydrate overload

Maximise dry matter intake during transition period.
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