Changes

The nature of the faeces can give clues to the existance of SARA within a herd. Suboptimal rumen function means that some feed passes to the colon before digestion. Therefore, many animals in a group of cows with subacute rumenal acidosis will have a looser faecal consistency, due to osmotic diarrhoea caused by colonic fermentation of feed. In turn, the udder, tail and rump will have large amounts of faecal staining/ In some animals, the colonic pH falls to such a degree that the microflora are killed and no hind-gut fermentation occurs. This leads to firmer, sticky faeces that contain undigested sugars. There may be other abnormalities to faecal appearance, for example cows may excrete undigested grain. Fibrin casts, indicative of colonic mucosal damage induced by an excess of acid, may also be seen. A low rumen pH can lead to the production of acidic urine and faeces. Cows may therefore be seen to swish their tails in the absence of flies due to the irritation this causes. When tail-swishing occurs frequently, faecal staining of the rump can be seen, which may be an indicator of SARA in many herds.  

The nature of the faeces can give clues to the existance of SARA within a herd. Suboptimal rumen function means that some feed passes to the colon before digestion. Therefore, many animals in a group of cows with subacute rumenal acidosis will have a looser faecal consistency, due to osmotic diarrhoea caused by colonic fermentation of feed. In turn, the udder, tail and rump will have large amounts of faecal staining/ In some animals, the colonic pH falls to such a degree that the microflora are killed and no hind-gut fermentation occurs. This leads to firmer, sticky faeces that contain undigested sugars. There may be other abnormalities to faecal appearance, for example cows may excrete undigested grain. Fibrin casts, indicative of colonic mucosal damage induced by an excess of acid, may also be seen. A low rumen pH can lead to the production of acidic urine and faeces. Cows may therefore be seen to swish their tails in the absence of flies due to the irritation this causes. When tail-swishing occurs frequently, faecal staining of the rump can be seen, which may be an indicator of SARA in many herds.  

Feeding behaviour can also be affected. Individual cows may show inappetance for 24-48h, with no other clinical signs and spontaneous resolution. Animals can also be seen to "drop the cud" while ruminating, and feed efficiency is reduced. This reduced efficiency may not be noticed in the field situation, but has been demonstrated experimentally and is associated with the passage of undigested food in the faeces.  

Feeding behaviour can also be affected. Individual cows may show inappetance for 24-48h, with no other clinical signs and spontaneous resolution. Animals can also be seen to "drop the cud" while ruminating, and feed efficiency is reduced. This reduced efficiency may not be noticed in the field situation, but has been demonstrated experimentally and is associated with the passage of undigested food in the faeces. * Reduced dry matter intake (Garrett and others 1999);

SARA can impact production parameters. Milk yield is lowered, although on farms where subacute rumenal acidosis is an ongoing, chronic problem, this may not be recognised. Milk butterfat levels are also reduced, which may be due to two factors. Firstly, milk fat is produced from acetate and butyrate, which in turn are produced from fibre in the diet. Dietary fibre is often reduced in SARA

SARA can impact production parameters. Milk yield is lowered, although on farms where subacute rumenal acidosis is an ongoing, chronic problem, this may not be recognised. Milk butterfat levels are also reduced, which may be due to two factors. Firstly, milk fat is produced from acetate and butyrate, which in turn are produced from fibre in the diet. Dietary fibre is often reduced in SARA

and so butterfat levels are, in turn, decreased. Alternatively, the changes in the rumen environment in subacute rumenal acidosis could interfere with the biohydrogenation of fatty acids, and milk fat could be reduced in this way.

and so butterfat levels are, in turn, decreased. Alternatively, the changes in the rumen environment in subacute rumenal acidosis could interfere with the biohydrogenation of fatty acids, and milk fat could be reduced in this way.

The incidence of a number of diseases is increased by concurrent subacute rumenal acidosis.

The incidence of a number of diseases is increased by concurrent subacute rumenal acidosis. For example, cases clinical acetonaemia and left displacement of the abomasum occur more frequently with herds where SARA is an issue. Loose faeces gives contamination of the environment and the udder, and in combination with the detrimental effects of SARA on the immune system, this can give a rise in levels of environmental mastitis.

* Increased numbers of cases of digestive disease,

 

including displacement of the abomasum;

* Laminitis. SARA predisposes to laminitis (Nordlund

* Laminitis. SARA predisposes to laminitis (Nordlund

2000). Affected herds may have a high prevalence of foot

2000). Affected herds may have a high prevalence of foot

laminitis has not been elucidated, it may involve the products

laminitis has not been elucidated, it may involve the products

of colonic fermentation rather than SARA per se;

of colonic fermentation rather than SARA per se;

 

 

* Poor reproductive performance. This is a reflection

* Poor reproductive performance. This is a reflection

of both reduced conception rates and a reduction in the

of both reduced conception rates and a reduction in the

intensity and duration of oestrous behaviour;

intensity and duration of oestrous behaviour;

===Laboratory Tests===

===Laboratory Tests===