Changes

===Clinical Signs===

===Clinical Signs===

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 and 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. An chronic, overall increase in dry matter intake is a common finding. This depression in intake may be mediated via pH or osmolality receptors in the rumen, or by pain caused by rumenitis. Animals may also fail to increase their food intakes in response to negative energy ballance, and excessive weight may be lost in early lactation. Cows may 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. An chronic, overall increase in dry matter intake is a common finding. This depression in intake may be mediated via pH or osmolality receptors in the rumen, or by pain caused by rumenitis. Animals may also fail to increase their food intakes in response to negative energy ballance, and excessive weight may be lost in early lactation. Cows may 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.