Changes

===Laboratory Tests===

===Laboratory Tests===

The diagnosis of subacute rumenal acidosis is aided by the measurement of the pH of rumenal fluid in a sample of animals. Cattle with the highest risk of SARA, i.e. those in early lactation, are selected and rumen fluid is obtained by rumenocentesis or, less commonly, stomach tube. Indicator paper or a pH meter is then used to measure the pH pf the samples. In general twelve animals should be sampled and if greater than 25-30% of the group have a pH less than 5.5, a diagnosis of SARA can be made. In a herd fed a total mixed ration as a single group, it might be useful to sample twelve recently (14-21 days) calved cows and twelve animals with the maximal dry matter intake (60-80 days calved) in order to evaluate the adequacy of the diet for all animals and to identify at what stage the feeding is problematic. Samples should be taken 6-10 hours after access to fresh TMR, or 2-4 hours after grain feeding in component-fed herds. The amount of concentrate fed in component-fed herds can be varied before sampling to determine what level of feeding is associated with SARA.

The diagnosis of subacute rumenal acidosis is aided by the measurement of the pH of rumenal fluid in a sample of animals. Cattle with the highest risk of SARA, i.e. those in early lactation, are selected and rumen fluid is obtained by rumenocentesis or, less commonly, stomach tube. Indicator paper or a pH meter is then used to measure the pH of the samples. In general twelve animals per group should be sampled, and if greater than 25-30% of the group have a pH less than 5.5 a diagnosis of SARA can be made. In a herd fed a total mixed ration as a single group, it might be useful to sample twelve recently (14-21 days) calved cows and twelve animals with the maximal dry matter intake (60-80 days calved) in order to evaluate the adequacy of the diet for all animals and to identify at what stage the feeding is problematic. Samples should be taken 6-10 hours after access to fresh TMR, or 2-4 hours after grain feeding in component-fed herds. The amount of concentrate fed in component-fed herds can be varied before sampling to determine what level of feeding is associated with SARA.

Previously, measurement of milk fat depression has been advocated in the diagnosis of SARA. However, this is an insensitive indicator as some animals with severe SARA can have normal milk fat tests. It is therefore important not to exclude a diagnosis of SARA in an underpoerforming dairy herd that has a normal milk butterfat levels.

Previously, measurement of milk fat depression has been advocated in the diagnosis of SARA. However, this is an insensitive indicator as some animals with severe SARA can have normal milk fat tests. It is therefore important not to exclude a diagnosis of SARA in an underperforming dairy herd that has a normal milk butterfat levels.

===Other Tests===

===Other Tests===