VCP 411: Medicine Section

SAMPLING

• Cows in early lactation ( 4 to 8 weeks after calving) are to be sampled, because they are likely to produce economically beneficial result for the following reasons:
• They are approaching the period of service, when nutrition needs to be at an optimum level
•  Peak Yield is also reached at this stage and the importance of reaching a satisfactory peak to achieve an overall high lactation production is well known.
• Blood samples should be collected preferably at morning hours between 9.00 AM to 12.00 Noon with appropriate anticoagulants.
• Samples should be collected with minimum excitement of animals.
• If necessary urine samples should be collected from lactating cows to test for ketones and results should be correlated with blood glucose levels of each cow.
• Rumen liquor, faeces and milk sample examinations are also suggested if necessary. One very important factor is that, in dealing with a problem herd, the unaffected animals should be sampled. For example, if there is a rapid reduction in the milk yield from an early or disappointing peak, then affected cows that have dropped from peak have already reduced their yields to match the food intake being received and as such their blood levels will be returning to normal. It could be said that these animals have already compensated for the poor feeding. The correct animals to sample in this instance would be those cows that have reached and are maintaining a reasonable peak yield, since they are the animals that are most likely to be affected by an imbalance between input and output. It is a failure to appreciate this critical point that hs resulted in many people finding little value in the metabolic profile test.
• In the individual preventive examination, the blood is sampled at 8 weeks prior to calving. It is considered that this procedure offered useful data concerning that susceptibility of each cow to the ‘parturition syndrome” i,e. metritis, retained placenta, hypocalcaemia, downer-cow syndrome and mastitis, because the parameters measured were considered to indicate the stage of energy balance and the liver efficiency of each animal. This concept of dairy herd monitoring emphasizes on its diet and its production demands and has found support in the Federal Republic of Germany as a prelude to the more classical profile approach.