Monday, September 24, 2018

Blood Serum Total Protein to
Evaluate Passive Transfer of Immunity

Researchers at the University of Guelph (Ontario) used a clinical refractometer with blood serum to assess passive transfer of immunity among calves delivered to a veal operation.

They had 149 Holstein calves in the population. They drew blood on arrival; samples were allowed to clot and by gravity separate the blood serum. Then a digital refractometer was used to read the blood serum total protein (BSTP).

They had a laboratory use the slower and more expensive test (radial immunodiffusion or RID) to arrive at "gold standard" values on the same blood samples - these were compared to the BSTP values.

The match between the values was good. In scientific terms, there were low levels of false negative and false positive values when RID numbers were compared with BSTP numbers. 

Thus, they confirmed once more that blood sampling during the first week of life is an effective way to monitor the overall effectiveness of the colostrum management program on a dairy. 

In an earlier report the same authors compared BSTP values for calves that died with surviving partner calves that arrive the same day from the same source. Again, calves that died had significantly lower BSTP than their partner calves that survived.  

At one of my calf-raising clients several years ago we compared BSTP for a year for calves that died and those that lived. He tested all calves at intake for BSTP. His overall rate of passive transfer failure was low - about 5% below 5.0. His mortality rate was slightly above 5%. However, we found that of the calves that died roughly 75% had passive transfer failure. Of course this was just one operation and one year so it's hard to generalize these findings to other farms. 

References: Renaud, D. L. and Others "Short Communication: Validation of methods for practically evaluating failed passive transfer of immunity in calves arriving at a veal facility." Journal of Dairy Science 101:9516-9520 October 2018.
Renaud, D.L and Others, "Clinical and metabolic indicators associated with early mortality at a milk-fed veal facility: A prospective case-control study." Journal of Dairy Science 101:2669-2678 2018.

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