For many years, veterinarians have stressed that adequate and timely consumption of clean colostrum is important. Toward this effort, monitoring systems have been developed. The most common system used on dairies today is measurement of total serum proteins in the first week of life to estimate the absorption of IgG from colostrum. Failure of passive transfer (FPT) is diagnosed when calves have STPs of less than a range of 5 to 5.5, depending on the reference once chooses to use. Goals for the percent of calves with FPT are usually less than 10%-15%.
    In recent years, it has become clear that when it comes to STP, more is better. Many farms have modified their goals. For example, calculating the percentage of calves that have STP below 6. A recent study by Cortese, in the Journal of the American Veterinary Medical Association, confirmed that calves with higher STP were healthier.
    One of the nice features of this study was that it involved a lot of calves, 39,619 in fact. Most were Holstein, but there were some Jerseys and Jersey/Holstein cross calves. Calves came from 15 dairy farms, and all received colostrum shortly after birth.
    STP was measured on the third day of life with a refractometer. The overall conclusion was that the STP range for optimal health of dairy calves was 6 to 8.5. Calves below 6 were at greater risk due to FPT, and calves higher than 8.5 were at greater risk because they were likely dehydrated at the time of testing due to disease. It is important to remember that STP does not directly measure IgG, and that other things, including dehydration, can affect STP.
    Here is some of the specific findings of the study: Average body weights at arrival were 85 pounds for Holsteins, 57.5 pounds for Jerseys and 70.4 pounds for crossbreds. Overall, the incidence of FTP was low. Only 2.1% and 8.8% of calves had STP equal to or below 5 and equal to or below 5.5, respectively. This is much better than studies that have looked at the incidence of FPT in dairy calves across the United States. In spite of this, 8.7% of calves died, specifically 7.9% of Holsteins, 18.8% of Jerseys and 8.5% of crossbreds. Of calves, 41% suffered from diarrhea at least once, with Jerseys again having the highest rate (51%), and 32% were diagnosed at least once with pneumonia. These death rates are significantly higher than the standards of the Dairy Heifer and Calf Association (5%), and the diarrhea and pneumonia rates are higher than the standards offered by Sheila McGuirk at the University of Wisconsin (diarrhea 25%, pneumonia 10%). So in spite of low rates of FPT, morbidity and mortality were significant challenges at this facility.
    Death was significantly associated with STP.
    Of calves with STP between 0 and 5, 26% died; 15% of calves with STP between 5 and 5.5 died; 14% of calves died with STP between 5.5 and 6; and only 10% died if the STP was greater than 6 and less than 8.5.
    For Jerseys, the death rate continued to decrease up to a STP of 8. The range of incidence of disease was smaller than for death. For example, 45% of calves in the lowest STP group had diarrhea (0-5.5) while 41% of the 6 to 8.5 group calves had diarrhea.
    For pneumonia, the percentages were 33% versus 26%. Calves in the lowest STP group were significantly more likely to get IV fluid therapy than those in the 6-8.5 group (11% versus 6.7%). Jerseys with STP between 5 and 5.5 were nearly twice as likely to get pneumonia as Holstein calves, and the percentage of calves treated with IV fluids was greater for Jerseys as well.
    Average daily gain was also greater for calves in the higher STP groups, and there was a clear tendency of increase from the 1.25 pounds in the lowest STP group to 1.49 pounds per day in the 6 to 8.5 group. However, these differences were not deemed to be statically significant.
    The authors concluded that STP concentration on day 3 should be between 6 and 8.5 for optimal health and growth, and that for Jerseys, the optimal STP may higher than for other breeds.     
    Overall costs of treatments and costs of lower daily gain were not included in the study, but it is highly likely that treatment costs for the group where 26% died was much higher than the group where 10% died. Other studies have shown negative effects of reduced daily gain on future milk production and negative effects of neonatal disease on milk production and survivability in the herd.
    Taking all of this together, STP levels in neonatal calves are a big deal, and yes, current standards for diagnoses of FPT are too low.
    In our practice, producers who consistently have STP values over 6 consistently feed 4 quarts of colostrum that has been tested for quality within four hours of birth, pasteurize colostrum or routinely check for bacterial contamination, and then feed another 2 quarts at the next feeding. Some may feed colostrum at the next feeding if it is available. Colostrum is as close to a miracle treatment as we have in bovine medicine. Adequate is just OK, more is clearly better.
    Bennett is one of four dairy veterinarians at Northern Valley Dairy Production Medicine Center in Plainview, Minn. He also consults on dairy farms in other states. He and his wife, Pam, have four children. Jim can be reached at bennettnvac@gmail.com with comments or questions.