Because of the structure of the bovine placenta, calves are born without any antibodies (aka “immunoglobulins” or “IgG”). Instead a calf relies on drinking colostrum, which contains antibodies that the cow has transferred from her blood stream. Once ingested, these colostral antibodies still have to be absorbed across the calf’s intestines into their blood stream. After birth, the gap between the intestinal cells start to close, so there is a limited time frame where antibody absorption can happen.
When calves don’t get enough antibodies, it is called “failure of passive transfer” or “FPT”.
There is also a condition called “agammaglobulinemia” – where calves absorb no antibodies at all.
How does antibody level affect calf health?
The two graphs below show how calf death rates vary with the different antibody levels of “none”, “not enough”, “enough” and “lots”. The data was collected over several years from calf ranches in the USA. The first graph shows low mortality years. Even though overall calf health was relatively good, you can see how the mortality rate with agammaglobulinemia (“none”) sky rockets.
The second graph show years where calf disease and mortality rates were higher (there were issues with Salmonella). The mortality rates were higher across all categories but again, the calves with no antibodies really suffered.
If calves without any antibodies get sick, they are more likely to die
What are the antibody levels in calves in our district?
In 2011 The Vet Group carried out a survey of calf colostral antibody levels: we sampled 1000 calves from 100 farms. Of these calves, 40% didn’t have enough antibodies (failure of passive transfer) and 10% of calves had no antibodies at all (agammaglobulinemia).
We also looked at what farm management factors were related to improved calf antibody levels. The first was always giving a feed of colostrum by hand. This reduced the chance of calves having no antibodies – which, as discussed above, is the most important thing to prevent. A great catch phrase for this is to “Assume none from mum“.
The second management factor was collecting newborn calves from the calving area and giving them their first feed of colostrum twice daily. This moved calves out of the “none” and “not enough” antibody categories into having “enough” or “lots”! This relates back to the closure of the intestines to antibodies with time. You could consider the first colostrum feed a race. For example, colostrum given within 3 hours of birth = gold, within 6 hours = silver, 12 hours = bronze.
What about now?
It’s been 10 years since the calf antibody survey, and it would be great to redo the survey as there’s been quite a few changes with colostrum management. The most widespread being the measurement of first-milking colostrum with a Brix refractometer to identify the best of what colostrum is available:
- ≥22% Brix: Feed 2 x 2 litres within 12 hours of birth
- 18-21% Brix: Feed 2 x 3 litres within 12 hours of birth
- <18% Brix: Feed to calves 2 days old or more
This Brix refractometer has been putting in the hard yards!
How do I know if my calves are getting enough colostrum?
We are able to estimate calf antibody levels by measuring blood protein in calves aged 2 to 10 days old. It is a simple, quick, and inexpensive test. We use the results to assess the colostrum managment at a herd level, so like to sample 10-12 calves. An achievable targets is to have 0% of calves with “none”, 80% with “enough” and 60% with “lots”!
The Vet Group – here to help diagnose, treat and prevent disease in your herd
