Colostrum Quality Testing

Testing colostrum quality

Colostrum quality can not be determined by appearance. Colour and consistency only indicate the fat components of the colostrum, and a measure of the IgG either in the colostrum or in the blood of the neonate is required to determine the immunological quality.

Storage: Colostrum can be stored, however this must be done correctly to prevent reduction in immunological status and to prevent outbreaks of disease. Disease outbreaks may occur from feeding colostrum as it is a very good medium for bacterial growth. The best way to store colostrum is to freeze it immediately after milking in a small, clean, secure container. It can be frozen for a year with minimal reduction in quality. It should be thawed thoroughly before giving it the the neonate by leaving it at room temperature, or by gently warming it in water (no hotter than 38 C). Thawing colostrum at high temperatures or by using a microwave can irreversibly denature the immunoglobulin (proteins) and thus reduce the colostrum's immunological status. Colostrum can be refrigerated for approximately 5-7 days. However, this must be done immediately after milking, and it must be discarded after this period to prevent colostrum with bacterial overgrowth being fed to the neonates.

Pasteurisation: If diseases such as Mycoplasma, Johnes and Bovine Leukaemia Virus are present on the farm it is important not to feed affected colostrum to the new born calves. To prevent the spread of these diseases, long time pasteurisation of the colostrum at low temperatures can be performed. However this causes a 40% reduction of antibody content.

1. Radial immunodiffusion

This is the gold standard test for measuring IgG levels in the calf blood. However, it is expensive and not readily available. It would be a more appropriate test in the individually affected calf.

2. Serum total protein

This is a simple, rapid and inexpensive test that may be performed on farm as part of a calf health investigation. However, with a sensitivity and specificity of approximately 80%, it is most appropriately used as a herd level test. It is recommended that a minimum of 12 samples are taken to allow interpretation on the herd level. It is important that the calves sampled are clinically healthy as dehydration can elevate the total protein levels increasing the proportion of false negatives results.

After blood sampling into a plain tube, the blood can be left to clot at room temperature and then by way of transferring the serum with a pipette or syringe, the total protein can be measured using a refractometer. Alternatively a centrifuge may be used. Using a cut off of 55 g/l, 4/12 or greater is sufficient to say failure of passive transfer is problem on the farm. If the result is 2-3/12, then sampling of further calves is recommended. On smaller herds where 12 calves may not be available at one time, samples should be taken as appropriately aged calves become available until 12 are sampled.

• It can be used as an on farm assessment of antibody levels in calves.
• A blood sample is taken when the calf is 2-8 days old.
• The total serum protein is measured using a refractometer.

The total serum protein values for calves

Total serum protein (mg/dl)	Amount of colostrum absorption
<4.5	None
4.5-4.9	Inadequate
5.0-5.2	Poor
5.3-5.4	Borderline
5.5-7.0	Acceptable

3. Zinc sulphate turbidity test (ZST)

This has similar properties to the measurement of serum total proteins regarding interpretation. However, samples usually need to be sent to a laboratory to be analyzed and there is concern that haemolysis can affect the accuracy. The cut off usually used is 20 units.

• An easy, quick test to determine the immunological status (amount of immunoglobulins)/adequacy of passive transfer in foals and calves.

Calves

ZST test results for calves

Amount of serum immunoglobulin (ZST UNITS)	Outcome	Cause of death/outcome
<10	Death	E.Coli infection; effects of diarrhoea and pnemonia
10-30	Less likely to die	Recurring diarrhoea that can lead to death and/or pneumonia
>30	Healthy	May have slight diarrhoea and/or pneumonia

Foals

If the foal has not nursed effectively from the mare 2-3 hours post partum then at least 1L of good quality colostrum must be given. The quality can be determined using a colostrometer. Specific gravity >1.060 is roughly equal to a colostrum IgG concentration of >3000 mg/dl. The immunological status is especially important in foals to prevent infection. IgG levels in foals peak at 18 hours post parturition.

Ideally check ZST at 12-18 hours or earlier if:

• Suspicion of FPT (eg. inadequate suckling etc).
• If colostrum is available.

Check ZST at 48 hours if:

• Foal is clinically normal.
• Financial constraints (can only afford to do the test once).
• No colostrum available to use at 12-18 hours anyway, so if there is a problem a plasma transfer would have to be performed to provide adequate antibodies.

Serum immunoglobulin levels in foals

Amount of serum immunoglobulin (mg/dl)	Age of foal	Action needed
<200	<18 hours old	IV plasma infusion
200-400	<18 hours old	Antibiotics treatment at first sign of infection and IV plasma infusion
>400	<24 hours	Oral colostrum

800 mg/dl is considered normal and these foals are at less risk of infection compared to foals with failure of passive transfer.

4. Lateral-flow immunoassays

These are relatively inexpensive calf side tests that are available in some countries. Manufacturers report a high sensitivity and specificity. The test reports a positive/negative result as opposed to a specific level and therefore gives less information than other tests.

Colostrometer

• Used to determine the immunological status (quantity of immunoglobulin especially IgG ) of the colostrum.
• It should be used before giving any foal or calf colostrum.
• Measures the specific gravity of the colostrum which correlates to the IgG concentration.
• The colostrum must be at room temperature (20°C). Below this the colostrometer will overestimate the amount of IgG present, and if it is above, the amount of IgG will be underestimated.

Colostrometer readings

Colostrometer colour	Colostrum quality	Quantity of immunoglobulin (mg)	Suitability for use
Green	Good	50-140 or more	Give to neonates for the first 24 hours or for longer if in abundance
Yellow	Fair	20-50	Only use in the first 24 hours if no 'green' colostrum is available
Red	Poor	<20	Only use after 24 hours for 2-3 days

Literature Search

Use these links to find recent scientific publications via CAB Abstracts (log in required unless accessing from a subscribing organisation).


Nutritional and immunological importance of colostrum for the new born. Prajakta Kuralkar; Kuralkar, S. V.; Veterinary World, Rajkot, India, Veterinary World, 2010, 3, 1, pp 46-47, 11 ref. - Full Text Article

References

Books

A.H. Andrews Bovine Medicine - Diseases and Husbandry of Cattle Blackwell Publishing 2004 2nd Edition

Koterba, Drummound and Kosch Equine Clinical Neonatology Williams and Wilkins 1990

P. Lydyard, A. Whelan and M.W. Fanger Immunology Garland Science 2nd Edition 2004

Websites

www.sheepandgoat.com