Page 753 - Veterinary Immunology, 10th Edition

Production Failure
VetBooks.ir Since colostrum represents the accumulated secretions of the udder

in late pregnancy, premature births may mean that insufficient

colostrum has accumulated. Valuable colostrum may also be lost
from mammals as a result of premature lactation or excessive
dripping. Cows milked continuously (without a drying-off period)
produce colostrum with reduced immunoglobulin concentrations.

Colostral IgG levels also vary among individuals, with up to 28% of
mares producing low-quality colostrum. It is not possible to assess
colostral quality simply by looking at it. Its IgG content should be
assessed using a colostrometer (a modified hydrometer) to measure

its specific gravity. This is normally in the range of 1.060 to 1.085,
equivalent to an IgG concentration of 3000 to 8500 mg/dL.
Colostrum with an IgG level of less than 3000 mg/dL may be
inadequate to protect a foal, and feeding supplemental, high-

quality colostrum may become necessary.

Ingestion Failure

In sheep or pigs, an inadequate intake may result from multiple

births simply because the amount of colostrum produced does not
rise in proportion to the number of newborn. It may be due to poor
mothering, an important problem among young, inexperienced
mothers. It also may be due to weakness in the newborn, to a poor
suckling drive, or to physical problems such as damaged teats or

jaw defects.

Absorption Failure

Failure of intestinal absorption is a major cause for concern in any
species. It is especially important in horses not only because of the
value of many foals but also because even with good husbandry,
about 25% of newborn foals fail to absorb sufficient quantities of
immunoglobulins. Alpacas also appear to experience a

disproportionate number of cases of failure of passive transfer.
Foals require serum IgG concentrations of at least 800 mg/dL 18 to
24 hours after receiving colostrum to ensure protection. Foals that

have less IgG than this are at increased risk for infection. If their

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