Colostrum and Immunity in Kittens

2010 | Queening | Cat Breeding Guide, Royal Canin SAS

Newborn kittens are incredibly vulnerable at birth and it is during these first few hours of life that complications can occur.  The risk of neonatal mortality is highest during this time and depends largely on the quantity and quality of colostrum available.  In this article, we will explore kitten immunity and how it relates to the colostrum from the queen. 

Immunity in Kittens

Newborn kittens possess a degree of immune competence, but do not have a fully matured immune system. Newborn kittens have reduced levels of antibodies (proteins that help fight infection) and an immature thymus (an organ important in the production of immune cells that fight infection). With a poorly functioning immune system, passively acquired immunity from the queen is critical for survival.
Colostrum, the first milk from the queen, is enriched in antibodies and provides this passively acquired immunity in the first few weeks of life. More than 90% of passive immunity is provided from this first drink.


Colostrum secretion from the queen is highest in the first 24 hours after the onset of lactation. Some queens may begin their lactation a few days before birth, and the quality of the colostrum at the time of first drink for the kittens may be suboptimal.

Moreover, the colostrum is only absorbed for a short period of time through the gut wall in the kitten. The optimal time for absorption is within the first eight hours after birth.

From this point, there is a gradual decline, with no further absorption after 48-72 hours. To achieve effective passively acquired immunity, it has been shown that kittens should receive 22ml/kg within this period of peak absorption.


Colostrum is a yellow coloured, thick mammary secretion that is high in antibodies. The antibodies in the colostrum are a reflection of the infectious agents the queen has been exposed to in her environment.

This includes the immune responses she has mounted to vaccinations. Hence, it is important that the kittens are born into the same environment the queen has been housed in. Keeping the queen up to date with vaccinations and providing good nutrition through pregnancy will produce better quality colostrum.

Orphaned Kittens

There may be situations where kittens do not have access to colostrum or milk from the queen. These orphaned kittens should be fed a good quality commercial milk replacement specifically for cats. Many of these milk replacements are formulated to be highly digestible and of a similar composition with regards to protein and fats, to the queen’s milk.

The use of adult plasma (portion of the blood containing antibodies) fed to kittens that have missed out on colostrum has not proven to be beneficial, and currently there are no colostrum replacements commercially available. 

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