FROM THE FARM REPORT: CASEIN IN COLOSTRUM REPLACERS

There is a host of different colostrum replacers on the market. Some colostrum replacers are directly derived from maternal colostrum that has been dried and should closely match what is provided by maternal colostrum with at least the IgG and nutritional components of the colostrum. Whereas some are formulated with different ingredients to represent what’s provided from maternal colostrum, not all are formulated in the same way. Colostrum replacers can be a good tool to have on hand in case maternal colostrum in the right quality, quantity, and cleanliness isn’t available.

The composition of colostrum includes 76% water, 5-7% fat, 14% protein, 2.7% lactose, and 1% minerals on an as-is basis. For colostrum replacers not derived only from maternal colostrum, what nutritional components matter? Commonly we focus on immunoglobulin G for transfer of passive immunity standards with colostrum or colostrum replacers. However, other parts of what is provided in the colostrum “package” is also important to the calf, and more understanding in this area is warranted. Take for example protein, which in colostrum, the main components are casein, albumin, and immunoglobulins. Whey proteins are often used in colostrum replacement formulation and have been shown to have similar serum IgG compared to maternal colostrum but have been shown to have higher apparent efficiency of absorption of IgG compared to maternal colostrum. The difference could be the casein in maternal colostrum which is higher than whey-based replacers. Casein interacts with chymosin in the abomasum to form the clot (“curd”) and whey. With whey proteins, the clot does not form so the proteins move faster to the small intestine and thus the hypothesis of why whey-based colostrum replacers have higher efficiency of absorption of IgG.

A recent paper published in the Journal of Dairy Science evaluated the addition of casein in colostrum replacers and did a comparison to maternal colostrum. To do this, the researchers had two colostrum replacers. One was a whey-based replacer lacking casein (compared to what maternal colostrum would provide), the second was also whey-based but casein was added to match that provided by the maternal colostrum used in the study. The researchers measured serum IgG and apparent efficiency of absorption in the calves fed the different colostrums.

Calves fed colostrum replacer without casein had higher concentrations at 6, 12, and 18 h after administration compared to both the colostrum replacer with casein and the maternal colostrum. The average serum IgG for all treatments did meet industry standards for successful transfer of passive immunity. The apparent efficiency of absorption was not different between the colostrum replacer without casein and the maternal colostrum and lowest for the colostrum replacer with casein.

The take-home for me is that the other components of a colostrum replacer might influence how calves absorb these immunoglobulins. In general, I think that mother nature knows best and in this case, colostrum has been “designed” or “packaged” in a way to meet the needs of the calf. When we start moving away from the original, it is important to understand not only what is there but how different components of the diet might affect the result we are looking to achieve. In this case, extra casein might not be needed to get the best absorption of IgG.

— Sarah Morrison

morrison@whminer.com