Continuing with the theme of nutrition at calving, we’ll now shift focus to how it relates to colostrum production along with management for the calf. Born essentially without immunity, calves don’t yet have the necessary antibodies to shield them from disease, which is why they have to rely on their mother for the immunoglobulin-rich nourishment of colostrum through passive immunity.
Colostrum compares physiologically to blood in that besides being very high in immunoglobulins that help prevent infection, it is also high in fat, energy, vitamins A and D, white blood cells and growth factors. Colostrum production within a cow begins several weeks before calving, providing a window of opportunity for a producer to have a little influence on colostrum quality and quantity, within reason.
A management practice to consider would be providing adequate levels of trace minerals to improve immunoglobulin concentration. That, paired with maintaining moderate to good BCS but not being overly fat at calving, sets a cow up with the best opportunity to produce plenty of antibody-rich colostrum.
Another management step that has been recognized as a method to improve colostrum quality is to vaccinate cows late in pregnancy, working with a veterinarian to choose the best products and determine the best timing. Producers should be aware that their first-calf heifers will produce colostrum in smaller volume and with lower immunoglobulin concentrations, but with each successive pregnancy, concentration will increase up to their third, after which it levels off.
So how does one know if a calf is getting this “liquid gold”? Calves should be up and nursing within two hours of birth. If there is concern a calf has not ingested colostrum or an adequate amount of it, observe the pair to be sure the calf knows how to nurse. If still in doubt, milk the cow and tube feed the calf. Factors that may have decreased this calf’s ability to consume colostrum include being cold and/or wet, or if the cow experienced dystocia during calving.
If you find you need to tube feed the calf, the rule of thumb is 2 quarts of colostrum by 6 hours old and an additional 2 quarts by 12 hours because calves are born with a finite number of receptors capable of absorbing antibodies. Within 24 hours after birth, a calf’s gut begins to close, and it becomes increasingly difficult for absorption of the antibodies in colostrum to happen. At this point, the calf’s intestine becomes impermeable to the large proteins. Therefore, many veterinarians stress the importance of calves nursing by 2 hours old and consuming at least 100 grams of colostrum since the colostral antibody uptake drops significantly after 6 hours old.
Read part one of this series, “West: Nutrition for the cow and fetus.”
