With cattle prices at historic highs, it’s important to get the 2015 calf crop off to a great start and minimize sickness and death. Most cattle producers know that colostrum is important for calves; this article will briefly review background information regarding colostrum, and provide some practical tips.
Colostrum is a critical source of antibodies, specialized proteins that provide protection against infectious diseases, including those caused by bacteria and viruses. The main antibody in colostrum is called immunoglobulin G (IgG). Newborn calves have a naive immune system; they do not have their own antibodies, and antibodies from the dam do not cross the placenta during pregnancy. Therefore, it is essential for the health and survival of a calf that they receive antibodies from colostrum very early in life, a process called transfer of passive immunity.
During the first hours of a calf’s life, their intestinal wall can absorb large molecules, including the antibodies in colostrum. This ability to uptake antibodies is most effective in the first six hours after birth. The efficiency of antibody absorption decreases over time (starting soon after birth), with essentially no absorption possible by 24 hours after birth.
Antibodies are produced in response to stimulation by various antigens, including bacteria, viruses and vaccines. To increase the concentration of specific antibodies in colostrum, heifers and cows can be vaccinated during late pregnancy. Vaccinations should be given no later than approximately six weeks before the expected start of calving, to allow time for antibodies to form and accumulate in the colostrum. It takes about three weeks for antibodies to be produced in response to most vaccines, and the process of putting antibodies into the colostrum occurs three weeks before calving.
There are several factors that determine the transfer of passive immunity in young calves, including the quality and quantity of colostrum, when it’s ingested and the level of hygiene. Colostrum quality, specifically the amount of antibodies present, varies widely among cows, breeds and farms. Good quality beef colostrum has at least 100 g/L of IgG. However, we rarely know the concentration of antibodies, so guidelines have been developed to estimate the likely concentration present in a cow’s colostrum.
Both the amount of colostrum and when it is ingested are important to the transfer of passive immunity. In general, the mother is the best source of colostrum for a newborn calf, and with most cow-calf pairs, no intervention is needed. To suck an adequate amount of colostrum, the calf must be strong enough to stand and suck, the mother must produce sufficient amounts of colostrum with a high concentration of antibodies, and she must be willing to allow the calf to suck. If the calf is slow to stand, or if the dam is unwilling to allow the calf to suckle, some assistance is needed.
In these cases, the cow and calf should be housed in a confined space, if possible, and carefully monitored, particularly if the cow shows any aggression towards her calf. These cows should be restrained and the calf assisted to find and latch onto the udder. If that fails, the calf should be given at least one litre of good-quality colostrum within four hours after birth and then either nurse from its dam or receive another litre of colostrum before it is 12 hours old.
Ideally, every calf receives its mother’s colostrum. However, this is not always possible. Therefore, an alternative source of colostrum is needed. It’s a good idea to store frozen colostrum. Mature cows from the same herd with ample colostrum are a good source. Colostrum from dairy cows has much lower concentrations of IgG, so it’s not ideal for beef calves. However, if dairy colostrum is the only source available, give double the recommended volume. Keep in mind that colostrum from another farm always has the potential to introduce an infectious agent.
There are also commercial sources of colostral antibodies that can be given to calves that do not get sufficient colostrum. The quality of these products is variable. So read the label. Beef calves need 150 to 200 g of IgG within the first 12 hours of life; lower-concentration products may be unable to supply that amount, although they may serve as a supplement for calves that have already consumed some colostrum. Having a good commercial colostrum replacement product on hand during calving season can literally be a lifesaver.
Good hygiene when collecting, storing and feeding colostrum is also important, as bacterial contamination reduces the efficiency of antibody absorption, besides being a source of disease.
Wash and dry your hands and the udder before you milk out the colostrum. Don’t collect from cows with any signs of mastitis, and milk the colostrum into a clean container with care to minimize contamination with manure or other contaminants.
Any container or nipple used to feed colostrum should be cleaned prior to each use and never used to feed or treat sick calves.
Fresh colostrum needs to be used within a few hours, or frozen immediately to minimize bacterial growth. Zip-lock plastic freezer bags that hold one or two litres work well. Place the bag in warm water (50 C) to thaw, as high heat will likely damage the antibodies.
As we have already stated, the best way for a calf to ingest colostrum is by suckling its dam. The next best option is to suck colostrum from a nipple bottle. When a calf is suckling (its mother or an artificial nipple), much of the ingested material is shunted directly into the abomasum (fourth stomach), which facilitates absorption of the antibodies. If a calf is too weak to suck, it may be necessary to use an esophageal feeder. Used incorrectly, these can harm and even kill a calf.
Be sure the tube is in the correct location and feed it down gently before releasing the colostrum.
When a calf does not absorb sufficient amounts of antibodies, that condition is termed failed transfer of passive immunity. It is the single greatest risk factor in pre-weaning mortality; calves with failed transfer of passive immunity are highly susceptible to infectious diseases and often die of diarrhea (scours) or respiratory disease (despite early detection and vigorous treatment).
The transfer of passive immunity can be confirmed by measuring blood IgG concentrations in the lab. A minimum 10 mg/mL is considered adequate. Alternatively, serum total proteins can be measured in the field or at your local vet clinic with a hand-held refractometer, with 5.2 g/dL considered a minimum acceptable value. Blood samples can also be taken at one to seven days of age to monitor the number of calves in a herd that failed to gain passive immunity as part of an investigation when a number of calves have become sick or died.
The authors are faculty members in the department of production animal health, Faculty of Veterinary Medicine, University of Calgary.