Failure of passive transfer (FPT) in calves is defined as a blood IgG level of less than 10 mg/ml at 24 to 48 hours after birth. Calves that experience FPT are more likely to become sick or die in the first two months of life than calves with adequate immunity. Many factors can contribute to FPT, but colostrum and the management of colostrum feeding are often involved. Feeding colostrum late or not at all and being forced to feed poor quality colostrum are primary causes of FPT in calves. Unfortunately, not all colostrum is the same. There is a lot of variability between cows and their colostrum quality. When colostrum is of lower quality, producers have three options: stored colostrum, supplement products, and colostrum replacer.
Storing excess high quality colostrum provides insurance in case the dam is unable to produce an adequate quantity of good quality colostrum due to mastitis, death, or various other causes. In some herds the supply of high quality colostrum is very limited, and supplement and replacer products can provide viable options for ensuring adequate immunity in calves.
Supplement or Replacer — What’s
Colostrum products that contain IgG are regulated by the USDA Center for Veterinary Biologics. Supplement products are unable to raise the blood concentration of IgG above the species standard, which is 10 mg/ml. Any product that is able to raise serum IgG concentration above 10 mg/ml may be called a colostrum replacer.
Typically, colostrum supplements contain less than 100 g of IgG per dose and are composed of bovine colostrum, other milk products, or bovine serum. Colostrum supplements can be used to increase the amount of IgG fed to calves when only low or medium quality colostrum is available. However, supplements cannot replace high quality colostrum. Even when a supplement is added to low quality colostrum, the IgG is often absorbed poorly, and antibody absorption is reduced compared to high quality maternal colostrum.
A limited number of products designed to replace colostrum are now on the market. These are bovine serum-based products and contain at least 100 g of IgG per liter plus fat, protein, vitamins, and minerals needed by the newborn calf. Colostrum replacer contains more immunoglobulin than supplement products and provides more antibodies than poor or moderate quality colostrum. In research trials, calves fed colostrum replacer have performed as well as calves fed maternal colostrum with no differences in IgG levels, efficiency of IgG absorption, incidence of scours, or growth rates.
Effect of ingredients on product
When comparing products, it is important to consider both the amount of IgG provided and the efficiency of IgG absorption, which is greatly influenced by ingredients and processing. The three primary sources of IgG in colostrum products are dried colostrum, blood serum or eggs. Egg-based colostrum supplements have mostly been replaced by dried colostrum and blood serum supplements. Most supplements contain 30 to 45 percent IgG or protein which, when fed according to the manufacturer’s directions, provides 45 to 50 mg/ml of IgG per dose. Ideally, when fed along with poor quality colostrum enough IgG would be absorbed to provide calves with 10 mg/ml of IgG in the blood and successful passive transfer. However, absorption rates differ depending on the ingredient used as the source of IgG. Supplement and replacer products based on bovine serum contain high levels of IgG and have absorption efficiencies similar to maternal colostrum (25 to 35 percent). Products based on colostrum or whey have variable IgG contents and absorption efficiencies ranging from 5 to 30 percent. Egg-based supplements to date are not well-absorbed, but can provide local protection in the intestine against scours causing bacteria.
The amount of IgG fed in a single feeding is another important factor affecting IgG absorption efficiency. As a result, when trying to attain greater passive immunity, feeding a better quality product or colostrum with higher concentration of IgG is more beneficial than feeding more of the original product by increasing the amount of powder or volume fed. In other words, don’t increase the concentration of IgG by adding more powder, but feed a higher quality product.
Another difference between colostrum supplements is the inclusion of Escherichia coli antibody (E. coli). This can be misleading, causing producers to believe that if they feed this product, it will protect their calves from E. coli as well as provide successful passive transfer. These products are designed to provide antibodies specific for E. coli, but unfortunately there are many different species of E. coli that are present in different areas of the country and on different farms. The E. coli found in a colostrum supplement manufactured in some other state or country will probably not have the ability to protect against the specific E. coli found on your farm.
Finally, read and follow manufacturer’s instructions for feeding; some products are mixed with water and fed in an extra feeding, others are added to colostrum, and the number of feedings recommended may vary.
High quality maternal colostrum is still the “gold standard” for feeding newborn calves. However, colostrum supplement and replacer products can be valuable tools to increase calf immunity when colostrum supplies are limited or disease eradication is desired. Colostrum supplements can be used to increase the amount of IgG fed to calves when no source of quality colostrum is available, but supplements cannot replace high quality colostrum. They do not contain sufficient quantities of antibodies to raise the blood IgG level in calves beyond what average quality colostrum will do. On the other hand, colostrum replacer contains greater levels of IgG and other nutrients and provides an effective, convenient method of providing passive immunity to calves when maternal colostrum is not available.