Part 2: Measures to manage colostrum quality
by Sally Colby
Dairy farmers know the importance of colostrum, but do they know how to get the most from it? Dr. Billy Smith, veterinarian at the University of Pennsylvania School of Veterinary Medicine, explained how to handle colostrum for optimum benefits.
Collection time can significantly alter colostrum quality. Smith explained fresh cows often have sphincter pressure from the start of milk production, which results in colostrum leakage. “The longer we wait after parturition, the less colostrum and the more dilute it becomes, and less likely to pass the immunoglobulin scoring,” he said. “The colostrum would fail to protect the calf because the cow is quickly producing milk behind that first colostrum, and it will be entering the gland system and diluting colostrum. The longer we wait to harvest it, the lower the quality.”
Smith said most dairy farms collect colostrum when the fresh cow fits into the sick or fresh cow milking. “If you’re milking sick cows at four in the afternoon and four in the morning, any cows that calve at five will wait almost 12 hours before they go to a parlor to be milked,” he said. “If you wait more than six hours, you’re going to ruin the colostrum. Either the cow will leak a lot onto the ground or it will be diluted.”
Ideally, the fresh cow should be milked within two hours of giving birth. “There is a recovery time for cows after calving,” said Smith. “They’re nervous and they don’t have ideal milk let-down. Even a portable milker won’t help. So wait a little while – several hours – for the cow to settle and have good let-down.” Colostrum from cows that wait longer than six hours for milking can still be good, but is less likely to measure adequate IgG levels.
Smith reminded dairy farmers that bloody colostrum kills calves because the iron from blood helps feed bacteria in the gut. But even if blood is the result of trauma, bacteria are always present in colostrum simply because there are so many ways bacteria can get into colostrum and milk. “If we have less than 100,000 bacteria/ml, the calf can deal with that,” said Smith. “It gets dicey when the count gets to 500,000, and anything over one million will ultimately kill the calf. So be careful about bacteria.”
When multiple calves are experiencing serious health issues, culturing colostrum is a good option. In many cases, results show that bacteria are coming from dirty milk lines or other equipment. Smith said coliform pathogens usually come from dirtiness or manure. “Lab testing can determine the specific bacteria and then you can deal with it,” he said. “For coliform bacteria, we want less than 10,000 CFU/ml of coliform pathogens for good quality colostrum. What we’re searching for is ‘how did the colostrum get so much pathogen in it, and are the pathogens specific to dirt and filth?’ We can identify that, go back to where cows are calving and see how they’re prepped for colostrum collection.”
Colostrum pooling, which is often a practice on large farms simply because numerous cows are calving in a short time period, can result in poor quality colostrum. Smith said poor quality colostrum dilutes any top-quality colostrum and lowers the chance for calves to get the ideal 50 grams/liter. There’s also a chance one cow is shedding highly pathogenic bacteria that can ruin an entire batch of colostrum.
Vaccines can also influence colostrum quality. As a cow matures and has more experiences/exposures to disease, colostrum quality improves, and vaccines can enhance that quality. “Many vaccines provide a great response in the cow,” said Smith. “The cow should be vaccinated according to the label; sometimes only once for a great response, especially if the cow has been vaccinated previously, but many recommend a two-time shot.” The initial shot triggers the primary response and results in a small increase in concentration of antibodies, and the second shot results in a much greater response. After proper immunization, immunoglobulins are transferred from the cow’s blood to milk, and optimum levels are present a week to several weeks prior to parturition.
Smith said through proper immunization and good colostrum, calves can be protected from E. coli scours, the number one killer of calves during the first three to five days of life. In addition to E. coli, preventive vaccines for the cow can include salmonella, mycobacterium paratuberculosis (Johne’s), mycoplasma bovis, listeria monocytogenes and BLV, all of which are transferred from cow to calf by colostrum intake.
Standard operating procedures for newborn calves should include tubing. “The one- to two-hour timeframe is when the calf is searching for first feeding,” said Smith. “If you wait four or six hours, the calf uses up a lot of brown fat and becomes exhausted. They go into a slumber and aren’t responsive. Many calves will be okay and become more aggressive, but never as aggressive as they were in the first two hours.”
Colostrum can be manipulated to prevent calf illness through specific treatments such as thermal pasteurization, ultraviolet radiation, high pressure processing or acidification. Smith said research on pasteurization shows as much as 26 percent loss of immunoglobulin. “Pasteurization will effectively destroy mycoplasma bovis, listeria, salmonella, E. coli and maybe the Johne’s organism,” said Smith. “It does improve absorption of immunoglobulins, so even though you lose some immunoglobulins, there’s no more bacterial interference.” Smith added that the problem with colostrum pasteurization is increased viscosity – it gums up the system and calves may not want to nurse it. Ultraviolet radiation and high pressure processing aren’t commonly used in the dairy industry.
Smith explained his current research project with acidified colostrum to determine whether IgG is altered during the process. “We don’t think it changes immunoglobulin concentration in colostrum, and we do know it will kill a lot of pathogens,” he said. “My research has shown that it will kill mycoplasma bovis readily, and one research paper says it does not negatively affect the Johne’s organism. I’m not sure that’s accurate because a pH of 4.0 to 4.5 is equivalent to complete pasteurization and should be acidic enough to neutralize pathogens. There’s still some work to do to see what acidification kills.”