Colostrum quality and first feeding
by Sally Colby
Every dairy farmer knows colostrum is liquid gold, full of health benefits and protective antibodies. Dr. Sandra Godden, who works in Veterinary Population Medicine at the University of Minnesota, said the time taken to ensure calves receive timely feedings of high-quality colostrum is time well spent, with both short and long term benefits.
“What we do with her as a calf is setting her up for future success or failure,” said Godden. “We have to get her started right.”
Godden reviewed colostrum basics, focusing on ensuring high levels of antibodies, or immunoglobulins. For the first several days, weeks and months, high concentrations of colostral antibodies ward off infection when the calf faces potential health challenges, buying time for the calf to produce its own acquired immune response.
But colostrum isn’t just about the antibodies. Goddard said good quality colostrum is rich in other goodies that help the calf with immunity and growth.
“One thing we’re still learning about is white blood cells, or leucocytes,” said Godden. “In normal, fresh colostrum, we have in excess of one million somatic cells, or leucocytes, per milliliter of colostrum. If I told you a cow had a one million SCC at any other time during lactation, it would mean mastitis. But colostrum from a healthy, non-infected gland has one million somatic cells, and this is normal. Some of the neutrophils, macrophages and lymphocytes in colostrum will be absorbed across the open gut, sit in the local lymphoid tissue for a couple of days, then die.”
The unknown factor is why those components are there and what they do. Goddard said some research indicates they may modify the calf’s developing immune system to some degree, but it’s unknown whether these little tweaks are relevant and result in a healthier calf. Other factors in colostrum that help stimulate the immune system or gut development include cytokines, interferons, growth factors, hormones, vitamins and minerals. A trypsin inhibitor prevents the stomach from digesting colostral protein, protecting the Ig so it’s intact and available in the small intestine.
Successful passive transfer is achieved when the serum immunoglobulin G level is 10 grams/liter or higher. Lower serum IgG levels indicate failure of passive transfer, leading to more illness, higher morbidity, higher treatment rates and higher mortality.
The timing between birth and first feeding affects IgG levels. Calves are born with an open gut that can absorb large protein molecules intact, but over the first 24 hours of life, the gut closes and loses the ability to absorb IgG.
Goddard outlined factors affecting colostrum quality, starting with the dry cow vaccination program. “Some vaccines we give during the dry period to protect the cow,” said Godden. “Other vaccines during the dry period are specifically to target colostrum quality.” Such vaccines target the scours pathogen and induce antibody protection against E. coli, rotavirus, coronavirus and some clostridial bacteria.
The dry cow ration should be balanced to meet the cow’s needs throughout transition. Feed should be pushed up and available, and fresh drinking water is also essential.
Wherever possible, identify and address cow stressors. Heat stress can impact colostrum quality and volume, so it’s important to provide dry cows with the same heat abatement as the milking herd. Goddard said the dry period length is important – a dry period of less than 40 days dry can impair colostrum volume, and if the dry period is less than 21 days, both volume and quality will be significantly impaired.
Other factors that may result in a low volume of colostrum production include a short dry period, twin pregnancy and advanced age. Some seasonal factors may also affect volume. Goddard referenced a Texas study showing that when there was a decrease in the temperature/humidity index or a decrease in the photoperiod, there was a decrease in colostrum yield. “If the temperature/humidity index is falling or the photoperiod is dropping [shorter day length], both are associated with lower volume of colostrum,” she said. “If you know you have shortages in fall, bank colostrum in spring and summer.”
Obtaining colostrum from the fresh cow is the next key. “Ideally, we milk cows very soon after they calve to harvest colostrum,” said Goddard. “If we milk at two hours versus 14 or 16 hours post calving, there’s a progressive decline in relative quality of the colostrum. We believe most of this is probably due to dilution in the gland.”
The goal for colostrum to ensure the calf receives 300 grams of IgG. Goddard said using a colostrometer to test for specific gravity is one way to check quality, but this tool isn’t highly accurate and is potentially affected by temperature. She recommends using a Brix refractometer, either digital or hand-held.
The recommendation for colostrum feeding is to ensure the calf receives 10% of its birthweight, so an 85-pound Holstein heifer calf should receive one gallon. Sufficient colostrum intake can be achieved in two ways: hand-feeding with a nipple bottle or through an esophageal tube. Either method is suitable as long as the calf receives the correct volume. Goddard said anyone administering colostrum via an esophageal tube should be properly trained on tube placement.
After an initial tube feeding, Goddard said it’s best not to tube feed again. “For the second or third feeding of colostrum or milk, I’d like to see people use a bottle or bucket,” she said. “With multiple tubings, we often see damage.” If a calf isn’t hungry six to eight hours after the initial feeding, it probably needs more time to digest the first large, fatty meal and will likely be hungry at the next feeding.
Not all calves willingly take a nipple bottle, and even if they do, may not want to consume three to four quarts at one time. Goddard suggested feeding the remaining colostrum via an esophageal feeder or waiting about four hours before offering the bottle again.
While gut closure occurs fairly rapidly, Goddard said there is value in feeding additional colostrum after the first 24 hours. “For herds struggling with higher than desirable scours or crypto in the first seven to 14 days, a second feeding of transition milk may help,” said Goddard. “If you’re feeding pasteurized milk to calves, I’d strongly recommend putting transition milk into the pasteurized milk pool – everyone benefits.”