Written by Dr. Vicky Lauer, Professional Services Veterinarian at ANIMART
If you’ve stayed up to date with calf-raising practices, it will be no surprise to hear an average-sized newborn Holstein calf should receive one gallon of high-quality maternal colostrum as soon as possible after birth. In order to be considered high quality, colostrum must have a Brix reading of 22% or higher, or fall in the green range at room temperature when tested with a colostrometer. This correlates to 10 grams per liter of antibodies, also known as immunoglobulins or IgG. What happens if the colostrum doesn’t reach the cutoff, or the cow gives less than one gallon? Below are some cow management tips to address these potential colostrum quality and quantity issues.
To truly rectify a colostrum problem, one must understand how it is formed. Cows start shifting antibodies from their bloodstream to the udder five weeks before calving. This process is called colostrogenesis. A cow must have a high level of antibodies in her bloodstream to generate colostrum with a high level of IgG. Thus, timing of vaccines is very important. It takes 2-3 weeks after a cow is first vaccinated to achieve a protective level of antibodies. If the cow has never received that vaccine before, antibody levels will subsequently decrease until a second booster dose is given. Once the animal is boostered, antibodies rise to an even higher level and remain fairly steady for an extended period of time. Most vaccines are labeled to be boostered at 3-4 weeks after the initial dose. For the above reasons, optimum timing of scours vaccines is at eight weeks pre-calving if the cow has been previously vaccinated. If it is a new vaccine, the initial dose should be given at 11-12 weeks pre-calving with the second dose given at eight weeks pre-fresh.
One of the largest determinants of colostrum quality is how soon the cow is milked after calving. Because higher milk production has been one of the key genic selections throughout the years, cows today produce colostrum that is very quickly diluted out with milk, lowering the colostrum’s antibody count. Ask any older farmer and they will tell you stories of holding a cow out of the tank for 3-5 days because she was still giving so much colostrum. Many cows now give saleable milk after only three milkings. If you wait eight hours after the cow calves to milk her, she will give a large volume of colostrum but it will be relatively low quality due to milk dilution. Ideally, cows should be milked within an hour after calving for the highest quality colostrum. Another factor is how much colostrum the cow gives at the first milking. Cows producing more than two gallons of colostrum often have lower quality colostrum, even if they are milked right after calving. These cows are such heavy milkers they transition to milk production too rapidly.
Optimum dry cow management is very important. Cows that have a dry period of less than three weeks generally produce poor quality colostrum. They simply haven’t had enough time to accumulate sufficient antibodies in the colostrum to protect the calf. Cows that leak excessively before calving also rarely have high-quality colostrum. As they leak, the colostrum is replaced by milk and lowers the antibody level. In pre-fresh heifers, research has proven heat stress decreases colostrum quality. Cows fed a diet deficient in selenium and Vitamin E also produce less colostrum, while diets low in protein or energy decrease colostrum quality. Thus, dry cows and heifers should receive a well-balanced diet throughout the dry period, and be adequately cooled for at least the last three weeks during the summer.
The final factor is the age of the cow. In general, first-calf heifers produce less colostrum with fewer immunoglobulins. However, as cows get older their colostrum tends to have higher antibody levels. This is not to say heifer colostrum is bad; it should be tested just like every cow’s and used if it is satisfactory. If there isn’t enough volume of colostrum to reach the one-gallon minimum, you may supplement the calf with extra colostrum from another cow or use colostrum replacer.
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