Around 30% of dairy farms in the United States use an intramammary teat sealant at dry-off. Researchers were curious if there was a difference between teat sealants relevant to protection against intramammary infections in the dry period and persistence of the teat sealant during the dry period. Pat Gorden, a dairy veterinarian with the College of Veterinary Medicine at Iowa State University, and Michelle Buckley, a postdoctoral research associate at Iowa State University, joined the "Have You Heard” podcast hosted by the American Association of Bovine Practitioners (AABP) to talk about their findings.
Gorden shared that he believes teat sealant plays a valuable role on farms, but he has heard frustrations with teat sealant usage on farms that he works with. Frustrations include buildup in meters and equipment, processors worried about the potential development of black spot defect in cheese from teat sealant ingredients, and the extra cost at dry-off.
The first study Gorden and Buckley conducted was an equivalence study looking at the efficacy of two commercially available teat sealants. Both teat sealants have the same active ingredients. The trial included six commercial farms and cows with a normal dry period (no less than 30 days and no more than 90), four functional quarters, not lame, no recent treatments, and no mastitis at dry-off. The cows were randomly assigned sealants, and then an aseptic milk sample was collected on the day of dry-off. Cows were milked, treated with an intramammary antibiotic, and then the teat sealant was administered. All farms used the same intramammary antibiotic for dry-off.
The production data analyzed included milk weights and somatic cell counts (SCC) from the last test prior to dry-off and then all tests within the first 120 days in milk. The study looked at new intramammary infections, cured intramammary infections, and health events including clinical mastitis, culling, or death. Results showed that the two teat sealants were equivalent in the study.
Where does it go?
The second study Gorden and Buckley conducted was to evaluate the persistence of intramammary teat sealant in the mammary gland during the dry period. This study consisted of 32 cows, or 126 quarters, on the Iowa State University dairy herd. The same two teat sealants were compared. Each cow received both treatments; the right front quarter and the back left quarter would receive one treatment, and the opposite quarters had the other treatment.
This study began with radiographs taken at different stages of the dry-off period, but just one radiograph per cow. From the radiographs, yes or no questions were answered if teat sealant was in three locations: the streak canal, the teat cistern, and the gland itself. Milk samples were taken at colostrum collection from each quarter. The samples were centrifuged down, and weights were recorded of teat sealant in the samples. At each milking following colostrum collection, researchers used strip cups and coffee filters to evaluate the amount of sealant in each quarter from the first 10 strips. Evaluation used a one through five scoring system, with one being none, two or three having small flakes, and four or five showing larger clumps. This procedure continued until there was no sealant present for a maximum of 21 days.
The key results they found were that there was a range of weights collected at freshening, with no difference between sealants. They did find a negative correlation between how much was removed and how long it took for a cow to leave the study. Three percent of all the quarters shed until 16 to 20 days in milk. There was no relation found between the percent of the cistern fill with sealant during the radiograph with days with residue.
Gorden and Buckley shared that they found it interesting to see how far the teat sealant traveled throughout the udder based on the protocol that was followed at the time of administration of the sealant. Administrators used the “pinch off” method at the base of the teat to give the teat sealant.
From their data, Gorden and Buckley asked the question: Is there a best practice for using teat sealant? They found no correlation between the location of teat sealant from the radiographs and mastitis in the first 120 days in milk.
Does that mean it is not necessary to pinch the base of the teat if the sealant is still going to move anyway? Do some cows need less sealant to fill the teat? In the future, the two researchers would like to increase the sample size for the second study and collect more radiographs to analyze how we can improve the usage of teat sealant.
