Evaluation of internal teat sealant persistence in the mammary gland during the dry period

The aim of this study was to characterize the behavior of 2 commercially available internal teat sealants containing bismuth subnitrate (SOa and ORBb) during the dry- and postfresh periods in dairy cattle. Digital radiography was used to monitor location and percentage of teat cistern fill at dry-off and during the dry period. Teat-level health parameters including infection status at dry-off and post-fresh as well as incidence of clinical mastitis were also assessed. Radiographic imaging revealed that 21.1% of teats had sealant present in the gland cistern at dry-off (SO= 23.6%, ORB = 18.5%) which increased to 55.9% (SO = 59.6%, ORB = 52.2%) at pre-fresh imaging. Quarters with sealant that had migrated into the gland shed noticeable amounts of sealant for twice as long (mean 14.34 milkings), compared to quarters that did not have sealant in the gland (mean: 7.12, P < 0.001). There was no correlation between sealant location and intramammary infection at dry-off or post-fresh, nor did sea ant location impact clinical mastitis in the first 120 days in milk. Milk leakage after dry-off also was not correlated with an increased risk of intramammary infection during the dry or post-fresh periods. There was no difference between treatments in any of the parameters evaluated. Prolonged sealant shedding is a common reason that producers cite for not utilizing internal teat sealant products in their dry-off protocols. Further research is indicated to determine the optimal amount of sealant required to provide protection while minimizing post-fresh shedding.