Avaliação da eficácia de selante interno de tetos no tratamento seletivo de vaca seca e prevenção da mastite bovina pós-parto

Abstract

The internal teat sealant is applied to dairy cows at the time of drying in order to prevent the entry of pathogens that cause mastitis, making this mechanism resemble a physiological for closing the teat channel. This is the first study developed in the region to demonstrate the effectiveness of an internal teat sealant in preventing postpartum bovine mastitis, as well as reducing the use of dry cow antimicrobials. The effectiveness of the internal teat sealant based on bismuth subnitrate in the prophylaxis of new intramammary infections (IMIs) during the dry and postpartum period was evaluated. The effects of this internal teat sealant when applied alone and the effect of using antimicrobials for dry cow were observed. Here, 38 gyrating cows were used, with varying age and number of lactations, with no history of clinical and subclinical mastitis during lactation. The mammary glands were subdivided into two categories considering two microbiological analyzes and SCC: negative in microbiological culture and low somatic cell count SCC <200,000 cells/mL (Group I) and positive with bacterial growth in the culture and/or high SCC (Group II). After the analysis of two negative cultures accompanied by low SCC, the teats for treatment I were selected: Internal teat sealant based on bismuth subnitrate (4g), and treatment II: application of antibiotic formulated for intramammary application in dry cows, based on Cloxacillin (600.0 mg) or benzathine cephalexin (500.0 mg). In a total of 149 mammary quarters evaluated, in 69 mammary quarters it was possible to apply a single internal teat sealant at the time of drying, while in 80 mammary quarters dry cow antibiotic-based therapy was used during drying. The mammary glands submitted to treatment in group I (teat sealant) did not show mastitis in the postpartum period, while among the teats submitted to antibiotic treatment (group II) 10 of the teats presented mastitis in the postpartum period. The results of the present study suggest that the use of the internal teat sealant based on bismuth subnitrate was effective in preventing new IMIs in the postpartum period. Additionally, it should be noted that the present result is also related to the previous control of contagious mastitis in the respective herd, thus characterizing the use of internal teat sealant as a possible tool in the fight against the indiscriminate use of antibiotics, and in the drying of considered cows low risk, in dairy farms that have good mastitis control.