Abstract
Simple SummaryInternal teat sealant (ITS) at drying off is a strategy used for the prevention of intramammary infections (IMI) during the dry period (DP), as it simulates the keratin plug’s purpose, which is to prevent the access of pathogens into the mammary gland. The results from randomized clinical trials provide valuable information about the efficacy of commercially available products to be used in dairy cattle, assisting farmers to choose the best protocols for mastitis control. This study evaluated a new ITS infused at drying off as an alternative to prevent IMI during DP in a tropical country. Our results showed no effect of treatments on risk of bacteriological cure, subclinical mastitis (SCM) cure, and new cases of SCM postpartum. On the other hand, the use of ITS combined with an intramammary antibiotic (SDCT) reduced the risk of clinical mastitis up to 60 days postpartum, the overall risk of new intramammary infections (NIMI), and the NIMI caused by major pathogens compared to the use of antimicrobial alone (ADCT). Thus, the use of ITS combined with an antimicrobial at drying off was effective to prevent NIMI and clinical mastitis up to 60 days postpartum.The effect of an internal teat sealant (ITS) on subsequent infection of the mammary gland was evaluated on the following mammary gland health indicators: (a) bacteriological cure of preexisting intramammary infections at drying off, (b) risk of postpartum new intramammary infections (NIMI), (c) cure and risk of new cases of subclinical mastitis (SCM), and (d) risk of postpartum clinical mastitis (CM). A total of 553 cows during late gestation were randomly assigned into two treatment protocols at drying off: (a) Dry cow therapy with 0.25 g of intramammary anhydrous cefalonium (ADCT; Cepravin®, MSD Animal Health); or (b) ADCT combined with ITS (SDCT; 4 g bismuth subnitrate; Masti-Seal®, MSD Animal Health, São Paulo, Brazil). Mammary quarter (MQ) milk samples were collected for microbiological culture and somatic cell count (SCC) at drying off and early lactation, and data from 1756 MQ were used in the multivariate logistic regression. There was no effect on the risk of bacteriological cure, SCM cure, and new cases of postpartum SCM. Still, SDCT reduced the risk of CM up to 60 days postpartum (DPP), overall NIMI risk, and the NIMI caused by major pathogens compared to ADCT. Thus, the DCT combined with ITS at drying off is effective for preventing NIMI during the dry period and CM up to 60 DPP.
Highlights
During the dry period of dairy cows, the mammary gland (MG) undergoes physiological and histological changes that affect udder health and milk production of the lactation [1,2,3]
The present study evaluated a new internal teat sealant (ITS) as an alternative strategy to prevent new intramammary infections (NIMI) during the dry period under tropical environmental conditions of milk production
Golder, Hodge, and Lean [14] reported that antibiotic-treated cows were 1.9 times more likely to develop subclinical mastitis (SCM) than cows treated with ITS used in combination with intramammary antibiotic
Summary
During the dry period of dairy cows, the mammary gland (MG) undergoes physiological and histological changes that affect udder health and milk production of the lactation [1,2,3]. The risk of NIMI during the dry period is increased when there is a non- or malformation of the keratin plug in the teat canals, which acts as a physical barrier against microorganisms [6,7]. The production of this keratin plug varies between cows [8]; 23.4% of the mammary quarter (MQ). Mammary quarters without keratin plug formation have 1.7 times greater chance of NIMI during the dry period than those with complete formation of this natural barrier [9]. MQs infected during the dry period have a higher risk of postpartum CM [11], and lower milk yield compared to uninfected MQs during the dry period [12]
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