Effectiveness of Intramammary Antibiotics, Internal Teat Sealants, or Both at Dry-Off in Dairy Cows: Clinical Mastitis and Culling Outcomes

Abstract

Intramammary antibiotic (AB) and internal teat sealants (TS) infusion at dry-off have been used to prevent intramammary infections (IMI) in dairy cows during the dry period and reduce the risk of mastitis during the dry period and subsequent lactation. A randomized clinal trial was completed on eight California dairy herds to estimate the effects of different dry cow therapies (AB, TS, AB + TS or None) on clinical mastitis and culling. A total of 1273 cows were randomized to one of the four treatment groups over summer and winter seasons. For each enrolled cow, microbiological testing was done on quarter milk samples collected from the first detection of clinical mastitis within the first 150 days in milk (DIM) in the subsequent lactation. Statistical analysis was done using generalized linear mixed models. There were no significant differences in the odds of clinical mastitis or culling between cows treated with AB, TS, or AB + TS compared to the controls. Dry cow therapy with AB and/or TS had no statistically significant effect on clinical mastitis and cow culling during the first 150 DIM.

Effectiveness of Intramammary Antibiotics, Internal Teat Sealants, or Both at Dry-Off in Dairy Cows: Milk Production and Somatic Cell Count Outcomes

“…The cows were enrolled between December 2016 and March 2017 (winter season) and between June 2017 and September 2017 (summer season), with all eight herds sampled during both seasons. The herd demographics and survey information are previously described [ 25 ]. Briefly, the study dairies had a mean lactating herd size of 1782 cows, which were primarily Holstein, Jersey, or crossbreeds.…”

“…The cows were enrolled on a weekly basis from the study herds and every two weeks from one herd according to the dairies’ dry-off schedules until the study sample size was achieved. The inclusion and exclusion criteria are previously described [ 25 ]. Briefly, all cows presented for dry-off were inspected by the study personnel at the parlor entry and any cows with low BCS or lameness were excluded [ 26 ].…”

Effect of Intramammary Dry Cow Antimicrobial Treatment on Fresh Cow’s Milk Microbiota in California Commercial Dairies

“…A random subset of 100 milk samples from 50 cows on 3 of the 8 study herds in the original trial described below were selected [ 24 ]. Choice of the 3 herds was based on the geographic representation of herds from California’s San Joaquin Valley and to minimize the number of freeze–thaw cycles.…”

“…Given the high prevalence and cost of mastitis in the dairy industry and the controversy of blanket intramammary antimicrobial dry cow therapy, more research is needed to fully understand the impacts and benefits of this practice to the microbiota. To address this aim, a subset of a repository of milk samples and its respective data from a state-wide dry cow therapy trial were employed [ 24 ]. We proposed to evaluate the effect of dry cow antimicrobial therapy on the udder milk microbiota by comparing the microbial populations in milk at dry-off (~60 days before calving) and post-partum from cows receiving an intramammary antibiotic infusion and cows that did not receive therapy.…”

Evaluation of the Compatibility between Different Teat Sealants and Intramammary Antimicrobials in Selective Dry Cow Treatment Protocols

“…Artificial internal teat sealants have been developed which can overcome the low production of the natural keratin plug during the dry period because not all cows will form a plug that is effective throughout the dry period. One approach to the prevention of intramammary infections during the dry period is to use a barrier inside a healthy teat [7]. This barrier takes the form a sealant, or "stopper", consisting of a suspension of basic bismuth subnitrate in a gel matrix, administered inside the cow's teat cistern, which prevents bacteria from entering the breast.…”