Intramammary antibiotic dry cow therapy (DCT) at the end of lactation is a key measure in the management and control of bovine mastitis. Currently, livestock production is under pressure to reduce antibiotic consumption, emphasizing the need to avoid medicating all cows at dry-off, and instead treat only infected cows. The study objective was to evaluate IMI cure risk, new IMI risk, and postcalving IMI risk between DCT-treated and untreated quarters over the dry period. The sample totaled 269 cows from 12 Finnish automatic milking system herds entering the dry period between 2019 and 2021. Cows eligible for the study had a final DHI test-day SCC >= 100,000 cells/ mL and had no clinical signs of mastitis. Based on odd or even identification numbers, cows with an SCC between 100,000 and 250,000 cells/mL were sequentially assigned to either receive DCT at dry-off (DCT100-250) or remain untreated (NoDCT100-250). All cows with an SCC >250,000 cells/mL received DCT (DCT>250). No quarters received teat sealants. Farmers collected aseptic quarter milk samples for microbiological quantitative real-time PCR analysis 0 to 4 d before dry-off and 0 to 4 d after calving. The outcome of the statistical model was the odds of a quarter having an IMI at freshening 0 to 4 d after calving. The statistical tool was a generalized linear mixed-effects model with logit link function and 2-level random intercepts, cows nested within herds. Quarter- level IMI prevalence at dry-off was 17.6% (45/256) for NoDCT100-250, 22.2% (83/374) for DCT100-250, and 32.0% (132/413) for DCT>250. Quarter-level IMI prevalence at freshening was 36.2% (84/232) for NoDCT100-250, 13.6% (50/369) for DCT100-250, and 11.6% (46/397) for DCT>250. The untreated quarters in the NoDCT100-250 group had a 1.1 times higher risk of failing to cure over the dry period than the treated quarters in the DCT100-250 group (unadjusted risk ratio [RR] 1.10, 95% CI 0.94-1.28) and a 1.2 times higher risk than the treated quarters in the DCT>250 group (unadjusted RR 1.15, 95% CI 1.00-1.33). The untreated quarters in the NoDCT100-250 group had a 1.5 times higher risk of having a new IMI over the dry period than did the treated quarters in the DCT100-250 group (unadjusted RR 1.48, 95% CI 1.35-1.63) and a 1.4 times higher risk than the treated quarters in the DCT>250 group (unadjusted RR 1.35, 95% CI 1.23-1.49). The principal cause of new IMI was NAS, followed by Streptococcus dysgalactiae. Quarters in the NoDCT100-250 group had 6.6 times higher odds for having an IMI at freshening than did quarters in the DCT100-250 group (95% CI 3.52- 12.21). According to our findings within the framework of this experiment, selectively DCT-treated cows with an SCC between 100,000 and 250,000 cells/mL at dry-off demonstrated that, although the group-specific cure risks over the dry period were high, untreated quarters had a higher risk of acquiring a new IMI over the dry period than did treated quarters, highlighting the effectiveness of DCT in reducing IMI risks. The prophylactic use of antibiotics, however, is not recommended, and in some countries is even prohibited.

Antibiotic dry cow therapy (aDCT) at the end of lactation is an effective mastitis control measure. Selective dry cow therapy means that only infected or presumed-infected cows are treated, instead of aDCT being used as a treatment for all cows. Because antibiotic resistance poses a global threat, livestock production is under increasing pressure to reduce antibiotic use. Changes in management should not, however, impair animal welfare or cause significant economic losses. Our objective was to compare milk yield and somatic cell count (SCC) between aDCT-treated and untreated cows in herds that used selective aDCT, taking into account risk factors for reduced yield and high SCC. The information source was 2015 to 2017 Dairy Herd Improvement data, with 4,720 multiparous cows from 172 Finnish dairy farms. The response variables were test-day milk yield (kg/d) and naturally log-transformed composite SCC (×1,000 cells/mL) during the first 154 d in milk (DIM). The statistical tool was a linear mixed-effects model with 2-level random intercepts, cows nested within herds, and a first-order autoregressive [AR(1)] correlation structure. The overall proportion of aDCT-treated cows was 25% (1,176/4,720). Due to the interaction effect, SCC on the last test day prior to dry-off affected postcalving milk yield differently in aDCT-treated cows than in untreated cows. A higher SCC prior to dry-off correlated with a greater daily yield difference after calving between cows treated and untreated. The majority of cows had SCC < 200,000 cells/mL before dry-off, and as SCC before dry-off decreased, difference in yield between aDCT-treated and untreated cows decreased. Postcalving SCC was lower for aDCT-treated cows compared with untreated cows. To illustrate, for cows with an SCC of 200,000 cells/mL before dry-off, compared with untreated cows, aDCT-treated cows produced 0.97 kg/d more milk and, at 45 DIM, had an SCC that was 20,000 cells/mL lower. Higher late-lactation SCC and lactational mastitis treatments were associated with higher postcalving SCC. A dry period lasting more than 30 d was associated with higher yields but not with SCC. Our findings indicate that a missed aDCT treatment for a high-SCC cow has a negative effect on subsequent lactation milk yield and SCC, which emphasizes the importance of accurate selection of cows to be treated.

Mastitis remains the most expensive disease of dairy cows, and antibiotic dry cow therapy (DCT) at dry-off is an important part of mastitis control. Regardless of the infection status, blanket DCT is administered to all quarters of all cows, which is controversial due to the worldwide problem of antimicrobial resistance. Even though selective DCT of only infected cows is a more sustainable approach, choosing animals for treatment is not always straightforward. Our aim was to evaluate whether the herd-level DCT approach is associated with early lactation udder health problems, taking into account the cow characteristics. The information source was 2015–2017 Dairy Herd Improvement data with 7461 multiparous cows from 241 Finnish dairy herds. Information on the herd-level DCT approach was obtained from farmers' questionnaire responses in 2017, and the three different approaches were selective DCT, blanket DCT, and no DCT. The statistical tool for the data analysis was a generalized linear mixed model with a random herd effect for binary outcomes and a linear mixed model with a random herd effect for a continuous outcome. The two binary outcomes were the odds of having high milk somatic cell count (SCC ≥ 200 000 cells/mL) on the first test-day within 5–45 days in milk (DIM) and the odds of mastitis treatment in early lactation up to 45 DIM. The third outcome was the mean milk lnSCC (× 1000 cells/mL) within 120 DIM. Selective DCT was the prevailing treatment practice in our data. Blanket DCT was associated with lower SCC after calving. Cows more likely to have high SCC after calving were older cows, cows with high average SCC during the previous lactation, and cows with high milk yield near dry-off. A mastitis treatment in the early lactation was more likely if, during the previous lactation, the cow had high average SCC, high peak milk production, or high milk yield near dry-off. Our findings indicate that DCT is still effective in mastitis control. Cows with high milk yield, especially near dry-off, and cows with persistently high SCC require attention when considering next lactation udder health.

Antibiotic dry cow therapy (DCT) is an important part of most mastitis control programs. Updating DCT recommendations is an ongoing topic due to the global problem of antimicrobial resistance. Finland, along with other Nordic countries, has implemented selective DCT for decades. Our study analyzed Dairy Herd Improvement (DHI) information from 241 Finnish farmers who participated in a survey about their drying-off practices. The aim was to evaluate herd-level associations between milk somatic cell count (SCC), milk production, and various antimicrobial DCT approaches both cross-sectionally in 2016 and longitudinally in 2012 - 2016. The three DCT approaches in the study were selective, blanket, and no DCT use. An additional aim was to evaluate whether dynamic changes occurred in herd-average SCC and annual milk production over five years, and whether these potential changes differed between different DCT approaches. The method for the longitudinal analyses was growth modeling with random coefficient models. Differences in SCC and milk production between farms with different DCT approaches were minor. Regardless of the farm's DCT approach, annual milk production increased over the years, while average SCC was reasonably constant. The variability in SCC and milk production across all DCT groups was low between years, and most of the variability was between farms. Compared to other milking systems, farms with automatic milking system (AMS) had higher SCC, and in 2016 higher milk production. The results of this study suggest that it is possible to maintain low herd-average SCC and good milk production when using selective DCT and following the guidelines for prudent antimicrobial use. Average SCC and milk production varied across the herds, suggesting that advice on DCT practices should be herd-specific. The methodology of growth modeling using random coefficient models was applicable in analyzing longitudinal data, in which the time frame was relatively short and the number of herds was limited.

BACKGROUND:Airway pressure release ventilation (APRV) is a ventilatory mode, which allows unsupported spontaneous breathing at any phase of the ventilatory cycle. Airway pressure release ventilation as compared with pressure support (PS), another partial ventilatory mode, has been shown to improve gas exchange and cardiac output. We hypothesized whether the use of APRV with maintained unsupported spontaneous breathing as an initial mode of ventilatory support promotes faster recovery from respiratory failure in patients with acute respiratory distress syndrome (ARDS) than PS combined with synchronized intermittent ventilation (SIMV-group).METHODS:In a randomized trial 58 patients were randomized to receive either APRV or SIMV after a predefined stabilization period. Both groups shared common physiological targets, and uniform principles of general care were followed.RESULTS:Inspiratory pressure was significantly lower in the APRV-group (25.9 +/- 0.6 vs. 28.6 +/- 0.7 cmH2O) within the first week of the study (P = 0.007). PEEP-levels and physiological variables (PaO2/FiO2-ratio, PaCO2, pH, minute ventilation, mean arterial pressure, cardiac output) were comparable between the groups. At day 28, the number of ventilator-free days was similar (13.4 +/- 1.7 in the APRV-group and 12.2 +/- 1.5 in the SIMV-group), as was the mortality (17% and 18%, respectively).CONCLUSION:We conclude that when used as a primary ventilatory mode in patients with ARDS, APRV did not differ from SIMV with PS in clinically relevant outcome.

BACKGROUND:Prone positioning has been shown to improve oxygenation in 60-70% of patients with acute lung injury (ALI) or acute respiratory distress syndrome (ARDS). Another way to improve matching of ventilation to perfusion is the use of partial ventilatory support. Preserving spontaneous breathing during mechanical ventilation has been shown to improve oxygenation in comparison with controlled mechanical ventilation. However, no randomized studies are available exploring the effects of preserved spontaneous breathing on gas exchange in combination with prone positioning. Our aim was to determine whether the response of oxygenation to the prone position differs between pressure-controlled synchronized intermittent mandatory ventilation with pressure support (SIMV-PC/PS) and airway pressure release ventilation with unsupported spontaneous breathing (APRV).METHODS:We undertook a prospective randomized intervention study in a medical-surgical adult intensive care unit of a university hospital. Of 45, 33 ALI patients (acute lung injury) within 72 h after initiation of mechanical ventilation, and in whom the prone position was applied according to a predefined strategy, were included in the study. After initial stabilization the patients were randomized to receive either SIMV-PC/PS or APRV with predefined general ventilatory goals (PEEP, tidal volume, inspiratory pressure and PaCO2-level). The protocol for prone positioning was the same for both treatment arms. Prone positioning was triggered by finding a PaO2/FiO2-ratio below 200 mmHg evaluated twice per day. The duration of each prone episode was 6 h.RESULTS:The first two episodes of prone positioning were analyzed. Gas exchange was measured before and at the end of prone positioning. Of the 45 patients enrolled, 33 were turned prone once and 28 twice. No significant differences were detected in baseline characteristics. Changes in oxygenation were analyzed in response to the first and second prone episodes 5 h and 24 h after randomization and initiation of SIMV-PC/PS or APRV respectively. Before the first prone episode the PaO2/FiO2-ratio was significantly better (P = 0.02) in the APRV-group (median; interquartile range) (162; 108-192 mmHg) than in the SIMV-PC/PS-group (123; 78-154 mmHg). The response in oxygenation to the first prone episode was similar in both groups: PaO2/FiO2-ratio increased 39.5; 17.75-77.5 mmHg in the SIMV-PC/PS-group and 75.0; 9.0-125.0 mmHg in the APRV-group (P = 0.49). Before the second prone episode, the PaO2/FiO2-ratio was comparable (SIMV-PC/PS 130.5; 61.0-161.0 mmHg vs. APRV 134; 98.3-175.0 mmHg). Improvement in oxygenation was significantly (P = 0.02) greater in the APRV group (82; 37.0-141.0 mmHg) than in the SIMV-PC/PS group (50; 24.0-68.8 mmHg) during the second prone episode. General ventilatory and hemodynamic variables and use of sedatives were similar in both groups during the study.CONCLUSIONS:APRV during prone positioning is feasible in the treatment of ALI patients. APRV after 24 h appears to enhance improvement in oxygenation in response to prone positioning.