Selective dry-cow therapy can be implemented successfully in cows of all milk production levels

Antibiotic stewardship on dairy farms can be heightened through the implementation of selective dry-cow cerned that this practice may be related to poor udder health outcomes in cows with high milk production at the time of dry-off. The objective of this study was to evaluate if the effect of culture-guided SDCT (CultSDCT) and algorithm-guided SDCT (Alg-SDCT) on and postcalving udder health and performance [when compared with blanket dry-cow therapy (BDCT)] varied according to milk production level before dry-off. Data were compiled from clinical trials conducted in SDCT and Alg-SDCT to a positive control, i.e., BDCT. In those trials, cows were enrolled 1-2 d before dry-off, randomized to their dry-cow therapy strategy and folincluded quarter-level antibiotic use at dry-off, quarterrisk, cow-level clinical mastitis and removal from the herd during 1-120 d in milk, and somatic cell count and milk yield during 1-120 DIM. The primary objective of and Alg-SDCT on these outcomes, when compared with BDCT, varied according to milk production level having low, mid or high production, based on her milk yield tertile group at the most recent herd test before enrollment (low: <23.7 kg/d, mid: 23.7 to 30.4 kg/d, and high >30.4 kg/d). Multivariable generalized estimating equations were used to estimate risk differ-ences and differences in means, and Cox regression was used to estimate hazard ratios. For Cult-SDCT, the proportion of quarters treated with dry-cow antibiotics within each milk production level were 40.7% (low), 41.7% (mid) and 47.2% (high). For Alg-SDCT, the proportions were 60.6% (low), 38.7% (mid), and 35.1% (high). Measures of udder health were not markedly different when comparing Cult-SDCT to BDCT and Alg-SDCT to BDCT. This was consistently observed in low, mid and high producing cows. In conclusion, the findings from this study indicate that Cult-SDCT and Alg-SDCT can be successfully implemented in cows of all milk production levels.

Automated summary

The implementation of selective dry-cow therapy can enhance antibiotic stewardship on dairy farms. This study aimed to evaluate the impact of culture-guided and algorithm-guided selective dry-cow therapy on udder health and performance. The findings suggest that both culture-guided and algorithm-guided selective dry-cow therapy can be successfully implemented in cows with different milk production levels.