Drying-off practices and cell count-based new infection and cure risk over the dry period on 765 German dairy farms

This observational study with voluntary participation investigated drying-off practices and dry period-related udder health key performance indicators in 3 important dairy production regions in Germany (the north [NR], east [ER], and south [SR]). Data from DHI testing and information about drying-off practices were collected during a single herd visit between 2016 and 2019 from 253, 252, and 260 farms in NR, ER, and SR, respectively. Abrupt cessation of lactation was most common in NR and ER, but only practiced on about half of the farms in SR (NR: 79%, ER: 75%, SR: 56%). Blanket dry cow therapy (BDCT, the use of antibiotic agents for all cows) dominated in NR and ER (63% and 65%, respectively), whereas in SR, primarily selective dry cow therapy (SDCT, targeted use of antibiotic agents at drying-off for individual cows according to farm-specific criteria; 56%) or even no use of antibiotic dry cow therapy (20%) were adopted. The use of teat sealants (TSL) with or without the use of antibiotics was most common in ER (66%), followed by farms in NR (54%), and least common in SR (30%). The median new infection risk (using a SCC threshold of 100,000 cells/mL of milk) during the dry period (NIRD; cows with SCC ≤100,000 before dry period and SCC >100,000 at first test-day post dry period) in NR, ER, and SR was 24% (interquartile range: 13%-35%), 25% (18%-35%), and 24% (8%-37%), and the cure risk during the dry period (CRD; cows with SCC >100,000 before dry period and SCC ≤100,000 at first test-day post dry period) in NR, ER, and SR was 63% (51%-72%), 57% (47%-65%), and 60% (42%-75%), respectively. The NIRD and CRD varied greatly between farms, indicating improvement potential on many dairy farms.