Gradual cessation of milking reduces milk leakage and motivation to be milked in dairy cows at dry-off.

The effects of gradual versus abrupt cessation of milking at dry-off in dairy cows are not well understood, but gradually reducing milk production in human mothers is known to reduce discomfort and milk leakage. This study compared the effects of abrupt versus gradual cessation of milking on milk leakage and dairy cow behavior. Holstein dairy cows were housed in groups of 6 and randomly assigned to either abrupt milk cessation (i.e., dry-off on d 0) or gradual milk cessation (i.e., skipped milkings beginning on d 0; dry-off on d 5). Four replicates were performed over time, for a total of 24 cows (mean ± SD; parity=2.3±1.2; milk production the day before d 0=24±5 kg/d). Intramammary antibiotic, internal teat sealer, and external teat sealant were administered at dry-off. Measurements were taken from d -3 to 8 relative to dry-off. Three periods were identified for behavior data: baseline (d -3 to 1), period 1 (abrupt cows dry, gradual cows milking; d 0-4), and period 2 (all cows dry; d 5-8). Lying time was recorded with data loggers. Video scan samples (5-min intervals) were used to measure feeding time and motivation to be milked (i.e., standing at the pen's exit gate). Milk leakage was monitored every 20 min during the 2-h period following the milking times of 0500 and 1500 h after complete cessation of milking (period 1 for abrupt vs. period 2 for gradual). Composite milk samples were taken before dry-off (d -1, 0, and 5) and at the start of the next lactation (colostrum, 24h and 7-10 d postcalving) to determine somatic cell score (SCS) and conduct bacteriological examinations in clinical mastitis cases. Regardless of treatment, dry-off resulted in reduced lying time [14.1 vs. 13.2h/d; standard error of the difference (SED)=0.2], reduced lying bouts (10.7 vs. 8.3 bouts/d; SED=0.2), increased lying bout duration (1.4 vs. 1.7h/bout; SED=0.03) and increased feeding time (5.0 vs. 5.9h/d; SED=0.2). Compared with baseline, the odds of standing at the gate increased for abrupt cows (period 1: odds ratio=6.2; 95% CI: 2.7-14.4; and period 2: odds ratio=5.2; 95% CI: 1.8-14.6). No increase in time spent standing at the gate was noted in gradual cows. Frequency of leakage was greater in abrupt versus gradual cows (75 vs. 27%). Although the gradual treatment showed an increase in SCS over the 5 d of reduced milking frequency, both treatments showed an increase in SCS at calving and both returned to pre-experiment levels within 7 to 10 d after calving. This work demonstrates that gradually reducing milking frequency in high-producing cows results in reduced time spent anticipating milking and reduced milk leakage after dry-off.