| dc.description.abstract | The dry-off period is a critical transition in the dairy cow’s lactation cycle, marking the switch from active milk production to a non-lactating state that allows mammary gland recovery. While a non-lactation period is essential for udder health and subsequent milk yield, an abrupt cessation of milking can negatively impact cow welfare. Modern dairy cows in conventional North American systems produce more milk at dry-off than cows in more natural or pasture- based systems. These differences are significant, with organic herds achieving 85% (range: 72 to 91%) of the yields recorded for conventional herds (Schwendel et al., 2015). High milk yield during late lactation leads to excessive milk accumulation in the udder at dry-off, increasing intramammary pressure and risk of udder engorgement, discomfort, milk leakage, and mastitis (Zobel et al., 2015; Gott et al., 2016).
Gradual dry-off protocols, which progressively reduce milking frequency before final milking cessation, have shown promise for easing this transition and improving dairy cow welfare by lowering milk yield and udder pressure before and after dry-off, respectively.
However, implementation of gradual dry-off can be challenging in conventional milking parlors. Automatic milking systems (AMS), with their ability to control milking frequency individually, offer a novel solution to implement welfare-focused gradual dry-off protocols with minimal additional labor.
This thesis evaluates the effects of a two-week gradual dry-off protocol delivered via AMS, compared to abrupt dry-off, on milk yield, milking behavior, lying behavior, udder characteristics, pain sensitivity, and milk leakage in 30 Holstein cows monitored from 74 days before expected calving to 5 days post dry-off. Cows undergoing gradual dry-off had a significantly greater reduction in milk yield in the two weeks before dry-off, particularly from
day -5 to -1 before dry off, and they produced 11% less total milk (348.4 ± 25.8 kg) than abruptly dried-off cows (392.9 ± 17.9 kg) over the 2-week period. After dry-off, gradual cows had fewer AMS refusals than abrupt cows (1.08 ± 0.2 vs. 1.70 ± 0.3 refusals/day), indicating reduced motivation to be milked.
Three-dimensional imaging revealed that teat spacing increased post dry-off in both groups, but abruptly dried-off cows had significantly greater teat spacing on Day 3 compared to gradual cows, suggesting greater udder engorgement. Udder volume and surface area increased after dry-off in both treatments, with no significant differences between groups. No significant differences were detected between treatments in udder firmness, pain responses during palpation, or lying behavior before or after dry-off. Milk leakage post dry-off was significantly higher in abruptly dried-off cows on Days 1, 3, and 5.
These results demonstrate that AMS can support gradual dry-off protocols that reduce milk yield prior to dry-off, lessen motivation to be milked, and decrease udder engorgement and milk leakage after dry-off, without negatively impacting behavior or causing detectable pain.
This approach offers a practical, scalable strategy to improve dairy cow welfare during the dry- off transition while maintaining operational feasibility.
By integrating gradual dry-off directly within the AMS, this study enables individualized control of milking frequency with minimal labor input. The application of 3D imaging technology to quantify dynamic udder changes provides a novel, non-invasive method for monitoring udder physiology. Additionally, using AMS refusal data as a behavioral indicator of milking motivation offers fresh insights into the cows’ affective states during dry-off. These combined innovations advance precision dairy management by linking automated milking technology, advanced imaging, and behavioral measures to enhance animal welfare in a commercial setting.
Overall, this work contributes important evidence supporting gradual dry-off in AMS environments as a welfare-friendly alternative to abrupt dry-off, advancing sustainable and humane dairy production practices. | en_US |
