Automated gradual reduction of milk yield before dry-off: Effects on udder health, involution and inner teat morphology

Abstract

Lowering milk production of high yielding dairy cows before dry-off may be beneficial for both physical health and welfare of the cow. Extending the milking intervals as well as restricting energy intake are the commonly used approaches to decrease milk secretion, but are mostly accompanied by adverse side effects. Our objective was to elaborate a new technique for reducing milk production taking the natural process of weaning into account, i.e. the abatement of the calf`s milk removal when shifting its diet from milk towards solid feed. We tested a software module by which the degree of udder emptying can be gradually decreased through automated early removal of the milking clusters over 10.4 ± 1.8 days on 26 Holstein cows that were close to dry-off and free of mastitis (SCC < 100,000 cells/mL and negative bacteriology in quarter milk samples). Milk yield was compared to 30 conventionally milked control cows, which had the same initial milk yields and fulfilled the same udder health criteria. After the period of incomplete milking, milk production immediately before dry-off was 35.3 ± 12.9% less in the experimental cows compared to the control cows. As expected, the duration of milking decreased with time of incomplete milking. Neither SCC nor bacteriology findings were altered by leaving residual milk in the udder. Ultrasonographic investigation of pre- and post-milking teat characteristics showed that all traits of inner teat morphology except teat end width were less changed through the incomplete milking process when compared to the changes occurring in the conventionally milked control cows (differences in changes ranged from - 2.0% for teat width to - 27.9% for the distal teat canal`s surface). These findings suggest that the mechanical strain on the teat was considerably decreased with termination of the milking process before udders were completely emptied. After several days of incomplete milking, the perimeter and the surface of the distal teat canal of the experimental teats were even smaller before attachment of the clusters when compared to the pre-milking values of the control teats, which might reflect a strengthening of the teat canals` functional defense mechanisms against the invasion of potential pathogens. Assessments in the following lactation showed that neither milk yield nor udder health were impeded by the targeted automated reduction of milk production before dry-off. The software module tested herein thus provides an effective tool for facilitating the dry-off process.