Influence of dairy cow personality traits on response to extended milking intervals and removal of supplemental concentrate in a free-traffic automated milking system

Abstract

Provision of supplemental concentrate in an automated milking system (AMS) is commonly used to encourage voluntary attendance; however, the motivation to voluntarily milk is highly variable between cows. The objectives of this study were to determine whether dairy cow personality is associated with (1) their short-term response to changes in factors believed to motivate voluntary AMS visits, such as udder pressure and provision of supplemental feed (modulated by longer milking intervals or removal of AMS concentrate, respectively); and (2) their milking activity, production, and feeding behavior after returning to pretreatment AMS milking interval and concentrate feed settings (i.e., behavioral flexibility). A total of 31 early-lactation Holstein cows (95 ± 13 DIM), who had been acclimated to, and were using, an AMS for 2 wk, were enrolled in this study. Baseline AMS settings restricted milking intervals to a minimum of 6 h and an AMS concentrate allocation of up to 5.4 kg/d DM. Previously, at 80 DIM, each cow was assessed for personality traits using a combined arena test consisting of exposure to a novel environment, novel object, and novel human. Principal component analysis of behaviors observed during the personality assessment revealed 3 factors (interpreted as sociable-explorative, active, and bold) that together explained 81% of the variance. Cow scores for each factor ranged from −2.29 to 2.34. Cows were exposed to each of 2 treatments in a crossover design, with a 6-d baseline period, followed by 2 experimental treatment periods of 6 d each, and finally a 6-d period during which all cows returned to baseline AMS settings (total duration of 24 d/cow). Treatments consisted of (1) increased minimum milking interval of 9 h and an AMS concentrate allowance of up to 5.4 kg DM/d (INT); or (2) supplemental AMS concentrate being removed and a minimum milking interval of 6 h (CONC). During the experimental periods, cows had more voluntary AMS visits on INT compared with CONC (7.3 vs. 5.2 visits/d), and cows who were more active had fewer voluntary AMS visits compared with less active cows (visits/d = −2.2 × activeness score + 6.0). Among cows in the INT-CONC treatment order group, more active cows made fewer voluntary AMS visits (visits/d = −4.1 × activeness score + 5.8) during the baseline 2 period. More sociable-explorative cows had greater milk yield (kg/d = 1.8 × sociable-explorative score + 36) in baseline 2 compared with less sociable-explorative cows. These results suggest that cow personality may not affect the response of cows to factors that affect voluntary AMS visits, although individual personality does influence overall behavior in AMS.