Patterns of milking unit kick-off as a proxy for habituation to milking in primiparous cows

Graphical Abstract

Summary: Habituation to the milking routine is a stressful process for primiparous cows, and animal reactions to new settings may represent a risk for both workers and cows. The objective of this study was to analyze the dynamics of milking unit kick-off (KO) behavior in primiparous (PRI) and multiparous (MUL) cows during the first 3 months of lactation. The odds of KO in PRI were higher than those of MUL during the entire monitoring period. The proportions of KO in PRI cows increased during the first week postpartum before decreasing after the first month of lactation, whereas KO in MUL remained stable during the whole monitoring period. Our results indicate that KO behavior in PRI cows persists over the course of the lactation, but the frequency of KO events declines after the first 30 days in milk.

Highlights

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  Milking unit kick-off has the potential to affect worker and animal welfare, as well as cow performance.

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  Occurrence of KO in MUL cows was consistent throughout the monitoring period, but PRI cows experienced periods of greater KO between the second and the fourth week of lactation.

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  Compared with MUL, PRI cows had doubled odds of KO during the first 90 days in milk.

Abstract

The onset of lactation and the subsequent habituation to the milking routine is a stressful period, particularly for primiparous (PRI) cows. The objective of this study was to describe the dynamics of milking unit kick-off (KO) behavior in PRI cows during the first 3 mo of lactation, considering multiparous (MUL) cows as a reference for comparison. In addition, the potential associations between KO and milk yield and mastitis presentation were investigated. A total of 869 cows (PRI = 199; MUL = 670) on a dairy farm in northern CO were included in the analysis. Cows calving between August and November 2020 were enrolled from 3 DIM until 90 DIM. Participants were milked 3×/day in a 60-unit rotary parlor and data from each milking session were downloaded from parlor management software. Milking unit kick-off was used as a proxy for habituation to the milking procedure. Kick-off events were reported by the milking system and defined as an abrupt interruption in the milk flow during the milking process. Cow KO events were recorded for each milking session. Subsequently, occurrence of KO was analyzed by grouping the 3 consecutive milking sessions in each day and categorized as yes or no, indicating whether or not an individual kicked at least once in a given day. Data were analyzed by repeated measures ANOVA and logistic regression, including parity category, calving season, occurrence of dystocia, and their potential interactions in the models. Least squares means for daily proportions of KO were calculated considering the number of cows with KO events per day in the PRI and MUL categories. Subsequently, odds ratios for the occurrence of KO in PRI versus MUL were calculated at multiple periods of time. When KO was analyzed by DIM, proportions of KO were greater in PRI than in MUL during the whole monitoring period. In PRI, proportions of KO increased from 0.10/d to 0.20/d between 3 DIM and 15 DIM, to start decreasing around 30 DIM and remaining above MUL up to 90 DIM. On the contrary, in MUL cows, proportions of KO remained close to 0.05/d during the 90-d period. Overall, the odds of KO were greater for PRI versus MUL cows (odds ratio [95% confidence interval] = 2.07 [1.58–2.73]). No differences in milk yield were established among KO categories, while the percentage of cows affected with mastitis was greater in cows grouped in the quartile with more frequent KO events. We concluded that the relationship between days in milk and the proportion of PRI cows displaying KO was not linear, but rather KO increased during the first 2 wk postpartum before decreasing after the first month of lactation. First-parity cows had greater levels of KO than MUL cows, which is most likely associated with the process of habituation to milking during their first lactation.