Stress Responses during Milking; Comparing Conventional and Automatic Milking in Primiparous Dairy Cows

Abstract

A comparative study was performed to evaluate the differences in behavioral and physiological stress responses during milking between cows that were milked by an automated milking system (AM-cows) and cows that were milked in a conventional tandem parlor (TM-cows). In a randomized design, 36 primiparous Holstein-Friesian dairy cows were observed and blood sampled (1-min intervals) individually during milking. AM-cows spent less time standing with their heads outside the feeding trough than TM-cows and had a lower heart rate. In addition, AM-cows had lower maximum plasma adrenaline and noradrenaline concentrations during milking. No differences were found in the number of steps. After tactile stimulation of the teats either by hand or by the cleaning brush, mean oxytocin concentrations did not differ. In AM-cows, however, elevated oxytocin levels were prolonged at the end of milking. Averaged over the first five blood samples, AM-cows tended to have higher plasma cortisol concentrations than TM-cows, but median fecal concentrations of the cortisol metabolite dioxoandrostane were comparable. Maximum quarter milk flow, maximum udder milk flow and residual milk as a percentage of the total milk volume was comparable. From this study it is concluded that behavioral and physiological responses, both in automatically and in conventionally milked cows, were relatively low and were typical for cows being milked. We therefore conclude that, as far as the welfare of the dairy cow during milking is concerned, automatic milking and conventional milking are equally acceptable.

Heart rate, heart rate variability, faecal glucocorticoid metabolites and avoidance response of dairy cows before and after changeover to an automatic milking system

“…Earlier studies found elevated (Gygax et al, 2008) or similar (Hagen et al, 2005) HR during lying posture in AMS compared to conventional milking systems; however, both studies reported on higher basal sympathetic tone in AMS. Hopster et al (2002) found no difference between HR and HRV measured during standing in the barn in either parlour or robotic milking systems. We suppose that stress related to the procedure of milking in the conventional system is acute, considering that between two milkings the cows are left undisturbed in the barn, without human presence, free to rest or perform their daily activities, just as in the robotic milking system.…”

“…AUCs calculated for HR, frequency domain and Poincaré measures of HRV indicated lower vagal and higher sympathetic activity in parlour milking. Hopster et al (2002) also reported lower HR in the waiting area in AMS, compared to PARL. Stress was presumably a result of aversive handling methods (Pajor et al, 2000) or crowding in the holding area (Morgan and Tromborg, 2007;Kovács et al, 2013).…”

“…Gygax et al (2008) reported an increased stress level (higher HR and lower vagal tone) in AMS, Hopster et al (2002) found lower HR and adrenaline levels in AMS, whereas Hagen et al (2005) found no difference in HR and HRV between AMS and PARL. Their results suggest that there are multiple factors that can influence the level of stress experienced during milking, which are needed to be identified and compared in further stress assessment studies.…”

“…In the present study, faecal cortisol concentrations were higher in the period of PARL than in AMS. Others have found no difference in cortisol concentrations measured in plasma (Hopster et al, 2002;Abeni et al, 2005), milk (Gygax et al, 2006) or faeces (Hopster et al, 2002). Considering that basal HRV parameters did not differ between the two study periods, the increase in hypothalamicpituitary-adrenal (HPA) activity in PARL can be linked to the effects of human interaction (Bauer et al, 2012) or the differences in the type of milking (Gorewit et al, 1992).…”

“…The handling method during PARL was the way the milker handled the animals, it was not an experimental condition. Although Hopster et al (2002) studied the effects of AMS 4 weeks after the changeover, we have found that an 8-week interval is more appropriate to exclude not only the effects of transition to the new milking system (Weiss et al, 2004(Weiss et al, , 2005Jacobs and Siegford, 2012b) but also the possible long-term effects of rough handling. Considering that cows can remember the site of the preferred feed for at least 6 weeks (Kovalčik and Kovalčik, 1986) and positive handling had prolonged effects on the avoidance reaction for 8 weeks , we supposed that unpleasant experiences might as well have a longer-term influence on behaviour.…”