statistically significant differences in eating time and feed intake after milking and omitted Ž
. milking. Milk yield per cow averaged 24.9 kg during days with omitted delayed by 1 h milking
Ž .
and 25.3 kg during the days without omitted milking P - 0.05 . It was concluded that cows show Ž
. some signs of discomfort after omitted milking urination ; this discomfort seemed to be greater in
Ž .
cows coming earlier to the milking parlour afterwards they preferred to stand rather than to lie . The 60 of cases of milk leakage found after omitted milking indicates that failed cluster
attachment can be accompanied by an extra risk factor for the occurrence of mastitis. However, omitted milking as a treatment did not influence feeding and aggressive behaviour or milking
order when unmilked cows were brought to the milking parlour the third time together with the milked cows. Our methods and results can be useful for estimating the effects of robot milking
failures on a cow. Future studies should pay particular attention to high-yielding cows and to longer periods of delayed milking. q 2000 Elsevier Science B.V. All rights reserved.
Keywords: Omitted milking; Cluster attachment failure; Milk leakage; Automatic milking; Dairy cattle; Behaviour
1. Introduction
Milking cluster attachment failures during automatic milking occur in the range from Ž
. Ž
. a few percent of cases to 12 Ipema et al., 1997 and 15 Mottram et al., 1995 . On
commercial farms, after milking failure a cow is mostly diverted to a separate area and waits for a stockman, who takes her back to the robot and supervises robot attachment.
Ž .
In experimental studies with an automatic milking system AMS where cow behaviour was studied, cows were not separated after milking failure. The stockman intervened
twice a day to ensure that any cows with failed milking andror too long an interval Ž
. since the previous milking were milked Stefanowska et al., 1999a,b . These cows were
brought to the milking robot individually. Usually, the same cows, ones whose udder conformation is less convenient for robot attachment, failed to be milked. It was
observed that when a visit to the AMS ended with a milking failure, cows returned to the AMS of their own free will after an average of 2 h, whereas milked cows returned
Ž .
after an average of 5 h Stefanowska et al., 1999a,b . It seems likely that a cow returns Ž
after a milking failure because she wants to eat concentrate dispensing stops after .
milking failure , or she expects to be milked, or both. It is not known whether cluster attachment failure has implications for the well-being and milk yield of a cow. It is
difficult to study the effects of milking failure in conditions of voluntary visits to the Ž
robot, since the conditions of individual cases are uncontrollable different milking .
intervals; different situation related to rest and feeding . In these circumstances it is difficult to explain individual reaction to milking failure and to compare individual cases
with each other. However, a trial on the effects of omitted milking in a traditional milking parlour might simulate the possible effects of cluster attachment failure. It
proceeds under human supervision and can be controlled adequately. This paper describes such a trial.
Ž .
Previous studies Mayer et al., 1984; Pfeilsticker et al., 1996 on the effect of the time interval between pre-milking stimulus and actual milking on milk yield found that
intervals of 3 and 15 min caused milk yield to decrease significantly by respectively 0.3
and 0.7 kg. Milk yield was not significantly different after a 60-min interval, possibly because the effect of a delay of milking after stimulation disappeared during the 60-min
interval while milk production resumed. The effect of delay of milking on cow behaviour was not investigated.
Our aim was to estimate the well-being of unmilked cows by comparison with milked cows and to relate these findings to the situation of automatic milking. Our hypothesis
Ž .
was that omitted milking cluster attachment failure unsettles a cow in some way and this will be reflected by her behaviour.
2. Materials and methods
