C .C. Ketelaar-de Lauwere et al. Livestock Production Science 65 2000 131 –142
139
70.5; P ,0.01. The cows spent between 71.3 and indoors by the cows between 10:00 and 17:00 h
90.8 of the time that they were lying between temperature effect50.4247; S.E.50.1; P ,0.01.
05:30 and 20:30 h at pasture predicted means. This The average black globe temperature between 10:00
was not related to sward height. and 17:00 h on these days ranged from 18.9 to
In the strip grazing experiment distance, the 32.18C. No such effects were found on the other days
cows spent between 79.5 and 86.0 of the time that of the rotational grazing experiment and in the strip
they could be outdoors at pasture, between 85.9 and grazing experiment.
91.2 of the time that they were eating forage On one of the observation days of the rotational
between 05:30 and 20:30 h grazing and between 91.1 grazing experiment lying time was much shorter than
and 96.3 of the time that they were lying between on all other observation days including those of the
05:30 and 20:30 h at pasture predicted means. strip grazing experiment. This day was the rainiest
Although some significance were found between of all observation days: it rained for 61.1 of the
these figures, they could not be related to the time that the cows could be outdoors.
distance between the pasture and the barn. 3.3.2. Time intervals between cows entering the
4. Discussion
barn In both experiments cows tended to enter the barn
4.1. Sward height in close succession. In the rotational grazing experi-
ment, 83.3 2.7 of the time intervals between The rotational grazing experiment showed that the
cows entering the barn were shorter than 6 min, and sward height affects the cows’ visits to an AMS if
6.7 0.8 of these time intervals ranged from 6 to fully automatic milking on a voluntary basis is
16 min predicted means with S.E. in brackets. In combined with grazing. At lower sward heights,
the strip grazing experiment, 78.4 2.4 of the time cows paid more visits to the AMS, and were milked
intervals between cows entering the barn were more often. This means that a farmer will have to
shorter than 6 min, and 8.2 0.8 of these time pay more attention to the daily milking frequency of
intervals ranged from 6 to 16 min predicted means his cows when he has offered them a fresh pasture,
and S.E. in brackets. because in such a situation they probably will be
more reluctant to return to the barn. According to Phillips 1993, there is an increase in grazing
3.3.3. Distribution of AMS visits over the 24-h intensity when a fresh pasture is offered to cattle.
period This would also account for the low percentage of
In the rotational grazing experiment, cows distrib- AMS visits between 08:30 and 11:30 h found on the
uted their AMS visits differently over the 24-h first days of experimental periods in our experiment,
period at different sward heights. The cows had a and the fact that cows spent more of their time eating
low percentage of AMS visits between 08:30 and forage at pasture on the first days of experimental
11:30 h and between 14:30 and 17:30 h, especially periods than on fourth days. However, total time
on the first days of the experimental periods, when spent grazing did not differ between different sward
they had been given a fresh pasture. In the strip heights, which is in agreement with findings of
grazing experiment, the distance between the pasture Phillips and Hecheimi 1989. Those authors never-
and the barn had no effect on the distribution of theless did find higher biting rates at lower herbage
AMS visits over the 24-h period. heights, which is reported also by Phillips and
Leaver 1986 and Rook et al. 1994. Unfortunately, we did not measure bite size in our experiment, but
3.3.4. Weather we did find an indication that cows spent more time
On the third days of the rotational grazing experi- at the feeding gate at low herbage heights; this, too,
ment, a positive relationship was found between the agrees with the results of Phillips and Hecheimi
black globe temperature outdoors and the time spent
140 C
.C. Ketelaar-de Lauwere et al. Livestock Production Science 65 2000 131 –142
1989, who found that cows spent more time eating lying times found in our experiment were in the
silage at low herbage heights. range of those reported by others Krohn and Munk-
Lying times were not affected by sward heights, sgaard, 1993; Singh et al., 1993. In our experiment
but if cows had access to the pasture they clearly it was striking that when the cows were on a ‘far’
preferred lying in the pasture rather than in the pasture for the first time, they spent less time in the
cubicles. This confirmed earlier findings Ketelaar-de feeding area and indoors and more time outdoors and
Lauwere et al., 1998. grazing than when they were on ‘near’ pastures or on
The decreasing sward height was probably not the a ‘far’ pasture for the second time. This may be a
only factor causing the extra time spent indoors and matter of habituation. Probably, it is a bit more
probably related to this the extra AMS visits on difficult to adapt to the AMS environment when it is
third days of the rotational grazing experiment. High combined with a ‘far’ pasture Broom, 1996, and
temperatures on these days may also have been therefore more time is needed for habituation.
¨ influential. Similar results were found by Krotzl and
Hauser 1997 and Ketelaar-de Lauwere et al. 4.3. Time intervals between cows entering the barn
1998. On fourth days of the rotational grazing experiment, the temperature did not contribute to the
In both experiments, cows returned to the barn extra time spent indoors and probably to the extra
several times in the period that they had access to the AMS visits, because no relationship was found
pasture. They always did this more quickly after one between the time spent indoors and the black globe
another than could be expected on the basis of an temperature outdoors on these days.
exponential factor alone. This phenomenon has been Another factor which may affect the cows’ be-
described previously
in comparable
situations haviour at pasture is rain. The shortest lying time
Ketelaar-de Lauwere et al., 1999. Connected with was found on the rainiest day of both experiments.
the group-wise entering of the barn, the cows also Phillips 1993 has stated that cattle are reluctant to
reported to the AMS quickly after one another. For a lie on wet grass.
farmer who combines grazing with fully automatic milking in an AMS, this means that in the period that
4.2. Distance cows have access to the pasture there will be peaks
in AMS visits and the AMS will be unvisited for The cows’ visits to the AMS in this study were not
several hours. Thus ‘group arrival’ of cows from affected by the distance between the pastures and the
pasture will negatively affect the throughflow of the barn. However, some indirect effects of the distance
AMS. This group behaviour is a result of the natural were found. Cows on ‘far’ pastures spent less time
habit of cows to act as a co-ordinated social unit lying on the pasture and more time standing or
Hurnik, 1994. Farmers should be aware of this walking in the central alley between the pastures and
phenomenon when deciding about what capacity the barn. In addition, it appeared that if they had
AMS to install. access to the pasture cows preferred lying in the
pasture rather than in cubicles, irrespective of the distance to the barn; this is similar to the findings of
the experiment about sward height. On both days of
5. Conclusions
