Effect of continuous keeping on pasture on heat expression
of dairy cows
Mariska Smit 0352756
Supervisors: Dr. F.J.C.M. van Eerdenburg en Drs. M.Newport
Abstract
70% of the fertility problems are caused by bad heat detection. But not only the farmer is the
cause of this, cows should show their behaviour better too. The length of oestrus differs
between cows and only half of the cows will show standing heat. Another big issue is the
husbandry. In The Netherlands, dairy cows are most of the time kept on concrete slatted
floors. This will not stimulate the cows to show their oestrous behaviour. In New Zealand
cows are kept on pasture all year long, which is more natural. Furthermore, in New Zealand
the cows are selected on fertility for decades and they have a seasonal calving system. In this
study 433 cows in New Zealand are observed and scored with de scoring system of Van
Eerdenburg et al., (1996) to compare these results with studies done in The Netherlands. Of
these 433, 261 cows did score 50 points or more in 24 hours. Average score per oestrus was
711,62 (SD 666,87) points. Mean score per 30 minutes observation was 388,58 (SD 351,97).
59,84% did show standing heat. The oestrous behaviour scores per observation are in this
study in New Zealand (237,21) significantly higher than these scores in The Netherlands
(121,15). There is no significant correlation found between oestrous behaviour scores and
parity, milk yield or lactation stage. Also not between oestrous behaviour scores and the
amount of cows in heat at the same time. There was a significant correlation between oestrous
behaviour score and environmental temperature and wind speed. The cows and their
behaviour are changing, so we have to learn how to look better at the cows to get our benefits
of them or keep cows in a more natural environment so they can show their behaviour better.
Introduction
Heat detection is underestimated by most farmers. Reimers et al. (1985) show that 70% of the
fertility problems are caused by bad heat detection. When the calving interval is not the
optimal 365 days, there will be losses on the farm. There will be losses for the daily milk
yield of the cow, but there are also losses by the number of calves that are born. (Van
Eerdenburg, 2008a) Therefore, good heat detection is very important.
Looking at the right time in the right way and act adequately after this observation is very
important to get the best out of your farm, and will lower costs.
Not only can the farmer improve on his observations, observe longer and more often, but also
the cow should show her behaviour better (Diskin et al., 2000; Heres et al., 2000; Roelofs et
al., 2004; 2005; Van Eerdenburg et al., 2002; Van Vliet et al., 1996).
The length of oestrus differs between the animals from as short as 4 hours to as long as 38
hours, using a definition of oestrus that includes all behavioural aspects of oestrous (Van Vliet
et.al., 1996). So the short periods are easy to miss. There are many studies which have
determined the oestrus length. Overall, the mean oestrus duration is 10,6 hours (Cavestany
et.al. 2008), where oestrus length is defined as the interval from the first accepted mount until
the last mount accepted.
Another cow problem is that only half of the cows will show standing heat (Roelofs et al.,
2005; Van Eerdenburg et al., 1996; Heres et al., 2000; Lyimo et al., 2000), while that is the
sign most farmers will look at. So more than half of the cows will be missed by the heat
detection of the farmers, if they only look at standing heat. That is why it is better to look at
1
more behaviour symptoms than only the standing heat. Van Eerdenburg et al., (1996) did
develop a scoring system for this reason.
Heat expression is influenced by husbandry too. (Britt et al., 1986, Vailes et al., 1990, Hackett
et al., 1984) In the Netherlands, dairy cows are most of the time housed in stables. Only 22%
of the cows will go outside on pasture form May till September, day and night. 54% Of all
cows will go outside on pasture only during the day in this same period. The other 24% will
even never come outside in The Netherlands. (CBS 2010) Farmers in the Netherlands are, due
to the high cost of the properties, forced to get as many cows as possible in a small area.
Furthermore, the stables are designed to reduce the workload for de farmer. These facts have a
big influence on the heat expression (Britt et al. 1986, Vailes et al., 1990). Husbandry will be
adjusted to the welfare of the cows as much as possible, but cows will never be in their
natural environment, so they never will show their natural behaviour fully. In particular, the
flooring is influencing the mounting behaviour of cows. Multiple articles report that cows
prefer dirt above concrete, they show more mounting, more standing heat and longer heat
expression on dirt than on concrete (Britt et al., 1986, Vailes et al., 1990, Pennington et al.,
1985 and 1986, Walker et al., 1996). On wet, slippery, concrete floors the cows will suffer
from lameness more than on pasture. And severely lame cows do not want to mount other
cows and will not show standing heat (Walker et al., 2008a). Also will severely lame cows
express oestrus with lower intensity compared to moderately lame cows and non lame cows
(Walker et al., 2008b). However, there is no correlation found between mild and subclinical
lameness and oestrus expression in cows. (Gomez et al., 2003, Van Eerdenburg et al., 2003)
In New Zealand, the cows are outside on pasture 24-7 the whole year long. The cows are
walking on grass or dirt except when they get milked or are waiting for the milking, then they
are standing on concrete. This way of husbandry is more natural for cows than the Dutch way,
so it is expected that the cows will show more natural behaviour.
In order to investigate the effect of the husbandry system, in the present study it is recorded
what New Zealand cows score with the scoring system of Van Eerdenburg et al., (1996).
These scores will be compared to scores of cows in The Netherlands. The climate in New
Zealand is comparable to the climate in The Netherlands, with the exception of the seasons,
which are half a year out of sync.
In New Zealand a strict seasonal calving system is used by the farmers: all cows will be
calving around August, because of the lack of grass in June and July. So all the cows will
show oestrous behaviour starting from August until November or later, depending on
which date the farmer starts mating. The mean size of a farm in New Zealand is about 500
cows, so there will be many cows on heat every day during September and October. There
will be more heat expression if there are more cows in oestrous at the same time. (Vailes
et al., 1990, Helmer et al., 1985, Van Vliet et al., 1996, Roelofs et al., 2005, Hurnik et al.,
1975, Diskin et al., 2000, Walton et al., 1987, Van Eerdenburg et al., 2008b). Also cows in
bigger groups may show more oestrus behaviour because of the sexual stimulation
provided by other animals in oestrus (Orihuela, 2000).
The cows will form a Sexually Active Group (SAG) if there are more cows in heat at the
same time. One cow can not show her behaviour properly when she is the only cow on
heat. Hurnik et al. (1975) found 12 mounts when 1 cow is in oestrus, 36 mounts when 2
cows are in oestrus and 56 mounts when 3 cows are in oestrus. So when there are more
cows in oestrus at the same time it is shown that those cows will score higher scores with
the scoring system of Van Eerdenburg et al., (1996). The small sizes of the farms in The
Netherlands with about 77 dairy cows in average and calving all year round make it likely
that only one cow is in oestrus on a particular day (CBS 2010).
2
Because cows in New Zealand are outside the whole year long, which is more natural, and
they are selected on fertility because of their seasonal calving system, which implies that there
will be more cows on heat at the same time, it is supposed that the cows in New Zealand get
higher scores than cows in The Netherlands overall.
3
Materials en methods
In total 433 different Holstein-Friesian (HF) cows were observed on 6 different farms on
the North Island of New Zealand from 20th of September until 29th of October 2010. The
cows were outside on pasture all year long, 24 hours a day. The cows had an average
lactation stage of 65,10 days, with an average milk production of 19,45 litres and parities
ranged from 1 to 15.
The observations took place after milking and feeding, because milking and feeding will
distract the cows from showing heat behaviour. After milking, walking to their pastures and
feeding, the herd will be lying down, except for the oestrous cows who will form a SAG. Van
Vliet et al., (1996) did find a higher detection ratio after feeding and milking, than before
Behaviour
Points milking. The observations took place 3
times a day for about 30 minutes. This
Mucous vaginal discharge (MU)
3
will be the most practical situation, in
Flehmen (FL)
3
which the detection rate will be the best,
Restlessness (RL)
5
like 77,1% found by Van Vliet et al.,
Being mounted but not standing (MnS)
10
(1996) and 90% found by Roelofs et
Sniffing vagina of other cow (SN)
10
al.(2005).
Resting with chin on other cow (CR)
15
During the observations, active cows
Mounting (or attempting) other cows (M) 35
were selected from the herd to observe
Mounting head side of other cow (MH)
45
and score for those 30 minutes. They did
Standing heat (SH)
100
not get out of the herd. With the scoring
Table 1: scoring system Van Eerdenburg et al., (1996)
system of Van Eerdenburg et al., (1996)
was counted which behaviour was seen how many times, and therefore what the score was of
that cow. Table 1 shows for which behaviour the cow gets points. When the cows are
observed for 30 minutes 2 to 3 times a day, a total score of 50 will be enough to conclude that
a cow is in oestrus (Van Eerdenburg et al., 1996). If a cow turns out to be in oestrus again on
other observing times, then the points will be summed for a maximum period of 24 hours.
At farm 1 they were milking 465 cows, which were subdivided into 4 groups. There was a
group with 153 cows which calved in spring this year (SPRING-herd), this group contained
cows which calved 10 weeks ago to cows which calved last week. So not every cow can be in
heat in the observation week, but some cows can show their second heat. Another group
contained 75 cows which was milked once a day (OAD-herd), these were all heifers which
calved this spring, from 10 weeks till 4 days ago. They were milked once a day, so they could
put more energy in growing and showing heat expression. In mornings the SPRING-herd was
milked first at 05:00, followed by the OAD-herd. At the end of the day the SPRING-herd was
milked around 16:00. The milking shed was a 40 aside swing over herringbone. The OADherd was also fed palm kernel after milking. The pasture size was 162 hectares, subdivided
into 77 paddocks with an average size of 2,1 hectares. Everyday the different groups went to a
fresh paddock. The SPRING-herd was observed at 8:00, 13:00 and 17:00, the OAD-herd was
observed at 9:00, 12:00 and 16:00. These times were determined by the time of milking,
because the SPRING-herd was milked first in the morning, which meant they could observed
first. The OAD-herd did not have to be milked in the evening, so they could be observed
before the SPRING-herd because in this week the sunset was around 18:15. The mean
lactation stage of the cows on this farm was 56,59 days, with an average milk yield of 23,96
litres. The parity ranged from 1 to 8.
At farm 2 they are milking 500 cows, which are subdivided into 3 groups. One group
contained 320 cows which were milked twice a day (TWICE). This herd contained cows
which calved in spring this year, but also cows which calved in autumn. There were 110
autumn calved cows which all have blue tail paint, so they could be recognized easily. The
4
other herd contained 170 cows which were milked once a day (ONCE). This herd contained
heifers and skinny cows, also from spring and autumn. In this herd were 80 autumn cows. The
milking did start at 6 in the morning in a 50 stands rotary milking-shed. The TWICE-herd was
milked first. At 07:30 the ONCE-herd was milked. Finally the 10 sick/lame/treated cows were
milked and milking was finished around 08:45. In the evening milking did start at 15:30 with
the TWICE-herd, followed by the sick/lame/treated cows and finished at 16:45. In the
evening the TWICE-herd was also fed maize, silage and palm kernel before milking at 14:30.
The pasture size was 250 hectares, subdivided into 96 paddocks of an average size of 2,6
hectares. The cows did get a fresh paddock every morning and evening and sometimes when
they have finished their paddock earlier, they were shifted to another paddock between
milking sessions. The TWICE-herd was often shifted to another fresh paddock at 12:00. The
observations of the TWICE-herd took place at 09:30, 14:00 and 18:00, the ONCE-herd was
observed at 10:30, 13:00 and 17:00. In the mornings observations started at the TWICE-herd,
because this herd was milked first. Because the TWICE-herd is shifted to another fresh
paddock at 12:00 the ONCE-herd will be observed first, so the TWICE-herd can be observed
at 14:00 when they were adjusted to their new paddock. In the evening observations started
with the ONCE-herd, because they did not have to be milked in the evening, so they could be
observed before the TWICE-herd because this week the sunset occurred around 19:20.
The mean lactation stage of the cows on this farm was 75,04 days, with an average milk yield
of 16,42 litres. The parity ranged from 1 to 13.
At farm 3 they were milking 375 cows, who all calved in spring this year, starting at the 10th
of August. At the time of observation there were 20 cows still carrying a calf and not milked
yet, so the observations took place on 355 cows. The milking started in the morning from
05:45 until 08:15, the evening milking took place from 15:30 until 18:00. They were milking
in a 2x20 stand herringbone milk shed, where the cows were also fed some concentrate mix.
The pasture size was 120 hectare, subdivided in 60 paddocks of each 2 hectare. Every
morning and evening they did get a fresh paddock. The observations took place at 10:00,
14:00 and 19:00. The average sunset was at 19:30.
The mean lactation stage of the cows on this farm was 43,06 days, with an average milk yield
of 26,30 litres. The parity ranged from 1 to 10.
At farm 4 they were milking 340 cows, whom all calved in spring this year. They started
milking at 05:30 in the morning until 8:00 and in the evening they started at 15:00 and were
finished at 17:00. They were milking in a 2x20 stands swing over herringbone milk-shed,
where cows did also get some concentrate mix. After milking the cows had to wait until the
last cow has finished milking, then they went to the paddock together. This because at this
moment there was not enough grass, so they all did get a good chance to eat. They were also
fed 4 bales of silage of approximately 1000 kg each, 2 in the morning and 2 in de evening
after milking. It was just spread out in the paddock, so they could choose silage or grass or eat
both. The pasture size was 120 hectares. The observations took place at 10:00, 14:00 and
18:00. The average sunset this week was at 19:35.
The mean lactation stage of the cows on this farm was 68,63 days, with an average milk yield
of 18,14 litres. The parity ranged from 1 to 15.
At farm 5 they were milking 560 cows whom were subdivided in a first (F) and second (S)
group. The second group contained all heifers and skinny cows. All cows in both groups had
calved this spring. The first group was milked first. In mornings milking took place from
05:00 till 8:30 and in the evening from 14:30 till 18:00. The first group finished around 06:30
and 16:00. They were milking in a 2x20 swing over herringbone milk-shed. They did not get
extra food. The pasture size was 205 hectares, subdivided in 64 paddocks of an average of 3,2
hectares each. The observations at the F herd took place at 09:00, 13:00 and 17:00. The S herd
was observed at 10:00, 14:00 and 19:00. The average sunset this week was at 19:40.
5
The mean lactation stage of the cows on this farm was 62,43 days, with an average milk yield
of 18,00 litres. The parity ranged from 1 to 14.
At farm 6 they were milking 550 cows subdivided into two groups who all calved last spring.
There was observed only one group. They were milked from 05:00 to 07:30 and from 14:30
to 17:00 in a 2x20 swing over herringbone milk-shed. They did not get extra food. The
observed herd was milked first and finishes around 06:30 and 16:00. The pasture size was 300
hectares, subdivided into 87 paddocks which were on average 3,4 hectares each. The
observations took place at 10:00, 12:30 and 17:00. The average sunset this week was at 19:48.
The mean lactation stage of the cows on this farm was 68,00 days, with an average milk yield
of 27,65 litres. The parity ranged from 1 to 11.
All observed cows on all farms were cows which calved in spring.
After each milking on all farms except farm 4, cows could walk straight back to their pasture.
They did not have to wait until all cows had finished milking. Sometimes they have to walk a
long distance (up to 2000 metres in accident scenery) to the paddock in the morning, but at
night they were kept close to the shed. That is why there was more time between the end of
milking and the observation in the morning.
In table 1 there is more information about those different farms.
Farm
1
Location
Kerikeri
Number of
dairy cows
465
Observed herd
sizes
SPRING: 153
OAD: 75
Pasture
size
162 ha
500
ONCE: 170
TWICE: 320
250 ha
375
355
120 ha
340
340
120 ha
560
F:300
S:240
205 ha
550
270
300 ha
-35.25, 173.79
2
Kerikeri
-35.26, 173.87
3
Pukekohe
-37.26, 174.80
4
Pukekohe
-37.24, 174.81
5
Taupo
-38.44, 175.75
6
Taupo
-38.45, 175.77
Milking
times
05.30-8.00
15.0017.30
6:00-8:45
15:3017:00
05.45-8.45
15.0018.00
5:30-8:00
14:4517:00
5:00-8:30
14:3018:00
5:00-7:00
14:3017:00
Extra Food
Palmkernel
Maize + palmkernel
+ silage
Concentrate-mix
Concentrate-mix
silage
-
-
Table 2 Information about the farms
The data collected during this study was about the environment and about the cows. Data
collected from the environment were temperature, rain, wind direction and velocity, humidity
and grass length collected during the 30 minutes observation period. Data collected about the
cows were breed, date of birth, milk yield and calving date.
6
Results
Oestrus behaviour scores
433 Cows were observed and scored with the scoring system of Van Eerdenburg et al.,
(1996), 261 of these cows scored 50 points or more in 24 hours, which means by this scoring
system that they were in oestrus at that moment.
For a good perception, cows whom were less than 30 days in lactation were deleted from the
data, because the behaviour they showed belonged to the first oestrus. There were 12 cows
who did score 50 points or more, but were less than 30 days in lactation. The mean score of
these cows was 174,21 per observation period of 30 minutes and 255,93 in 24 hours. Of these
cows 3 were seen twice in 24 hour, the others only once. The highest score in 24 hours was
1223, this was also a cow observed twice and the only cow of those 12 who did show
standing heat.
The remaining 249 cows did score 50 points or more and were 30 days or longer in lactation.
Those 249 cows had an average score of 711,62 points per oestrus.
Mounting on the head side and standing heat were only seen on cows in oestrus, the other
behaviours were also seen on cows not in oestrus.
The highest score in 24 hours was 3691, the highest score in one observation period of 30
minutes was 2098.
The mean score per 30 minutes observation was 388,58
Of the 249 cows in oestrus half of the cows (123) did score between 50 and 500 points, the
other half did score between 500 and 3691. Of all these cows, 9 cows did score more than
2000 points.
Figure 1: amount of oestrous cows per score
Of the 249 cows in oestrus 149 cows (=59,84%.) showed standing heat in one or more of
those 3 observation periods of 30 minutes.
The maximum number of standing heats recorded during one observation period was 19,
during one oestrus this was 29. The mean amount of standing heats during one oestrous
period was 6,2.
7
In all the behaviours observed on the 249 cows in oestrus, sniffing was the most common
behaviour. Of all the recorded behaviours 53,4% was sniffing. When the calculation is made
per observation period of 30 minutes than sniffing was seen 8,42 times per cow.
Behaviour
MU
FL
RL
SN
MnS CR
M
MH
SH
47
96
17
3552
295
515
1121
102
913
Total times seen
Percentage 0,7% 1,4% 0,3% 53,3% 4,4% 7,7% 16,8% 1,5% 13,7%
Mean times seen per
8.42 0.70 1.22
2.66 0.24
2.16
cow per 30 min. 0.11 0.23 0.04
Table 3: amount of recorded behaviours (MU = Mucous vaginal discharge, FL = Flehmen, RL =
Restlessness, SN = Sniffing vagina of other cow, MnS = Being mounted but not standing, CR =
Resting with chin on other cow, M = Mounting (or attempting) other cows, MH = Mounting head side
of other cow, SH = Standing Heat)
In 5% of the observations only 1 cow was in oestrus, with a mean score of 232,6 points (SD
125,6). In 22% of the observations 2 cows were in oestrus with a mean score of 413,5 (SD
261,51). In the other 73% of the observations more than 2 cows were in oestrus at the same
time, with a mean score of 434,3 points per observation per cow (SD 387,93). There was no
significant difference between these scores (P> 0,05).
Oestrus behaviour score in relation to cow factors
Pearsons correlation over all 249 oestrus cows on all farms between the behaviour scores and
parity was -0.044, between behaviour scores and milk yield was -0.004 and between
behaviour scores and lactation stage was 0.069. None of these correlations are significant
(P>0,05)
There was no significant difference found between cows observed once, twice or tree times in
their 24 hour oestrus period in mean score, parity, milk yield and lactation stage.
There were also no significant differences found between heifers and older cows in mean
score, milk yield or lactation stage.
Pearsons correlation over all 249 oestrus cows but than differentiated for the farms between
total behaviour score and parity, milk yield and lactation stage can be seen in table 4. But also
none of these correlations are significant.
Total
Parity
Milk
Lactation
score vs.
yield
stage
farm 1
-0,1872
0,0883
-0,0572
farm 2
0,2246
0,1803
0,1584
farm 3
-0,0153
-0,2264
-0,1356
farm 4
-0,2504
-0,2160
0,2999
farm 5
-0,1673
0,0865
0,0675
farm 6
0,0814
0,1849
0,0377
Table 4: Pearsons correlation between total score and cow factors on the different farms
8
More differences between the 6 farms can be seen in table 5.
farm
mean
score
24h
1
2
3
4
5
6
651,33
547,03
667,47
714,07
849,43
696,50
highest
score
per 30
min
928
1880
2075
1098
2098
1163
highest
score
per 24 h
mean
observations
per cow
mean
score 30
min
mean
parity
mean
milk yield
mean
lactation
stage
1378
3690
3210
2238
3435
1853
1,71
1,53
1,66
1,71
1,77
2,03
369,22
325,20
320,56
399,60
499,78
318,22
2,05
4,10
3,44
4,67
4,24
5,62
22,08
17,09
25,94
17,87
18,11
29,12
62,82
75,11
46,34
69,85
62,25
68,61
Table 5: difference between farms in scores and cow factors
Oestrus behaviour score in relation to environment factors
Data collected about the environment did show a significant correlation between score in
that observation period of 30 minutes and temperature. The Pearsons correlation is -0,244
with P<0,05.
Also was found a significant correlation between score in 30 minutes and wind strength.
The Pearsons correlation is 0,229 with P<0,05.
There was no significant correlation between score and rain, humidity or grass length.
Figure 2: score versus temperature
Figure 3: score versus wind speed
9
Discussion
It can not be concluded yet, that walking outside on the pasture all year round is better for
showing oestrous behaviour in cows, because there are too many differences between The
Netherlands and New Zealand. Like the year round calving system versus seasonal
calving system, small herds versus large herds and milk production. Another point is
lameness. Because of the more natural floor surface in New Zealand, there will be less
lame cows than in The Netherlands with the slatted concrete floors. Severely lame cows
do not want to mount other cows and will not show standing heat (Walker et al., 2008a)
and they express oestrus with lower intensity compared to moderately lame cows and non
lame cows (Walker et al., 2008b). There is no correlation found between mild and
subclinical lameness and oestrus expression in cows. (Gomez et al., 2003, Van
Eerdenburg et al., 2003).
Lame cows do have physical limitations that prevent them of showing intense oestrus
behaviour, but also the hormonal status will influence the oestrous behaviour. There are
various opinions about the oestradiol measurements in cows and the relation to oestrous
behaviour. The overall conclusion is that there is no correlation between oestrous
behaviour intensity and oestradiol level in the peripheral blood. (Walker et al., 2008a,
2008b; Morris et al., 2011; van Eerdenburg, 2008b). Because when there was a correlation
observed, these correlations were not high enough to conclude a direct relation (Lyi mo et
al., 2000; Roelofs et al., 2004). So other hormones have to be investigated (van
Eerdenburg, 2008b).
In the report of Morris et al., (2011) the cows that did ovulate were all healthy cows and
only 50% of the lame cows. The other 50% of the lame cows did not ovulate or did even
not respond to GnRH injection for ovulation induction. All cows that did ovulate did also
show oestrous behaviour and all cows that did show oestrous behaviour did ovulate. In
this study they concluded that the cows did not show oestrous behaviour, because they did
not ovulate. They suggest that this is caused by low LH pulse frequency due to the stress
in lame cows, because of this low LH pulse frequency there will not develop a good
follicle which results in a not functional corpus luteum. This is in accordance with the
report of Van Eerdenburg (2008b) where he reports that LH is correlated with oestrous
behaviour. Only LH is measurable in live, free living animals, but this will be correlated
with GnRH. The not functional corpus luteum found by lame cows by Morris et al., can
explain the low progesterone production that is found in lame cows by other authors
(Walker et al., 2008b, Morris et al., 2011).
Oestrous behaviour scores
Of the oestrous cows, in the present study, 60% did show standing heat in one or more of the
3 observation periods of 30 minutes. This is in accordance with Roelofs et al., (2005) and
Lyimo et al., (2000). But this is higher than found by other authors (Van Vliet et al., 1996;
Fonseca et al., 1983; Roelofs et al., 2004). This may be due to a bigger Sexual Active Group
(SAG) in New Zealand. In the study of Cavestany et al., (2008) they observed 33 cows and 15
heifers continuously for oestrous behaviour also on a pasture based system and with a
seasonal breeding system, so this is more comparable to the situation in New Zealand. They
only mentioned the amount of standing heats during one oestrus period and per hour per cow
(26,8 and 2,5 per hour) or per heifer (48,2 and 5,6 per hour), so it is difficult to compare these
data with the percentages of the other studies and the records of the present study. In the
present study an average of 4 standing heats per observation period of 30 minutes was
noticed, converted this will be 8 standing heats per hour. This is more than the data of
10
Cavastany et al., (2008). In that report they only observed 15 synchronised heifers and 33
cows, so that may be the reason for the lower amounts of standing heat in that study.
Because as mentioned above; there will be more cows showing mounting activity and
standing heat when there are more cows in oestrus at the same time. In the report of Roelofs
et al., (2005) they did find standing heat in 58% of the oestrous periods, but standing heat was
shown in only 20% of the oestrous periods when there was only 1 cow in oestrus. And the
behaviour score doubled when there were more than 2 cows in oestrus. They reported that
mounting behaviour and standing heat were responsible for this increase in score (Roelofs et
al., 2005).
According to Helmer et al. (1985), the heat detection ratio will be influenced more by the
amount of cows which are in heat than the time the observations took place. Furthermore,
Van Vliet et al.,(1996) and Hurnik et al., (1975) found higher behaviour scores after milking
and feeding than before milking and feeding. So the time of observation is an important
parameter too.
Only 1 of the 14 cows (7%) who scored more than 50 points, but were less than 30 days in
lactation did show standing heat. This is comparable to the 7% standing heat Van Eerdenburg
(2008b) found during first oestrus.
The maximum number of standing heats recorded during one observation period was 19,
during one oestrus this was 29. This is almost 6 times of the amount Van Vliet et al.,
(1996) did find in their study. They observed 50 cows, 12 times a day for 30 minutes and
did find a maximum score of 5 standing heats during one oestrous period. It is suspected
that the score will be higher per oestrus while there are more observation moments and
thus a longer observation time. So maybe this big difference will be due to more cows in
heat at the same time. Or due to the selection on fertility, which is based, primarily, on an
accurate oestrus detection (Reimers et al., 1985). During the study of Van Vliet et al.,
(1996) the majority of the standing heats (77%) did occur when there were more cows in
oestrus at the same time. Another explanation could be that this behaviour may be due to
the more natural New Zealand environment. Because the study of Van Vliet et al., (1996)
took place in The Netherlands in a free stall barn with a concrete slatted floor.
In the report of Cavestany et al., (2008) and this study the amount of cows that did show
standing heat is not as high as expected based on the older reports (Van Vliet et al., 1996;
Fonseca et al., 1983; Roelofs et al., 2004, which can be due to genetics and management
(Van Eerdenburg 2008b).
Sniffing was the most common of all behaviours observed in this study (53,4% of all the
recorded behaviours). In one observation period sniffing was seen 8,42 times per cow
average. Roelofs et al (2005) did record 25,7 times sniffing per oestrus per cow in a free stall
barn with cubicles. And they report that sniffing was together with chin resting seen in all
oestrous periods. During oestrus the behaviour of a cow changes, mediated by oestrogens
(Roelofs 2008) or GnRH (Van Eerdenburg, 2008b). Because not all cows show standing heat
anymore, the other behaviours will be more important to look at. When the cows are observed
for many oestrous behaviour signs instead of only standing heat, than the period in which
oestrous behaviour is seen will be longer and so less cows will be missed when observing less
intense. For example the study of Roelofs (2008) were the relation to ovulation time is
mentioned, it will take 30,6 (± 5,1) hour from first behaviour sign until ovulation compared to
26,4 (± 5,2) hours from first time standing heat is observed until ovulation. So it is important
for farmers in order to detect oestrous cows to look at more behaviour symptoms like sniffing
and chin resting than only look for standing heat.
11
In this study there is no significant difference found between oestrous behaviour scores and
the amount of cows in heat at the same time. Which is not in agreement with many other
studies. (Vailes et al., 1990; Helmer et al., 1985; Van Vliet et al., 1996; Roelofs et al., 2005;
Hurnik et al., 1975; Diskin et al., 2000; Esslemont et al., 1985; Walton et al., 1987; Van
Eerdenburg, 2008b) Maybe this may be due to the amount of cows in the different groups.
Because in only of 5 of the 93 observations (5%) there was only 1 cow in heat. In 68 of the 93
observations (73%) more than 2 cows were in heat at the same time. So there were to few
‘single’ cows in heat to make any conclusions in this respect.
Oestrous behaviour score in relation to cow factors
Pearsons correlation over all oestrous cows between the behaviour scores and parity, milk
yield or lactation stage were not significant (P>0,05).
There are a number of reports about the correlation between milk yield and oestrous
behaviour. Some report that a high milk production decreased the intensity of oestrus
(Lopez – Gatius et al., 2004; Wiltbank et al., 2006; Ferguson et al., 1990; Harrison et al.
1990), while others report that there is no difference in oestrous behaviour between cows
with low or high milk production (Dachir et al., 1984; Fonseca et al., 1983; Heres et al.,
2000; Van Eerdenburg et al., 1996; Van Eerdenburg et al., 2002; Van Eerdenburg, 2008b).
The present study confirms the results of the second group.
Van Eerdenburg et al. (1998) found different scores between first, second and third heat. The
first heat scored lower than the third heat, the second heat did score the highest number of
points. During the present study, the cows were only observed for one week per farm. So it is
not sure if these cows did show their first, second or third heat. By deleting all the cows who
were less than 30 days post partum, it is supposed that the cows showing first heat were
deleted from the dataset.
In the present study there was no significant difference found between score and parity. This
in accordance with the report of Van Eerdenburg et al. (2002). Although others did report an
effect between oestrous behaviour and parity, they did find that primiparous cows did have a
higher intensity of oestrus than multiparous cows. (Roelofs et al. 2005) The primiparous cows
had also a longer duration of oestrus and displayed more sniffing and mounting than
multiparous cows (Roelofs et al. 2005). But Van Vliet et al., (1996) did find the opposite
relation, in their study multiparous cows did score higher than primiparous cows. This factor
remains unclear and needs more investigation.
Oestrous behaviour score in relation to environmental factors
The data did show a significant correlation between score in that observation period of 30
minutes and temperature (r = -0,244; P<0,05.) and wind speed (r = 0,229; P<0,05).
There was no significant correlation between score and rain, humidity or grass length.
In the present study, the scores where lower during rain than during dry periods, but there
was no significant correlation. Also there was one observation period within it rained for
10 minutes, the other 20 minutes were dry. But during those 10 minutes there was no
oestrous behaviour seen. Although there were 2 cows in heat at that moment. And in those
20 minutes left over, those 2 cows did score 315 and 200 points. This is in concordance
with Cavestany et al., (2008), where during a rainstorm and wind, not a single activity was
recorded in heifers, although 3 of them were in oestrus.
Not every cow was a 100% HF cow. Most times there was some Jersey added, which makes
them a Kiwi cross breed. But Hackett et al., (1984) mentioned that, although reported by
12
Heres et al, 2000), the genetic difference has a very low influence on heat expression in
comparison to the environmental influence.
Total oestrous behaviour score New Zealand compared to The Netherlands
There are 4 reports about studies in the Netherlands that scored cows with the same behaviour
scoring system of Van Eerdenburg (1996) for oestrous cows and showed their scores as a
mean result in their study (Van Eerdenburg et al., 1998; Lyimo et al., 2000; Roelofs et al.,
2004 and 2005). Results of these studies are shown in table 6. The results of these studies
were compared with the data collected during this study in New Zealand. The calculated mean
per observation is the mean per oestrus divided through the amount of observations per
oestrus, because in the article of Van Eerdenburg (1998) the mean per observation was not
mentioned. The calculation is done for every study, so these studies can be compared to the
study of Van Eerdenburg (1998). Although, by dividing the mean per oestrus through the
amount of observations per oestrus the score will be lower, because not every observation
period did produce points.
NZ
NL
NL
NL
NL
(this study)
Van Eerdenburg 1998
Lyimo 2000
Roelofs 2004
Roelofs 2005
T-test
Significance
Mean per
oestrus
Mean per
observation
711,62
582,75
1115
1047
1132
1,980
P>0,05
388,58
208
223
298
-5,229
P<0,05
Calculated
mean per
observation
237,21
72,84
139,38
130,88
141,50
-7,136
P<0,01
Amount of
observations
per 24h
3
8
8
8
8
Table 6: comparing New Zealand (NZ) and The Netherlands (NL) in oestrous behaviour scores
There is no significant difference between the Dutch and New Zealand mean scores per
oestrus. This is because of the studies in The Netherlands observed 8 times a day, where in
this study in New Zealand was observed 3 times a day. So in total there would be a higher
score in 8 times 30 minutes than in 3 times 30 minutes. But the mean scores per observation
(measured or calculated) differ significantly between The Netherlands and New Zealand. So
in New Zealand a cow in oestrus does score a higher oestrous behaviour score in one
observation period with the scoring system of Van Eerdenburg et al., (1996), than a cow in
The Netherlands.
The reason for this difference is not clear. Because there are several differences between the
environments in these studies. The studies in The Netherlands were observed in free stall
barns with slatted floors, in this study in New Zealand the cows were outside whole year long
on pasture. Another difference is the herd size. In the Dutch studies the herd sizes were
smaller than in New Zealand, this in combination with the whole year round calving system in
The Netherlands and the seasonal calving system in New Zealand. The amount of cows in
oestrus at the same time will be higher in New Zealand than in The Netherlands. But Roelofs
et al., (2005) did make a difference in 1, 2 or more than 2 cows in oestrus at the same time
with their behaviour scores. Comparing these results of Roelofs et al., with results of this
study in New Zealand, there is no significant difference between the observation with 1 or
more than 2 cows in oestrus. Rather, there is a significant difference between the behaviour
scores when there were 2 cows in oestrus. So with only two cows in oestrus there can be
13
concluded that there is a difference between New Zealand and The Netherlands due to
something in the environment.
Animals in oestrus
NZ (this study)
NL (Roelofs 2005)
T-test
Significance
Average points per observation
1
2
>2
232,6
413,5
418,6
207
314
360
0,455
1,702
1,243
P<0,30
P<0,01
P<0,20
Table 7: comparing oestrus behaviour scores per observation per amount of animals in oestrus at
the same time in New Zealand (NZ) and The Netherlands (NL)
Conclusion
Oestrous behaviour scores per observation are in New Zealand significantly higher than in
The Netherlands.
There is no significant difference found between oestrous behaviour scores and parity, milk
yield or lactation stage.
There is no significant difference found in this study between oestrous behaviour scores and
the amount of cows in heat at the same time. This will be caused by the small amount of
observations in with only one cow was in oestrus (5%) comparable to 2 or more cows in
oestrus (95%) at the same observation period.
There is a significant correlation between oestrous behaviour score and environmental
temperature and wind speed.
The higher scores in New Zealand can be due to more cows in oestrus at the same time or can
be due to the more natural environment in New Zealand. Comparing the results of this study
to those of Roelofs et al (2005) it appears that the higher scores in New Zealand are due to the
environment.
14
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