(extracted from 1996 Annual Report submitted to Saskatchewan Agricultural Development Fund)
This year the W.C.V.M. behaviour group was given the unique opportunity to conduct behavioural observations on cattle in a P.F.R.A.(Prairie Farm Rehabilitation Administration) community pasture setting. The community pasture systems serves as a "summer camp" for cattle, complete with breeding services and daily supervision provided by cowboys and pasture managers. Typically each pasture contains a mix of cattle from various herds exposed to multiple bulls. For ethologists who are studying cattle behaviour, the community pasture situation is rare and it affords us the unique opportunity to study cattle under natural range condition where the cattle have minimum restrictions on their movement and social groupings. In addition, the community pasture system presents unique questions and challenges which are seldom confronted by cattle producers who are tending a single cow/calf herd. This does not mean the questions are not important. In fact, the opposite is true in Saskatchewan where roughly 40% (around 400,000 cows) are sent to community pastures for grazing and breeding each year. The social dynamics, movement patterns and the behavioural questions arising from the community pasture systems are extremely important for the beef industry in Saskatchewan when one considers the large numbers of cattle involved in the community pasture "experience". Several questions immediately surface:
Determine the extent to which cattle within a community pasture system form subgroups which are representative of their respective herds or origins. Determine if cattle show spatial orientation and "drift" towards their home farm.
Progress to Date
Materials and methods:
site was the Rudy-Rosedale Community Pasture, situated approximately 50
Km south of Saskatoon, Saskatchewan. Two groups of cow-calf pairs and breeding
bulls were studied between May and October 1996. The first comprised 78
cows and their calves from 6 patron herds exposed to 2 Limousin bulls.
These were grazed initially on 65 ha of improved pasture and were later
moved to a 260 ha field. The second group was composed of 126 cow-calf
pairs from 4 patron herds and was exposed to 4 Charolais bulls. This group
first occupied 500 ha of native pasture and was later moved to an area
of about 1090 ha.
Relationship between conception rates and body condition scores
before and after the grazing season, subjective condition scores were recorded
for each cow based on manual palpation of back fat. Scoring was from 1
(extremely thin) to 5 (overly fat). Optimum breeding condition was judged
to be about 4 or less on this scale. At the end of the grazing season 108
cows were found to be pregnant (85.7%) and we looked to determine whether
failure to conceive was associated with poor body condition. Mean condition
scores for all cows increased slightly over the grazing season from 3.94
to 4.15. However there was no significant difference in condition scores
between pregnant and open cows either before (3.95 and 3.81 ns) or after
(4.15 Vs 4.19 ns) the grazing season, though such a relationship has been
shown in previous studies. Typically there is a correlation between higher
condition scores at the start of a grazing season with higher conception
rates. Our findings suggest that given a reasonable standard of nutrition
overall, minor differences in body fat reserves are not predictive of ability
to conceive. There are undoubtedly other factors worth considering, including
the relative ranging behaviour of cows and bulls within the field. Later
analysis of data obtained in the summer of 1996 will investigate some of
Social grouping and location preferences during late-season grazing
investigates two hypotheses. Firstly that cattle will preferentially associate
with members of their own home herd, even after several months of sharing
a range with animals from other farms. And secondly, that herd groupings
will tend to show a preferences for certain locations within the field.
Social group composition
The area within 200m of the perimeter of the large field was divided into rectangular zones of 600 m (+/-200m) in length. These were defined in relation to features within the field and were thus not all the same size. There were 36 such zones making up the 14 km perimeter of the field. This area was traversed using a combination of walking and motor vehicle on 10 occasions during September and October 1996. Cattle of the 4 patron herds in this field had been colour coded using red, green, yellow or blue ear tags at th e start of the grazing season. Observations consisted of noting the numbers of adult cattle of the 4 herds found in each location on each occasion. In total 706 animal locations were recorded, accounting for about 56% of the cows on each observing day. Only 15 of the 36 available locations were ever seen to be occupied by cattle (this is an ongoing problem in range utilization at this site, which we are also interested in investigating). Where animals were seen, the mean number in a location was 17.5, and animals thus associated in space were regarded as a "group" for the purpose of this study.
For each herd and each group observed, the likelihood of observing such proportions of animals was calculated as a binomial probability score. Each score was classed as either "extreme" or "non-extreme" according to whether the probability fell within the upper or lower 25% of the probability distribution or within the middle 50%. For example if a group of 15 cows of which 7 were from the red herd was seen, the probability of seeing this many reds or more by coincidence is .309 based upon the total number of reds in the pasture and the total number of cows in the pasture. In other words finding a group of 15 cows in which 7 were from the red group would not be unusual based on probabilities and would not represent proof that the red cattle were clustering together. Such a group would be classed as "non-extreme" as regards the number of reds. On the other hand, if a group with 22 red cows out of a total of 38 was seen, the probability of seeing this many reds or more together would be .008 since it represents nearly all the red cows. This is considered rather unlikely to happen by chance and would be classed as "extreme". For the four herds the frequency of each class was compared for 41 groupings in a 4 X 2 contingency table. The overall chi-square of 14.67 with 3 df is significant at p=0.0021. This is interpreted as suggesting that there is a strong tendency for herdmates to be seen in association with each other rather than in company with members of the other herds.
to observe a higher number of incidences where a group of cattle was made
up of predominantly more cattle from a specific herd than one would expect
by random chance. At this point in the analysis it is difficult to tell
whether herdmates prefer each others' company, independent of the location,
or whether they merely tend to prefer the same locations. However, the
casual observation made by cowboys and pasture managers who claim that
cattle regroup into natal herds appears to hold true under our scrutiny.
Implications of findings:
finding could have tremendous implications on the method of determining
the proper bull to cow stocking ratios. Instead of trying to meet a specified
ratio of bulls to cows, community pasture managers may also need to maintain
an adequate number of bulls based on the number of patrons using the pasture
and the number of subgroups of cattle which may form. This would be especially
true under extensive range conditions and would depend upon the bulls'
ability to locate the various subgroups.
Preference for a particular location
It does appear that the 4 herds had preferred locations. This was particularly apparent for the green and blue herds but less so for red and yellow. This is quite well seen in the figure. Some groups were never observed in some locations while other groups were seen quite often. Another point to note is that locations 6 and 7 contained the source of drinking water and the use of these areas by all herds was expected. It is easier to assess the preference of the individual herds for specific locations by observing areas which lack such features.
with local farmers the suggestion has arisen that there may exist a phenomenon
of "home drift". This is taken to mean that in the late part of the grazing
season, mixed community pasture herds may be seen to de-aggregate out of
a large group, go back into their original home herd groupings and gravitate
towards their home farms. If this were true it would beg several interesting
questions such as what triggers the drift, is it poor pasture quality or
forage availability, or lengthening nights? Also, how would cattle know
which direction was home? Most of the cattle are trucked to the community
pasture. Spatial orientation in cattle is an area about which next to nothing
is known at present. These preliminary results appear neither to support
nor to refute the notion of "home drift". Two of the herds (blue and green)
did tend to cluster in regions of the field closer to their own farms,
but since much of the field was not used by the animals at all there were
few degrees of freedom here to test for significance. A process of clustering
together as the season advanced was only apparently seen in the case of
the red herd. Blue and green were apparently already clustered by the beginning
of September and the yellow herd showed little tendency to cluster at all.
Implications of the findings:
not entirely clear if all groups "drift" toward their home farm as the
season advances, but if the observation has merit it could mean that the
best way to maintain optimum pasture utilization would be to stock pastures
with cattle from patrons who reside on all sides of the community pasture.
Some community pastures join boundaries and patrons all lying in one direction
may be forced to deliver to the same pasture. If the "drift" phenomena
holds true this policy may need revision if the community pasture wants
to optimize forage utilization and avoid clustering of cattle at specific
"ends" of the pasture.
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