Calving Systems in Ontario
The cow-calf industry is characterized by a unique combination of variation and tradition. Wide variety is found in the breeds, people and scale of operations involved. Tradition is firmly rooted in the evolution of the Ontario beef cow enterprise from the olde tyme mixed-farm, where a few dual purpose cows in the barn provided milk and meat. So its little wonder that the sector features diversity and innovation in the organization of calving and production systems. But are the innovators any better off than those using tried and true methods? That was the major theme of a recent industry study conducted in Ontario. It yielded some intriguing results �
The study was inspired by systems research conducted with the beef herd at the New Liskeard Research Station (Kemptville College, University of Guelph), in Northern Ontario. That experiment compared winter barn calving with pasture calving in summer. As previously reported in Cattlemen, the pasture group had a lower calving assistance rate and a lower rate of calf treatment, but a similar weaning rate, compared with the barn group. And these benefits, combined with lower costs for bedding and capital facilities made pasture calving look pretty attractive.
Research station trials are interesting, but what about the real world ? We wanted to find out what kinds of results producers were getting with innovative calving systems, and how they stacked up against conventionalists. To get these answers, we created a 4-page checkbox questionnaire and mailed it out to 122 Ontario beef cow calf operators. OMAF extension staff and industry contacts were instrumental in providing a list of candidate farms. Target group criteria included good record keeping skills and an expectation of willingness to cooperate in the study. And we also wanted to strike a balance between traditionally managed and innovative operations. In Ontario, tradition means late winter/early spring calving in a barn or small yard. We asked our contacts for leads for folks who calved at other times of the year, or in wide open spaces.
Responses were obtained from 62 herds, representing over 5,000 cows. We categorized them as either Confinement or Extensive calving, based on the major calving location. [Confined herds used a barn or small yard; Extensive used a large outdoor areas like a pasture or bush lot]. These two groups were similar for number of herds, number of cows per herd, operator experience, and geographic location, giving a solid foundation for statistical comparison.
We were surprised by the distribution of the calving systems by season (see Figure 1). Our expectation was that almost all of the Extensive calving herds would be calving during summer, with most Confinement (barn/yard) herds calving during winter months. In fact, although Extensive herds tended to calve later in the year, there was a large degree of seasonal overlap. Spring (Mar/Apr) was the peak season for both management categories. So our initial basis for comparison was between management groups, not seasons.
Figure 1. Distribution of Herds by Major Season of Calving
Pregnancy rates were similar for both Confinement and Extensive groups (see Table 1). However, when it came to calving time, the assist rate with mature cows was over 3 times greater for those in Confinement systems. This could be due to an increased need for assistance in confined situations, but more likely is related to the increased opportunity to observe labour and get in there to "help". Backing up this viewpoint is the high survival rate of newborn calves in both systems. Although Extensive cows received much less human intervention, they were just as successful at delivering and mothering up their calves.
With heifers, assist rates were high (25% range) but similar between groups. Based on this and comments submitted by respondents, first calvers are viewed as a high risk group, and garner extra attention, even from herd managers who are content to let the cows look after themselves.
Calf survival from 24 hours to weaning was also similar between management groups, along with weaning rate per cow calving. So cows enjoying the wide open spaces were just as capable of raising their progeny to weaning as those who had the benefit of barns and yards around calving time.
Time commitment during the calving season tends to be a limiting factor controlling herd size, especially with cold weather confinement systems. On many of these farms, calving season is a mix of apprehension, stress and sleep deprivation. And with good reason � you need to make sure cows aren't calving into a snow bank, save chilled calves and help out when cows are in calving distress. One more check at 2:00 a.m. won't hurt. You need live calves.
Although the cows were spread over much larger areas in Extensive systems, managers spent less time per cow on routine herd checks than in Confinement systems. The net result was that only one half the amount of time per cow was expended in Extensive systems, compared with the stay at home cows, but calf survival was not impacted. Time commitment probably contributed to the differences observed when managers were asked to estimate the maximum number of cows which they could manage during calving season. On average, Extensive herd managers estimated a maximum of 144 cows per full time person, 50% more than for Confined herds.
Several measures of calf performance and herd productivity were considered. There were no differences between any measures, including weaning weight, sale weight and lbs weaned per cow calving. So in terms of animal productivity, it was a wash.
Further analysis was done to calculate the impact of specific factors on key outcomes like calving rate, assisted birth rate, calf mortality, and treatment rate for disease. In essence, the statistical procedures pooled all of the herds, stirred them, and let the significant factors float to the top (see Table 2). Contrary to our expectations, the effect of season of calving was minimal; it was how the cows were managed that counted. One of the results of interest is the effect of herd size. For each 10 cow increase, calving rate decreased by 0.1%. This indicates that as herd size increased over the range in this study (20 - 300 hd) fewer calves were delivered from the cows retained for calving, but the degree of effect was fairly small.
The data collected included the location of the herd during precalving, calving, and postcalving periods, and whether special birthing pens or yards were used. Location of the herd during the precalving and calving periods was found to have a dramatic impact on calving assistance and calf health and survival. Calves from dams which spent the precalving period in a barn or yard had a neonatal mortality rate 8 times that of those which spent this period in a field or bush. This effect may be due in part to a lack of exercise in confined cows during gestation, resulting in poor muscle tone and lack of endurance at calving. Another factor may be manure buildup on confined cows, which would tend to introduce more infectious organisms to newborns during initial suckling, compared with cows which spent the precalving period in large areas. This theory is supported by the impact of location on calf treatment rate � calves from a barn/yard calving location had a treatment rate which was 5 times higher than those from the great outdoors.
One puzzling finding was that moving calves to a separate field or bush for the postcalving period was associated with a higher calf treatment rate than those which remained in the calving season location, or returned to the precalving area. Reasons for these results are not apparent but may be related to a management strategy such as mass treatment in herds which had a previous history of calfhood disease, or simply additional stress on newborns due to moving to a new location.
When the combinations of precalving and calving locations were considered, calving assist rate with heifers stood out. Heifers which remained in a confined location for calving, and those which were brought into confinement from pasture, had an assist rate 4 times that of heifers which spent these periods out on pasture. There was no indication that the lower assist rate with pasture heifers had any negative effect. In addition, the worst combination of locations in terms of overall calf survival was to keep cows in confinement and calve them in special birthing pens or yards. These calves suffered a birth to weaning death loss 4 times that of herds which spent both precalving and calving periods in extensive situations. An overall assessment of these results points to unintended negative impacts on calf health and calving ease associated with increased human intervention and relative confinement of animals during the precalving and calving periods.
What did we learn? There are a number of very different calving strategies in use in Ontario. In general, the use of large outdoor areas such as pastures and bush lots as precalving and calving locations were clearly associated with benefits, including reduced calving assistance, lower calf treatment rates, and lower calf mortality. And these benefits were achieved within systems which required less operator time for calving checks, and without negative impacts on calf weaning weights or herd productivity. Innovative producers showed that research results had application in the field, and reported many of the advantages predicted by the research station experiment.
Bottom line: Ontario beef cows can do quite well with limited human intervention and housing. In general, they know how to give birth and how to raise their calf. Much of what we think of as "help" may actually be a hindrance ! Producers wanting to expand herds to multiples of 100 cows, with minimal increase in capital facilities and calving time stress should consider "free range" methods. Happy calving!
Acknowledgements: Thanks to our extension and industry contacts, and to all the producers who shared their records, making the project possible. The study was a collaborative effort by OMAF's Tom Hamilton, Barry Potter and Nancy Noecker. Summer intern Jeremias Cull compiled results and liased with producers. Thanks to Dr. Steve Miller, University of Guelph, for valuable comments on the technical paper this article is based on.
|Cow Pregnancy Rate (%)||95.4||91.4||Ns|
|Heifer Pregnancy Rate (%)||94.2||93.6||Ns|
|Liveborn rate 1 (%)||97.3||93.5||Ns|
|Cow Assisted Birth Rate (%)||12.9||3.8||p <.05|
|Heifer Assisted Birth Rate (%)||29||24||Ns|
|Calf 24hr Survival Rate 2 (%)||98.9||99.1||Ns|
|Calf Survival, 24hr to Weaning 3 (%)||98.0||97.9||Ns|
|Calf 200 day wt 4 (lbs)||615||609||Ns|
|Cow Productivity 5 (lbs)||598||590||Ns|
1 # calves born alive / # calves delivered X 100
2 # calves alive at 24 hrs / # calves born alive X 100
3 # calves weaned / # calves alive at 24 hrs X 100
4 adjusted to 200 days of age, male calf, mature dam equivalent
5 200 day wt per cow calving
|Calving Rate||Herd Size||0.1% for each 10 cow increase in herd size|
|Cow Assisted Birth Rate||Birthing Location||Separate birthing yards or pens gave 5X the assist rate of pasture birth location|
|Heifer Assisted Birth Rate||Sequence of Precalving Calving Location||Barn/yard Barn/yard and Pasture Barn/yard gave 4X higher assist rate than Pasture Pasture|
|Neonatal Calf Mortality||Precalving Location||Barn\Yard gave 8X in mortality relative to Field,Bush,Pasture|
|Weaning Rate||Sequence of Precalving – Calving Location||Barn or Barn/yard Same Area gave WR relative to others|
|Death Loss, Birth to Weaning||Calving Location||Confinement with separate yards gave 4X death loss relative to Extensive with pasture/bush precalving calving areas|
|Calf Treatment Rate||Calving Location||Barn/yard Calving Area gave 5X higher treatment rate than other locations (Pasture, Field, Bush)|
|Postcalving Location||Separate Field or Bush gave treatment rate 2-3 X higher than those remaining in calving location or returned to precalving area|
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