Does Pasture Calving Make Sense?

The most stressful time of year for most cow-calf producers is calving season. You've invested a lot into those cows - hay, pasture, minerals, and a bull to breed them, just to mention a few items. And the cow only gets one opportunity per year to pay you back. It all rides on gettinga live, vigorous calves that will grow steadily to weaning without problems. If you're calving in winter or early spring, cold weather can be a challenge for both calves and people! Calving problems are a concern, and once the calf is up and nursing, the risk of a scours outbreak is always in the back of your mind. These worries lead to multiple barn checks day and night, and as calving season wears on, you and your family are getting worn out.

For small herds, confinement calving in a barn is a viable option. Of course, you have to keep up with the bedding and be on top of any sickness that flares up. Night checks are a tiring chore, but with small numbers, it's not too bad. But if you want to expand up to 80-100 cows or more, the combination of building costs, calving time labour and increasing risk of disease outbreak is daunting. Is there a practical way to manage large numbers of cows while reducing the amount of calving time labour, stress and risk per cow?

Ongoing work at the New Liskeard Agricultural Research Station1 (NLARS) has compared traditional barn calving in late winter with pasture calving in early summer. A recent review of this data included records from 1998 - 2012, including 1,172 winter born calves and 1,146 summer born calves. These results, collected over the past 15 years gives great insight into what producers can expect if they switch from barn calving to pasture calving.

The original New Liskeard beef herd was split into two management groups. The Winter calving group was bred starting in May, and calved in Feb-Mar. The pregnant cows wintered in an open front barn, with near-term cows brought into enclosed, non-heated calving pens. After a newborn calf was successfully mothered up by the cow, the pair was returned to the open front barn. These cow-calf pairs went to pasture after green up in May.

The Summer calving group was bred starting in September. Cows went to pasture in May, and calved on grass in June-July. If a cow required assistance at calving, it was either helped on pasture or brought back to the barn for more serious intervention. After pasture season, the cow-calf pairs were moved to open barns, with weaning occurring in January.

Calving Outcomes

Getting live calves and healthy cows is the goal of any calving system. In order to ensure this is achieved, it is common for producers to check on cows around the clock and intervene quickly if they think a cow is having trouble giving birth. But what happens when the cows are calving out on pasture, away from our intense surveillance?

It turned out that the pasture calving cows received far less assistance than their barn calving herdmates (Fig. 1). Only 1.8% of mature cows calving on pasture received assistance, compared with 4.6% of barn calving cows (Table 1). So the assist rate for barn calving cows was 2.5 times greater than that of pasture cows. First calving heifers showed a similar pattern, with only 5.9% of pasture calving heifers receiving assistance, while 15.5% of barn calvers were assisted. This gave an assist rate for barn calving heifers which was 2.6 times greater their pasture counterparts.

Graph indicating rate of calving assistance

Text equivalent of Diagram

Pasture calvers received much less assistance when giving birth, but did this compromise calf survival? The answer is no … the survival rate of pasture born calves was the same as that of barn born calves, about 95% from birth to weaning. So providing much less assistance did not compromise the weaning rate of pasture born calves. There are several potential reasons for this. It could be that the barn calvers got unneeded help, just because they were close at hand. Another reason could be that the pasture cows were less stressed when calving, since they were not confined and were under much less intense human observation. This may have allowed them to more fully express their innate calving ability. Another potential factor is birth weight, as pasture born calves averaged about 2 lbs lighter at birth.

Calf Health

Calf health records were available from 2005-2012. They were summarized to give both the number of separate disease occurrences and the total number of treatments administered (Table 1). For example, a calf identified as having scours and treated on 4 consecutive days would be classed as having 1 disease occurrence and 4 total treatments. It the same calf was later treated for respiratory problems and given a course of treatments over 3 days, it would be classed as having 2 disease occurrences and 7 total treatments.

The results showed that Winter born calves had a disease occurrence which was 3 times greater than that of Summer born calves (Fig.2). As well, the treatment rate for Winter calves was 2.25 times greater than that for Summer calves. A likely reason for the improved health status of pasture calves is the environment they were born into. In barn calving, the overall density of animals and repeated use of calving pens can lead to the build-up of disease causing microbes, in spite of diligent clean up and lots of bedding. This can get to the level where the calf's defenses are overwhelmed. In contrast, the pasture environment is likely to have much less contamination since the animals would be entering a relatively clean environment in spring, and have much more area per head than those in confinement.

Graph indicating calf health outcomes

Text equivalent of Diagram

Calf Performance

Calves were weighed at around 200 days of age, and adjusted weaning weights (AWW) were calculated by BIO2. Winter born calves were slightly heavier, with an average AWW of 646 lbs., compared with the Summer born calves at 633 lbs., a 13 lb. advantage for the Winter group.

Summary

Compared with cows calving in a barn in Winter, pasture calving cows in Summer had a much lower rate of calving assistance. Despite significantly less intervention at calving, the pasture born calves had an equally high rate of survival from birth to weaning. As well, the pasture born calves also showed a much improved health status. Barn born calves had a rate of disease occurrence which was 300% greater and a treatment rate that was 225% greater than those born on pasture.

In this long term study, Summer pasture calving showed significant benefits over Winter barn calving in terms of ease of calving and health status of calves. These advantages should be associated with lower labour costs and less stress on workers at calving time, as well as reduced facilities costs since calving barns and pens would not be necessary. Pasture calving may be a viable alternative system for traditional cow-calf operations wanting to increase cow numbers while reducing calving time labour per cow and reducing facilities costs per cow, or for the start-up of new large scale beef cow herds.

Table 1. Calving System Comparison

 
Calving Season
Statistical Significance*
Winter
Summer
Assisted Births
- Heifers (%)
15.5
5.9
***
Assisted Births
- Cows (%)
4.6
1.8
**
Calf Survival, Birth to Weaning (%)
95.4
94.9
NS
Disease Occurrence
(# per 100 calves born)
46.7
15.5
***
Total Treatments
(# per 100 calves born)
83.0
37.0
***

*Explanation: NS = non significant ; ** = p<.01; *** = p<.001

1part of Kemptville College, University of Guelph

2Beef Improvement Opportunities, Guelph. Adjusted to 200 days of age, for age of dam, sex of calf and for twins.

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