Final report for OW18-013
Project Information
Increasing evidence suggests that climate change is increasing the likelihood of co-occurring periods of
precipitation deficit and warm temperatures over the next century. Maintaining ecosystem function and
agricultural productivity on rangelands during increasingly intense and frequent periods of drought
presents scientific, economic, and social challenges. Rangeland livestock producers are often the first to
feel the impacts of drought; these impacts can be especially pronounced on California’s annual
rangelands (where the majority of precipitation and forage growth occurs in fall, winter and spring).
Structured interviews of ranchers conducted prior to and following the conclusion of California’s 2012-
2015 drought have highlighted the proactive and reactive strategies employed by ranchers to mitigate
drought effects. While early weaning is a strategy used by significant numbers of ranchers, very little
research has been conducted in annual rangeland systems to determine whether such a strategy is
beneficial economically or ecologically. The broad goal of this project is to quantify the costs and
benefits of early weaning as a drought management strategy for fall-calving cow-calf operations in
California. We will quantify the influence of early weaning on forage resources, evaluate influence on
cow and calf performance, and analyze the economic tradeoffs associated with early weaning compared
to traditional weaning strategies.
The overarching goal of this project is to work with fall-calving cow/calf ranchers to understand
the potential net economic and environmental benefits of early weaning as a drought
management strategy. Specific objectives include:
1. Quantify the influence of early weaning on cow and calf performance, pasture utilization, soil
protection, and plant biodiversity and examine how year-to-year variation in precipitation
influences early weaning effects.
2. Develop decision tools to help producers evaluate the economic and ecological tradeoffs
associated with early weaning compared with traditional weaning strategies using data
collected in objective #1.
3. Create and deliver a basic decision support guide that synthesizes the economic and ecological
tradeoffs with producer expert input to allow producers to determine how and when early
weaning may work as a drought adaptation practice for a particular enterprise.
Cooperators
- (Researcher)
- (Researcher)
- (Researcher)
- (Researcher)
- (Researcher)
- (Researcher)
- (Educator and Researcher)
Research
We are in the initial stages of this project. To date, we have held a producer steering committee meeting, developed a detailed project schedule, and collected initial body condition scores on the cows. This winter, we will read forage transects and plots, and wean the first calves (in early March). Normal weaning will occur in late May or early June.
2019 marked our first full year of data collection and experimental treatment:
- February 2019: Establish forage production monitoring sites. Assign cattle to early weaning and traditional weaning treatment groups.
- March 19, 2019: Wean calves in early weaning group. Collect individual weights on weaned calves. Collect body condition scores on all cows (early weaning and traditional).
- March 26, 2019: Cattle placed on paired treatment pastures (3 early weaning pastures and 3 traditional pastures).
- May 28-June 1, 2019: Forage samples collected at 15 sites in 6 pastures. Measurements included total forage production, forage harvested, species richness (grazed and ungrazed), percent bare ground (grazed and ungrazed), and percent invasive plants (grazed and ungrazed).
- May 30, 2019: Wean calves in traditional weaning group. Collect individual weights on early weaned and traditional weaned calves. Collect body condition scores on all cows.
- June 6, 2019: All cows placed back on paired treatment pastures.
- September 1, 2019: All cows removed from paired treatment pastures.
- October 1-2, 2019: Forage samples collected at 15 sites in 6 pastures. Measurements included residual dry matter (RDM) outside grazing exclosures to determine quantity of forage harvested. Exclosures reset for year 2 data collection.
- December 12, 2019: Body condition scores collected on all cows prior to breeding.
In 2020, we collected our second season of cattle production and forage production data.
- March 20, 2020: Weaned calves in early weaning treatment. Collected individual weights on weaned calves. Collected body condition scores on all cows (early wean and traditional wean).
- March 27, 2020: Following fence-weaning protocols, turned all cattle back onto paired treatment pastures.
- June 1-5, 2020: Forage samples collected at 15 sites in 6 pastures. Measurements included total forage production, forage harvested, species richness (grazed and ungrazed), percent bare ground (grazed and ungrazed), and percent invasive plants (grazed and ungrazed).
- June 5, 2020: Wean calves in traditional weaning group. Collect individual weights on early weaned and traditional weaned calves. Collect body condition scores on all cows.
- June 12, 2020: All cows placed back on paired treatment pastures.
- September 1, 2020: All cows removed from paired treatment pastures.
- October 7, 2020: Forage samples collected at 15 sites in 6 pastures. Measurements included residual dry matter (RDM) outside grazing exclosures to determine quantity of forage harvested.
Results
We collected data on the following parameters in 2019 and 2020:
- Calves: calf weights at early weaning (March 19, 2019 and March 20, 2020) and traditional weaning (May 30, 2019 and June 5, 2020).
- Cows: body condition scores (which correlates to subsequent conception rates) at breeding (Dec 2018), early weaning, traditional weaning, and rebreeding (Dec 2019)
- Forage: total forage production (May 2019 and 2020), forage harvested (May 2019 and 2020; October 2019 and 2020), species richness (May 2019 and 2020), percent bare ground and invasives (May 2019 and 2020). Invasives included yellow starthistle, medusahead, and Italian thistle.
Calf Weights
|
|
2019 |
2020 |
||||
|
Treatment/Class |
n |
3/19 Wt |
5/30 Wt |
n |
3/20 Wt |
6/5 Wt |
|
Early Wean – Steers |
21 |
403 |
529 |
26 |
372 |
474 |
|
Early Wean – Heifers |
21 |
388 |
500 |
16 |
381 |
484 |
|
|
|
|
|
|
|
|
|
Trad Wean – Steers |
23 |
|
623 |
23 |
|
597 |
|
Trad Wean – Heifers |
19 |
|
596 |
19 |
|
569 |
Cow Body Condition Scores
|
|
2019 |
2020 |
||||||
|
Treatment/Class |
n |
Dec 2018 |
3/19/19 |
5/30/19 |
n |
Dec 2019 |
3/20/20 |
6/5/20 |
|
Early Wean Cows |
42 |
5.0 |
5.1 |
6.4 |
42 |
4.9 |
4.8 |
6.3 |
|
Trad Wean Cows |
42 |
5.0 |
5.0 |
6.2 |
42 |
5.1 |
4.7 |
5.6 |
Forage Production
|
|
|
Total Production |
% Harvested |
Forage Remaining (Jun 1) |
|
Early Weaning |
2019 |
2373 lbs/ac |
38% |
1470 lbs/ac |
|
2020 |
2724 lbs/ac |
47% |
1455 lbs/ac |
|
|
Traditional Weaning |
2019 |
2224 lbs/ac |
51% |
1101 lbs/ac |
|
2020 |
2510 lbs/ac |
42% |
1461 lbs/ac |
Discussion
Precipitation and forage production were slightly above the long-term average for 2018-2019. Even so, we measured differences in forage removal at the end of the growing season and (more importantly) at the beginning of autumn. Cattle producers on California's annual rangelands typically focus on conserving enough dry forage at the beginning of autumn to carry their grazing operations through until fall germination and the resumption of grass growth. Autumn 2019 presented a key point of analysis; SFREC did not receive germinating rain until late November (making fall dry forage reserves critical).
As expected, the early weaned calves were significantly lighter than the traditional weaned calves. In addition, early weaned calves did not gain as rapidly post-weaning as their non-weaned contemporaries. Cattle managers also noted that the early weaned calves (which were placed on irrigated pasture in April and May) had a much higher incidence of pink eye than the traditional weaned calves (which were grazed with their mothers on annual rangeland during this period). This is an unexpected result and merits further study in year 2.
Finally, as expected, early weaned cows recovered body condition score more rapidly than the traditional weaned cows. This could have bearing on conception rates in years following drought conditions.
While SFREC did not experience drought conditions in year 1 of this project, several foothill ranchers have contacted the project team to let us know that they did wean early due to loss of fall forage to wildfire. This suggests that there may be additional value to a better understanding of this strategy.
Our 2020 calf performance and body condition scores were similar to 2019. In addition, we found that early weaned calves continued to show a higher incidence of pinkeye, which may be related to both the stress of early weaning and the forage conditions where they were grazed post weaning.
Forage monitoring results, however, did not follow the pattern suggested in 2019 (less utilization by early weaned cows resulting in greater forage conservation). The timing and quantity of precipitation, as well winter and springtime air and soil temperature regimes, likely resulted in confounding forage production data (for this project as well as for the SFREC facility in general). Fall germination did not occur until November. Following above average rainfall in December 2019, January 2020 was below average, and February 2020 was among the driest on record. Average to above-average late spring precipitation may have resulted in regrowth of grazed forages while coming too late to benefit forage in grazing exclosures. These results likely confirm the significant differences between annual rangeland forage productivity in California's Mediterranean climate and perennial rangeland forage productivity in other regions of North America.
As drought conditions returned to Northern California in late 2020 and through 2021, we used the information generated by this project to develop several tools for ranchers to use in evaluating ranch-specific drought strategies. We created the Drought Decision Support Tool for Ranchers, which provides a planning template and financial analysis tools to help ranchers evaluate proactive and reactive drought strategies. We also created a bulletin outlining the finding of our early weaning research and providing practical information to help ranchers in California's annual rangeland systems determine whether early weaning is an appropriate drought management strategy.
Research Outcomes
Education and Outreach
Due to COVID-19 restrictions on in-person field days and workshops in 2020, we presented drought management information as part of the UC Rangelands Lab's Working Rangelands Wednesdays webinar series: https://www.youtube.com/channel/UCQnxWe9UGmy_-aHg06YZZkw
Participation Summary:
Our initial outreach efforts have included a producer steering committee meeting in October 2018 and a data collection session (body condition scores) in December 2018. The steering committee meeting resulted in a detailed project schedule that represents real-world management conditions for foothill cattle producers.
We presented preliminary results at two field days held at the UC Sierra Foothill Research and Extension Center in 2019.
- Ranching in a Drying Climate: this field day focused on a variety of research into forage productivity and ranch management strategies. Participants included ranchers, extension professionals, university researchers, and agency staff.
- UC Davis Beef Day: this field day focused on a variety of cattle health and management topics. Participants included ranchers, extension professionals, university researchers, and agency staff.
Presentations are attached.
2019_May15_RanchinginDryingClimate
2019_Sep24_EarlyWeaning_BeefDay
In 2020, due to COVID-19 restrictions, we utilized a series of bi-weekly webinars focused on drought management to provide information to producers and agricultural professionals. These presentations can be viewed at https://www.youtube.com/channel/UCQnxWe9UGmy_-aHg06YZZkw.
In 2021, we presented information from this project virtually and at in-person workshops, including:
- Drought Programs for Ranchers Webinar (May 2021)
- Sierra Valley Rancher Drought Workshop (June 2021)
- Indian Valley Rancher Drought Workshop (June 2021)
- Rio Vista Rancher Risk Management Workshop (June 2021)
Education and Outreach Outcomes
Conducting research into ranch drought strategies like early weaning is complicated by the fact that we can't predict drought. In our case, our two years of data collection coincided with relatively normal precipitation and forage production conditions. While we were able to note some significant differences in calf weights and values, as well as body condition scores, we did not find significant value from early weaning in terms of forage conservation (due to growing conditions in our data collection years). Drought research, by its nature, is somewhat opportunistic. Future research into early weaning of fall calves in annual rangeland systems should occur during actual drought conditions.
Another unexpected (if anecdotal) finding from our project was that many of the early weaned calves developed pinkeye post weaning. This was likely due to post weaning forage resources and management, but it may also suggest that early weaned calves may have some stress-induced immunity problems. Following the performance of early weaned calves in annual rangeland systems, and designing a post-weaning nutrition and vaccination program specific to early weaned calves, may be helpful.