Early Weaning of Beef Calves: A Drought Management Strategy on Annual Rangelands

Progress report for OW18-013

Project Type: Professional + Producer
Funds awarded in 2018: $41,184.00
Projected End Date: 03/31/2022
Grant Recipient: University of California Extension
Region: Western
State: California
Principal Investigator:
Dan Macon
University of California Cooperative Extension
Expand All

Project Information

Abstract:

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.

Project Objectives:

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

Click linked name(s) to expand/collapse or show everyone's info
  • Dr. Jeremy James (Researcher)
  • Jeff Stackhouse (Researcher)
  • Josh Davy (Researcher)
  • Devii Rao (Researcher)
  • Dr. Tina Saitone (Researcher)
  • Dr. James Oltjen (Researcher)
  • Patricia Beard
  • Sue Hoek
  • Joe Fischer
  • Greg Lawley
  • Tim Reid

Research

Materials and methods:

 

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.
Research results and discussion:

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. 

Participation Summary
5 Farmers participating in research

Educational & Outreach Activities

2 Published press articles, newsletters
4 Webinars / talks / presentations
2 Workshop field days
2 Other educational activities: We held a rancher steering committee meeting and a data collection (body condition scoring) session.

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:

478 Farmers
280 Ag professionals participated
Education/outreach description:

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.

 

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.