Silvopasture for Poultry Production with Outdoor Access: Impact on animal welfare, economic, and environmental parameters

Progress report for LS20-332

Project Type: Research and Education
Funds awarded in 2020: $279,078.00
Projected End Date: 03/31/2023
Grant Recipient: Virginia Tech
Region: Southern
State: Virginia
Principal Investigator:
Dr. Leonie Jacobs
Virginia Polytechnic Institute and State University (Virginia Tech)
Co-Investigators:
John Fike
school of Plant and Environmental Sciences, Va Tech
Dr. John Munsell, PhD
Virginia Tech - Department of Forest Resources and Environmental
Gabriel Pent
Dept. of Crop and Soil Environmental Science, Virginia Tech
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Project Information

Abstract:

A silvopasture system involves intentionally integrating trees, shrubs and livestock on the same land. To date, these systems have largely been designed for ruminant livestock, such as cattle. However, novel silvopastures are being developed for poultry because these systems have potential to provide high quality habitat and feed sources that may improve bird health and welfare. The purpose of this project is to develop and assess sustainable poultry-based silvopastures. The research team combines expertise in broiler welfare (PI) and silvopasture production (co-PIs), plus large and small-scale poultry farmers as collaborators. Applying a systems-approach, we will assess animal welfare, economic, and environmental outcomes when integrating poultry production with novel silvopastures.

To meet certification requirements, organic chicken producers have to provide outdoor access. These ranges are grass pastures, yet chickens prefer overhead cover and shelter in their outdoor range. This habitat preference may be realized through the implementation of silvopastures. Using a novel silvopasture system could increase land-productivity through additional income from vegetation and reduced feed costs. Chickens may benefit from natural cover and increased range use, which is often limited. In turn it can lead to improved leg and feet health, diet diversity, and improved meat quality. Silvopastures would also improve animal comfort as the vegetation moderates understory microclimate. Environmental benefits could include improved soil quality, air quality, and biodiversity, which in turn can improve societal acceptance of poultry production. Although silvopasture systems offer many potential benefits, they have received little study in a poultry context, and even less extension and outreach effort. The project will contribute knowledge for family farm poultry systems, both on a large and small-scale, to provide information on how to improve profitability and stability.

 

Project Objectives:

This proposal is directed to poultry-centered silvopasture production systems. With this project, we aim to move existing organic poultry production systems toward more sustainable agriculture, in which animal welfare, economics, and the environment are balanced, and we want to strengthen awareness of existing silvopasture-based poultry production systems by collecting case studies that provide success stories and resources on how to overcome challenges. We will assess animal welfare, economic, and environmental parameters of combining silvopasture with poultry production by fulfilling three objectives:

Year 1:

  1. Experimental trial: Compare broiler chicken production with access to existing silvopastures to broiler production with access to grass pasture, at the VT Shenandoah Valley AREC, focusing on:
    • Animal welfare: behavior, fear, leg and feet health
    • Economics: animal yield and theoretical land yield
    • Environment: biodiversity and soil parameters

Year 1-3:

  1. Field trial:
    • (A) Compare broiler chicken production with access to a newly planted silvopasture on a large-scale commercial USDA Organic farm to grass pasture access on the same farm
    • (B) Compare broiler chicken production with access to established silvopastures on two small-scale commercial farms to grass pasture access on the same farms, focusing on:
      • Animal welfare: behavior, fear, leg and feet health
      • Economics: animal yield and theoretical land yield
      • Environment: biodiversity and soil parameters
  1. Increase adoption of poultry-based silvopasture practices by:
    • (A) Surveying silvopasture- and traditional-system poultry producers about their experiences, concerns and opportunities for applying these practices
    • (B) Creating and disseminating case studies from above-mentioned and other established silvopasture producers through extension
    • (C) Showcasing poultry silvopastures through research center and on-farm field days and web-based delivery tools
    • (D) Disseminating technical and budget information to producer and agency communities.

For objective 1 and 2, the same measures will be collected at four different sites: (1) the Virginia Tech Shenandoah Valley AREC, (2) a USDA Organic large-scale farm where we will plant a new silvopasture, (3 and 4) two small-scale broiler farms with established silvopastures. At all sites, we aim to compare measures in flocks with and without access to silvopastures (meaning grass range versus silvopasture range). Objective 3 is aimed at educating industry stakeholders and promoting the system’s benefits.

Cooperators

Click linked name(s) to expand/collapse or show everyone's info
  • Wil Crombie - Producer
  • Adam Downing - Technical Advisor (Educator and Researcher)
  • Casondra Fields - Technical Advisor
  • Reginaldo (Regi) Haslett-Marroquin - Technical Advisor
  • Pam Miller - Technical Advisor - Producer
  • Brent Wills - Technical Advisor - Producer

Research

Materials and methods:

Our combined ‘research and extension approach’ includes a controlled experimental design (objective 1) comparing silvopasture access to grass pasture access for small flocks of broilers, executed at the Shenandoah Valley Agricultural Research and Extension Center (AREC). For objective 2, we will perform a field trial with a similar approach as objective 1, but applied at commercial farms. On each of the site (with possible exception of Wil Crombie’s farm), we will have a silvopasture-flock and a grass pasture-flock serving as a control to compare specific parameters related to welfare, economics and environment.

At the end of this study, an extension report will illustrate all these potential benefits and will contain photos and input from new and experienced silvopasture/broiler chicken producers than can serve as an educational document for industry stakeholders. Two field days will provide additional information on feasibility of the integrated system for interested parties and educate industry stakeholders on the system possibilities (objective 3).

Year 1 Objective 1 - Experimental trial: Compare broiler chicken production with access to existing silvopastures to broiler production with access to grass pasture, at the VT Shenandoah Valley AREC

Two experiments were conducted from April to May (Experiment 1; Exp 1) and June to August 2021 (Experiment 2; Exp 2). All procedures were approved by the Virginia Tech Institutional Animal Care and Use Committee (IACUC protocol 20-044).

Animals and housing 

In total, 886-day-old Ross 708 mixed-sex chicks in Exp 1 and 648 chicks in Exp 2 were obtained from a commercial hatchery (Harrisonburg, VA, USA). Birds were Marek’s vaccinated at the hatchery. Upon arrival, chicks were arbitrarily selected and housed in 12 identical pens (5.7 m2) with 73 or 74 birds per pen in Exp 1 and 53 or 54 birds per pen in Exp 2. Pens contained pine wood shavings (~5 cm depth), a heat lamp (day 1-8), a cardboard feed flat with feed (day 1-8), one bell drinkers (Plasson® Broiler Drinker complete, Or-Akiva, Israel), and one pet champion poultry drinker (Stout Stuff LLC, made in china), and one feeder (Superbowl poultry feeder, LaGrange, NC, USA). The chicks were fed commercial starter (day 0-15), grower (day 15-25), and finisher (day 25-42 or 43) diets meeting NCC recommendations (National Chicken Council 2017). Ambient temperatures were 35°C on day 1 and gradually reduced to 23°C on day 22 (Exp 1) or day 23 (Exp 2). Lighting was provided continuously for the first week and reduced to 12h light and 12h dark until day 22 (Exp 1) or day 23 (Exp 2).

In Exp 1, birds from each pen were equally but randomly allocated over 16 pasture-based treatments resulting in 53 birds per plot originating from all 12 pens. In Exp 2, complete pens (53-54 birds) were randomly allocated to 12 pasture-based plots with chicken coops. On day 22 (Exp 1) or day 23 (Exp 2), birds were transported for 1.5h to the pasture-based experimental site located at the Shenandoah Valley Agricultural Research and Extension Center (AREC) in Raphine, VA, USA. After transportation, birds were kept inside the coops for two days in Exp 1 and one day in Exp 2 to get acclimated to their new housing conditions. From days 24-41 or 42, coop doors in each plot were opened at approximately 8:00 am and closed at approximately 5:00 pm.

All pasture-based plots (125m2, 16 in Exp 1, and 12 in Exp 2) contained a chicken coop  (6.55m2) constructed from wood, chicken wire, and tarp . The coops contained a wooded platform perch (0.05m x 0.1 m x 2.4 m) and the same feeder and bell drinker as when housed indoors. Coops were moved laterally across the plot each week. Plots were fenced with 1m-high and 50-meter-long FlexNet electric fences (PoultryNet®, Washington, IA, USA), connected to a 30-volt electric cattle fence.

Treatments

The silvopasture plots (8 replicates in two locations in Exp 1 and 6 replicates in two locations in Exp 2; Figure 1) contained a 10-12-year-old mixed hardwood stand of black walnut (Juglans nigrea L.) and hickory (Carya spp. Nutt.) trees and 30 newly planted saplings per plot (American hazelnut (Corylus americana), black walnut (Juglans nigra), persimmon (Diospyros virginiana L.), southern red oak (Quercus falcata Michx.), and southern pine (Pinus spp.) of approximately 30 cm height and 1 cm calipers. Saplings were planted in six rows with inter and intra-row spacing of 1.5 m. Canopy cover in all silvopasture and open pasture plots were calculated from photos using ImageJ software (1.5.3k, National Institute of Health, USA). The images were taken at ground-level in the center of the plot straight upwards. Photos were converted to 8-bit, binarized, and then the number of black (canopy) and white (sky) pixels were calculated as a percentage of total pixels. The canopy cover for silvopasture plots was (mean ± standard deviation) 31.7 ± 16.7% in Exp 1, and 33.3 ± 10.9% in Exp 2.

The open pasture plots (8 replicates in two locations in Exp 1 and 6 replicates in two locations in Exp 2; Figure 1) contained ground vegetation. Ground vegetation in the open pasture and silvopasture plots were similar and consisted of tall fescue (Festuca arundinacea Schreb.), orchardgrass (Dactylis glomerata L.), honeysuckle (Lonicera japonica Thunb.), greenbrier (Smilax spp. L.), Virginia creepers (Parthenocissus quinquefolia L. Planch.), horsenettle (Solanum carolinese L.), common milkweed (Asclepias syriaca L.), and thistle (Sonchus spp. L.). Canopy cover in open pasture plots was 0 ± 0% in Exp 1 and Exp 2.

Aerial view showing 8 silvopasture plots and 8 grass pasture plots

Experimental setup for objective 1 at the VT AREC. The orange rectangles indicate 8 silvopasture plots that will hold 50 broilers each. The maroon rectangles indicate the 8 grass plots that will hold 50 birds each.

Data will be collected, focusing on aspects of animal welfare, economics and environment.

Animal welfare. Range use may benefit leg health, footpad health and fearfulness. For all sixteen 50-bird flocks, range use will be assessed via two approaches; cameras (e.g. Bushnell Trophy Cam) and live observations. One photograph per hour will be taken within the chicken coop and used to calculate the percentage of birds outdoors each hour. Hourly live observations will be performed at plot level to count birds in the range between 8 AM and 5 PM on days 29, 30, 34, 35, 40, and 41. The observer will sit down 5 m from the plot to prevent changes in the birds’ behavior. The percentage of birds near, middle, and far from the coop, and the total percentage of the flock in the range were calculated.

Assessment of how the management systems affect bird fearfulness will be determined with a Tonic Immobility test. The test consists of placing a chicken on its back in a U-shaped cradle and restraining it for 15 sec (Stadig et al. 2017). The chicken is then released and the time until righting (latency) is recorded, with longer durations of tonic immobility associated with greater fear. The test will be performed in week 5, after birds have had sufficient time to adopt to their respective environments, and 10 birds per coop will be assessed.

On the following day, leg condition will be assessed via a latency-to-lie test, in which birds are placed in a tote with a small amount of water. The time (latency) until the birds sit down will be recorded as an indicator of leg health or strength. In addition, footpad dermatitis and hock burns will be scored on a 0-4 categorical scale, with increasing scores indicative of worse lesions (Welfare Quality® Network 2009).

Economics. Economic productivity of the poultry system will be assessed by measuring animal growth (coop-level n = 50 per coop), feed conversion (coop-level, n = 8 per treatment) and whole-carcass yield (individual level n = 10 per coop). Feed intake will be recorded per group, starting from day 1 by weighing provided and left-over feed (difference = consumed feed). All birds will be weighed prior to processing on day 42 and carcass weights will be recorded thereafter for a sample of 10 birds per coop.

Environment. Temperature and humidity will be monitored in the range and within the coops using temperature-humidity sensors. We will assess soil quality on each plot twice to assess potential benefits from silvopasture/broiler production integration for the environment. Outdoor range soil quality will be assessed at three locations in each range (n = 16). To determine soil chemical properties, samples will be systematically collected at four distances from the coop (close, middle, end of range), resulting in 4 samples per flock per sampling time (baseline or post-experiment; total sample n(16*4*2)=128). At each location the surface litter will be removed and a sample collected with bucket soil augur. All samples will be homogenized separately by depth in a bucket onsite to obtain a single 50-g sample for each depth. Samples will be air dried and sieved with a 2-mm soil sieve. Soil sample analyses will be done to assess C and N, soil microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), C and N fractions, and phospholipid fatty acid content (PLFA). The latter is used as a biological indicator of overall soil quality (Quideau et al. 2016).

We propose to quantify insect diversity using a combination of direct observations, pitfall traps and sticky cards. Flowering plants will be observed directly to assess the quantity and diversity of pollinators, which will be grouped into the following categories: lepidoptera (butterflies), bumblebees, honeybees, other native bees, hoverflies, and wasps. Sticky cards will be used to assess flying insects, especially lady beetles. Pitfall traps will be used to assess ground beetles and orthoptera (especially crickets). We expect insect abundance and diversity to be greater in complex habitats with trees and native grasses than in conventional grass pastures.

JACOBS and GRAD STUDENT will be responsible for animal measures and soil collection with the technician, PENT will be responsible for silvopasture related measures, the environmental measures will be coordinated by JACOBS and soil samples will be analyzed through the South Dakota State University Soil Analysis Service Lab led by Dr. Sandeep Kumar (please see the letter of commitment for this contractual service here: Letter of Commitment SD STATE). 

Year 1-3 Objective 2A - Field trial: Compare broiler chicken production with access to a newly planted silvopasture on a large-scale commercial farm to grass pasture access on the same farm

Our cooperating large-scale VA-based poultry producer (SVO farmer Pam Miller) operates 3 commercial broiler chicken houses for approx. 90,000 birds. Each of the houses used in their system has pop holes along its length; these holes provide birds with access to grass pasture. On one of these three pastures we will establish a new silvopasture incorporating woody species and native grasses. Targeted woody species include Red Mulberry (Morus rubra), hazelnuts, pawpaw, and serviceberry. These species grow fairly rapidly and can provide shrubby cover and long-term feed resources. In addition to shrub cover, we will plant switchgrass (a native warm-season species) using sprigs (rather than seed) to generate rapid cover. Switchgrass is of interest given its potential to trap and reduce dust, to store carbon in deep root systems, and to serve as a source of bedding material or heating fuel for poultry operations.

The silvopasture system with trees, shrubs and grasses will be planted in rows parallel to the length of the house. The row-planting and space in between grasses, trees and shrubs (within rows) will allow for birds to move freely throughout the pasture. We will work with the landowners to design and install a mix of woody species and switchgrass based on their preference of vegetation and the physical layout of the space. The flocks with access to this newly established silvopasture plot will be compared to a control flock in one of the two adjacent houses.

For three production rounds spread over two years, we will collect data on animal welfare parameters (described for objective 1: fearfulness, leg health, footpad dermatitis and hock burns) in a sample of 80 birds per flock (two flocks per round) at week 5 of age. In addition, farmer and processing plant records will provide information on mortality, animal yield and carcass rejections. Litter moisture and soil quality data (6 samples per treatment (2), per round (3) = 72 soil samples total) will be assessed as described for objective 1.

 

Year 1-3 Objective 2B - Field trial: Compare broiler chicken production with access to established silvopastures on two small-scale commercial farms to grass pasture access on the same farms

 Similar to objective 2a, animal welfare, economic and environmental parameters will be assessed on two small-scale broiler operations (VA and MN). At these sites, producers already have integrated chicken production with silvopastures, or they have trees and shrubs as part of the outdoor range for broilers. The setup on the VA farm (small-scale producer Brent Wills) will be similar to the large-scale farm in that two flocks will be simultaneously grown, one with and one without access to shrubs and trees in their outdoor range (pasture versus silvopasture). All their birds have access to an outdoor range when temperatures allow. Broilers have full access to pasture and/or woods at all times once they come out of the brooder, usually at 2-3 weeks old, depending on time of year and weather. They grow a commercial hybrid breed (Freedom Rangers). All of their pastures border woods and fringe areas, so the birds have access to woods, trees and shrubby type vegetation, typically oak, hickory, maple, sourwood, pine thickets and the associated brambles and brushy vegetation. Their flock sizes depend on demand. Their pens allow for 80 birds per pen. They use Salatin-style pasture pens that offer 120 sf of “indoor” space per pen (10’x12’) as well as an A-frame pen with the same floor dimensions. For this study we will collect data during three rounds of production, with birds either with access to pasture (conventional outdoor range), or to vegetation (silvopasture).

On the MN farm (small-scale producer Wil Crombie), they grow birds according to the Regeneration Farms system/design for 5 years now. They have 40 acres and planted 20,000 hazelnut shrubs, around 5,000 elderberry bushes and a few thousand tree species, including oak, sugar maple, chestnut, basswood and Honey Locust. They currently have two active chicken barns. Their birds have outdoor access to grasses, Comfrey, Hazelnut and Sugar maple leaves and other naturally occurring plant species that are inside the paddocks. They also sprout grains within the paddocks. A single flock consists of 1,500 birds and is housed in a steel structure barn (18'x90'). The birds have outdoor access to circa 1.5 acres. At this point, we are not sure yet whether we can simultaneously assess birds with and without vegetation access as on the other farms and at the AREC.

For both farms, measurement include fearfulness, leg health, footpad dermatitis, hock burns on 80 birds per flock (n = 2 per farm, per round), assessed a week prior to processing. In addition, farmer and processing records will provide information on mortality and animal yield. Litter moisture and soil quality (6 samples per treatment (2), per round (3) = 72 soil samples total per farm) will be assessed as described for objective 1.

JACOBS and GRAD STUDENT will be responsible for animal measures, and collection of soil samples together with the technician, FIKE and MUNSELL will be responsible for silvopasture related measures. The environmental measures will be supervised by JACOBS and soil samples will be analyzed through the South Dakota State University Soil Analysis Service Lab lead by Dr. Sandeep Kumar.

 

Year 1-3 Objective 3: Increase adoption of poultry-based silvopasture practices

3A. Surveying silvopasture- and traditional-system poultry producers about their experiences, concerns and opportunities for applying these practices

Online search plus network search of southeastern US-based small and large scale silvopasture producers in combination with poultry. In addition, the director of the American Pastured Poultry Producers Association (APPPA) is willing to assist in the search for volunteers for the interviews among their members. We aim to perform at least six quantitative in-depth interviews in person, over the phone, or via email depending on geographical location and producer preference. Questions will relate to productivity, animal welfare, and environment. Additionally, we will ask about particular challenges and how they were overcome, including potential exposure to predators. We will collect photo material for the extension publication; a case-study report (b) (online and hard copies). Role of farmers: partake in interviews, allow or provide photos at/from farms. GRAD STUDENT will interview, perform farm visits, supervised by JACOBS.

3B. Creating and disseminating case studies from abovementioned and other established silvopasture producers through extension

Outcomes from interviews and farm visits will be structured and organized into an extension publication with photos and text. JACOBS will coordinate, GRAD STUDENT will write, collate, and disseminate (online and hard copies). MUNSELL, DOWNING, PENT and FIKE will advise on extension documents. Consultants and farmers will be involved with development and dissemination.

3C. Showcasing poultry silvopastures through research center and on-farm field days and web-based delivery tools

Two field days will be organized during which interested stakeholders are welcomed to visit at least one of the participating farms. The large-scale farmer already indicated willingness to assist with this field day and allow for visitors. The Shenandoah Valley AREC will be the location of a second field day for interested parties. These days will provide interested parties to see and experience a silvopasture approach and ask questions about this system. Some research outcomes will be presented to attendees for education purposes. Role of farmer: allow access to farm and talk about experiences. JACOBS will coordinate, FIKE and PENT will lead actual field days.

3D. Disseminating technical and budget information to producer and agency communities

Based on data collected for objective 1 and 2, we will be able to formulate some poultry-silvopasture system scenarios and calculate associated budgets for those scenarios. These will be disseminated as technical information with targeted audience being industry stakeholders. MUNSELL and DOWNING will coordinate silvopasture aspects of the technical and budget outcomes, JACOBS will coordinate animal-related aspects. Consultants and farmers will be involved with development and dissemination.

 

For objective 1 and 2, we will repeatedly assess the same measures at four different sites: (1) the Shenandoah Valley AREC, (2) a large-scale farm where we will plant a new silvopasture, (3) and (4) two small-scale broiler farms with established silvopastures. At all sites, we aim to compare measures in flocks with and without access to silvopastures (meaning grass range versus silvopasture range). This results in flocks as the experimental unit, with at (1) 16 flocks (8 with and 8 without silvopasture access), (2) 6 large-scale flocks (3 with and 3 without silvopasture access), (3) 6 small-scale flocks (3 with and 3 without silvopasture access), and (4) 3 small-scale flocks with silvopasture access. The commercial farms differ in farm size (small-scale versus large-scale), “age” of silvopasture system (newly established (year 0) versus well-established (~year 5)), and flock access to vegetation within a farm (flocks either have access to grass pasture or access to silvopasture). The first factor will illustrate the feasibility of integration vegetation production and broiler chicken production on a large scale compared to a smaller scale farm. The well-established silvopasture systems will be on small-scale farms, as the approach has not yet been used by large poultry producers. Our approach, in which we will plant a silvopasture system on a large farm, will provide insight regarding benefits associated with new silvopasture systems. The established systems (small-scale farms and the experimental trial from objective 1) will serve as “proof of concept” for a more commercial application, and will illustrate potential benefits on a longer term. Thus, the large-scale production system will illustrate the potential benefits on the short term, and the small-scale farms benefits on the long term.

Research results and discussion:

We have faced challenges due to the pandemic, that in part resulted in a delay in the research activities. A new challenge has arisen this year (winter/spring 2021-2022) with the spread of highly pathogenic avian influenza across the US.

Objective 1 - Experimental trial: Compare broiler chicken production with access to existing silvopastures to broiler production with access to grass pasture, at the VT Shenandoah Valley AREC: We managed to successfully complete two replicates (Experiment 1 and Experiment 2), rather than one, of the experimental trial with the support of the Young Scholar Enhancement Grant Award. Some of the sample and data analyses are ongoing.

Animal welfare

Range use: Based on live observations in Exp 2, more birds in silvopasture plots were using the outdoor range compared to birds in the open pasture plots (p = 0.004), with a mean of 15% of birds outside in silvopasture compared to 9% in open pasture. although generally numbers were low in both treatments, birds in silvopasture ranged further from the coop (p < 0.001) with more birds in the middle section of the plot compared to the open pasture birds (0.56% vs 0.10% of birds). Based on hourly photos taken from day 21 through day 41 of age in Exp 2, more birds in the silvopastures used the range compared to birds in the open pastures (p = 0.038). On average, 7.6% of silvopasture birds were observed outside the coop, compared to 6.2% of open pasture birds.

Fearfulness: Silvopasture birds showed shorter tonic immobility durations (79s vs 104s in Exp 1 and 59s vs 103s in Exp 2) than open pasture birds (p = 0.031 in Exp 1, and p < 0.001 in Exp 2). Shorter tonic immobility durations indicate less fear in the silvopasture treatment compared to the open pasture treatment.

Leg health: Silvopasture birds showed lower (better) footpad dermatitis scores than open pasture birds in Exp 1 and Exp 2 (p = 0.012 in Exp 1 and p = 0.004 in Exp 2). In Exp 1, 95% of silvopasture birds had no lesion on their footpads, compared to 83% in open pasture birds. In Exp 2, 85% of silvopasture birds had no lesions, compared to 66% in open pasture birds. In Exp 1, silvopasture birds showed lower hock burn scores, thus healthier hocks than open pasture birds (p = 0.049), with 85% vs 75% of birds showing no hock lesions respectively. In Exp 2, silvopasture birds tended to have lower hock burn scores than open pasture birds (p = 0.074), with 97% vs 91% of birds showing no hock lesions respectively. In Exp 1 but not in Exp 2, silvopasture birds had worse gait scores than open pasture birds (p = 0.019 in Exp 1 and p = 0.217 in Exp 2). Latency to lie did not differ between treatments in either experiment. The latency to lie for silvopasture vs. open pasture in Exp 1 was 452s vs 403s, and 523s vs 548s in Exp 2. These latencies indicate that leg strength was good in both treatments.

 

 Economics

Animal growth and feed conversion: During the three weeks birds had access to pasture, animal daily gain and feed conversion were similar across treatments (Table 1).

Table 1. Bird average daily gain (g) and mortality-adjusted feed conversion ratio for broilers kept in silvopasture or open pasture treatments.

 

 

 

 

Treatment

Spring 2021

Summer 2021

On pasture

On pasture

Day 22-25

Day 25-42

Day 23-25

Day 25-43

Day 1-43

Average daily gain (g) (mean ± SEM)

Silvopasture

56.88 ± 1.83

87.31 ± 2.53

40.96 ± 0.95

91.59 ± 2.85

62.61 ± 1.58

Open pasture

54.45 ±  2.26

88.73 ± 1.96

42.53 ± 2.82

91.89 ± 1.93

62.97 ± 0.90

 

Treatment

Day 22-25

Day 25-42

Day 25-42

Day 1-42

Adjusted FCR

Silvopasture

0.15 ± 0.01

1.20 ± 0.01

1.06 ±  0.02

1.73 ± 0.04

Open pasture

0.17 ± 0.00

1.22 ± 0.03

1.07 ±  0.12

1.74 ± 0.03

Body weight and carcass yield (Table 2): Final body weights were recorded for 77-80 birds per treatment group in Exp 2. Final weights did not differ between treatments in Exp 1 (p = 0.883) or Exp 2 (p = 0.423). After each trial, 79-84 carcasses were used per treatment to determine carcass yield. These carcasses were cut and only included thighs with bone, wings with bone, and breast meat. Yield in either experiment did not differ between treatments (p = 0.378 in Exp 1 and p = 0.107 in Exp 2).

Table 2. Mean ± standard error of live weights and carcass yields for both treatments and both experiments.

 

Spring 2021 (Exp 1)

Summer 2021 (Exp 2)

 

Silvopasture

Open pasture

Silvopasture

Open pasture

Live weight (kg)

2.95 ± 0.042

2.96 ± 0.040

2.77 ± 0.043

2.80 ± 0.041

Carcass yield (kg)

1.74 ± 0.024

1.70 ± 0.027

1.63 ± 0.024

1.58 ± 0.025

Environment

Temperature/humidity: Temperature and humidity was monitored in the range and within the coops. In the range, we used two weather stations (one per treatment) that collected data every 5 minutes starting May 5th through May 18th 2021. Outcomes and treatment effects are presented in Table 3. Relative humidity, dew point, soil moisture and PAR values differed between treatments, with humidity, dew point and PAR lower but soil moisture higher in silvopasture compared to open pasture.

Table 3. Mean ± standard deviation of range microclimate measures in both treatments (Exp 1). Statistical test outcomes (p-values) indicate the treatment effect (silvopasture versus open pasture).

 

Silvopasture

Open pasture

Treatment P-value

Temperature  (˚C)

13.61

± 6.84

13.82

± 9.06

0.152

Relative humidity (%)

64.83

± 17.98

70.88

± 17.02

< 0.001

Dew point (˚F)

43.67

± 11.25

46.48

± 13.13

< 0.001

Soil moisture (%)

99.84

± 3.62

16.78

± 10.48

< 0.001

Photosynthetically active radiation (PAR; uM/m^2s)

171.4

± 320.1

272.43

±  466.9

< 0.001

In-coop microclimate was assessed in four or five coops, twice per day. Outcomes and treatment effects are presented in Table 4. Temperatures at time of sampling (either early morning or late afternoon) tended to differ in spring but not summer, with cooler in-coop temperatures in silvopasture. Minimum coop temperatures were lower in silvopasture in spring but not summer. Maximum coop temperatures were lower in silvopasture in summer, but not spring. Only in summer, minimum humidity differed, with higher humidity in silvopasture coops.

Table 4. Mean ± standard deviation of in-coop microclimate measures in both treatments (Exp 1). Statistical test outcomes (p-values) indicate the treatment effect (silvopasture versus open pasture).

 

Spring 2021

Summer 2021

 

Silvopasture

Open pasture

P-value

Silvopasture

Open pasture

P-value

Temperature (˚C)

20.9

± 5.9

22.8

±  6.8

0.064

26.0

± 5.5

27.3

± 7.2

0.352

Min temperature  (˚C)

12.3

± 7.4

14.7

±  6.3

0.023

20.3

± 5.5

22.6

± 8.2

0.249

Max temperature  (˚C)

33.4

± 7.3

32.3

±  9.0

0.618

42.6

± 7.1

47.1

± 3.7

0.0002

Relative humidity (%)

49.5

± 19.9

45.5

±  20.6

0.171

61.9

± 22.8

61.1

± 27.4

0.766

Min relative humidity (%)

24.6

± 13.7

28.0

±  17.0

0.206

24.4

± 9.8

19.3

± 3.9

0.0005

Max relative humidity (%)

71.7

± 22.6

70.0

±  21.4

0.484

79.5

± 18.6

71.8

± 25.0

0.223

 

Soil quality: We have collected soil samples before Exp 1 (baseline), after Exp 1, and after Exp 2. In between Exp 1 and 2, cattle was allowed to access the pastures used for the birds’ plots. Analysis of the baseline soil samples was performed in March 2021 in Dr. Sandeep Kumar's lab. Analysis of post-experimental soil samples was performed by Ward Laboratories, Inc. (Kearney, Nebraska), as Dr. Kumar left SD State University for a position elsewhere. An overview of collected soil samples is shown in Table 5. Both laboratory and statistical analyses of soil parameters is ongoing.

Table 5. Overview of soil samples collected and current analysis status for Obj 1.

Sample collection date

Time point

Season

Samples per treatment (n)

Samples total (n)

Samples analyzed (n)

Samples to be analyzed (n)

Analysis location

3/3/2021

Baseline

Spring

6

12

12

0

SDSU

21/5/21

Post-experiment

Spring

24

48

12

36

Ward lab

12/8/2021

Post-experiment

Summer

18

36

12

24

Ward lab

 

Phospholipid fatty acid content (PLFA) is considered a biological indicator of overall soil quality (Quideau et al. 2016). Values over 4,000 are considered indicative of excellent soil health. Samples at all time points showed excellent soil health, but especially the baseline samples showed excellent quality compared to spring and summer samples (p <0.001)(Table 6).

β-Glucosidases are produced by a variety of organisms (plants, animals, fungi and bacteria; Esen, 1993). Monitoring β-Glucosidase activity can provide an early indication of changes in soil organic carbon. β-Glucosidase activity responds to management effects, and can serve as an indicator for soil metabolic functioning, with higher values indicative of better soil quality (Stott et al., 2010). The open pasture plots showed better soil quality compared to silvopasture, based on this indicator (p = 0.054). Timing of sampling had a greater impact on the outcomes (p < 0.001), with best values in the baseline samples compared to the spring or summer samples (Table 6).

Table 6. Soil sample analysis outcomes (means) for samples collected at three timepoints in both treatments.

 

Baseline

Spring

Summer

Silvopasture

Open pasture

Silvopasture

Open pasture

Silvopasture

Open pasture

Β-Glucosidase (µg pNP g-1 soil h-1)

357

352

141

192

114

174

PLFA (ng/g)

182,614

151,667

151,667

14,529

17,028

14,890

14,233

33,897

58,605

58,605

4,964

6,020

5,233

5,367

117,580

55,396

55,396

4,536

4,915

4627

3,837

16,383

9,686

9,686

2,913

3,435

2,823

2,620

Insect diversity: Using pitfall traps (1 per plot) and sticky traps (3 per plot), we intend to determine insect biodiversity in each treatment group. Insect identification is currently ongoing, with approximately half of the pitfall samples of Exp 1 completed. A summary of insects identified in the open pasture treatment is presented in Table 7.

Table 7. Overview of soil samples collected and current analysis status for Obj 1.

Classification

Open pasture (total n)

Annelids

5

Aphids

28

Arthropods

452

Lipidoptera

2

Gastropods

27

Isopods

105

Unidentified

5

Total

624

Objective 2A - Field trial: Compare broiler chicken production with access to a newly planted silvopasture on a large-scale commercial farm to grass pasture access on the same farm: Due to limitations related to the pandemic, we could not visit the cooperating farm early in 2021. Further delays were caused by challenges related to identifying certified organic vegetation to plant in the pasture. Because of seasonal limitations, planting of vegetation at the commercial farm had to be postponed to the spring of 2021 (3/3/2021). Nine baseline soil samples were collected from three pastures, and sample analysis was performed in March 2021 in Dr. Kumar's lab. A new challenge has arisen this year (winter/spring 2021-2022) with the spread of highly pathogenic avian influenza across the US. Currently there is no concrete outlook on when additional data collection can occur at this farm.

Objective 2B - Field trial: Compare broiler chicken production with access to established silvopastures on two small-scale commercial farms to grass pasture access on the same farms: Due to limitations related to the pandemic, we could not visit the cooperating farms in 2020. We visited one of the two farms in 2021 (Brent Wills farm), and collected data from one round of broiler chicken production. For this production round, two plots (65 Freedom rangers/plot) were set up, one with access to open pasture, one with access to some silvopasture-like vegetation.

Animal welfare

Fearfulness: Based on assessments of 56 or 57 birds per treatment, fear did not differ between treatments (p = 0.130). Birds in the silvopasture treatment showed a mean tonic immobility duration of 66 ± 6 sec, compared to 54 ± 5 sec in open pasture birds.

Leg health: Silvopasture birds showed lower (better) footpad dermatitis scores than open pasture birds (p = 0.001), with 79% of birds with perfect footpads, compared to 52% in the open pasture plot. Hock burns scores did not differ (p = 0.120), with most birds  (92% in open pasture, 82% in silvopasture) showing healthy hocks regardless of treatment. Leg strength did not differ, with birds showing similar latencies to lie (480 sec in open pasture vs 473 sec silvopasture; p = 0.804). Gait scores were similar across treatments, with most birds (98% in open pasture, 96% in silvopasture) showing perfect gait (p = 0.510).

Economics

Body weight and carcass yield: Live body weights did not differ between treatment groups in this trial, yet carcass weights tended to differ, with birds from the silvopasture plot slightly heavier than birds from the open pasture plot (Table 8).

Table 8. Overview of body weights (means and standard error) and carcass yields from the small-scale farm trial.

 

Silvopasture

Open pasture

P-value

Live weight (kg)

2.28 ± 0.04

2.26 ± 0.03

0.560

Carcass yield (kg)

2.05 ± 0.04

1.96 ± 0.03

0.089

Environment

Soil quality (Table 9): Baseline and post-trial soil samples (8 total) were collected from two pastures, and the analysis of the samples was performed by the Ward lab. Soil quality seemed numerically better in the open pasture compared to the silvopasture, but statistical analysis was not performed.

Table 9. Soil sample analysis outcomes (means) for samples collected in both plots, before and after the production round.

 

Silvopasture

Open pasture

 

Beta-Glucosidase (µg pNP g-1 soil h-1)

PLFA (ng/g)

Beta Glucosidase

(µg pNP g-1 soil h-1)

PLFA (ng/g)

Baseline

32

5510

37

6509

Post-trial

30

6372

54

7369

 

Objective 3A - Surveying silvopasture- and traditional-system poultry producers about their experiences, concerns and opportunities for applying these practices: We are in the process of getting the interview and survey methods approved by the Virginia Tech Institutional Review Board.

Objective 3B, C, D: Nothing to report

 

 

 

Participation Summary
4 Farmers participating in research

Education

Educational approach:

This project has a slow start due to the Covid-19 pandemic.

  • 2020 - current: We have recruited one PhD student for the project that will be in charge (under supervision) of the majority of data collection in the project
  • 2021- current: We recruited one undergraduate student in the department of Animal and Poultry Sciences for the experimental trials at the Shenandoah Valley Agricultural Research and Extension Center (Virginia Tech). This student obtained funding via the Young Scholar Enhancement Grant. In addition she is contributing to the insect biodiversity assessment in exchange for hourly wage.
  • 2022: An undergraduate student in the department of Animal and Poultry Sciences is involved and contributes to data collection related to range use observations in exchange for 1 course credit. 

Educational & Outreach Activities

1 Consultations
1 Curricula, factsheets or educational tools
1 Published press articles, newsletters
3 Webinars / talks / presentations

Participation Summary:

4 Farmers
Education/outreach description:
  • Consultation 

We have been consulted by the CEO of a commercial broiler chicken integrator on recommendations for their new sustainable broiler chicken farm. More specifically, we provided recommendations for vegetation to plant in chicken pastures, including grasses, clover, trees and shrubs. Furthermore, we facilitated contact with extension agents and researchers on soil regeneration. 

  • Curricula, factsheets or educational tools (educational video)

We recorded video material during planting vegetation at the commercial poultry farm and at the VT AREC. This material was used for a "15 minutes in the forest" section, which is an extension video on planting trees, and features a description of the project. 

  • Published press articles, newsletters (newsletter)

The PI is the co-founder of the Poultry Extension Collaborative (PEC). This collaborative consists of poultry extension faculty from four U.S. universities. The graduate student and the PI wrote a newsletter on incorporating silvopasture in poultry production. This newsletter is peer-reviewed by the other PEC members and distributed to newsletter subscribers (300+), on the PEC website, and promoted through the PEC Facebook page. 

  • Talks and Presentations

We have held our first and second stakeholder advisory council meetings during which the project was discussed in detail. Project results from Obj 1 were presented via a virtual poster presentation on the North American Agroforestry Conference (June 29 2021). In addition, project results from Obj 1 were presented in an oral presentation (and peer-reviewed abstract) at the International Poultry Scientific Forum in Atlanta (January 24 2022). 

Upcoming activities

  • Presentation: Stakeholder advisory council
  • Extension tour/talk: Virginia Agroforestry Training and Demonstration Tour - JACOBS will talk about silvopasture for chickens and the ongoing project as a small component of the two-day activity. 
  • Educational tool: Stakeholder interviews and subsequent reporting.

Learning Outcomes

1 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation

Information Products

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.