Sustainable and profitable control of invasive species by browsing goats on small farms

Final Report for LS03-150

Project Type: Research and Education
Funds awarded in 2003: $14,199.00
Projected End Date: 12/31/2004
Region: Southern
State: Texas
Principal Investigator:
Dr. James Muir
Texas A&M AgriLife Research
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Project Information


This planning grant proposed to put meat goat producers, landowners with brush invasion, extension personnel, and researchers together to determine:

1. Is there an interest in controlling brush by natural means, especially using goat and hair sheep browsing/grazing?

2. Which invasive species are problematic?

3. Are there questions, both in terms of the farming systems as well as of a plant/animal interface nature, that need to be researched before these enterprises can flourish?

The plan was to facilitate farmer, extension and researcher exchange of information at three locations, namely south-central Georgia, St. Croix and north-central Texas. At these exchanges, it would be determined whether further research was needed and what issues needed to be addressed by this research.

Project Objectives:

1. Evaluate farmer perception of intensive, short duration goat browsing (ISDGB): this was accomplished, with the perception being positive.

2. Review whether ISDGB methodology already exists: yes, it does although not at a for-hire basis using goats or hair sheep in the 5 regions represented in the study.

3. Design on-farm experiments to test ISDGB: this has been accomplished only in general terms, and the teams (goat-owners, landowners, researchers) are in place to look at greater detail at five states/territories in the southern SARE region.

4. Increase awareness of ISDGB: this was accomplished and will expand when the web site and extension fact sheets are complete.

5. Develop a full research proposal on ISDGB: this was accomplished and grant R&E LS05-175 (2005-2008) covering ISDGB efforts in Puerto Rico, Florida, Georgia, St. Croix and Texas, was funded by Southern SARE.


The invasion of fallow cropland, pasture and woodland by native and non-native weeds is a common problem throughout the southern USA, Puerto Rico and the U.S. Virgin Islands (USVI). In Florida alone, 29% of non-cultivated plants are classified as non-native (Langland and Stocker, 2001). Native mesquite (Prosopis glandulosa), cedar (Juniperus spp.), and greenbrier (Smilax spp.) are examples of widespread southeastern USA invasive plants resulting from overgrazing by cattle and its disruption the natural balance in plant communities (Welch and Hyden, 1996; Racher and Britton, 1997; Taylor and Fuhlendorf, 2003). Kudzu (Pueraria lobata), coral vine (Antigonon leptopus) cogongrass (Imperata cylindrica), Japanese climbing fern (Lygopodium japonicum), and leucaena (Leucaena leucocephala) are well-documented examples of non-natives that have become widespread invasive species in the region (Miller, 1988; Engle et al., 1994; Langland and Stocker, 2001; Terrill et al., 2003). Most of the non-native species have proved very difficult to eradicate once established. For example, current guidelines for kudzu control warn that repeat applications of herbicide may be necessary for 5 to 10 years after initial treatment (Demers and Long, 2002).

For this reason, it is not hard to understand why both public and private landowners are often overwhelmed by the logistics and cost of controlling these invasives. Dade County Florida Parks and Recreation Department has spent $2.3 million for the removal of invasive plants from 500 acres of upland area since 1993 (Langland, 2003). In one year alone, the State of Florida budgeted $12 million for control of wetland species alone (Langland, 2003). The environmental repercussions of widely applied and indiscriminate chemical and mechanical control are poorly understood, however. This is particularly true in natural areas where special care is needed to minimize damage to non-target vegetation, soil and fauna that depend on them (Langland and Stocker, 2001).

Non-chemical methods exist for controlling invasive weeds. Non-grass weedy invaders can sometimes be suppressed using grass-fueled fires (Briggs et al, 2002) but this rarely results in 100% eradication and is sometimes a socially or environmentally unacceptable means of brush management. Other methods commonly used include grubbing, root-plowing, removal by hand, chaining, and herbicides (Taylor, 1992; Hart, 2001), all of which have environmental and economic downsides. Biological control of regrowth following mechanical or chemical brush control has proven more effective than single-control approaches (Magee, 1957; Green and Newell, 1982). The use of small ruminants for biological control may be more socially acceptable (Ball, 2004) and their forage predilections (Huston, 1978) and specialized digestive tracts (Huston et al., 1986; Hofman, 1989) make them better brush control tools than other larger ruminants. In addition, goat and sheep feed preferences are determined by a complex mixture of genetics, learned behavior, and feed availability (Malechek and Provenza, 1983) that can be manipulated to produce specific modifications in plant communities.

The use of intensive, short duration goat/sheep browsing (ISDGB) may be an efficacious, remunerative, and ecologically mild form of manipulating vegetation (Muir et al., 1997; Briggs et al., 2002). The use of small ruminants for brush control is not completely unknown in the southern USA (Bull, 2000) and has been supported by SARE grants (LS01-119) in the past. The commercial application of this practice, namely contracting herds specifically to suppress invasive vegetation (Ball, 2004), is not, however, widespread in the southeastern USA or its Caribbean territories but has been successful elsewhere (Green and Newell, 1982). At the same time, market demand for goat and sheep meat is strong (, indirectly encouraging over-stocking on ecologically sensitive rangelands where most small ruminants have traditionally been raised (Malechek and Leinweber, 1972) and in the eastern United States where most producers have limited land areas to utilize. The growing invasive plant problems, in conjunction with a strong small ruminant market, provide a fortuitous opportunity to combine profitable animal husbandry with biological control of weeds. The details for this union of circumstances, however, have not been developed.


Click linked name(s) to expand/collapse or show everyone's info
  • Tomas Terrill
  • Elide Valencia
  • Stuart Weiss
  • Mary Williams


Materials and methods:

The planning grant was originally designed to facilitate landowner/small ruminant/researcher/extension workshops to examine the potential commercial applications of ISDGB in three locations: Terrill (FVSU) at Georgia, Valencia (UVI) at St. Croix, and Muir TAMU) in Texas. With the addition of Williams (USDA-ARS) in Florida and Valencia’s move to Puerto Rico (UPR) and subsequent addition of Weiss (UVI) at St. Croix, a total of five distinct locations were identified.

Research results and discussion:

Four farmer/researcher/extension workshops and field visits were held during the 2003-2004 period, one more than planned:

Fort Valley, GA, June 18-19, 2003

St. Croix, USVI, January 12-13, 2004

Mayaguez, PR, January 14-16, 2004

Stephenville, TX, April 14-15, 2004

Additional members were recruited to the effort. These included:

1. Two additional research sites within the Southern SARE region beyond Georgia, St. Croix and Texas, namely southern Florida and Puerto Rico.

2. At all sites visited, goat-owner and landowner interest was so high that new team members were added

3. Dr. Mary Williams, forage agronomist with the USDA-ARS Florida, has joined the research team and will be included as an additional site in the pre-proposal for a full research grant.

Additional interaction with farmers took place at all locations during the 2004-2005 period in which an R& E grant proposal was prepared. Small ruminant owners and landowners with weed-invaded land agreed to participate in future efforts if funding became available.

Fort Valley, GA: Jones, Ussery, Owens, McCorvey & Taylor

St. Croix, USVI: Schuster, Doward, Hamilton, Scribner, Jones

Mayaguez, PR: Rodriguez & Ramirez

Stephenville, TX: Seale, Turner, Weiss and Priddy

Florida: Henry

Invasive species that landowners identified as needing control and that goat-owners thought they could possibly tackle via intensive commercial meat goat browsing at each location included, in order of importance:

1. Georgia: Kudzu (Pueraria lobata), hardwood saplings (Quercus spp.) & greenbrier (Smilax spp.)

2. St. Croix: tantan (Leucaena leucocephala), corral vine, cassia (Acacia spp.)

3. Puerto Rico: tantan, cassia & corral vine

4. Florida: kudzu, weeds in perennial peanuts

5. Texas: greenbrier, mesquite (Prosopis spp.), sumac (Rhus spp.), shinnery oak (Quercus spp.)

Questions that both goat-owners and landowners had regarding brush control via goat browsing was:

1. Definition of brush control vs. brush suppression

2. Plant toxicity to animals

3. Effects of over-stocking on animal performance

4. Stocking rates needed to control (exterminate vs. suppress) browse

5. Rotations (and duration) needed to control vegetation

6. Timing (season) ideal for long-term, effective suppression

There were additional concerns that involved topics outside the plant/animal interface, including marketing, fencing, predation, and security. These concerns will be brought to the attention of researchers and extension personnel more directly connected to these aspects of ISDGB.

Participation Summary

Educational & Outreach Activities

Participation Summary:

Education/outreach description:

The main outcome of this planning grant was the Southern SARE preproposal and, subsequently, full proposal that resulted from the various planning workshops held in the region. The proposal was eventually funded (R&E LS05-175, 2005-2008) and, as a result, the local and regional R&E teams that were organized during LS03-150 (2003-2005) are now starting to address the issues raised by landowners with invasive weeds, small ruminant producers looking for additional income, and university agencies (research, extension and education) looking for science-based answers to ISDGB plant:animal interface questions.

Project Outcomes

Project outcomes:

Southern-SARE Planning Grant LS03-150 funded a series of forums in which small-scale landowners, limited-resource goat/sheep farmers, extension personnel and researchers determined 1) whether ISDGB was already being widely employed in the southeastern USA, Puerto Rico and the U.S. Virgin Islands, 2) what farmer/landowner perceptions of ISDGB are, and 3) what limitations exist to its wider commercial application. At all locations (south-central Georgia, north-central Texas, St. Croix and Puerto Rico) the answers were uniformly 1) only one successful commercial application was found (Ball, 2004), 2) landowners were interested in the concept but goat/sheep farmers were in doubt how to apply ISDGB and, 3) questions arose as to the efficacy of ISDGB and the plant:animal interface tools needed to apply it commercially. In addition, both landowners and goat-owners were in doubt as to the economics of such contracts, a problem identified in other regions (Hart, 2001).

Although difficult to quantify, the net effect of these encounters was to raise awareness of the commercial potential involved in using goats to control invasive browse on both self-owned and contracted land. Besides the individual interests, general interest will be heightened through the website presently being constructed by the grant participants.

Economic Analysis

No economic analyses were performed. However, this has been included in R&E grant LS05-175.

Farmer Adoption

This phase will be focused during the R&E LS05-175 (2005-2008), according to plans outlined during LS03-150 (2003-2005). Land owner (invaded land) and animal owner (goats and hair sheep) interest was high, indicating that farmer-to-farmer, fact sheet, popular article and web-based dissemination of both the concept and research results will be readily adopted by small ruminant producers and both public and private landowners.


Areas needing additional study

Areas needing additional study were identified during this planning grant (LS03-150 2003-2005) and were proposed for R&E grant LS05-175 (2005-2008). These focused primarily on plant:animal interface questions but also included economics factors and education (promulgation) efforts involving the commercialization of ISDGB.

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.