Sponsoring Institution
National Institute of Food and Agriculture
Project Status
Funding Source
Reporting Frequency
Accession No.
Grant No.
Project No.
Proposal No.
Multistate No.
Program Code
Project Start Date
May 1, 2010
Project End Date
Apr 30, 2013
Grant Year
Project Director
Silent, AY.
Recipient Organization
DOVER,DE 19901
Performing Department
Agriculture & Natural Resources
Non Technical Summary
Invasive species are becoming a problem throughout the state of Delaware and the rest of the United States. An invasive species, whether it is a plant or animal, is a species that has been introduced to an area to which it is not native and subsequently disrupts the natural balance in that habitat. While there are both plant and animal invasive species in Delaware, many of the hardest to control are weeds. For example, invasive Canada thistle and Johnson grass are two noxious weeds in Delaware according to the USDA's list of noxious weeds. While these are not the only invasive weed species in Delaware they are prime examples and methods of effective control need to be evaluated. Animal grazing is a very effective tool for managing weed and brush growth. Goats, sheep, cattle, and horses have all been previously used to control brush and weeds. In addition, goats have been successfully used for the control of abandoned farmland pastures invaded by herbaceous weeds, vines, multiflora rose bushes and hardwood saplings for years. When goats are used to manage defoliation this has been shown to result in a substantial increase in vegetative cover by favorable grass and legume species while reducing or eliminating unwanted shrub species (Luginbuhl et al., 1995). Concurrently, goats are becoming increasingly important contributors to the income of many producers in Delaware as indicated by a 43% increase in goat numbers from 2002 to 2007 (Delaware Census of Agriculture, 2007). Therefore, due to increasing goat numbers in the state of DE combined with environmental concerns of herbicide use and the inefficacy of other control methods, the proposed study aims to evaluate the effectiveness of goats as a biological control agent for the control of invasive weeds in DE. This project is in collaboration with the Delaware Department of Transportation and hopes to promote a sustainable and environmentally friendly means of invasive weed control to the citizens of Delaware.
Animal Health Component
Research Effort Categories

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
Knowledge Area
307 - Animal Management Systems;

Subject Of Investigation
3820 - Goats, meat, and mohair;

Field Of Science
1140 - Weed science;
Goals / Objectives
It is the objective of the proposed project to evaluate whether or not goats can be an effective method of invasive weed control in Delaware and how many seasonal grazing periods are required for successful control. Expected outputs include a research project at Delaware Department of Transportation's Wrangle Hill site, incorporation of new techniques (forage biomass, nutritive analysis, and botanical) into undergraduate and graduate research projects at DSU, presentations/seminars on the use of goats in invasive weed control to producers, researchers and other professionals, and publication of two scientific articles. This experiment will be conducted within 3 years (February, 2010 - January, 2013) to evaluate whether or not goats can be an effective and sustainable method of invasive weed control in Delaware. Data will be collected and analyzed by the end of the experiments for each year. This timeline was developed such that enough data will be available in order to submit abstracts and present at the 2010, 2011 and 2012 Southern Section American Society of Animal Science Meetings as well as American Society of Animal Science Meetings each year. Potential products from conducting this project include the development of new skills and techniques by students, staff, and faculty at DSU as well as the promotion of a sustainable and environmentally friendly means of invasive weed control in DE. In addition, one graduate student will be trained in these techniques and will use the data as part of their thesis work at DSU. Undergraduate students will also be provided opportunities to work and volunteer on this project, therefore increasing the teaching capacity at DSU and help in training well-qualified students for Food and Agricultural Science professions.
Project Methods
A grazing experiment will be conducted during the 2010, 2011, and 2012 growing seasons at Delaware Department of Transportation's Wrangle Hill site in New Castle County to investigate the potential effects of goat grazing on pastures infested with browse and weedy species. The experimental design will be a randomized complete block design with pastures being the experimental unit. The two treatments will include a no grazing control and a goat alone grazing. Three replicates will be used for grazed treatment and two for the control. Replicate paddocks for grazing will be 1.2 ha each and control replicates will be 0.4 ha each. Forty goats will be allocated to each grazing treatment and will be rotationally stocked among replicates by grazing one replicate for approximately two weeks and then allowing 4 weeks rest. Water and trace minerals will be provided free choice at all times. Animals will be weighed at each rotation time during the growing season (spring, summer, and fall). Grazing will be initiated during May and end during September of each year. Pastures will be evaluated for forage biomass, nutritive values, species diversity and effect of grazing on browse species during spring, summer, and fall of each grazing season. Forage biomass will be determined according to Webb (2008). Prior to harvesting the forages within each quadrant, the area will be visually evaluated by trained evaluators for botanical composition using the double DAFOR scale as described by Brodie (1985) and Abaye et al. (1997). The scale (D=dominant, A=abundant, F=frequent, O=occasional, and R=rare) will be used to evaluate the relative abundance of species. Visual estimates of percentage ground cover and percentage of grass, legume, and weed species will also be made. Autumn olive and muliflora rose measurements will include shrub height, branch length, and shrub survival. Shrubs will be randomly identified and tagged with a letter in each paddock in the grazing treatments and control plot. Shrubs will be measured at spring, summer, and fall during each growing season. Any broken or dead branch due to goat browsing will also be recorded. Shrub survival will be also be measured in May and September by counting the number of shrubs or clumps surviving in each treatment. All data will be analyzed using SAS and data will be presented annually at national Animal Science and Invasive Weed control meetings as well as to goat producers at workshops/seminars. Acceptance of the information by this community, assessed by interest generated after presentations, and by goat producers, assessed by surveys administered to producers at workshops/seminars, will be used as an evaluation criterion. Impact will also be evaluated by information obtained from collaborating personnel at Delaware Department of Transportation to evaluate the impact and accomplishments of the proposed study.

Progress 01/01/11 to 12/31/11

OUTPUTS: Delaware State University collaborated with Delaware Department of Transportation (DelDoT) to use goats on one of their sites for biological management of three invasive shrubs including Autumn Olive, Multiflora Rose and Japanese Honeysuckle. The site was selected and approximately five acres of land at this DelDoT site was divided into five fenced paddocks with 3 treatment (with goats; 1.1 acres each) and 2 control (without goats; 0.7 acres each) paddocks. A graduate student, Jenna Warren, was hired to work on this project. In June 2010, thirty-five crossbred meat type goats, mixed sex and age, from our Hickory Hill goat herd were used in the experiment. The study lasted 112 days (9 sample dates from June to October, 2010). In 2011, twenty-nine adult does were used in the experiment which lasted 92 days (August to November, 2011; due to weather and delayed kidding). During both years, goats at the DelDoT site were used to browse each treatment paddock for 14 days, after which they were moved to the next treatment. On rotation days (every two weeks), all DelDoT paddocks (treatments and controls) were analyzed and visual estimates of percentage ground cover were made. In addition, a visual technique to describe botanical composition of pastures, the double DAFOR scale, was used to describe Autumn Olive, Multiflora Rose and Japanese Honeysuckle presence in each paddock. Simply, this technique rates plants/shrubs as dominant (covers most of the area), abundant (covers 50-75% of the area), frequent (less than 50% of area), occasional (present a few times in area) and rare (present once or twice in area) in a pasture/paddock. Ten shrubs which were a mix of autumn olive and Multiflora rose were marked in the treatment paddocks and 5 were marked in control paddocks. These shrubs were measured for height and 4 branches per shrub were measured for length. Additionally, on rotation days, animal body weights were measured and recorded. The results from this project were presented at the national meeting of the American Association of Animal Science (New Orleans, July 2011) and also at the Association of Research Directors Biennial meeting (Atlanta, April 2011). The results from this project were also disseminated in the Wild and Wooly newsletter Spring 2011 edition ( In addition to the graduate student working on the project, two additional students were taught methods used in data collection. PARTICIPANTS: Dr. Dahlia Jackson (PI) from Delaware State University serves as project director. Dr. Jackson is a Small Ruminant Specialist and during the last year and a half has been responsible for getting the objectives of the project underway. Graduate student, Jenna Warren was the graduate student working on the project and has successfully defended year one results and is now a PhD student in the Department of Animal Science at the University of Tennessee. Kwame Matthews is another graduate student that assisted on this project with Brittley Fisher (seasonal technician) and Kevin Beaudoin, undergraduate pre-veterinary student. Students were involved with data collection and daily checks at study site. TARGET AUDIENCES: The target audiences for this project are research scientists, extension agents, sheep and goat producers as well as undergraduate and graduate students. The research data obtained from this study will be utilized to educate the target audience on the use of goats for invasive weed control in Delaware. With the results accrued through this study, DSU and DelDoT will be able to create workshops and training for producers that wish to lease animals out for weed control on highways or personal property. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

At this point, only the data for summer 2010 has been analyzed. The results from the DelDoT site indicated that the goats were only effective in managing the growth of Japanese Honeysuckle when the treatment paddocks were compared to the controls. There was more percentage ground cover within the control pastures compared to the treatment paddocks ((averaging 35% for both at the start of the study and by the end averaging 26% for the browsed paddocks and 41% for the control paddocks). Although branch length for autumn olive and multiflora rose decreased in the control paddocks, there was more significant decrease in the treatment groups. There was no effect observed on invasive shrub height over the study period and body weights were maintained until they had to be supplemented during the last 4 week period (late September to early October), due to lack of vegetation. They were supplemented with hay as soon as this was realized but were removed and brought back to Hickory Hill when they failed to gain weight by the next sample date. The graduate student working on this project was able to graduate after 1 year of data collection when this data was combined to a related project. She also won 2nd place in the graduate student poster competition in Atlanta Georgia at the Association of Research Directors Biennial meeting. In addition, two additional students were taught methods used in data collection and assisted during summer 2011 on the project.


  • J.C. Warren, D.J. OBrien and R. Beaman. 2011. Use of Goats for Controlling Invasive Weeds in New Castle County Delaware. Presented ARD 16th Biennial Research Symposium. 2nd Place (Graduate Poster Presentation) in Sustainable Plant and Animal Production Systems.
  • J.C. Warren, D.J. OBrien, C. Heckscher, R. Beaman, N.C. Whitley. 2011. Goat browsing for invasive shrub and internal parasite control. J. Anim. Sci. Accepted. J. Anim. Sci. 89 (E- Suppl.1):T398 (p. 401).
  • Wild and Wooly newsletter Spring 2011 edition (