Ecological, Sustainable and Economic Impact of Legume-based Pasture Systems for Limited-Resource Small Ruminant Farmers in the Virgin Islands

2001 Annual Report for LS99-107

Project Type: Research and Education
Funds awarded in 1999: $110,410.00
Projected End Date: 12/31/2003
Region: Southern
State: U.S. Virgin Islands
Principal Investigator:
Elide Valencia
University of the Virgin Islands

Ecological, Sustainable and Economic Impact of Legume-based Pasture Systems for Limited-Resource Small Ruminant Farmers in the Virgin Islands


Rotational vs. continuous grazing effect on average daily gains (ADG) of lambs and dry season (DS) yield of guineagrass Leucaena was investigated. Higher ADG occurred on continuos grazing (CG; 68 g/d) compared to rotational grazing (RG; 46 g/d). Forage yield was better on RG (3.5 Mg/ha) compared to CG (1.8 Mg/ha). At season end, sheep on CG were supplemented with legume as regrowth of leucaena was affected. Grazing selectivity was favored by CG, but resulted in weedy grass encroachment. Although ADG are better under CG, additional costs were incurred with supplementation. Forage yield during the DS is better under RG and benefits the grass legume over story.

Objectives/Performance Targets

1. To compare pasture and small ruminant production (sheep and goats) on N-fertilized guineagrass, no-till seeded legume hedgerows, and pure guineagrass swards.

2. To compare pasture productivity and economic costs and returns on forage and goat production on no-till planting of legumes (25% of planted area) in native/or improved pastures.

3. To compare goat milk production using tropical grasses-perennial soybean (Neonotonia wightii) combinations vs. alfalfa hay.

4. To promote and facilitate adopting the technology of these legume-based systems by forage and livestock producers, as production principles emerge from the research.


In the seasonally dry eastern Caribbean islands, growing small ruminants are sensitive to availability of high quality tropical grasses. The potential for improved weight gains by growing hair sheep and dry season yield of guineagrass (Panicum maximum Jacq.) Leucaena (Leucaena leucocephala Lam de. Wit) was investigated. St Croix White hair lambs (4 mo. of age) were utilized to compare two different grazing systems, with three replicates within each treatment. In the continuous grazing system (CS) each replicate of lambs (n = 5) grazed guineagrass leucaena (10 15% over story) pastures (.14 ha) at a stocking rate of 650 kg BW/ ha/d for a period of 98 d. In the rotational grazing system (RS) each replicate of lambs (n = 5) grazed guineagrass leucaena (10 15% over story) pastures (.14 ha) at 650 kg BW/ ha/d for 126 d. In the RS, each .14 ha pasture was subdivided into 3 equal paddocks and lambs were moved every 14 d which allowed each paddock a 28 d rest period. Lambs were weighed weekly throughout the trial. Forage dry matter yield was estimated in five .25 m areas in each paddock. Pastures were sampled every 28 d in CS and every 14 d in RS. All data were analyzed using GLM procedures of SAS. There was a trend for higher average daily gain for sheep on CS (68 ± 3.7 g/d) compared to those on RS (46 ± 3.7 g/d). However, seasonal forage yield was favored by RS (3.5 ± .4 Mg/ha) compared to CS (1.8 ± .4 Mg/ha). At season end, sheep on CS had to be supplemented with leucaena on a cut carry system (1.6 kg DM/d) as regrowth of leucaena was affected. Grazing selectivity increased under CS, but also favored encroachment of the low quality hurricane grass (Bothriocloa pertusa). These results suggest that weight gains are slightly better under CS, but will require supplementation during the dry season. Forage yield during the dry season is better under RS and may favor the grass legume over story in the long term.

A major setback to CG was that mid-way through the dry season, forage dry matter yield decreased to <1,000 lb acre. Leucaena regrowth was affected and contributed little forage yield. Guineagrass was enough to allow for selective grazing, but leucaena had to be supplied in a cut and carry system in order for lambs to gain similar weights as those on RG. Under RG, leucaena regrowth was adequate to supply 30% of forage dry matter. The grass component was also enough to meet animal needs. Partial budgeting analysis showed that monetary gains from RG are positive but relatively small ($52/acre). In the long run, the monetary differences could become magnified, depending upon the relative influence of factors such as changes in pasture botanical composition, weed encroachment, and parasites. We observed that over time, in the CG, guineagrass and leucaena declined due to selective grazing. Live weight gains from CS also should a slight decline. Also higher parasite counts were observed under CS. Forage field days and pasture walks were held in 2000 and 2001 to disseminate information to livestock farmers, extension agents, and the local media. There was positive participation from both livestock farmers and extension personnel. Experimental results were presented at the 2001 Annual Animal Science Meeting in Indianapolis. Two factsheets (pasture establishment and another on managing pasture resources) are in press and will be made available to livestock farmers for this years Agricultural and Food Fair (February 2002). On farm research for both objectives 1 and 2 are in final phase and being analyzed for publications. A draft publication on the Economics of forage-fed Small Ruminants in the U.S. Virgin Islands is in review. Problems occurred with objective 3 as the farmer co-operator lost several Does that were to be used for the milk production study. One additional forage field day is planned for the summer 2002.

Impacts and Contributions/Outcomes

The rapidly growing demand for mutton and chevon (goat meat) in the U.S. Virgin Islands has helped fuel the Small Ruminant Industry. The University of the Virgin Islands, Agronomy program and SARE LS99-107 helped goat producers and sheep farmers reduce feed costs by 80% with the use of improved forages and advanced grazing technique. For instance, farmers were able to fatten weaned goats (ave. 30 lbs) on improved pastures in five months (10 goats/acre), compared to eight months on low quality pastures. Total animal live-weight gain increased by 40%. Legume incorporation in grass pastures was as effective as N grass fertilization and better during the dry season in maintaining sheep weight gains. This forage and low input grazing system contributed to a relatively lower cost of meat production.

Valencia, E., and R.W. Godfrey. 2001. Grazing method effects on growth rate of St. Croix White hair sheep lambs on a tropical grass-shrub legume over-story. J. Anim Sci. 79:59.

Valencia, E. and G. D’Souza. 2002. Factsheet: Pasture establishment in the U.S. Virgin Islands. 4 p. (In press).

Valencia, E., L.E. Sollenberger, and G. D’Souza. 2002. Factsheet: Managing pasture resources. 4 p. (In press).