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

2002 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


In 2002, field research assessed seedling vigor and forage yield of the summer forage legumes Lablab (Lablab purpureus), Cowpea (Vigna unguiculata), and forage soybean (Glycine max). Lablab had higher seedling vigor and two-fold increases in herbage yield compared to Cowpea and forage soybean. Grazing of Lablab with growing lambs indicated that animal weight gains were three-fold higher on Lablab-guineagrass grazing compared to those supplemented with Lablab (cut-and carry). Increased weight gains noted with unrestricted grazing of Lablab suggests that this legume can be efficiently and economically grazed and that it also has potential for use as a special purpose pasture for weaned lambs.

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.


Scarcity of guineagrass (Panicum maximum Jacq.), particularly during the dry season, is a major limitation to growing small ruminants in the U.S. Virgin Islands. In our continued search for forage legumes to increase seasonal forage distribution and quality, leucaena (Leucaena leucocephala Lam de. Wit.) and lablab (Lablab purpureus) were used in cut-and-carry feeding and grazing systems. Lablab is a fast growing and high yielding semi-annual forage legume, but it’s potential as an animal feed for grazing or supplementation has not been documented. Small ruminant feeding studies were conducted at farmer co-operators farms.

The first study assessed the effects of legume supplementation of leucaena (LS) and nitrogen fertilization on the average daily gain (ADG) of St Croix white hair sheep, herbage mass (HM, Mg ha-1) and nutritive value of guineagrass. Treatments consisted of N rates (0 or 56 kg ha-1; N0 and N56) broadcast-applied on shredded guineagrass stands (15-cm stubble height) at the initiation of the rainy reason (September). St. Croix white hair lambs with an average weaning weight of 13.6 kg (n = 4) were assigned to replicated paddocks (.14 ha). Guineagrass pastures were stocked at 760 kg body weight ha-1 d-1 for 21 d followed by a 21 d rest period. Legume source was fed three times a week at 0.68 kg head-1 d-1 (dry matter basis). Herbage mass was estimated in three 0.25 m2 areas in each paddock every 21 d. Lambs were weighed weekly throughout the trial. All data were analyzed using analysis of variance procedures. Both N56 and LS did not affect HM (3.2 Mg ha1), but HM on N0 fell below 1.5 Mg ha-1 at 14-d grazing limiting grass on offer and requiring cut-grass supplementation for 7 d. Crude protein concentration (8.5%) and in vitro organic matter disappearance (54%) were not affected by treatment. Three was a trend (P=.09) for higher ADG on LS (70 g d-1) compared to N56 (60 g d-1) and differed (P<.05) from N0 (57 g d-1). These results suggest that sheep weight gains can be improved with LS supplementation and this maybe more economical than N fertilization on intensively managed guineagrass pastures. In a follow-up study, the feeding value effect of lablab on average daily gains (ADG) of weaned lambs (15 kg BW) during June-August 2002 (dry season) was investigated. Treatments were unrestricted grazing of guineagrass supplemented with lablab (SL; 0.5% animal live-weight on a dry matter basis), unrestricted grazing of both guineagrass and lablab (GL), and unrestricted grazing of guineagrass (control) in a randomized complete block with two replicates. Lambs (n = 4) grazed pastures (.14 ha) and were supplemented for a 96-d period, after a preliminary adjustment feeding period of 14-d. Lambs were weighed weekly throughout the trial. Herbage mass (HM) was estimated in five .25m2 areas in each paddock every 21-d. Data were analyzed using GLM procedures of SAS and mean separation when significant was conducted with LSMEANS. There were significant differences (P<.05) among treatments for ADG. There was a four-fold increase in ADG for GL (72.8 ± 6.2 g/d) compared to the control (18.5 ± 6.9 g/d). Average daily gain of lambs on GL was also much higher than SL (36.4 ± 6.4 g/d). There were difference among treatments for HM (P<0.05). At season end, HM on offer for GL (3.64 ± .3 Mg/ha) was two-fold higher than SL (1.9 ± .3 Mg/ha) and control (1.3 Mg/ha). These results indicate that weight gains of St. Croix white hair can be increased with summer grazing or supplementation of lablab. The weight gains observed with unrestricted grazing of lablab justify its establishment as a special purpose pastures for use with weaned lambs during the dry season. Forage field days, workshops, and pasture walks were held on St. Croix and St. Thomas to disseminate information to small ruminant producers, extension agents, and local media. More than 100 producers and extension personnel participated in these activities. Experimental results were presented at national meetings. Data was presented at 2002 American Forage Grassland council meeting held in Bloomingdale, Minnesota and an abstract was submitted to Animal Science Meetings for discussion in June 2003. Two fact-sheets (Pasture establishment in the U.S. Virgin Islands and Managing pasture resources) were published and made available to livestock farmers for this years Agricultural and Food Fair. On farm research for objectives 1, 2 and 3 were terminated this year and are being analyzed. It is projected that two articles will be submitted for Journal publications in 2003. A farmer bulletin “Economics of forage-fed Small Ruminants in the U.S. Virgin Islands” is being reviewed to meet objective 4. A no-cost extension was requested and approved to summarize results for publication.

Impacts and Contributions/Outcomes

Data from these studies indicate that leucaena and lablab can be used efficiently and economically in different feeding system in the U. S Virgin Islands. To date, this project has identified three legumes (Desamnthus, glycine, and lablab) with potential for use as small ruminant feed and for incorporation in sustainable pasture systems in the U. S Virgin Islands. Sound management practices to favor persistence of these legumes in the farming systems used in the Virgin Islands have been developed and discussed with farmers during field days and workshops. Farmer co-operator farms, today, serve as a model for managing productive grass-legume pastures. With the provision of low-input and high quality legume forages, resource-limited small ruminant farmers have been able to up-grade their sheep and goat herd. Three goat farmers on St. Croix introduced pure-bred Boer goats to improve their Spanish-native goat herd. In addition, Sheep farmers have introduced Doper Rams to cross with the St. Croix white hair sheep for improved hybrid vigor.


Valencia, E. and G. D’Souza. 2002. Factsheet: Pasture establishment in the U.S. Virgin Islands. University of the Virgin Islands, Agriculture Experiment Station Publication. 4 p.

Valencia, E., L.E. Sollenberger, and G. D’Souza. 2002. Factsheet: Managing pasture resources. University of the Virgin Islands, Agriculture Experiment Station Publication. 4 p.

Valencia, E. 2002. Legume and N fertilization effects o growth of St. Croix White hair sheep on guineagrass (Panicum maximum Jacq.) pastures. p.267. In: Proc. of the American Forage Grassland Council. Bloomington, Minnesota. July 14-17, 2002.

Valencia, E., R.W. Godfrey, and S. Weiss. 2003. Grazing and supplementation effects of Lablab (Lablab purpureus) on weight gains of St. Croix White hair sheep lambs during the dry season. J. Anim Sci. 81: (in press).