Intensive management of tropical hair sheep in Martinique (FWI)

Abstract

Martinique (61°W, 14.4°N) is a 1100 km2 large volcanic island of the Caribbean (Lesser Antilles). The main grassland areas receive less than 2 meters rainfall yearly, and have a marked dry season. The largest area is situated in the south-eastern irrigated area ("PISE", 10 % of the agricultural area of the island). SECI (experimental station on irrigated crops) has been studying the effects of irrigation on sheep breeding for more than 15 years, with the scientific support of INRA. SECI is financed by the local authorities (Conseil General) to improve agriculture in the PISE. A first study (1981-85) showed that local hair sheep responded to the better feeding conditions when Digitaria decumbens pastures are irrigated. The individual production of the ewes increased by 50 %, the stocking rate increased by 300 %. The annual gross margin increased by 12 000 FF per hectare with irrigation. From 1987 to 1992 we compared 2 irrigated and grazed grasses Digitaria decumbens(D.d.) and Cynodon nlemfuensis (C.n.). The milk production of ewes with twin lambs was measured weekly for 3 lambing seasons. Milk yield for the first 30 days was 47.6 vs 39.0 kg and for the first 70 days, 87.1 vs 71.7 kg, for D.d. and C.n. respectively. Nevertheless, analysis showed that the differences in milk production did not explain all the differences in the lamb growth rates. Possible hypotheses of greater parasite loads, higher energy expenditure in walking, lower levels of grass intake and the possible toxicity of C.n. (cyanogenic glucosides) are suggested. Performance analysis revealed that D.d. was better than C.n. for sheep production (2.25 vs 1.61 lamb weaned per ewe yearly, 1250 vs 966 kg liveweight of lamb weaned yearly per hectare). If fertility (88 % vs 85 %) and prolificacy (180 %) are not different, mortality at weaning is lower on D.d.(10.4 %), compared with C. n. (22.3 %). The growth performances are also different (A.D.G.10-30 d 175 vs 147 g/d; A.D.G.30-70 d: 137 vs 120 g/d, for D. d. and C. n., respectively). The average live span of the ewes decreases on C.n. from 4 to 3 years, after the second year of experiment.