L'association d'ovins et de bovins sur prairies irriguées en Martinique

Abstract

The mixed grazing of sheep with cattle in Pangola irrigated pastures was studied in Martinique (FWI) over a two year period by measuring the animal and surface performances recorded for five production systems in pasture: "Martinik" hair ram or ewe lambs, Brahman heifers alone, ram or ewe lambs mixed with heifers. No difference was recorded between systems in stocking rates expressed as kg of metabolic body weight (MBW) per hectare ranging between 488 and 536 kg MBW/ha. Mixed grazing increased the body weight gain for ram lambs (13 %) and to a lesser extent, ewe lambs. Mixed grazing increased heifer growth rate by 10 % but the differences were not significant. This increase in production was lin-ked to a lower infection rate of the sheep by Huemonchus contortus, particularly for the ram lambs, to a decrease in herbage mass and to an improvement in the sward structure (leaf to stem ratio). The analysis of herbage production showed that mixed grazing of sheep and cattle limited nitrogen losses by decreasing the residual herbage mass. However, control of nitrogen fertilization remains the major constraint limiting the improvement of intensive grazing systems in the humid tropics.