Productive response of tropical lambs reared in two contrasting management systems after weaning and using woody forage species

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anglais. A silvopastoral grazing system (SP) was compared with confinement (CF) to determine the growth and general performance of weaned Pelibuey lambs under experimental conditions. Animals were from the Experiment Station “Indio Hatuey” flock of Matanzas, Cuba. The trial began with weaning in March and April at 4 months after lambing, with the lambs weighing around 13 kg, and lasted for 125 days. After being drenched with Levamisol, 25 lambs were grown on the SP with 18 to 21 lambs/ha, and 25 lambs were grown in CF. A rustic shed was used for CF with 1.5 to 1.8 m2 per animal. The CF lambs were fed cut and carried chopped forage (60% Pennisetum purpureum, 40% Morus alba), and dehydrated citrus pulp at 0.8 to 1.0 kg/lamb per day was offered as supplement in both treatments. The nutritive value of the woody forage species established in both systems was determined with the French expression system. Data were analyzed by Proc Mixed procedure of SAS. For the whole experimental period differences (P< 0.001) were obtained for average daily gain and incidence of gastrointestinal parasitism, mainly from Haemonchus contortus (2117 vs. 144 EPG of faeces) for SP and CF feeding systems, respectively. Lambs from CF (88.5 vs. 48.2 g/d) and males (77.8 vs. 58.9 g/d) exceeded SP and females in daily weight gains. Morbidity rate was explicitly higher in SP, and consequently, the survival level was better under CF experimental conditions (8% mortality in SP vs. 0% in CF). Advantages of the CF feeding system were mainly related to the reduced helminthiasis, which influences feed intake and efficiency, morbidity, growth rate, and survival rate as well. Under the particular conditions of this experiment, these results suggest that CF of lambs, adopting integrative approach with rational use of natural and local resources, can be a good alternative for improving the growth and welfare of growing lambs in the tropics.