Post-grazing residue control, season and forage characteristics of tropical pastures grazed by goats and ewes in Guadeloupe (FWI)

Abstract

Creole goats (G) and Martinik sheep (S) were reared on rotationally grazed tropical pastures to test the effect of post-grazing residue control on forage production, and morphological and chemical composition. A system in which residuals were mown (RM) was compared to the control system (RR) during three seasons (dry, intermediate and rainy) over one year. Mean weight of herbage mass at the beginning of the grazing periods differed among treatments, 3,123 vs. 5,010 kg DM/ha in GRM and GRR plots, and 2,538 vs. 3,753 kg DM/ha in SRM and SRR plots, respectively. The sward structure was improved in the RM systems. A higher leaf proportion (42% vs. 36%), a similar stem proportion (around 43%), and a lower debris proportion (15% vs. 19%) were noted in GRM. In the SRM and SRR plots, corresponding values were for leaves 46% vs. 36%; stems, 36%; and debris, 17% vs. 20%. The 29% difference in herbage accumulation in favor of goat over sheep pastures appears to be related to their higher nitrogen nutrition index (82 vs. 60%, respectively). Seasonal effects were discussed. Chemical composition of the forage did not differ between treatments or among seasons. The crude protein content reached 115 and 90 g/kg DM before grazing and 85 and 65 g/kg DM after grazing in goat and sheep plots, respectively. Forage characteristics did not limit kid and lamb growth, and the average daily live weight gain did not differ between treatments. It is recommended that the post-grazing forage residues be consumed by associated herbivores to achieve the same effect as mowing in a more practical way.