Effects of silvopastoral areas on milk production at dual-purpose cattle farms at the semi-humid old agricultural frontier in central Nicaragua.

摘要

In extensive cattle production systems, the composition of grazing areas may significantly influence productivity. In dual-purpose cattle production systems in the lowland tropics, pasture lands with trees, so-called silvopastoral areas, are considered as being important, particularly to facilitate the management of crossbred European native cattle. The aim of the study was to quantify the effects of silvopastoral areas on production at dual-purpose cattle farms in the semi-humid lowlands of central Nicaragua. The relationships between seasonal milk production and herd data, and the proportions of land use types were examined for 74 farms by stepwise regression analysis. The results showed significant positive effects on saleable milk production of areas of degraded pasture (DGPS) (P<0.001), natural and cultivated pastures with moderate tree density (MTCP and MTNP) (P<0.05), and cultivated pasture with low tree density (LTCP). However, negative effects of land use types under natural pasture with low tree density (LTNP) (P<0.01) was also observed, suggesting that on smaller farms, high stocking rates resulted in overgrazing. Analysis by season confirmed the positive effects of DGPS on saleable milk production at the end of the dry season (P<0.01), and of MTNP at the beginning of the wet season (P<0.05). This suggests that degraded pasture may be important as a source of cattle feed at the end of the dry season whilst MTNP are particularly important at the beginning of the wet season. The area of Brachiaria brizantha had positive effects on saleable milk production at the end of the dry season (P<0.01), suggesting that the use of this species is an important option for farmers. The study concluded that silvopastoral systems for dual-purpose cattle production developed in the study area by maintaining useful naturally regenerated trees in grazing areas with relatively low stocking rates and limited amounts of supplemental fodder. Increases in the meat:milk price ratio is likely to reduce tree cover. Further studies are recommended on broadleaf plants in the grazing areas and their nutritional values in the dry season, the feasibility of increasing the availability of supplemental fodder for milk production in the dry season, and the impact of land use types on seasonal grazing decisions..