The grazing behavior and diet selectivity of two lamb breeds on secondary successional pastures in the Chiloé Archipelago

Abstract

The aim of this experiment was to investigate the grazing behavior and diet selectivity of the Chilota and Suffolk Down lamb breeds on secondary successional pastures in the Chiloé Archipelago (Chile). Eight Chilota and six Suffolk Down lambs (males) and their dams were selected and marked on their backs with an identification number. A 1-ha paddock of Calafatal (the principal feed resource for ruminants in Chiloé) was used every month. Additionally, every month, eight Chilota lambs and their dams were allowed to graze a 1-ha paddock of naturalized pasture. Data were recorded over a 24-h period once a month for 3 consecutive months through direct observations of grazing behavior. Subsequently, feces were extracted for microhistological analysis. The results showed that the consumption of grasses was highest and the consumption of shrubs the lowest despite the dominance of shrubs in Calafatal. The longer browsing times for Chilota lambs (P=0.02) did not reflect a higher content of shrubs in their feces relative to Suffolk Down lambs (P=0.01). Although the diet composition was similar between breeds and between pastures, the richness of plant species (particularly grasses) and the selection of plants by lambs were higher in Calafatal than in naturalized pasture due to the higher grass content of the naturalized pasture. In summary, Chilota and Suffolk Down lambs grazing Calafatal showed a similar grazing behavior. The longer browsing times of Chilota lambs did not reflect a higher shrub content in their feces relative to Suffolk Down lambs.