The role of learning and experience in the development of dietary choice by sheep and goats

摘要

To test the role of maternal influence on the development of diet preference, sheep (Scottish Halfbred ewes and Suffolk x twin iambs) and goats (British Saanen does and pure-bred twin kids) grazed four mixed swards of perennial ryegrass (Lolium perenne L. cv Parcour) and white clover (Trifolium repens L. cv Kent Wild White). Following synchronised parturition, offspring were either reared naturally or cross-fostered between animal species. The offspring were weaned at 18 weeks of age and they continued to graze the mixed swards (ca 20 % clover) until their preference for grass or clover was tested at 21 weeks. For the test there were 12 plots, each 50 × 50 m, 50 % clover : 50 % grass by area (50 × 25 m of clover monoculture alongside 50 × 25 m ofgrass monoculture) each at 6 cm sward surface height. Groups of four animals were released at 10:30 h onto the dividing line between grass and clover. Each of the four treatments was replicated three times and the preference test ran for 72 h. The behaviour (grazing, ruminating or idling) of one focal animal per group was observed during daylight hours (07:00 to 20:00 h) and whether it was positioned on grass or clover.