Vertical Distribution of Botanical Components in Four Pastures Mixtures Grazed Solely by Goats

Four different grasses (perennial ryegrass (Lolium perenne L.), prairie grass (Bromus willdenowii Kunth), cocksfoot (Dactylis glomerata L.) and timothy (Phelum pratense L.)) sown with white clover (Trifolium perenne L.) were evaluated under rotational goat grazing lo 10 cm in a cool temperate environment. Detailed measurements of the composition of vertical sward horizons, In spring, summer and autumn, showed significant differences in sward structure between pasture miX:tures. Prairie grass and cocksfoot swards were the tallest (>25 cm) in spring with the top of the sward dominated by grass leaf. The prairie grass sward was also taller in summer. Distribution of grass stem in spring rc0ected the reproductive development of swards, perennial ryegrass and prairie grass having the greatest amount of stem especially in the upper horizons (> 10 cm). Prairie grass continued lo have significantly greater amounts of grass stem during summer owing to recurrent Oowering. Timothy was the shortest sward, especially in autumn (5-10 cm). Timothy stood out as having significantly more clover (P<0.05) than all other mixtures in all horizons; it also contained significantly less dead and grass stem than the other swards. In all pasture mixtures iJie amount of dead material in the base of the sward (<10 cm) increased significantly (P<0.05) over the year. The tall swards (prairie grass and cocks foot) also had proportionally more dry weight in the middle horizons of the sward in spring and summer than ryegrass.