DIRECT OBSERVATION OF BITING FOR STUDYING GRAZING BEHAVIOR OF GOATS AND LLAMAS ON GARRIGUE RANGELANDS

In any heterogeneous environment, classical methods used to estimate d aily DMI and daily diets of grazing animals are difficult to implement . To investigate the grazing behavior of a goat and a Ilama, feeding o n the garrigue in their respective flock, we therefore used a techniqu e based on direct observation of biting. The observations were carried out in spring and early summer, and under decreasing vegetation avail ability conditions for each season. In high vegetation availability co nditions, daily DMI at pasture was 44 g DM/kg BW0.75 (6th day in paddo ck: d6) and 76 g DM/kg BW0.75 (d3) for the goat vs. 42 g DM/kg BW0.75 (d3) and 53 g DM/kg BW0.75 (d3) for the Ilama during spring and summer , respectively. The goat's diet (% DMI) was mainly composed of browse (89 to 99%), whereas the Ilama's consisted of grass (55 to 78%). The c hoices made by the two animals were confirmed by the evolution of the consumption levels of the forage species in each paddock. As vegetatio n availability decreased, the daily DMI of the two animals fell and th eir requirements were no longer satisfied. In spite of shifts in daily diets, grass DM always accounted for at least 35% of the Ilama's diet but never exceeded this value for the goat. Diurnal variations were o bserved in the diets of both animals, which may reveal differences in grazing strategies: the goat seemed to be selective first, whereas the Ilama tried to eat quickly first. The morphological structure of brow se species influenced instantaneous intake rates in the two animals. B ecause both animals occasionally focused on plant species that permit high intake rates, the curve of cumulative DMI within a meal vs. time bounced from time to time, and could not be adjusted to a mono-exponen tial model as with penned animals. The technique we used thus not only provides consistent data on the daily intake and daily diets of goats and Ilamas grazing a shrubby, heterogeneous environment but also info rmation on the process of diet selection itself along the grazing jour ney.