Very few trials have been conducted on the use of Calopogonium caeruleum in ruminants. The general consensus is that its low palatability makes it unsuitable for grazing.
Calopogonium caeruleum is not well consumed by ruminants. It has been reported to be avoided by sheep and cattle (Pillai et al., 1985; Middleton et al., 1982). It was referred to as a non-palatable cover crop species in rubber and oil palm plantations in Malaysia (Wahab, 2001). When caeruleum calopo is grown with other species, it is not, or only slightly, consumed. Depending on climatic conditions or other causes, animals progressively overgraze the other species leading to their decrease, or disappearance in extreme situations (Pillai et al., 1985; Middleton et al., 1982; Chong et al., 1991). It is recommended not to cultivate Calopogonium caeruleum alone for grazing, and when associated with other species it is necessary to adapt carefully the stocking rate to the availability of those species.
In sacco DM degradability (48 h) of both wet (50%) and dry (40%) season material was quite low, which could be explained by the high fibre content (Muhr et al., 1999a).
In Australia, Brahman cross steers (300 kg) allowed to graze continuously for 3 years on a Guinea grass/caeruleum calopo pasture, at 2.5 to 3.75 steers/ha, had an average daily weight gain of 0.49 to 0.54 kg/head the first two years, and only 0.2 kg/head the third year. Over this last year the Guinea grass proportion dramatically decreased from an average of 50% to almost 0, and Calopogonium caeruleum proportion increased from 30 to 70% (Middleton et al., 1982).
In Malaysia, two studies led to similar negative results with sheep grazing multispecies pastures including Calopogonium caeruleum in rubber plantations. Under immature rubber trees the proportion of caeruleum calopo increased from 5 to 40% after 8 months (Pillai et al., 1985). When sheep grazed a pasture with a high yield of 2 to 2.5 t DM/ha under immature rubber trees at various stocking rates (4 to 14 sheep/ha), and were supplemented indoors with 100 g/d of palm kernel cake, they neglected Calopogonium caeruleum even at high stocking rates, which led to 93-99% proportion of caeruleum calopo after several months of grazing. The average daily weight gain decreased with increasing stocking rate from 106 to 84 g/d. Under mature rubber trees, pasture yield was much lower (0.5 to 0.8 t/ha) and sheep allowed to graze at 2 to 8 sheep/ha and supplemented indoors with 100 g/d of palm kernel cake consumed all forage species including caeruleum calopo. Daily weight gain dramatically dropped from 99 to 26 g/d when stocking rate increased from 2 to 4 sheep/ha and was almost null (19 to 11 g/d) at the highest stocking rates (Chong et al., 1991).