Limpo grass (Hemarthria altissima)

Limpo grass is well-grazed by ruminants. However, due to its prostrate habit, animals cannot fully utilize it. It is considered particularly valuable for autumn and early dry-season grazing when other grasses are of low palatability and nutritive value (Lacerda et al., 2004; Göhl, 1982).

In Florida, several experiments reported in vitro OM digestibility values ranging from 70%, in young limpo grass, down to 40% in mature stockpiled grass. Limpo grass is more digestible than other summer grasses such as Bahia grass (Paspalum notatum) and it maintained its digestibility with advancing maturity better than Paspalum notatum (Newman et al., 2009a; Sollenberger et al., 1989). A similar pattern was reported in steers where unlike other grasses (Cynodon dactylon, Paspalum notatum and stargrass Cynodon spp.), the in vivo OM digestibility of Hemarthria altissima forage was maintained (57-58%) or increased (46 to 58%) between 4 and 10 weeks (Arthington et al., 2005).

Studies on continuously grazed (continuous stocking) limpo grass pastures have reported average daily gains of cross-bred yearling heifers that range from 225 to 665 g/d. In cow-calf operations, cows can gain 1 unit of body condition score when grazing limpo grass pastures during the summer. However, the relatively low protein content of the grass may result in protein deficiencies in cattle grazing it. For instance, cows grazing limpo grass during the winter will lose body condition if their diet is not adequately supplemented. Protein supplements are recommended for cattle grazing stockpiled limpo grass. The quantity of supplemental protein required increases as the plant is defoliated, and a higher proportion of stems are consumed (Newman et al., 2009a). 

In Florida, several strategies have been used successfully to avoid such deficiencies, including protein supplementation, growing Hemarthria altissima with a legume, addition of N fertilizer and managing grazing for consumption of leaves rather than stems (Newman et al., 2009a; Kretschmer et al., 1979). Feeding growing cattle that were grazing limpo grass in a six-pasture rotational grazing program (5 weeks between grazings) with 113-225 g/d of crude protein from a urea-based supplement improved animal gains (from 180 to 320 g/d). Heifers grazing stockpiled limpo grass and grazing annual ryegrass three times per week had the same performance as heifers receiving 2.3 lb/head/d of cottonseed meal. Interseeding limpo grass with aeschynomene improved animal gains nearly as much as protein supplements. Increasing N fertilizer from 50 kg N/ha to 145 kg N/ha increased protein intake and daily gains in beef cattle. Additional gain (90 g/day) was found when a urea-based supplement was fed at the 145 kg N/ha level. However, a protein supplement did not improve gains in growing cattle that were rotationally grazed at a stocking rate allowing significant amounts of residual forage during the summer, presumably due to a higher leaf-to-stem ratio. Under continuous grazing, maintaining a pasture height of about 40 cm resulted in better animal gains and stand persistence than maintaining a height of 20 or 60 cm. Replacement heifers grazing stockpiled limpo grass and receiving 0, 1.1, or 2.3 kg/head/d of cottonseed meal gained 315, 590 and 770 g/d, respectively (Newman et al., 2009a).