In Situ Crude Protein and Dry Matter Disappearance of Stockpiled Limpograss.

Limpograss [Hemarthria altissima (Poir.) Stapf et C.E. Hubb.] is a suitable forage for autumn stockpiling due to greater herbage accumulation and digestibility than other warm-season grasses at late maturity during the fall-winter in Florida. The objective of this study was to evaluate the effects of stockpiling period on crude protein (CP) and dry matter (DM) ruminal ‘in situ’ disappearance of different limpograss cultivars. The experiment was conducted in Gainesville, FL from August to December 2012. Two new cultivars (Kenhy, and Gib) and the current most planted limpograss cultivar (Floralta) were stockpiled for 8, 12, or 16 wk in a randomized complete block design with three replicates. Samples of each treatment were incubated in two steers (Bos sp.) for 0, 3, 6, 9, 12, 24, 48, and 72 h and the DM and CP disappearance was fitted in the non-linear model proposed by Ørskov and McDonald (1979). The DM and CP fractions were described as A, rapidly degradable; B, potentially degradable; and C, undegradable. There was no difference in DM fraction A among cultivars; however, Kenhy had greater fraction B (600 g kg^-1) than Gib (580 g kg^-1), which was greater than Floralta (540 g kg^-1). Kenhy and Gib had lesser fraction C than Floralta (250 vs. 290 g kg^-1). Forage harvested at 8 wk regrowth interval had the greatest DM fraction B and the least fraction C; however, there was no difference between 12 and 16 wk. Crude protein fraction A (450 g kg^-1) and C (350 g kg^-1) were similar among cultivars but fraction B was greater for Kenhy and Gib than Floralta (240 vs. 180 g kg^-1). Crude protein fraction A was greater at 8 and 12 wk than 16 wk regrowth interval (500 vs. 420 g kg^-1). Forage harvested at 8 wk had the greatest CP fraction B (250 g kg^-1) and there was no difference between 12 and 16 wk (170 g kg^-1). Crude protein fraction C was the least at 8 wk (240 g kg^-1), followed by 12 wk (342 g kg^-1), and 16 wk (390 g kg^-1). The new limpograss cultivars presented superior CP and DM disappearance when compared to the current most planted cultivar, which could positively impact animal performance. Longer stockpiling regrowth periods may enhance herbage accumulation but decreased DM and CP disappearance.