In Situ Disappearance Parameters of Ecoturf and ′Florigraze′ Perennial Peanuts.

Perennial peanut (Arachis glabrata Benth.) is a widely used warm-season legume in Florida. Ecoturf is a germplasm selected in Florida with superior forage accumulation and nutritive value; however, there is limited information about regrowth interval effects on Ecoturf nutritive value. The objective of this study was to investigate the effects of regrowth interval in in situ disappearance of CP and NDF fractions. The experiment was conducted in Ona, FL, from July to October of 2014 and 2015. Treatments were the split-plot arrangement of ‘Florigraze’ and Ecoturf (main plots) harvested at 4, 8, and 12 wk of regrowth interval (sub-plots), distributed in a randomized complete block design with four replicates. Samples were incubated in two rumen-fistulated steers for 0, 3, 6, 9, 12, 24, 36, and 72 h. Crude protein and NDF disappearances were calculated according to Ørskov and McDonald (1979) and McDonald (1981). Effective disappearance was estimated by fixing the passage rate at 0.05 h^-1. Ecoturf had greater CP concentration than Florigraze (193 vs 168 g kg^-1). Crude protein was greater at 8 than 12 wk (188 vs 171 g kg^-1); however, both intervals were similar to 4 wk (181 g kg^-1). There was no difference in CP effective disappearance between genotypes (mean = 715 g kg^-1); however, it was greater for 8 than 4 and 12 wk (737 vs 703 g kg^-1). Neutral detergent fiber concentration was not affected by either genotype or regrowth interval (mean = 398 g kg^-1). Ecoturf had greater NDF effective disappearance than Florigraze (367 vs 311 g kg^-1). Ecoturf may replace Florigraze in ruminant diets when greater degradable CP and NDF are required. Harvesting at 8-wk regrowth interval is an effective strategy to improve perennial peanut nutritive value.