A new high-yielding bermudagrass hybrid, Tifton 85, produced 26% higher DM yield (P = .05) with 11% higher IVDMD (P = .05) than Coastal in two 3-yr yield trials. Tifton 78 and Tifton 85 were established in duplicate .81-ha pastures in 1988 and were grazed during 1989, 1990, and 1991 using a variable stocking rate method. Four tester steers per pasture with 269 kg initial BW grazed continuously for 169 d/yr beginning in April. Forage mass, targeted at 2,800 kg of DM/ha, was maintained by adjusting stocking rates at 14-d intervals to correspond with ground-level forage samples taken at 14-d intervals. Pastures received 84 kg of N/ha in March, June, and August of each year. Nutritive value was assessed using whole masticate samples from two esophageal cannulated steers grazing each pasture in late May, mid-July, or early September. The 3-yr mean masticate analyses revealed similar CP for Tifton 78 and Tifton 85 in May and July, but higher (P < .05) CP for Tifton 85 than for Tifton 78 in September. The IVDMD was higher (P < .05) in May and September for Tifton 85 than for Tifton 78; and, mean and medium particle sizes were greater (P < .05) for Tifton 85 than for Tifton 78 in May, July, and September samples.(ABSTRACT TRUNCATED AT 250 WORDS)
This paper describes the restrictions that make improved recurrent restricted phenotypic selection (RRPS) more efficient than mass selection for increasing Pensacola bahiagrass forage yields. Eight cycles of RRPS have given a consistent first‐year space‐plant forage yield increase of 16.4% per cycle. Cycle 6, compared with commercial Pensacola bahiagrass as the control, yielded 91% more in the spaced‐plant‐progress test and 84% more in a seeded small‐plot test. Cycle 4 yielded 16% more liveweight gain than the control in a 3‐year replicated grazing trial which was expected based on forage yields from a small plot clipping test. In a seeded test, Cycle 6 yielded two‐thirds as much as F1 hybrid 2 × 3 in the first year and almost as much as the hybrid in the unusually dry second year. In vitro dry matter digestibility of the forage was not reduced by six cycles of RRPS. Improved RRPS allows one cycle per year and is four times more efficient than ordinary mass selection in increasing bahiagrass yields.
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