Stubble Height Effects on Limpograss Pasture Characteristics and Performance of Beef Heifers

Limpograss (Hemarthria altissima [Poir.] Stapf. & C.E. Hubb.) is a C4 species used in Florida beef production systems because of its cool-season growth, persistence on poorly drained soils, and high yield and digestibility. Animal performance on limpograss pastures, however, has been limited by low herbage crude protein (CP). This study evaluated the effect of canopy height of limpograss pastures and N supplementation of grazing cattle on sward characteristics and weight gain and blood urea N (BUN) concentration of yearling beef heifers. Under continuous stocking, six treatments were imposed that included all combinations of three stubble heights (20, 40, and 60 cm) and two N-supplement levels (S, supplemented; NS, unsupplemented). During 1998 and 1999, treatments were replicated twice and arranged in a completely randomized design. Seasonal (84 d) daily gains from heifers grazing limpograss pastures were not different (p= 0.25) between the two years and averaged 522 g. For the intermediate stubble, 40-cm, there was no effect of supplementation on daily gains (P= 0.1), but daily gain increased 40 and 70% due to supplementation (P \u3c 0.01) of heifers on pastures grazed to 20 and 60 cm, respectively. These data show that limpograss stubble height has an impact on pasture nutritive value affecting daily gains. Stubble height of approximately 40 cm seems to provide optimum gains of animals receiving no N supplement on continuously stocked pastures

Effect of Storage Time and Temperature on Recovery of \u3ci\u3eSynergistes jonesii\u3c/i\u3e from Rumen Fluid and Feces

Synergistes jonesii is a rumen bacterium that degrades 3,4-dihydroxypyridine (3,4 DHP), the toxic breakdown product of mimosine in leucaena (Leucaena leucocephala). Fecal culture is the most practical way to determine S. jonesii presence in zoological ruminants, particularly if feces can be collected from night penning facilities. Fresh rumen fluid and fecal or fecal slurry (sheep [Ovis spp.] only, 1:4 wt to vol. feces and culture media) from cattle (Bos spp.) and sheep, known to be colonized by S. jonesii, were subjected various storage times (0, 6, 12, and 24 h) and temperatures (5, 23, and 38 oC). Samples were inoculated into a culture medium that contained 3,4 DHP. In general, storage temperature had no affect on detection frequency. Regardless of animal species, detection of S. jonesii was higher (P=0.001) in rumen (97%) than in fecal (40%) samples and level of detection in rumen samples was relatively unaffected by storage time. Detection frequency was similar for both fecal sample types regardless of time (34% fecal vs. 29% fecal slurry). For all fecal samples, detection frequency generally exhibited a linear decline (P=0.01) with time. This study showed that it will be important to collect fresh fecal samples (\u3c 6-h old) from night penning facilities, and because detection levels were low in fecal material, fecal assay would be most accurate on a whole herd rather than an individual animal basis

Measurement of the Positive Muon Lifetime and Determination of the Fermi Constant to Part-per-Million Precision

We report a measurement of the positive muon lifetime to a precision of 1.0 parts per million (ppm); it is the most precise particle lifetime ever measured. The experiment used a time-structured, low-energy muon beam and a segmented plastic scintillator array to record more than 2 x 10^{12} decays. Two different stopping target configurations were employed in independent data-taking periods. The combined results give tau_{mu^+}(MuLan) = 2196980.3(2.2) ps, more than 15 times as precise as any previous experiment. The muon lifetime gives the most precise value for the Fermi constant: G_F(MuLan) = 1.1663788 (7) x 10^-5 GeV^-2 (0.6 ppm). It is also used to extract the mu^-p singlet capture rate, which determines the proton's weak induced pseudoscalar coupling g_P.Comment: Accepted for publication in Phys. Rev. Let

Sheep research and development, 1965

Sheep research and development - 1965 / D. S. Bell -- Improvement of lamb meat production through breeding / D. S. Bell, C. F. Parker and L. E. Kunkle -- Breeding performance of Targhee ewes maintained under bluegrass pasture vs. ladino clover pasture vs. barn confinement management / D. S. Bell and C. F. Parker -- Ram effect on ewe fertility / C. F. Parker and D. S. Bell -- Creep feeding native lambs / J. K. Judy, J. H. Cline, W. J. Tyznik, C. F. Parker and D. S. Bell -- Studies of the protein and energy requirements of growing-finishing lambs / R. R. Johnson, J. H. Cline and D. S. Bell -- Visual and ultrasonic evaluation of creep fed slaughter lambs / C. F. Parker, D. L. Davis and J. K. Judy -- Forages for summer feeding of farm flocks / R. W. Van Keuren -- Characteristics of consumer-preferred lamb carcass / L. E. Kunkl

Improved Measurement of the Positive Muon Lifetime and Determination of the Fermi Constant

The mean life of the positive muon has been measured to a precision of 11 ppm using a low-energy, pulsed muon beam stopped in a ferromagnetic target, which was surrounded by a scintillator detector array. The result, tau_mu = 2.197013(24) us, is in excellent agreement with the previous world average. The new world average tau_mu = 2.197019(21) us determines the Fermi constant G_F = 1.166371(6) x 10^-5 GeV^-2 (5 ppm). Additionally, the precision measurement of the positive muon lifetime is needed to determine the nucleon pseudoscalar coupling g_P.Comment: As published version (PRL, July 2007