Plant litter is an important nutrient pool in grassland ecosystems. Management practices affect litter quality and may affect nutrient dynamics in pastures by altering the rates of nutrient mineralization and immobilization. The effect of management intensity on litter decomposition and nutrient disappearance was evaluated in a litter bag study on continuously stocked 'Pensacola' bahiagrass (Paspalum notatum Flü gge) pastures growing on Pomona and Smyrna sands. Treatments were three management intensities: Low (40 kg N ha 21 yr 21 and 1.3 animal units [AU, one AU 5 500 kg live weight] ha 21 stocking rate [SR]), Moderate (120 kg N ha 21 yr 21 and 2.7 AU ha 21 SR), and High (360 kg N ha 21 yr 21 and 4.0 AU ha 21 SR). Litter relative decomposition rate (k) was greater for High (0.0030 g g 21 d 21 ) than Low (0.0016 g g 21 d 21 ). Litter N, acid detergent insoluble N (ADIN), and lignin concentrations were greater for High than the other intensities at the end of the 168-d incubation period because of faster decomposition of soluble compounds. Across management intensities, approximately one-half of litter N remaining at the end of the incubation period was bound to acid detergent fiber (ADF). Net N mineralization through 128 d of incubation was only 200 to 300 g kg 21 of total N. Increasing management intensity resulted in faster litter turnover and greater nutrient release, but nutrient release from litter was small and significant quantities of nutrients were immobilized even under the most intensive management.

Over 2 yr, a total of 96 steers (approximately 7 mo of age) were allocated to 1 of 4 weaning management strategies: 1) control: weaned on the day of shipping; 2) creep-fed: allowed free-choice access to concentrate before weaning and shipping; 3) preweaned: weaned and provided supplemental concentrate on pasture before shipping; and 4) early-weaned: weaned at 70 to 90 d of age and kept on pasture. On the day of shipping, steers were loaded together onto a commercial livestock trailer and transported 1,600 km over 24 h before being received into the feedlot. At the feedlot, steers were penned by treatment (4 pens/treatment) and provided access to free-choice hay and concentrate in separate feeding spaces. Samples of blood were collected on d 0, 1, 4, 8, 15, 22, and 29 relative to shipping. Steer performance was assessed over the receiving period, including DMI of hay and concentrate, ADG, and G:F. Predetermined contrasts included control vs. early-weaned, creep-fed vs. preweaned, and control vs. creep-fed and preweaned. Overall ADG was greater (P < 0.01) for early-weaned vs. control steers (1.39 vs. 0.88 kg). In wk 1, early-weaned steers consumed more concentrate and less hay compared with control steers (P < 0.03), and preweaned steers consumed more concentrate (P < 0.01) but a similar amount of hay (P = 0.75) compared with creep-fed steers. Average DMI was greater for preweaned compared with creep-fed steers (2.84 vs. 2.50% of BW; P = 0.01) and tended to be greater for early-weaned compared with control steers (2.76 vs. 2.50% of BW; P = 0.06). Feed efficiency of early-weaned steers was greater than that of control steers (G:F = 0.17 vs. 0.12; P < 0.01) but similar for preweaned compared with creep-fed steers (P = 0.72). Plasma ceruloplasmin concentrations were less (P < 0.05) in control vs. early-weaned steers on d 0, but increased sharply after shipping and were greater in control vs. early-weaned steers on d 15 and 22 (P < 0.05). Creep-fed steers also experienced greater (P < 0.05) plasma ceruloplasmin concentrations than preweaned steers on d 29. These data suggest that early-weaned steers have improved performance in the feedlot compared with steers weaned directly before transport and feedlot entry. Differences in preshipping management appear to significantly affect measures of the acute phase protein response in steers.

Plant litter is an important pathway of nutrient return to the soil in grazed swards, but the effects of pasture management on litter mass and composition are not well understood. This research evaluated the effect of management intensity, defined in terms of N fertilization and stocking rate (SR), on litter mass, deposition rate, and chemical composition in continuously stocked 'Pensacola' bahiagrass (Paspalum notatum Flü gge) pastures growing on Pomona and Smyrna sands. Treatments were three management intensities: Low (40 kg N ha 21 yr 21 and 1.3 animal units [AU, one AU 5 500 kg live weight] ha 21 SR), Moderate (120 kg N ha 21 yr 21 and 2.7 AU ha 21 SR), and High (360 kg N ha 21 yr 21 and 4.0 AU ha 21 SR). Greater management intensity resulted in less litter mass on the pasture early in the growing season and more litter mass later in the season. Rate of litter deposition was generally greatest for High and ranged between 23 and 40 kg organic matter (OM) ha 21 d 21 compared with 13 to 30 kg OM ha 21 d 21 for Low and Moderate management intensities. Increasing management intensity from Low to High resulted in greater litter N (14.1 vs. 22.9 g kg 21 ) and P (0.8 vs. 1.3 g kg 21 ) concentrations and lesser C:N (f40 vs. 22), C:P (649 vs. 433), and lignin:N (5.8 vs. 4.4) ratios. More intensive pasture management was associated with greater litter deposition rate and litter quality than less intensive management, suggesting a larger nutrient contribution from litter in intensively managed swards.

Forage legumes increase nutritive value and provide N to grass‐based grazing systems. Few legumes have a long stand life in the southeastern US, but persistence is documented for rhizoma peanut (RP; Arachis glabrata Benth.). Several RP introductions have been released recently from the University of Florida, but their responses to grazing management have not been evaluated. The objective was to determine productivity, persistence, and nutritive value of three RP cultivars (‘Florigraze’, ‘UF Peace’, and ‘UF Tito’) and the germplasm Ecoturf grazed every 3 or 6 wk to remove 50 or 75% of pre‐grazing canopy height. Herbage accumulation (HA) was not different among RP entries and averaged 8790 and 6210 kg ha‐1 in Years 1 and 2, respectively. Greater HA occurred for the regrowth interval of 6 wk vs. 3 wk in the 50% removal treatment (8040 and 7010 kg ha‐1, respectively), and the response approached significance (P = 0.073) for the 75% treatment (7800 vs. 7140 kg ha‐1, respectively). Treatments had minimal effect on nutritive value, and all entries had crude protein (CP) ≥ 140 g kg‐1 and in vitro digestible organic matter (IVDOM) ≥ 660 g kg‐1. Grass encroachment was greater in Ecoturf and Florigraze when grazed every 3 wk (13 and 24%, respectively) than every 6 wk (7 and 15%, respectively), but regrowth interval did not affect grass percentage in Peace and Tito. New RP cultivars and germplasm had similar HA as Florigraze, but also greater percentage RP and lesser weed frequency than Florigraze, especially under frequent or close grazing.

Brahman × British crossbred heifers (n = 40 and 38 heifers in yr 1 and 2, respectively) were used to evaluate the effects of calf weaning age and subsequent management system on growth and reproductive performance. On d 0, heifers were ranked by BW (89 ± 16 kg) and age (72 ± 13 d) and randomly assigned to a conventional management group that was normally weaned on d 180 (NW; n = 10 heifers annually) or early weaned (EW) on d 0 and 1) limit fed a high-concentrate diet at 3.5% of BW (as fed) in drylot until d 180 (EW180; n = 10 heifers annually), 2) limit fed a high-concentrate diet at 3.5% of BW (as fed) in drylot until d 90, then grazed on Bahiagrass pastures until d 180 (EW90; n = 10 heifers annually), or 3) grazed on annual ryegrass pastures until d 60 (yr 1; n = 10 heifers) or 90 (yr 2; n = 8 heifers), then on Bahiagrass pastures until d 180 (EWRG). On d 180, all heifers were grouped by treatment and rotated on Bahiagrass pastures until d 390. Grazing heifers were supplemented at 1.0% BW until d 180 and at 1.5% BW from d 180 to 390. From d 0 to 90, EW180 and EW90 heifers were heavier (P ≤ 0.02) than NW and EWRG heifers, whereas NW heifers tended (P = 0.09) to be heavier on d 90 than EWRG heifers. In yr 1 and 2, EW180 heifers were heaviest (P < 0.0001) on d 180. In yr 1, EWRG heifers were lightest (P < 0.0001), whereas EW90 and NW heifers had similar BW (P = 0.58). Conversely, EW90, EWRG, and NW heifers achieved similar BW on d 180 of yr 2 (P ≥ 0.18). Positive correlations were detected (P ≤ 0.05) between liver IGF-1 mRNA abundance on d 90 and ADG from d 0 to 90 and between liver IGF-1 mRNA abundance on d 180 and ADG from d 90 to 180. The EW180 heifers were youngest (P ≤ 0.01) at puberty. From d 260 to 340, the percentage of pubertal heifers was greater (P ≤ 0.03) for EW90 vs. NW heifers but did not differ (P ≥ 0.15) between EWRG and NW heifers. The ADG from d 0 to 90 and the plasma IGF-1 on d 90 and 180 explained approximately 34% of the variability in age at puberty. In summary, the EW90 and EW180 heifer management systems evaluated in this study altered the BW at the time of NW and were good alternatives for anticipating puberty achievement compared to NW heifers.

The increasing cost of commercial fertilizers and environmental problems associated with improper fertilization management have prompted the need to re-examine commercial N sources that can effectively supply N to pastures while minimizing N losses. This 3-year study evaluated the effects of selected N sources on bahiagrass (Paspalum notatum Fl€ ugge) responses, soil properties and N losses. Treatments consisted of a factorial combination of 6 N sources [(i) ammonium nitrate (AN), (ii) ammonium sulphate (AS), (iii) urea (U), (iv) urea treated with Agrotain (U + Agrotain), (v) SuperU and (vi) ammonium sulphate nitrate] and 3 N levels (0, 60 or 120 kg ha À1 year À1 ), replicated three times. Bahiagrass dry-matter yield (DMY), crude protein (CP) concentration, N uptake and recovery were not affected by N source, with the exception of AN that resulted in reduced DMY in 2010 compared with the other sources. Bahiagrass DMY, CP concentration, N uptake and recovery increased linearly as N levels increased. Nitrogen fertilization showed no effect on soil pH or soil N accumulation. Soil pore-water N concentrations from treatments fertilized with N were similar to the control plots indicating no threat to the environment. At the N levels evaluated in this study, selection of N source should be based on the fertilizer cost.

Early weaning of calves (Bos spp.) increases pregnancy rates of beef cows; however, there is little information on nutritional management of the weaned calf on pasture. This research evaluated the effect of concentrate supplementation level on performance of early weaned (90 d of age) beef calves grazing annual ryegrass (Lolium multiflorum Lam.)–rye (Secale cereale L.) mixtures on Adamsville (uncoated, hyperthermic, Aquic Quartzipsamment) and Pomona (sandy, siliceous, hyperthermic Ultic Alaquod) sands. Three levels of supplement (10, 15, and 20 g kg−1 of calf body weight [BW]) were evaluated in a completely randomized design with three replicates. The concentrate contained 146 and 700 g kg−1 of crude protein (CP) and total digestible nutrients (TDN). Pastures were rotationally stocked with a 7‐d grazing and 21‐d rest period. Two calves were assigned as testers to each pasture, and additional animals were used to maintain a similar herbage allowance across treatments. There was no effect of concentrate supplementation level on herbage mass, accumulation, allowance, or nutritive value. Calf average daily gain (ADG; 0.74–0.89 kg), liveweight gain (LWG) per hectare (950–1320 kg), and stocking rate (SR; 5.5–6.5 animal units [AU] ha−1) increased linearly, and forage intake decreased linearly (18–11 g kg−1 BW) as concentrate rate increased. Grazing time was 284, 230, and 234 min d−1 (linear and quadratic effects) for the 10, 15, and 20 g kg−1 BW supplement treatments, respectively. Feeding systems with modest levels of supplementation (10 g kg−1 BW) of calves grazing cool‐season grasses are practical options for early weaned calves during winter in the southeastern USA.

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