Walter H. Schacht

Effects of nitrogen fertilization and dried distillers grains supplementation: Forage use and performance of yearling steers

In a 3-yr study, corn dried distillers grains plus solubles (DDGS) were evaluated as a substitute for forage and N fertilizer in yearling steers grazing smooth bromegrass. A total of 135 steers (330 +/- 10 kg) were used in a randomized complete block design to measure the effects of DDGS supplementation and N fertilization on animal and pasture performance. Steers were initially stocked at 6.8 animal unit month (AUM)/ha on nonfertilized smooth bromegrass pastures (CONT), at 9.9 AUM/ha on smooth bromegrass pastures fertilized with 90 kg of N/ha (FERT), or at 9.9 AUM/ha on nonfertilized smooth bromegrass pastures with 2.3 kg of DDGS DM supplemented daily (SUPP). Paddock was the experimental unit, with 3 replications per year for 3 yr. Paddocks were strip-grazed and put-and-take cattle were used to maintain similar grazing pressure among treatment paddocks during the 160-d grazing season. In vitro DM disappearance declined quadratically (P < 0.01), whereas CP and standing crop showed cubic responses (P < 0.01) throughout the grazing season. Crude protein was greater (P < 0.05) for FERT compared with CONT and SUPP. Standing crop was 18% greater (P < 0.01) for FERT than CONT and was 10% greater (P < 0.01) than SUPP. Adjusted stocking rates (AUM/ha) were greater (P < 0.01) for FERT and SUPP compared with CONT. Final BW were greater (P < 0.01) for SUPP steers compared with CONT and FERT steers. Similar results were observed for ADG, with SUPP steers gaining more (P < 0.01) compared with CONT and FERT steers. Total BW gain per hectare was increased (P < 0.01) by 53% with FERT and by 105% with SUPP. Feedlot ADG was similar among treatments (P = 0.88), and SUPP steers maintained their BW advantage through the finishing phase. Dried distillers grains can be used to substitute effectively for N fertilizer by increasing the performance of yearling steers grazing smooth bromegrass and increasing stocking rates compared with nonfertilized pastures.

Soil quality response of reestablished grasslands to mowing and burning

Prescribed burning and mowing are management practices commonly used on grasslands even though there is limited knowledge of long-term effects on soil quality. The influences of mowing and burning on soil quality were determined on 2 reestablished tallgrass sites in eastern Nebraska dominated by silty clay loam soils. Burn treatments included seasonal (i.e., October, May, or July) prescribed burning at either 1-year or 4-year intervals. Mow treatments included seasonal mowing at 4-year intervals. Both burn and mow treatments have been imposed at Site 1 since fall 1981. Only the burn treatments have been applied at Site 2 since fall 1979. Soil quality measurement were made at both sites in summer 1994. Season of application of the mow and burn treatments and season X treatment interactions were not significant. Infiltration rates at Site 1 for the mow and annual burn treatments were slower than for the control, whereas infiltration rate was comparable for the year burn treatments and the control. Unlike Site 1, the 1-year and 4-year burn treatments at Site 2 had similar infiltration rates, and the burn treatments had slower infiltration rates than the control. Generally, soil bulk density, pH, electrical conductivity, total nitrogen content, and organic matter content were similar for all treatments. Results demonstrate that repeated burning or mowing treatments can detrimentally impact infiltration rates on silty clay loam sites; however, soil properties other than those measured would need to be studied to explain infiltration response.

Above-ground biomass yields at different densities of honey mesquite

Dense stands of honey mesquite (Prosopis glanddosa TOR. var. glandulosa) negatively impact livestock handling and herbaceous forage production; however, very little information ls available on the effect of stand density on biomass production of herbage and wood. Our study compared above-ground yields of berbage and wood in undisturbed, cleared, and 3 levels of thinned (100, 300, and 900 stems ha-‘) stands of mesquite. Total removal of the mesquite canopy resulted in a 45 % increase in herbaceous standing crop compared to the control in the first 2 years post-clearing. Herbage yields for the thinning treatments were intermediate although herhage yields for the 900 stems ha-’ (2,017 kg ha-‘) treatment was similar (P > 0.1) to the control (l&49 kg ha-‘) and lower (P 7,500 stems ha-‘). Growth rates of individual mesquite stems were 2- to J-fold greater (P c 0.1) for the 100 and 300 stem ha-’ stands than for the higher-density stands during the relatively wet growing season of 1992. Under the drier 1993 conditions, however, growth rates were similar (P > 0.1) for all treatments. Results indicated that severe thinning to less than 900 stems ha-’ increased the amount of available forage and positively influenced the potential growth rates of the remaining mesquite stems.

Stomatal variability of native warm-season grasses from the Nebraska Sandhills

Soil moisture deficit is usually the major limiting factor for herbage production in the Sandhills of Nebraska. We examined inter-population and interspecific variability in stomatal characteristics and drought tolerance in sand bluestem (Andropogon hallii Vitman), little bluestem [Schizachyrium scoparium (Michx.) Nash], prairie sandreed [Calamovilfa longifolia (Hook) Scribn.], and switchgrass (Panicum virgatum L.). Ramets were collected during the dormant season across an aridity gradient from east to west (ranging from 560 mm to 340 mm average annual precipitation) in the Sandhills of Nebraska. Plants were grown in individual pots under greenhouse conditions. Once plants were well established, stomatal characteristics were determined and stomatal conductance (gs) was measured through a dry-down period of no watering. Populations did not differ in stomatal characteristics across the gradient, except for stomatal density on the adaxial leaf surface of prairie sandreed and the abaxial leaf surface of sand ...

Early summer grazing effects on defoliation and tiller demography of prairie sandreed.

Grazing strategies should be designed to maintain vigorous populations of plant species critical for livestock production, wildlife habitat, and/or ecosystem functions. Treatments consisting of 5- to 7-day, mid-month grazing periods in June or July at 16, 32, or 48 animal unit days (AUD) per ha, were replicated 3 times and applied to the same pastures in 1995 and 1996 to quantify cattle use and tiller recruitment and mortality of prairie sandreed [Calamovilfa longifolia (Hook) Scribn.], a rhizomatous species characterized by dispersed populations of tillers. Cumulative grazing pressure (AUD Mg -1 ) was used to quantify treatments because of differences in phytomass among pastures and dates. Grazing pressure ranged from 10 to 90 AUD Mg -1 and accounted for 69, 61, and 77% of the variation in percentage of tillers grazed, mean defoliation of grazed tillers, and use of prairie sandreed, respectively. As grazing pressure increased from 10 AUD Mg -1 , percentage of tillers grazed increased from 48 to 90%; defoliation of grazed tillers increased from 54 to 74%; and utilization of prairie sandreed increased from 27 to 67% at plateaus beginning at 50 to 60 AUD Mg -1 . When spring precipitation was above average, 45 to 55% use in June or July increased tiller densities, however, these increases were not sustained or repeated in the following year with average precipitation. Utilization was 50% at 28 AUD Mg -1 and 60% at 40 AUD Mg -1 . Relatively large increases in utilization per-unit-change of grazing pressure below 20 AUD Mg -1 indicated that yearling cattle selectively grazed prairie sandreed. The high degree of correlation between percentage of prairie sandreed tillers grazed and use of prairie sandreed (R 2 = 0.91 in June and 0.90 in July) suggests that percentage of grazed tillers can be used to monitor early-summer use of this species in the Nebraska Sandhills.

Stocking rate and grazing frequency effects on Nebraska Sandhills meadows

Abstract Nearly one-half million ha of the Nebraska Sandhills is comprised of highly productive wet meadows. A study was conducted from 1998 to 2001 to evaluate the effects of stocking rate and grazing frequency on herbage dynamics, disappearance, and composition of a wet meadow dominated by cool-season vegetation. Defoliation characteristics were measured on 2 key species. Stocking rates were 148, 296, and 444 AUD ha−1 combined with a grazing frequency of 3 (F3) or 5 (F5) times. Cumulative standing crop disappearance and height reduction increased linearly with increasing stocking rate. Disappearance was 1,920, 2,700, and 3,090 kg ha−1 for the 148, 296, and 444 AUD ha−1 stocking rates, respectively. Greater disappearance at the highest stocking rate was expected based on calculated intake estimates for that stocking rate. Percentage of tillers grazed and percentage height reduction increased with stocking rate for both key species. Percentage of tillers grazed was greater under F3 compared to F5. This li...

Prediction of leaf:stem ratio in grasses using near infrared reflectance spectroscopy.

Leaf:stem ratio of grass stands is an important factor affecting diet selection, quality, and forage intake. Estimates of leaf:stem ratios commonly are based on a labor intensive process of hand separating leaf and stem fractions. Near infrared reflectance spectroscopy (NIRS) has been used successfully to predict forage quality and botanical composition of vegetation samples. The objective of this study was to evaluate the use of NIRS to predict leaf:stem ratios in big bluestem (Andropogon gerardii Vitman), switchgrass (Panicum virgatum L.), and smooth bromegrass (Bromus inermis Leyss.). A total of 72 hand-clipped samples of each species was taken from seeded monocultures in eastern Nebraska throughout the 1992, 1993, and 1994 growing seasons. Leaf:stem ratio was determined first for each sample and then the entire sample was ground. Samples were scanned by a Perstorp model 6500 near infrared scanning monochromator. Three calibration equations were developed based on using 18, 36, and 54 (1/4, 1/2, and 3/4 of total samples, respectively) samples. These 3 calibration equations were used to determine the number of samples necessary to achieve an r2 of 0.70 or higher for each data set. Big bluestem and switchgrass had coefficients of determination (r2) of less than or greater than 0.69 for all calibration equations except for the equation using only 18 samples of big bluestem r2 = 0.60). Smooth bromegrass had a r2 ranging from only 0.06 to 0.14 for the calibration equations regardless of the number of samples used. Near infrared reflectance spectroscopy was a rapid means of estimating leaf:stem ratios in monocultures of big bluestem and switchgrass but it was not suitable for smooth bromegrass.

Smooth bromegrass pasture beef growing systems: Fertilization strategies and economic analysis1

In recent years, prices for N fertilizer have increased dramatically, reducing net returns of fertilized pasture systems. A 5-yr study from 2005 to 2009 was conducted to evaluate management strategies and relative differences in profitability for 3 methods of backgrounding calves on smooth bromegrass pastures. Forty-five steers were used each year for a total of 225 animals in a randomized complete block design. Treatments included pastures fertilized in the spring with 90 kg N/ha (FERT), nonfertilized pastures with calves supplemented daily with dried distillers grains plus solubles (DDGS) at 0.6% of BW (SUPP), and control (CONT) pastures that had no fertilizer or supplementation applied. Pastures were rotationally stocked and put-and-take cattle were used to maintain similar grazing pressure on all treatments. Forage production was greatest for the FERT paddocks, intermediate for SUPP paddocks, and least for CONT paddocks (P < 0.01). Stocking rates were greater for SUPP pastures compared with nonfertilized pastures because of increased forage production and replacement of approximately 0.79 kg of forage for each 1 kg of supplement fed. At the conclusion of grazing, SUPP steers were 40 kg heavier than either the FERT or CONT steers, which resulted in increased gross revenue of

Spring Growth and Use of Cool-Season Graminoids in the Nebraska Sandhills

44.14/steer for the SUPP treatment (P < 0.01). Net returns were greatest for SUPP at

Botanical composition of goat diets in thinned and cleared deciduous woodland in northeastern Brazil.

17.55/steer (P < 0.01), whereas both the CONT and FERT treatments had negative net returns of -