The Effect of Dairy Compost on Summer Annual Grasses Grown as Alternative Silages

SS20 forage sorghum (Sorghum bicolor), SS10 sorghum-sudan (Sorghum spp. hybrid), SM60 pearl millet (Pennisetum glaucum), Nutrifeed (Pennisetum spp. hybrid), and CA 737 grain sorghum (Sorghum bicolor) were grown under irrigation at the Stephenville Research and Extension Center in the spring seasons of 1998 and 1999. Dairy manure compost was incorporated into subplots at 11.2 t DM ha⁻¹ each yr. The sorghum-sudan and forage sorghum hybrids produced consistently high tonnage both years (P<0.05), while the grain sorghum was among the lowest yields both years. Fiber concentrations were lowest (P<0.05) for the grain sorghum, and in sacco DM disappearance and CP concentrations were consistently highest for both the grain sorghum and the hybrid Pennisetum. The application of compost over two seasons increased soil phosphorus (P) to 2.4 times that of soil without compost and increased average forage P concentration by 32% the second year. Average forage P concentrations were highest (P<0.05) in the millet (0.214% Yr 1 and 0.258% Yr 2, respectively), the hybrid Pennisetum (0.221% Yr 1 and 0.228% Yr 2, respectively) and the grain sorghum (0.193% Yr 1 and 0.199% Yr 2, respectively). Pearl millet had the greatest P uptake from the soil (25.9 kg ha⁻¹ Yr 1 and 36.2 kg ha⁻¹ Yr 2, respectively), while forage sorghum had the lowest P uptake from the soil (17.9 kg ha⁻¹ Yr 1 and 13.4 kg ha⁻¹ Yr 2, respectively).     

Interannual Herbaceous Biomass Response to Increasing Honey Mesquite Cover on Two Soils

This study quantified herbaceous biomass responses to increases in honey mesquite (Prosopis glandulosa Torr.) cover on two soils from 1995 to 2001 in north central Texas. Vegetation was sampled randomly with levels of mesquite ranging from 0% to 100%. With no mesquite covering the silt loam soils of bottomland sites, peak herbaceous biomass averaged (±SE) 3 300 ± 210 kg · ha⁻¹ vs. 2 560 ± 190 kg · ha⁻¹ on clay loam soils of upland sites (P = 0.001). A linear decline of 14 ± 2.5 kg · ha⁻¹ in herbaceous biomass occurred for each percent increase in mesquite cover (P = 0.001). The slope of this decline was similar between soils (P = 0.135). Herbaceous biomass with increasing mesquite cover varied between years (P = 0.001) as did the slope of decline (P = 0.001). Warm-season herbaceous biomass decreased linearly with increasing mesquite cover averaging a 73 ± 15% reduction at 100% mesquite cover (P = 0.001) compared to 0% mesquite cover. Cool-season herbaceous biomass was similar between soils with no mesquite, 1 070 ± 144 kg · ha⁻¹ for silt loam vs. 930 ± 140 kg · ha⁻¹ for clay loam soils, but averaged 340 ± 174 kg · ha⁻¹ more on silt loam than on clay loam soils at 100% mesquite cover (P = 0.004). Multiple regression analysis indicated that each centimeter of precipitation received from the previous October through the current September produced herbaceous biomass of 51 kg · ha⁻¹ on silt loam and 41 kg · ha⁻¹ on clay loam soils. Herbaceous biomass decreased proportionally with increasing mesquite cover up to 29 kg · ha⁻¹ at 100% mesquite cover for each centimeter of precipitation received from January through September. Increasing mesquite cover reduces livestock forage productivity and intensifies drought effects by increasing annual herbaceous biomass variability. From a forage production perspective there is little advantage to having mesquite present.     

Kenaf Dry Matter Production,Chemical Composition,and In Situ Disappearance When Harvested at Different Intervals

Kenaf (Hibiscus cannabinus L.) is a tropical plant that has potential as a forage crop. However, data on the amount and quality of forage produced by kenaf is scarce. The objectives of this research were to determine 1) the DM yield, proportions of leaf and stalk, and chemical composition and 2) the in situ OM and N disappearance of kenaf harvested throughout the growing season. Kenaf (‘Everglades 41’) was planted in June of 1990, 1991, and 1993. The seeding rate was 5.6 kg/ha and 100 kg of N /ha was applied shortly before or after planting. Harvesting began 40 d after planting (DAP) with additional harvests at 10-d (1991 and 1993) or 20-d (1990) intervals. Daily whole plant DM accumulation ranged from 12.6 to 17.2 g/m². At 101 DAP, 726 to 974 g of DM were harvested/m². As kenaf matured, the proportion of the total plant DM represented in leaves decreased (P<0.01) from 68% at 40 DAP to 44% at 101 DAP. Leaf DM contained more (P<0.01) than twice the CP as stalk DM at all harvests. Delaying harvest decreased (P<0.01) whole plant CP concentration from 22% at 40 DP to 15% at 101 DAP, because the stalks made up a larger proportion of the total biomass. The OM in the leaves was twice as digestible (P<0.01) as the OM in the stalks (89.3 vs 44.8%). The N in the leaves was more (P<0.01) digestible than the N in the stalks (93.2 vs 61.5%). Kenaf can be grown during the summer season and harvested as high quality forage as early as 40 DAP. Whole plants harvested at 80 DAP produced from 426 to 729 g/m² of DM and had a CP content of 14 to 19%. Harvesting later than 80 DAP will increase DM yield, but CP content and in situ OM and N disappearance will decrease.     

Spatial Redistribution of Nitrogen by Cattle in Semiarid Rangeland

Nitrogen (N) availability can strongly influence forage quality and the capacity for semiarid rangelands to respond to increasing atmospheric CO₂. Although many pathways of nitrogen input and loss from rangelands have been carefully quantified, cattle-mediated N losses are often poorly understood. We used measurements of cattle N consumption rate, weight gains, and spatial distribution in shortgrass rangeland of northeastern Colorado to evaluate the influence of cattle on rangeland N balance. Specifically, we estimated annual rates of N loss via cattle weight gains and spatial redistribution of N into pasture corners and areas near water tanks, and used previous studies to calculate ammonia volatilization from urine patches. Using measurements of plant biomass and N content inside and outside grazing cages over 13 yr, we estimate that cattle stocked at 0.65 animal unit months (AUM) · ha^?1 consumed 3.34 kg N · ha^?1 · yr^?1. Using an independent animal-based method, we estimate that cattle consumed 3.58 kg N · ha^?1 · yr^?1 for the same stocking rate and years. A global positioning system tracking study revealed that cattle spent an average of 27% of their time in pasture corners or adjacent to water tanks, even though these areas represented only 2.5% of pasture area. Based on these measurements, we estimate that cattle stocked at 0.65 AUM · ha^?1 during the summer can remove 0.60 kg N · ha^?1 in cattle biomass gain and spatially redistribute 0.73 kg N · ha^?1 to areas near corners and water tanks. An additional 0.17 kg N · ha^?1 can be lost as NH₃ volatilization from urine patches. Cumulatively, these cattle-mediated pathways (1.50 kg N · ha^?1) may explain the imbalance between current estimates of atmospheric inputs and trace gas losses. While NO_x emission remains the largest pathway of N loss, spatial N redistribution by cattle and N removed in cattle biomass are the second and third largest losses, respectively. Management of cattle-mediated N fluxes should be recognized as one means to influence long-term sustainability of semiarid rangelands.     

Livestock Grazing Impacts on Herbage and Shrub Dynamics in a Mediterranean Natural Park

Shrub encroachment can be explained by the abandonment of extensive livestock farming and changes to land use, and it is a common problem in the Mediterranean mountain pastures of Europe, with direct effects on biodiversity and landscape quality. In this paper, the effects of livestock exclusion vs. grazing on the dynamics of shrub and herbaceous vegetation were analyzed in a Spanish natural park located in a dry Mediterranean mountain area over a 5-yr period. Twelve 10 × 10 m exclosures were set up in six representative pasture areas of the park (with two replicates per location). Each year, the shrub number, volume, and biomass were measured in April, and the herbage height, biomass, and quality were measured in April and December (which represent the start and end of the vegetative growth season). A sustained increase of the shrub population and individual biomass was observed throughout the study, which was reflected in total shrub biomass per ha. Growth was greater in nongrazed exclosures (2 563 kg dry matter [DM] · ha^?1 · yr^?1), but it also happened in the grazed control areas (1 173 kg DM · ha^?1 · yr^?1), with different patterns depending on the location and shrub species. Herbage biomass did not change when grazing was maintained, but it did increase in places where grazing was excluded (291 kg DM · ha^?1 · yr^?1), mostly as a consequence of the accumulation of dead material, with a concomitant reduction in herbage quality. It was concluded that at the current stocking rates and management regimes, grazing alone is not enough to prevent the intense dynamics of shrub encroachment, and further reductions in grazing pressure should be avoided.     

Growth of Chickasaw Plum in Oklahoma

Management of rangelands for wildlife and livestock entails understanding growth of clonal shrubs such as Chickasaw plum (Prunus angustifolia Marsh.). We studied growth of this species in one county in north-central (Payne) and two counties in northwestern Oklahoma (Ellis, Harper) during 2006 and 2007. We estimated age of stems and roots by growth rings and area of stands with the use of a handheld GPS unit. Based on zero-intercept regression models, stands grew at similar rates (overlapping 95% confidence intervals [CIs]) among counties with a pooled estimate of 31.0 m² · yr⁻¹ (95% CI = 26.5–35.6 m² · yr⁻¹; n = 95). This rate showed considerable variability within and among study sites (r = 0.52). Stem diameter increased (zero-intercept models) more rapidly in north-central Oklahoma (5.27 mm · yr⁻¹; 95% CI = 5.01–5.53 mm · yr⁻¹; r = 0.90; n = 53) than in northwestern Oklahoma (3.68 mm · yr⁻¹; 95% CI = 3.55–3.81 mm · yr⁻¹; r = 0.91; n = 102); data were pooled because of similar rates in Ellis and Harper counties. Stem height was a power function of stem age (y = 0.97x^0.28; r = 0.56), indicating rate of growth in height (m · yr⁻¹) declined with age according to dy/dx = 0.27x^−0.72. Knowledge of the area expansion rate of Chickasaw plum clones aids in management planning to increase or decrease canopy coverage by this shrub.     

Effects of Grazing Intensity,Precipitation, and Temperature on Forage Production

Questions have been raised about whether herbaceous productivity declines linearly with grazing or whether low levels of grazing can increase productivity. This paper reports the response of forage production to cattle grazing on prairie dominated by Kentucky bluegrass (Poa pratensis L.) in south-central North Dakota through the growing season at 5 grazing intensities: no grazing, light grazing (1.3 ±  animal unit months [AUM] · ha^-1), moderate grazing (2.7 ±  AUM · ha^-1), heavy grazing (4.4 ±  AUM · ha^-1), and extreme grazing (6.9 ±  AUM · ha^-1; mean ± SD). Annual herbage production data were collected on silty and overflow range sites from 1989 to 2005. Precipitation and sod temperature were used as covariates in the analysis. On silty range sites, the light treatment produced the most herbage (3 410 kg · ha^-1), and production was reduced as the grazing intensity increased. Average total production for the season was 545 kg · ha^-1 less on the ungrazed treatment and 909 kg · ha^-1 less on the extreme treatment than on the light treatment. On overflow range sites, there were no significant differences between the light (4 131 kg · ha^-1), moderate (4 360 kg · ha^-1), and heavy treatments (4 362 kg · ha^-1; P &spigt; 0.05). Total production on overflow range sites interacted with precipitation, and production on the grazed treatments was greater than on the ungrazed treatment when precipitation (from the end of the growing season in the previous year to the end of the grazing season in the current year) was greater than 267.0, 248.4, 262.4, or 531.5 mm on the light, moderate, heavy, and extreme treatments, respectively. However, production on the extreme treatment was less than on the ungrazed treatment if precipitation was less than 315.2 mm. We conclude that low to moderate levels of grazing can increase production over no grazing, but that the level of grazing that maximizes production depends upon the growing conditions of the current year.     

Effects of Forage Management on Pasture Productivity and Phosphorus Content

The objectives of the current study were to determine the amounts of above- and below-ground plant biomass production, P uptake by forage, and P concentration of cool-season grass forage as influenced by management and season. Five forage management treatments were evaluated over 3 years in smooth bromegrass (Bromus inermis Leyss) pastures. Management practices were: ungrazed (U), hay harvest/fall stockpile grazing (HS), rotational stocking to residual sward heights of 10 (10R) or 5 (5R) cm, and continuous stocking to maintain sward height at 5 cm (5C). Forage samples were hand-clipped within and outside grazing exclosures monthly from April through November of each year and analyzed for mass and P concentration. Root samples were collected at the initiation and completion of the study for determination of root length density (RLD) and root surface area density (RSAD). Phosphorus concentrations of forage outside the grazing exclosures did not differ among 5C, 5R, and 10R treatments, which were greater than U paddocks in April and August and less than HS paddocks in June. Mean annual forage productivity was greater in HS, 10R, 5R, and 5C paddocks (6 744 ± 62 kg · ha^-1 mean ± SE) than in the U paddocks (1 872 ± 255 kg · ha^-1). Mean P concentration of forage outside exclosures was greatest during the spring (0.21 ± 0.01%), and lowest during the fall (0.13 ± 0.01%). Mean annual P uptake by forage followed the same trend as forage production, being greater in the HS, 10R, 5R, and 5C paddocks (13.9 ±  kg · ha^-1) than in the U paddocks (3.7 ±  kg · ha^-1). After 3 years, RLD decreased in the ungrazed paddocks, but was unchanged in the HS, 10R, 5R, and 5C paddocks. Forage production and P uptake by forage is stimulated by forage harvest, either by grazing or hay harvest in smooth bromegrass pastures.     

Performance of spring-calving beef suckler cows and their progeny to slaughter on intensive and extensive grassland management systems

The performance of rotationally grazed beef suckler cows and their progeny to slaughter on two lowland grassland management systems differing in stocking rate (SR) and fertiliser nitrogen (N) level was compared over eight years. The two Systems were 1) Intensive (INT): SR of 0.56 (bull production) or 0.71 (steer production) ha cow^? 1 unit, 211 kg fertiliser N ha^? 1, two silage harvests, and 2) Extensive (EXT): SR of 0.69 (bull production) or 0.88 (steer production) ha cow^? 1 unit, 97 kg fertiliser N ha^? 1 and one staggered silage harvest. A cow unit was defined as a cow plus progeny to slaughter. On the silage harvesting area, the mean application rate for fertiliser N was 110 and 80 kg ha^? 1 for first and second harvests, respectively. Herbage dry matter digestibility both pre- and post-grazing was similar (P > 0.05) for the two systems, whereas herbage crude protein concentrations were generally significantly lower for the EXT than the INT system. There was no difference (P > 0.05) between the Systems in cow live weight, body condition score or their changes or in calf live weight gain from birth to weaning. Post-weaning, live weight gain, slaughter weight, carcass weight, kill-out proportion, estimated carcass gain, carcass conformation score or carcass fat score did not differ (P > 0.05) between the systems for heifer, steer or bull progeny. It can be concluded that similar animal performance levels can be expected in an extensive grassland-based suckler calf-to-beef system compatible with the EU, Rural Environmental Protection Scheme as that attained in a more intensive System comprising of both a moderately high SR (~ 1.25 higher) and fertiliser N application (~ 2.1 higher).     

Fire and Nitrogen Effects on Purple Threeawn (Aristida purpurea) Abundance in Northern Mixed-Grass Prairie Old Fields

Purple threeawn (Aristida purpurea Nutt. varieties) is a native grass capable of increasing on rangelands, forming near monocultures, and creating a stable state. Productive rangelands throughout the Great Plains and Intermountain West have experienced increases in purple threeawn abundance, reducing overall forage quality. Our objectives were to 1) reveal the effects of prescribed fire and nitrogen amendments on purple threeawn abundance and 2) assess nontarget plant response posttreatment. Season of fire (no fire, summer fire, fall fire) and nitrogen addition (0 kg N · ha^?1, 46 kg N · ha^?1, and 80 kg N · ha^?1) were factorially arranged in a completely randomized design and applied to two similar sites in southeastern Montana. We evaluated fire and nitrogen effects on purple threeawn basal cover, relative composition, and current-year biomass one growing season postfire at two sites treated during different years. Spring weather following fire treatments was very different between years and subsequently impacted community response. Initial purple threeawn biomass at both sites was 1 214 ± 46 kg · ha^?1 SEc. When postfire growing conditions were wet, current-year biomass of purple threeawn was reduced 90% and 73% with summer and fall fire, respectively. Under dry postfire growing conditions, purple threeawn current-year biomass was reduced 73% and 58% with summer and fall fire, respectively. Nitrogen additions had no effect on purple threeawn current-year biomass at either site. Current-year biomass of C₃ perennial grass doubled with nitrogen additions and was not impacted by fire during a wet spring. Nitrogen additions and fire had no effect on C₃ perennial grass current-year biomass following a dry spring. Prescribed fire appears to be a highly effective tool for reducing purple threeawn abundance on semiarid rangelands, with limited detrimental impacts to nontarget species.     

Evaluation of Low-Stress Herding and Supplement Placement for Managing Cattle Grazing in Riparian and Upland Areas

Management practices are often needed to ensure that riparian areas are not heavily grazed by livestock. A study was conducted in Montana during midsummer to evaluate the efficacy of low-stress herding and supplement placement to manage cattle grazing in riparian areas. Three treatments were evaluated in three pastures over a 3-yr period in a Latin-square design (n = 9). Each year, naïve 2-yr-old cows with calves were randomly assigned to the three treatments: 1) free-roaming control, 2) herding from perennial streams to upland target areas, and 3) herding to upland sites with low-moisture block supplements. Stubble heights along the focal stream were higher (P = 0.07) in pastures when cattle were herded (mean ± SE, 23 ± 2 cm) than in controls (15 ± 3 cm). Global positioning system telemetry data showed that herding reduced the time cows spent near (< 100 m) perennial streams (P = 0.01) and increased the use of higher elevations (P = 0.07) compared with controls. Evening visual observations provided some evidence that free-roaming cows (44% ± 19%) were in riparian areas more frequently (P = 0.11) than herded cows (23% ± 6%). Fecal abundance along the focal stream was less (P = 0.07) with herding (61.9 ±  kg · ha⁻¹) than in controls (113.2 ±  kg · ha⁻¹). Forage utilization within 600 m of supplement sites was greater (P = 0.06) when cows were herded to low-moisture blocks (18% ± 6%) compared with controls and herding alone (8% ± 2%). Moving cattle to uplands at midday using low-stress herding is an effective tool to reduce use of riparian areas. Herding cattle to low-moisture blocks can increase grazing of nearby upland forage but may not provide additional reduction in cattle use of riparian areas compared with herding alone.     

Comparison of Swine Diets Containing a Food Waste Product Made with Wheat Middlings and Corn or a Corn/Soybean Diet,

Although pigs will readily consume wet food waste (FW), the high moisture content contributes to spoilage and feeding management problems. The use of a dry, processed FW product was compared with a traditional corn and soybean (CS) diet using growing swine in two performance trials and one digestibility trial. The FW diet contained approximately 20% processed FW (DM basis). In Trial 1, 24 gilts (76.4 kg) housed in eight replicated pens (four pens per treatment) were fed in a 6-wk trial. Intake, BW gain, feed efficiency, and carcass characteristics were compared. Feed intake and BW gain averaged 3.4 and 3.6 kg of DM/d and 0.87 and 0.85 kg/d for gilts fed traditional and FW diets, respectively. There were no differences in these or any other measurements (P>0.05). In Trial 2, 12 barrows (84.3 kg) housed in four replicated pens (two pens per treatment) were fed in a 6-wk trial. Intake, BW gain, feed efficiency, and carcass characteristics were compared. Feed intake and BW gain averaged 3.1 and 3.3 kg of DM/d and 0.62 and 0.71 kg/d for barrows fed traditional and FW diets, respectively. Four growing gilts (68.2 kg) were used to compare digestibility in a crossover design. There were no differences (P>0.10) for DM, CP, ADF, or NDF digestibility when feed intake averaged 1.9 kg of DM/d for both FW and CS diets. The use of up to 20% processed FW may be suitable in commercial swine diets.     

Animal and Vegetation Response to Modified Intensive–Early Stocking on Shortgrass Rangeland

A comparison of animal gains and vegetation trends was made from 2002–2008 between a continuous season-long stocking (SLS) system and a modified intensive–early stocking system (IES) with late-season grazing (IES 1.6× + 1; 1.6 times the number of animals of the SLS system from May 1 to July 15, and 1 times the number of animals of SLS from July 15 to October 1) on shortgrass native rangeland of western Kansas. The continuous season-long stocked system placed animals at a density of 1.37 ha · steer^?1 from May through October, or 2.63 animal unit months (AUM) · ha^?1, whereas the intensive–early stocked system with late-season grazing (3.33 AUM · ha^?1) stocked pastures at 0.85 ha · steer^?1 from May through the middle of July, and then stocked pastures at 1.37 ha · steer^?1 for the remainder of the grazing season by removing the heaviest animals mid-July each yr. Average daily gains (0.78 vs. 0.70 kg · d^?1, P = 0.039) and total animal gain (58 vs. 52 kg, P = 0.042) were different between the continuous season-long stocked and the intensive–early stocked animals during the first half of the grazing season. No difference was found between average daily gain (0.61 vs. 0.62 kg · d^?1, P = 0.726) and total animal gain (48 vs. 49 kg, P = 0.711) for the continuous season-long stocked and intensive–early stocked with late-season grazing animals during the last half of the season. Total individual animal gain (106 vs. 101 kg, P = 0.154) and average daily gain (0.70 vs. 0.66 kg · d^?1, P = 0.152) was not different between the continuous season-long stocked and the intensive–early stocked system animals that were on pasture the entire grazing season. Total beef gain on a land-area basis (96 vs. 77 kg · ha^?1, P = 0.008) was greater for the modified intensive–early stocked system with late-season grazing with greater animal densities. Changes in residual biomass and most key vegetation components at the end of the grazing season were not different between the two systems.     

The effect of maropitant on intraoperative isoflurane requirements and postoperative nausea and vomiting in dogs: a randomized clinical trial

ObjectiveTo establish if preoperative maropitant significantly reduced intraoperative isoflurane requirements and reduced clinical signs associated with postoperative nausea and vomiting (PONV) in dogs.Study designRandomized clinical trial.AnimalsTwenty-four healthy, client-owned dogs undergoing routine ovariohysterectomy.MethodsPremedication involved acepromazine (0.03 mg kg⁻¹) combined with methadone (0.3 mg kg⁻¹) intramuscularly 45 minutes before anaesthetic induction with intravenous (IV) propofol, dosed to effect. Meloxicam (0.2 mg kg⁻¹) was administered intravenously. Dogs were randomly assigned to administration of saline (group S; 0.1 mL kg⁻¹, n = 12) or maropitant (group M; 1 mg kg⁻¹, n = 12) subcutaneously at time of premedication. Methadone (0.1 mg kg⁻¹ IV) was repeated 4 hours later. Anaesthesia was maintained with isoflurane in oxygen, dosed to effect by an observer unaware of group allocation. The dogs were assessed hourly, starting 1 hour postoperatively, using the short form of the Glasgow Composite Pain Score (GCPS), and for ptyalism and signs attributable to PONV [score from 0 (none) to 3 (severe)] by blinded observers. Owners completed a questionnaire at the postoperative recheck.ResultsOverall mean ± standard deviation end-tidal isoflurane percentage was lower in group M (1.19 ± 0.26%) than group S (1.44 ± 0.23%) (p = 0.022), but was not significantly different between groups at specific noxious events (skin incision, ovarian pedicle clamp application, cervical clamp application, wound closure). Cardiorespiratory variables and postoperative GCPS were not significantly different between groups. Overall, 50% of dogs displayed signs attributable to PONV, with no difference in PONV scores between groups (p = 0.198). No difference in anaesthetic recovery was noted by owners between groups.ConclusionsMaropitant reduced overall intraoperative isoflurane requirements but did not affect the incidence of PONV.Clinical relevanceMaropitant provided no significant benefits to dogs undergoing ovariohysterectomy with this anaesthetic and analgesic protocol, although clinically significant reductions in isoflurane requirements were noted.     

Ventenata and Other Coexisting Exotic Annual Grass Control and Plant Community Response to Increasing Imazapic Application Rates

Ventenata (Ventenata dubia [Leers] Coss.) is an exotic annual grass that can invade intermountain rangeland plant communities, where it can form monotypic stands, degrade wildlife habitat, and reduce livestock forage. There is limited information on ventenata control in rangelands as it has only recently been identified as a substantial problem. Imazapic is a pre-emergent herbicide commonly used to control other exotic annual grasses and, therefore, is likely to control ventenata in rangelands. We evaluated five application rates of imazapic (0 − 175 g ae ∙ ha^− 1) on ventenata and other exotic annual grass control and plant community response at two rangeland sites in 2 yr (2014 and 2015). Imazapic reduced exotic annual grass (largely ventenata) cover and density, with greater control with increasing imazapic rates. Exotic annual grass density at the highest levels of control (82%−94%) was 184 − 299 plants ∙ m^− 2 the first yr after imazapic application. Exotic annual grasses fully recovered in the second or third yr after imazapic application. Bare ground generally increased with imazapic application. However, density of perennial vegetation (grasses and forbs) did not vary among treatments. Perennial vegetation cover generally did not increase with imazapic control of ventenata and other exotic annual grasses. Imazapic can control ventenata; however, even at the highest rates, control was not enough to shift the dominance from exotic annual species to perennial species. Integrating other treatments with imazapic application may be a strategy to improve ventenata control and increase perennial vegetation and will require further investigation. The difficulty and likely expense of achieving substantial and lasting control of ventenata suggest, similar to other exotic annual grasses, that preventing ventenata invasion and dominance should be a high management priority.     

Vegetation Response to a One-Time Spent Drilling Mud Application to Semiarid,Mixed-Grass Prairie

Landspraying while drilling (LWD) is an approved disposal method for water-based drilling mud (WBM) systems in western Canada. The mud is applied either on cultivated land, where it is incorporated by cultivation, or on vegetated land where it is not incorporated. This study examined the effects of summer WBM application (0, 15, 20, 40, and 80 m³ · ha^?1) on native vegetation properties. Our results indicated that LWD increased bare ground but decreased lichen cover at the 80 m³ · ha^?1 rate relative to the untreated control. Nitrogen (N), sulfur (S), and magnesium (Mg) concentrations in aboveground plant tissue increased with increasing LWD rate in samples taken 45 d after WBM application, but these differences disappeared 1 yr after treatment. Increase in tissue concentration of phosphorus (P) with LWD rate, however, was only detected 3 yr after LWD. Nonetheless, these changes in tissue chemistry were not associated with significant changes in biomass yield or species composition. Overall, our results suggest that single WBM applications at rates (≤ 20 m³ · ha^?1) commonly used in western Canada, if properly managed, are unlikely to adversely affect native prairie vegetation.     

Method of Supplementation May Affect Cattle Grazing Patterns

Supplement placement can be used to manipulate livestock grazing patterns. The objective of this case study was to compare the effect of low-moisture blocks (LMB) and range cake (barley-based cylindrical cubes, 2 cm in diameter, and 2 to 8 cm long) supplementation on cattle grazing patterns in Montana foothill rangeland. One group of nonlactating cows (n = 79) was fed cake 3 times per week (1.8 kg · cow⁻¹ · feeding⁻¹), and the other group (n = 81) had continuous access to LMB in separate pastures using a crossover design. Movement patterns of cows were recorded with global positioning system collars during four periods (2 wk · period⁻¹) during autumn. Range cake was fed on accessible areas, and LMB were placed in higher and steeper terrain. Intake of LMB averaged (mean ± SE) 318 ± 50 g · d⁻¹. Cows fed LMB (8.07° ± 0.20°) were observed on steeper slopes (P = 0.08) than cows fed range cake (6.96° ± 0.19°). Forage utilization decreased as slope increased to a greater degree when range cake was fed than when LMB was fed (P = 0.001). Cows spent more time (P = 0.05) within 100 m of LMB (274 ± 23 min · d⁻¹) than at range cake feeding sites (67 ± 24 min · d⁻¹). Strategic placement of LMB on high, steep terrain appears to be a more practical and effective approach than traditional hand-feeding range cake on intermediate terrain to improve uniformity of cattle grazing on rugged rangeland.     

Rough Agave Flowers as a Potential Feed Resource for Growing Goats

The objective of this study was to evaluate the effect of different levels of rough agave (Agave scabra Ortega) flowers on dry matter intake (DMI), average daily gain (ADG), volatile fatty acid (VFA) production in the rumen, and particular serum metabolites and minerals of native × dairy growing goats (Capra hircus L.). Forty female goats with an initial weight of 11.1 ±  kg (mean ± SD) were used in a completely randomized design experiment that lasted for 84 d. Goats were fed a completely mixed ration (30% roughage, 70% ground corn [Zea mays L.] and soybean [Glycine max {L.} Merr] meal). Treatments consisted of offering goats (4 pens · group⁻¹, 2 goats · pen⁻¹) air-dry rough agave flowers, which replaced alfalfa (Medicago sativa L.) hay at 0% (control; T0), 25% (T25), 50% (T50), 75% (T75), and 100% (T100) of the of the roughage portion of the diet. Values of nutritional parameters for rough agave flowers were in vitro organic matter digestibility, 493 g · kg⁻¹; crude protein, 115 g · kg⁻¹; and metabolizable energy, 6.29 MJ · kg⁻¹ DMI. There were differences (P < 0.05) in ADG (range, 108–155 g · d⁻¹) between diets. Goats fed T0 had higher (P < 0.05) gains than goats fed T50 and T100. DMI was not affected by dietary treatments (range, 3.4% to 3.6% of body weight). Feed conversion ratio (FCR, defined as DMI/ADG) increased (P < 0.05) 27% with total substitution of alfalfa by rough agave flowers, in comparison with T0. Lower (P < 0.05) values of total VFA were obtained with T100, in comparison with all other dietary treatments. These results demonstrated that totally replacing alfalfa with rough agave flowers in diets did not affect DMI but decreased AGD and compromised FCR. Thus, rough agave flowers have the potential to partially replace alfalfa in diets for growing goats.     

Supplementing Guinea grass with fresh sweet potato foliage for milk production by Bunaji and N'Dama cows in early lactation

Forage from three sweet potato cultivars (A = TIS-87/0087; B = TIS-8164; C = TIS-2532.OP.1.13 at 30% daily dry matter intake), dried brewers' grains (DBG) and cottonseed meal (CSM) each at 2.5 kg were supplemented to Guinea grass (GG) to form four diets: Diet A = GG + TIS-87/0087; Diet B = GG + TIS-8164; Diet C = GG + TIS-2532.OP.1.13, and Diet D = GG + DBG + CSM (as control). Treatments were assigned as 4 × 4 Latin squares design over 60 days (10-day adaptation and 5-day sampling) using Bunaji and N'Dama cows in early lactation. The 48-h rumen dry matter (DM) degradation ranged (P < 0.01) from 407 g kg^? 1 DM for GG to 791 g kg^? 1 DM for sweet potato cultivar TIS-87/0087. Bunaji dry matter intake varied (P < 0.05) between 7.1 kg day^? 1 in Diet B and 8.9 kg day^? 1 in Diet D, but was similar (P > 0.05) among diets for the N'Dama cows. The metabolisable energy (ME) intakes were higher for Diet D although, it recorded the least efficiency of ME utilization for milk production. Milk yields were significantly (P < 0.01) higher in the Bunaji than the N'Dama cows, which is typical of their true breed differences. Total solids, ash, protein, fat, and sugar contents of the milk were similar among diets for both cow breeds, except Bunaji ash contents that ranged (P < 0.05) from 0.77 g 100 g^? 1 for Diet B to 0.83 g 100 g^? 1 for Diet D. The results suggest that sweet potato forage could be utilized as whole or partial replacement for DBG and CSM to save cost under smallholder farming systems.     

Effect of Concentrate Feeding Level on Production of Holstein Cows Grazing Winter Annuals

A replicated randomized block trial was conducted to determine the response of Holstein cows rotationally grazing annual ryegrass-Crimson clover pasture to supplemental concentrate. Within each of 2 yr, 16 Holstein cows were assigned to one of four blocks by energy-corrected milk yield, days in milk, and parity. Treatments included one of four levels of concentrate based on the following grain to milk ratios: 0 kg concentrate or 1 kg for each 7, 5, or 3 kg of energy-corrected milk. Average chemical composition (DM basis) of pasture during each grazing season was 22.5% DM, 18.5% CP, and 21.5% ADF in 1996 and 23.5% DM, 14.6% CP, and 25.2% ADF in 1997. Concentrate DMI averaged 0, 4.4, 6.2, and 8.3 kg/d for 0, 1:7, 1:5, and 1:3 treatments in 1996, respectively. Yield of milk and components increased linearly as the amount of concentrate fed increased. A quadratic response was observed for yield of milk fat and protein as yield of these components increased up to 1:5 and then reached a plateau. Concentrate DMI in 1997 averaged 0, 4.4, 6.1, and 10.5 kg/d for 0, 1:7, 1:5, and 1:3 treatments, respectively. Yields of milk and milk protein, lactose, and solids-not-fat increased linearly as the amount of concentrate fed increased. Regression analysis predicted that pasture alone would support milk yields of 20.4 kg and that the increase in milk yield diminished with each increase in amount of concentrate fed. These data indicate that the amount of concentrate fed when high quality annual ryegrass-crimson clover pasture is readily available can be limited to 1 kg for each 4.5 kg of energy-corrected milk to optimize income over concentrate cost.