Shortgrass range vegetation and steer growth response to intensive-early stocking

A 9-year grazing trial was conducted to compare shortgrass vegetation and steer responses under intensive-early stocking (IES) at 2 stocking rates to season-long stocking (SLS). The stocking rates were (1) equal to SLS, with twice as many steers used for the first half of the SLS grazing season (2X-IES), and (2) greater than SLS. with 3 times as many steers used for the same period (3X-IES). The hypothesis tested was that SLS and 2X-IES would be similar and sustainable in terms of productivity and vegetation composition, whereas 3X-IES would be different and not sustainable. The 3 treatments were assigned to 6 pastures in a randomized-complete block. Grazing was initiated on or near 1 May each year and continued until about 15 July for IES and about 1 October for SLS. Steers were weighted at initiation of grazing and in mid-July, and SLS steers were weighed in October. Vegetation data were collected in July and October in each pasture from 10 randomly located plots. Species composition of grasses was estimated, and grasses and forbs were clipped separately to determine biomass availability. Steer total gain and average daily gain (ADG) under SLS and 2X-IES were equal (P>0.10) during the early season, but 3X-IES gain and ADG were less (P0.10). Grass and total biomass availability were reduced (P<0.10) over time by 3X-IES. The hypothesis was supported: SLS and 2X-IES were equal in terms of both livestock performance and vegetation responses, but livestock performance and biomass availability were reduced and vegetation composition changed under 3X-IES. Thus, 3X-IES was not sustainable. While SLS and 2X-IES appear biologically equal, using them simultaneously on separate land areas may reduce market variability risk by marketing twice per year.This material was digitized as part of a cooperative project between the Society for Range Management and the University of Arizona Libraries.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

A comparison of estrus synchronization with Syncro-Mate-B® to natural service

Conception rates and subsequent calving dates were compared between cows synchronized with Syncro-Mate-B® and inseminated by appointment and nonsynchronized cows bred by natural service. Average conception date was seven days earlier in the synchronized cows

Steer nutritional response to intensive-early stocking on shortgrass rangeland

Steer nutritional response to vegetation conditions created by 4 grazing treatments was evaluated during the final 2 years (1987-88) of a 9-year grazing trial. Treatments were season-long stocking (treatment 1) at a moderate stocking rate and intensive-early stocking at 3 stocking rates: equal to season-long stocking by using twice as many steers for the first half of the season-long stocking grazing season (double-stocked-intensive-early stocking, treatment 2), and 2 rates greater than season-long stocking made by stocking at 2.5 or 3 times the stocking density or season-long stocking (2.5X- and triple-stocked-intensive-early stocking, treatments 3 and 4). Each treatment was replicated twice in a randomized-complete block. Three esophageally fistulated steers were placed in each pasture to collect diet samples for nutritional analyses, including crude protein and cell wall constituents. Total feces were collected from 3 steers in each pasture to estimate fecal output and calculate forage intake. Diet digestibility was estimated using alkaline-peroxide lignin as an internal marker. Three or 4 sampling periods were conducted during each grazing season. Herbage availability and dietary crude protein were similar among treatments in 1987, but both declined as stocking density increased in 1988. Cell wall constituents generally increased as stocking density increased in 1987, but were similar among treatments in 1988. Digestibility and forage intake were unaffected by grazing treatments in both years. Steer average daily gain declined as stocking density increased in both years. Seasonal changes in diet quality and forage intake reflected the precipitation pattern with improved nutrition whenever precipitation caused growth of the warm-season shortgrasses. Nutrient intake was reduced by stocking rates greater than that employed under season-long stocking, but was generally similar between season-long stocking and double-stocked-intensive-early stocking.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

Steer nutritional response to intensive-early stocking on shortgrass rangeland

Steer nutritional response to vegetation conditions created by 4 grazing treatments was evaluated during the final 2 years (1987-88) of a 9-year grazing trial. Treatments were season-long stocking (treatment 1) at a moderate stocking rate and intensive-early stocking at 3 stocking rates: equal to season-long stocking by using twice as many steers for the first half of the season-long stocking grazing season (double-stocked-intensive-early stocking, treatment 2), and 2 rates greater than season-long stocking made by stocking at 2.5 or 3 times the stocking density or season-long stocking (2.5X- and triple-stocked-intensive-early stocking, treatments 3 and 4). Each treatment was replicated twice in a randomized-complete block. Three esophageally fistulated steers were placed in each pasture to collect diet samples for nutritional analyses, including crude protein and cell wall constituents. Total feces were collected from 3 steers in each pasture to estimate fecal output and calculate forage intake. Diet digestibility was estimated using alkaline-peroxide lignin as an internal marker. Three or 4 sampling periods were conducted during each grazing season. Herbage availability and dietary crude protein were similar among treatments in 1987, but both declined as stocking density increased in 1988. Cell wall constituents generally increased as stocking density increased in 1987, but were similar among treatments in 1988. Digestibility and forage intake were unaffected by grazing treatments in both years. Steer average daily gain declined as stocking density increased in both years. Seasonal changes in diet quality and forage intake reflected the precipitation pattern with improved nutrition whenever precipitation caused growth of the warm-season shortgrasses. Nutrient intake was reduced by stocking rates greater than that employed under season-long stocking, but was generally similar between season-long stocking and double-stocked-intensive-early stocking.The Journal of Range Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 202

An experimental and numerical study on the spatial and temporal evolution of a scour hole downstream of a rigid bed

The present study consists of a new mathematical-experimental investigation on local scour downstream of a rigid bed. New scouring experiments, under both steady and unsteady flow conditions, were carried out and the scour patterns were measured with a 3D Laser Scanner. The initial bed shear stress induced by the turbulent flow over the sand bed was estimated by analysing velocity profiles. A mathematical model simulating the local scour downstream of a rigid bed and using both information relating to the turbulent flow and the physical and mechanical properties of the sand was developed. The mathematical structure of the model includes a second order partial differential parabolic equation with the shape of the mobile bed as unknown parameter. The sediment transport was computed by the Einstein approach. The space-time evolution of the simulated scour holes are in good agreement with the measured ones for both steady and unsteady flow tests. © 2014 Taylor & Francis Group, London