Recommended strategies for dealing with drought include maintaining a conservative stocking rate, maintaining grazing flexibility by having yearlings as one of multiple enterprises on the ranch, and leaving a significant amount of herbaceous production at the end of the grazing season. We perform an economic analysis of these grazing strategies using a bio-economic multiperiod linear programming model with variable annual forage production and beef prices. We evaluate the economics of conservative versus flexible grazing where stock numbers are adjusted to match forage conditions. The deterministic model estimates that a flexible grazing strategy could nearly double net returns relative to a conservative strategy, but realizing this substantial economic potential means higher production costs, and it depends on a quality climate forecast that is not currently available. Maintaining grazing flexibility was determined to be very important for managing variable forage conditions, and its importance increased with the level of variability. Without annual variation in forage production, over 80% of available forage would optimally be allocated to cow-calf production. As forage variability increased to levels observed on the arid rangelands of the western United States, a 50:50 forage allocation between cow-calf and yearling enterprises was found to be optimal, but optimal cow numbers decreased over time as dry conditions force herd reductions. As compared to a cow-calf ranch only, adding flexible yearling enterprises increased average annual net ranch returns by 14% with conservative stocking and by up to 66% with flexible grazing. Herd expansion beyond a conservative level should occur with yearlings because adjusting cow numbers is too expensive relative to the potential short-term gain, even if forage conditions are known with certainty. Resumen Las estrategias recomendadas para los periodos de sequia incluyen el uso de carga animal conservadora, el uso de recría de terneros como una de las múltiples actividades del establecimiento para mantener la flexibilidad de pastoreo, y la reserva de una buena cantidad de forraje en pie. Se realizó un análisis de dichas estrategias utilizando un modelo bio-económico de múltiples periodos con programación lineal y con producciones anuales de forraje y precios de carne variables. Se evaluaron los resultados económicos del pastoreo conservador versus flexible en el que el número de animales se ajusta de acuerdo a las condiciones del forraje. El modelo determínistico estimó que una estrategia de pastoreo flexible podría casi duplicar el ingreso neto comparado con una estrategia conservadora, pero la concreción de este potencial económico sustancial implica mayores costos de producción y depende de la calidad de pronósticos climáticos que no están disponibles por el momento. Se determinó que mantener la flexibilidad de pastoreo es muy importante para manejar condiciones de forraje variables y que su importancia aumenta con el nivel de variabilidad de la producción forrajera. Sin v...
Two studies were conducted to evaluate the effects of postweaning management of British crossbred heifers on growth and reproduction. In Exp. 1, 239 spring-born, crossbred heifers were stratified by weaning BW (234 ± 1 kg) and allotted randomly to 1 of 2 treatments. Treatments were fed at a rate equivalent to 1.14 kg/d while grazing dormant forage (6.5% CP and 80% NDF, DM basis) and were 1) 36% CP containing 36% RUP (36RUP) or 2) 36% CP containing 50% RUP (50RUP). Supplementation was initiated in February (1995 and 1996) or November (1997 and 1998) and terminated at the onset of breeding season (mid May). Heifers were weighed monthly up to breeding and again at time of palpation. After timed AI, heifers were exposed to breeding bulls for 42 ± 8 d. In Exp. 2, 191 spring-born, crossbred heifers were stratified by weaning BW to treatments. Heifer development treatments were 1) pasture developed and fed 0.9 kg/day of a 36% CP supplement containing 36% RUP (36RUP), 2) pasture developed and fed 0.9 kg/day of a 36% CP supplement containing 50% RUP (50RUP), and 3) corn silage-based growing diet in a drylot (DRYLOT). Heifers receiving 36RUP and 50RUP treatments were developed on dormant forage. Treatments started in February and ended at the onset of a 45-d breeding season in May. Heifer BW and hip height were taken monthly from initiation of supplementation until breeding and at pregnancy diagnosis. In Exp. 1, BW was not different (P ≥ 0.27) for among treatments at all measurement times. However, 50RUP heifers had greater (P = 0.02; 80 and 67%) pregnancy rates than 36RUP heifers. In Exp. 2, DRYLOT heifers had greater (P < 0.01) BW at breeding than 36RUP or 50RUP developed heifers. However, BW at pregnancy diagnosis was not different (P = 0.24) for between treatments. Pregnancy rates tended to be greater (P = 0.10) for 50RUP heifers than 36RUP and DRYLOT. Net return per heifer was US$99.71 and $87.18 greater for 50RUP and 36RUP heifers, respectively, compared with DRYLOT heifers due to differences in pregnancy and development costs. Retention rate after breeding yr 3 and 4 was greatest (P ≤ 0.01) for 50RUP heifers. Thus, increasing the supply of MP by increasing the proportion of RUP in supplements fed to heifers on dormant forage before breeding increased pregnancy rates, cow herd retention, and net return compared with heifers fed in drylot.
Field data collected over a 20-year period at 8 sites in northwestern New Mexico was used to determine Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis Beetle and Young) recovery following control with tebuthiuron (N-[5-(1,1dimethylethyl)-1,3,4-thiadiazol-2-yl]-N-N9-dimethylurea) and to relate understory perennial grass yield to overstory canopy cover. Tebuthiuron killed between 80% and 95% of mature Wyoming big sagebrush plants within 18 months of chemical treatment, but through recruitment plant numbers equaled or exceeded pretreatment density (plants/m 2) at 3 of the 8 sites and were increasing at other locations near the study's end. Wyoming big sagebrush canopy cover averaged ,2% the first 10 years after herbicide treatment but had returned to near pretreatment levels (.15%) at 2 sites, to between 5% and 10% at 4 sites, and to less than 3% at the remaining 2 sites. Treatment life was projected to exceed 35 years for 6 of the 8 study sites. Higher rates of tebuthiuron generally extended treatment life. Annual average perennial grass yield increased on treated areas relative to untreated rangeland at all study sites over the 20-year study period. Grass yield was highly variable between years, with pronounced increases when weather and environmental conditions were favorable for grass growth. A nonlinear S-shaped curve best described overstory-understory relationships and also defined the time path of Wyoming big sagebrush recovery, which differed by study site. Resumen Datos obtenidos durante un periodo de 20 añ os en ocho sitios en el Noroeste de Nuevo México fueron usados para determinar la recuperació n de ''Wyoming big sagebrush'' (Artemisia tridentata ssp. wyomingensis Beetle and Young) después de control con ''tebuthiuron'' (N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N-N9-dimethylurea), y para relacionar la ganancia del estrato vegetal de pastos perennes con la cobertura del estrato arbustivo. El ''tebuthiuron'' eliminó entre el 80 y el 95% de las plantas maduras de ''Wyoming big sagebrush'' dentro de 18 meses después del tratamiento químico, pero debido a la recuperació n el nú mero de plantas igualó o excedió la densidad de pre-tratamiento (plantas/m 2) en 3 de los 8 sitios y se incrementó en los otros sitios cerca del término del estudio. La cobertura promedio de ''Wyoming big sagebrush'' fue ,2% los primeros 10 añ os después del tratamiento con el herbicida, pero regresó pró ximo a los niveles de pre-tratamiento (.15%) en 2 sitios, entre 5% y 10% en 4 sitios, y a menos de 3% en los 2 sitios restantes. La vida proyectada del tratamiento excedió los 35 añ os en 6 de los 8 sitios de estudio. Altos niveles de ''tebuthiuron'' generalmente extendieron la vida del tratamiento. El promedio anual de ganancia en producció n de pastos perennes en á reas tratadas comparadas con pastizales no tratados se incrementó en todos los sitios a lo largo del periodo de estudio de 20 añ os. La ganancia de pasto fue altamente variable entre añ os, con pronunciados incrementos cuando las condiciones climá t...
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