Search

The conservation and management of black‐tailed prairie dogs (Cynomys ludovicianus) have been contentious issues in grasslands of central North America for much of the past century, primarily because of the perception that they compete with livestock for forage. Studies quantifying the magnitude of competition between prairie dogs and cattle are difficult to conduct because of the large spatial and long temporal scales needed to quantify how competition varies in response to interannual variation in precipitation and prairie dog abundance. We examined variation in mass gains of yearling steers in shortgrass steppe of northeastern Colorado, USA, with and without prairie dogs from 2008–2019, a period that encompassed a full cycle in prairie dog abundance from a nadir following plague‐induced population collapse, to peak abundance following population recovery, to plague‐induced population lows again. Analyses of cattle grazing distribution with global positioning system (GPS)‐collars revealed preferential grazing on colonies following a period of unusually high vegetation production, and preferential grazing off colonies following a period of rapid vegetation senescence, but these patterns were not clearly related to cattle mass gains. Across all 12 years of the study, average daily mass gain (ADG) during the growing season was 0.97 kg/steer/day in pastures where prairie dogs were controlled annually, and 0.95 kg/steer/day in pastures where they were not. Average daily mass gain was a quadradic function of precipitation and a linear function of prairie dog occupancy within a pasture, with a generalized linear mixed model predicting an 8.0% decrease in ADG as prairie dog occupancy increased from 0 to 60% of a pasture with average growing‐season precipitation. We did not detect a significant interaction between precipitation and prairie dog occupancy, but one limitation of our study is that the only drought year (2012) occurred when prairie dogs occupied low percentages (10–25%) of the study pastures. Prairie dogs had a small but detectable negative effect on cattle mass gains during the growing season in shortgrass steppe. The magnitude of this effect can be used by managers in combination with market conditions and the spatial extent of prairie dog colonies to estimate economic effects of prairie dogs on livestock operations. © 2021 The Wildlife Society. This article is a U.S. Government work and is in the public domain in the USA. : Mass gain of cattle during the growing season declined linearly by 8% as prairie dog occupancy of shortgrass pastures increased from 0 to 60%. Decisions on the need to manage prairie dog populations could be based on the magnitude of the effect documented in our study, market values of cattle, and the costs of prairie dog control, but managers should also consider the potential for drought to coincide with peak prairie dog abundance, the frequency and timing of plague epizootics in the prairie dog population, and costs of alternative forage sources during drought. [ABSTRACT FROM AUTHOR]

Salt marshes of Samborombón Bay (Argentina) have been grazed sporadically at very low stocking rates, but in the last decade, grazing intensity increased due to agriculture expansion. We investigated the effect of cattle grazing on vegetation and soil salinity on the most extended Spartina densiflora community. This community develops along an elevation gradient where the frequency and duration of tidal flooding and soil salinity increased as elevation decreased. Vegetation and soil data were collected from a national park excluded to cattle grazing for 30 years and from an adjacent commercial livestock farm continuously grazed by cattle. As elevation level decreased, plant cover, richness and diversity of functional groups and species decreased. As we expected, grazing altered soil salinity and vegetation composition in different extent along the elevation gradient. Grazing changed vegetation structure more intensively in the high elevation level because it reduced the competitive exclusion exerted by S. densiflora, allowing the increase in floristic richness. Grazing increased soil salinity and the contribution of salt-tolerant species only in the medium but not in the low elevation level probably because the higher frequency and duration of tidal flooding counterbalanced the increase in evaporation promoted by biomass removal in the low respect to the medium elevation level. While grazing may cause positive impacts for plant conservation in the high elevation level, it may cause negative consequence for livestock production because of the reduction in forage quality along the entire elevation gradient. [ABSTRACT FROM AUTHOR]

Stocker performance and production from mixed cool- and warm-season perennial pastures are important determinants of agricultural sustainability that can be influenced by management. We evaluated the factorial combination of three sources of nutrient application (inorganic only, organic+inorganic combination, and organic only) and two forage utilization regimes [low grazing pressure (LGP) and high grazing pressure (HGP)] on steer stocking density and rate, performance and production during 7 years of pasture management {tall fescue [Lolium arundinaceum (Schreb.) Darbysh.] overseeded into existing Coastal bermudagrass [Cynodon dactylon (L.) Pers.] sod} on a Typic Kanhapludult in Georgia, USA. Nutrient source had few major impacts on responses, except for lower animal performance with organic fertilization (broiler litter) than with organic+inorganic and inorganic only fertilization, especially with LGP. Seasonal changes in stocking weight and rate occurred, not only as expected due to environmental conditions and dominant forage species present, but that also counteracted expected differences imposed by grazing pressure; signaling negative feedback of HGP on forage productivity. Steer performance was greatest in spring and summer under both grazing pressures, but was significantly reduced with increasing grazing pressure in the autumn and winter due to low forage availability. Across years, steer gainha−1 (863kgha−1) was not different between grazing pressures, but gainha−1 declined with time under HGP and was stable with time under LGP. Reducing grazing pressure to a moderate level can lead to equivalent steer production as HGP, and would likely contribute to a more sustainable balance among production, socio-economic and environmental goals. These multi-year results will help cattle producers in warm, moist climates design and implement more sustainable grazing systems. [ABSTRACT FROM AUTHOR]

In this research it was evaluated the influence of different forage allowances and combinations of forage allowances along the year on the pasture accumulation dynamic and animal performance. The experiment was conducted in a natural pasture area with yearling beef heifers maintained in continuous grazing with variable stocking rate. The treatments utilized with fixed forage allowances during the year were 4; 8; 12 e 16kg 100kg-1 of live weight; and the treatments of forage allowance combinations were 8 on Spring and 12 on Autumn- Winter-Summer (8-12%); 12 on Spring and 8 on Autumn- Winter-Summer (12-8%); 16 on Spring and 12 on Autumn- Winter-Summer (16-12%), constituting a experimental design in randomized blocks with two replicates of area. The primary and secondary productions were evaluated on the accumulation period of 2007-2008. The results proved that in situations of very low forage allowances, e.g. 4%, the individual performance of animals and per area were prejudiced. Management of forage allowance combination of 8-12% promoted increase of 35% on the individual performance of animals (0,345kg animal-1), and of 20% on the production per area (209kg ha-1 of LW) when compared to a management of 12% over the year. [ABSTRACT FROM AUTHOR]

With the aim of strengthening the capabilities for beef production in the eastern region of Cuba, alternatives were validated for calf production and cattle fattening in grazing conditions. Thus, grazing systems were designed with compensation areas composed of biomass banks, associated with legumes and sugarcane, and strategic supplementation to the herds. For each purpose, the feeding balance of the year and of the dry season were elaborated. The herd was organized in two groups of production with line grazing, and several reproductive technologies were combined. The alternatives described permitted producing more than 148 kg of liveweight at weaning per cow in the reproduction stage and 165 kg of liveweight in calves at weaning. Birth rate was higher than 80 %, and the age of incorporation to reproduction was reduced in 4.2 months, and the age at first calving was reduced between 8 and 10 months. These alternatives permitted creating capacities for the fattening of bulls from the rearing unit and of milk lines on sustainable basis, with great biological and economical efficiency. The additional investments for the alternatives described are recovered in economically acceptable periods, if the weed infestation is inferior to 20 % of the area of the productive system. These periods are increased as the degradation of the system increases by the weed action. It is recommended to extend this work to all the units of cattle production. [ABSTRACT FROM AUTHOR]

With the objective of knowing the preference of young cattle for twelve forage species of the Trujillo State, Venezuela (Chlorophom tinctoria, Morus alba, Pithecellobium pedicellare, Gliricidia sepium, Guazuma ulmifolia, Cordia alba, Trichantera gigantea, Tithonia diversifolia, Leucaena leucocephala, Moringa oleífera, Azadirachta indica and Samanea saman) a cafeteria test was performed through foliage intake measurements, by means of a Latin square design with a 12-day evaluation period. The chemical composition (CP, CE, NDF, Panicum maximum phenols, condensed tannins, protein precipitable tannins and total sterols) and the in situ ruminai degradability (DMD and OMD) of the forages were determined. The most preferred species were: P. pedicellare (327,98 g DM), L. leucocephala (325,63 g DM), M. alba (293,37 g DM), G ulmifolia (292,48 g DM), C. tinctoria (277,18 g DM) and C. alba (274,49 g DM). The foliages of G sepium (108,05 gDM), T. diversifolia (106,09 g DM), Ai oleífera (76,28 g DM), A indica (76,19 g DM) and S. saman (58,72 g DM) were moderately consumed. However, the biomass of T. gigantea (1,39 g DM) was practically rejected. During the experimental period different trends were observed in the intake of each species. Nevertheless, no significant relationship was observed among the intake and chemical composition, the concentration of secondary metabolites and ruminai degradability. It is concluded that to carry out preference trials with animals for the selection of species with potential for silvopastoral systems is important.

Performance and production of growing cattle (Bos taurus) on Coastal Bermudagrass [Cynodon dactylon (L.) Pers.] pasture are affected by forage allowance, but possible interactions with fertilizer nutrient source (i.e., inorganic vs. organic) and time have not been well described. We evaluated the effects of 3 nutrient sources with equivalent N rates: 1) inorganic, 2) crimson clover (Trifolium incarnatum L.) cover crop plus inorganic, and 3) chicken (Gallus gallus) broiler litter, factorially arranged with 2 residual forage mass levels [grazing to maintain high (4,528 ± 1,803 kg/ha) and low (2,538 ± 1,264 kg/ha) forage mass], on cattle stocking density, ADG, and BW gain during 5 consecutive summer grazing seasons. Across grazing seasons, residual forage mass and nutrient source both affected response variables, but interactions between these variables were rarely significant (P ≤ 0.10). Across grazing seasons and nutrient sources, increasing grazing pressure to maintain a lower forage mass reduced ADG (0.67 vs. 0.88 kg/d; P < 0.00 1) but increased BW gain/ha (726 vs. 578 kg/ha; P < 0.001) due to greater stocking density(8.7 vs. 5.8 steers/ha, P < 0.001; mean BW of growing Angus steers of 212 kg). Inorganic fertilization led to greater stocking density than other nutrient sources (8.2 vs. 6.8 steers/ha, P < 0.001) because of greater forage production. Stocking density to achieve the 2 targeted forage mass levels was widely different during the initial grazing seasons of the study but nearly similar at the end of 5 yr. Cattle performance tended to decline with time during each grazing season under both residual forage mass levels, perhaps as a result of declining forage quality, because performance was positively associated with grazing season precipitation under high forage mass. Steer BW gain/ha was greater (P < 0.05) with lower forage mass early in the grazing season of all years but not necessarily later in the grazing season. Steer BW gain/ha was also greater (P < 0.05) with a lower forage mass during the early years of the study but was similar during the later years of the study. Significant variations in cattle performance and production with time confirmed the short-term seasonal effects but suggested that the long-term effects may also be of importance in maintaining productivity and environmental quality of grazed pastures. [ABSTRACT FROM AUTHOR]

Relationships were developed to predict ammonia (NH3) nitrogen losses from cattle manure in animal housing, during manure storage, following field application, and during grazing. Ammonia loss in each phase was predicted using a mechanistic model for NH3 volatilized from the surface of an aqueous solution of ammonium where the NH3 is transported to the free atmosphere through a pathway with finite resistance. Ammonia emission rate was a function of the ammoniacal N content in the manure, ambient temperature, manure pH, manure moisture content, and the exposed manure surface area. Model relationships were calibrated by selecting values for the resistance to NH3 transport for the various loss pathways, which predicted daily and annual emissions similar to those reported in published studies. In further evaluation, these calibrated relationships predicted average annual losses similar to those documented in previous work over a range in climate locations. These relationships were integrated into a whole-farm simulation model to provide a tool for evaluating and comparing long-term nitrogen losses along with other performance, environmental, and economic aspects of farm production. Whole-farm simulations illustrated that the use of a free stall barn, bottom-loaded slurry storage, and direct injection of manure into the soil reduced NH3 emissions by 33% to 50% compared to other commonly used dairy housing and manure handling systems in the northeastern U.S. The improvement in nitrogen utilization more than offset the increased cost in manure handling, providing a small increase in farm profit. The farm model provides a research and teaching tool for evaluating and comparing the economic and environmental sustainability of dairy and beef production systems. Keywords. Ammonia emission, Cattle production, Farm model, Nitrogen loss, Simulation. [ABSTRACT FROM AUTHOR]