Search Results (6)

For cattle raised on tropical grass pastures, it is essential to explore strategies that circumvent climatic seasonality that affect forage availability and quality. We hypothesize that the intensification of grazing systems, with rotational and deferred methods, combined with ammonium nitrate or urea supplementation, are excellent strategies to increase ruminal efficiency and animal productivity. For this purpose, 8 cattle with cannulas were distributed in rotational and deferred grazing systems, supplemented with urea or ammonium nitrate, and evaluated throughout the four seasons of the year over a period of two years. Dry matter intake and digestibility were measured using indigestible neutral detergent fiber, titanium dioxide and chromium oxide markers. Ruminal kinetics and degradability of DM and nutrients were measured using the nylon bag technique. Urine parameters were used to estimate microbial nitrogen compounds synthesis and efficiency of microbial protein synthesis. The rotational grazing improves NPN intake, NDF and ADF digestibility, and gross energy. Ammonium nitrate supplementation showed improved efficiency in microbial protein synthesis without negatively affecting feed intake, positioning it as a valuable nitrogen source for grazing cattle. Full article

Current management paradigms suggest deferring grazing rangeland for two years post-fire to avoid additional stress on native grass species, but there is little research supporting these recommendations. This study was conducted within and adjacent to the burn area of a wildfire to evaluate the differences in diet quality, botanical composition, and foraging behavior of beef cattle on burned and unburned rangeland in the spring and fall of the year following a fire. Diet composition and masticate samples were collected during 20 min bite-count periods using six ruminally cannulated cows in burned and unburned sites in June and September. Diets differed between burned and unburned sites across seasons, but the differences were most apparent in June. Cattle grazed more selectively on burned sites in June, consuming a higher quality diet dominated by forbs. In September, cattle shifted to grass-dominated diets with fewer differences between burned and unburned sites. This indicates that the nutritional flush on post-fire rangelands may be minimized by the end of the first growing season post-fire. Additionally, in the first spring post-fire, cattle may shift grazing pressure away from vulnerable perennial native grass species to the early-seral forbs, commonly associated with the post-fire environment. Full article

Stockpiling forage (i.e., deferring grazing) is one way to provide forage for livestock during intervals of low pasture growth, but there are trade-offs as nutrient content declines with increasing forage maturity. Phosphorous (P) concentration, crude protein (CP) content and organic matter digestibility (OMD) were evaluated in two C3 and four C4 grasses native to the South American Campos grasslands. These were: Bromus auleticus (BROAUL) and Nasella neessiana (NASNEE) as C3 grasses and Andropogon lateralis (ANDLAT), Mnesithea selloana (MNESEL), Paspalum dilatatum (PASDIL), and Paspalum notatum (PASNOT) as C4 grasses. The grasses were grown in pots during five stockpiling periods (450, 900, 1350, 1800 and 2250 degree days, approximately 20, 40, 60, 80 and 100 days). As the forage deferment increased, the nutritional value decreased more in C4 than in C3 grasses. Short rest periods (approximately 40 days) are recommended for PASDIL and MNESEL, and medium rest periods (approximately 80 days) for ANDLAT and PASNOT. However, the C3 grasses BROAU and NASNEE maintained high P and CP concentrations and may be the most appropriate option for long rest periods (≥100 days). This information is important to manage different Campos grassland communities for the optimal rest period according to the dominant species. Full article

(1) Background: Desertification is one of the most important environmental impacts around the world. In the semiarid grassland of North of Chile, overgrazing has deep effects on arid lands and consequently on its economy and social development. It is necessary to conduct very detailed studies to determine how the climate, the botanical composition and the grazing system affects this process; (2) Methods: In this paper, we have determined the effect on arid grasslands of three goat managements: exclusions, continuous and deferred grazing on forage biomass, richness, Berger–Parker’s dominance and Shannon’s diversity. This study was developed in Las Cardas Range Station (CEALC) of the University of Chile in the Coquimbo region. The effect of annual and seasonal rainfall on biomass, diversity, richness and dominance parameters was determined; (3) Results: Allochthonous, endemic and native species showed significant changes both for seasonal and annual precipitation. In contrast, the grazing system only affected dominance and biomass of native and endemic species. Deferred grazing was the only management system that increased overall biomass productivity, especially on the best forage plant species. Exclusions showed a positive influence on more endangered species, which were the most vulnerable to goat overgrazing; (4) Conclusions: In consequence, we proposed a network of areas under deferred grazing combined with exclusions. This strategy can increase simultaneously forage productivity, grassland conservation and preservation of associated resources as hunting and wildlife tourism. Moreover, this strategy of range management will allow the sustainability of community of farmers in one of the poorest and most desertified areas in South America. Full article

This study aimed to evaluate the accumulation, structural characteristics, and chemical composition of deferred signal-grass pastures that were subjected to four treatments: without nitrogen fertilization, intercropped with calopo (Calopogonium mucunoides), and fertilized with urea N (50 kg ha⁻¹ and 100 kg ha⁻¹) for 2 years. The design was in randomized blocks, with two blocks and two repetitions of each treatment per block. There were effects of the interaction between treatment and year on green dry mass, forage accumulation, density of vegetative tillers, and crude protein content (simulated grazing). The effects of the treatments on the height, falling index, green dry mass/dead dry mass ratio, number of dead, live and total tillers, and crude protein content (direct cutting) were also observed. Signal-grass–calopo-intercropping ensured adequate mass and forage accumulation and crude protein content equivalent to those of fertilized pastures. In addition, the intercropped pasture showed a higher percentage of leaves and a higher crude protein content compared with those for the other treatments (simulated grazing). The green dry mass/dead dry mass ratio was highest in the intercropped pasture and was equivalent to only that of the pasture fertilized with a low dose of nitrogen. Therefore, signal-grass–calopo-intercropping may be recommended for deferment. Full article

Rangelands cover ~23 million hectares and support a $3.4 billion annual cattle industry in California. Large variations in forage production from year to year and across the landscape make grazing management difficult. We here developed optimized methods to map high-resolution forage production using multispectral remote sensing imagery. We conducted monthly flights using a Small Unmanned Aerial System (sUAS) in 2017 and 2018 over a 10-ha deferred grazing rangeland. Daily maps of NDVI at 30-cm resolution were first derived by fusing monthly 30-cm sUAS imagery and more frequent 3-m PlanetScope satellite observations. We estimated aboveground net primary production as a product of absorbed photosynthetically active radiation (APAR) derived from NDVI and light use efficiency (LUE), optimized as a function of topography and climate stressors. The estimated forage production agreed well with field measurements having a R² of 0.80 and RMSE of 542 kg/ha. Cumulative NDVI and APAR were less correlated with measured biomass ( $R^2$ = 0.68). Daily forage production maps captured similar seasonal and spatial patterns compared to field-based biomass measurements. Our study demonstrated the utility of aerial and satellite remote sensing technology in supporting adaptive rangeland management, especially during an era of climatic extremes, by providing spatially explicit and near-real-time forage production estimates. Full article