Effects of rotational poultry grazing on herbaceous vegetation and NIRS characteristics in Mediterranean olive agroecosystems

Rotational vs. Continuous Grazing Affects Animal Performance on Annual Grass-Subclover Pasture

Changes in basal cover and botanical composition were recorded at four stocking rates, both under continuous and rotational grazing in the Northern Cape. The experiment was conducted with cattle. Results suggested that heavier stocking rates could be applied under rotational grazing than under continuous grazing without veld deterioration occuring. After four seasons, botanical composition deteriorated only under continuous grazing. Plant basal cover decreased significantly at the heavy stocking rates, both under rotational and continuous grazing. This result illustrates the danger of grazing strategies based on an injudicious increase in stock numbers. Basal cover was found to be a better indicator of trends in veld condition than botanical composition, despite annual fluctuations resulting from rainfall variability. Changes in the botanical composition apparently occur only where veld deterioration is more advanced.

The future of grazing research

Biological control of Canada thistle in temperate pastures using high density rotational cattle grazing

Native Aspen Parkland landscapes consist of a complex mosaic of plant communities, including riparian meadows, upland grasslands, and forests. Sustainable livestock production in this environment depends on an understanding of livestock grazing behavior among communities, particularly under contemporary, intensive management rotational grazing systems. This study examined seasonal patterns of absolute (kg ha-1) and relative (%) herbage utilization, as well as plant community visitation, across a Parkland landscape by 150 heifers in two rotations of a high-intensity, low-frequency grazing system. Graminoids constituted more than 92% of the total herbage utilized. Absolute graminoid utilization within each grazing period was greater (P < 0.05) throughout the growing season from riparian meadows (2003 to 2114 kg ha-1) than from upland grasslands (762 to 1041 kg ha-1) or forests (782 to 800 kg ha-1). In contrast, relative graminoid utilization remained similar (P > 0.05) among communities in either rotation, suggesting heifers grazed in proportion to graminoid availability (57–61% in first rotation, 44–54% in second rotation). Although riparian meadows represented a small fraction of the landscape (~ 4%), and provided up to 9.5% of the total forage used, the majority of herbage removal at the paddock level continued to originate from upland grasslands and forests. Patterns of visitation indicated heifers initially visited riparian meadows more often within each 3–4 day grazing period, regardless of entry date. While upland grasslands were least visited in June, forests were least visited in August. Based on these utilization and visitation patterns, we discuss the implications of using high-density, rotational livestock grazing for the sustainable management of Aspen Parkland rangelands. Key words: Aspen forest, cattle grazing, forage quality, herbage utilization, riparian meadow, rotational grazing, upland grassland

This work evaluated if strategic control based on no more than three or four annual treatments is useful to control Rhipicephalus microplus infestations on cattle when it is applied to intensive rotational grazing and silvopastoral systems with high stocking rates in subtropical areas. In the intensive rotational grazing system, three annual treatments with chemical acaricides were applied on cattle in two different schemes: between spring and early summer and from late winter and late spring. Strategic control based on three treatments with chemical acaricides from late winter to late spring plus an additional fourth treatment in summer was tested in the silvopastoral system. In the intensive rotational grazing systems, the control schemes allow to reach a significant reduction in the tick load on cattle considering a time interval from spring to autumn. However, the efficacy levels were not high enough in some specific moments, namely, the tick counts of summer and autumn (there were not significant differences between treated and control groups). The scheme evaluated in the silvopastoral grazing system yielded better results than those tested for the intensive rotational system, because significant differences in tick load between treated and control groups were observed in all post-treatment counts and when the analysis was performed for the whole study period. However, values of efficacy in the count-by-count comparison were disparate, ranging from 64.1 to 99.7. Although the efficacy values obtained in the silvopastoral system were better than those of the rotational grazing systems, the total tick load on treated cattle in autumn was not low enough (mean abundance values 25.14 and 38.14). Ticks were more evenly distributed among hosts in late summer and autumn than in spring or early summer, where few hosts carry most of the ticks. Some management strategies as intensive rotational systems or silvopastoral structures can lead to a more efficient forage use, but they imply greater tick challenge than in extensive grazing systems. In these situations, the schemes of strategic control bases on three or four annual treatments should be complemented with additional tactical treatments in late summer or autumn.

The objective of this study was to measure growth, covering and chemical composition of native vegetation under two grazing systems. Goats and sheep with an esophageal fistula were used to collect forage intake samples under rotational and continuous grazing systems. Changes in dry matter, vegetation cover and botanical composition were monitored. Dry matter values changed from 30 to 471 kg ha-1 in continuous grazing and from 101 to 1,151 kg ha-1 in rotational grazing. Such behavior was partially due to a higher annual rainfall during the study period (600 mm) than the mean annual rainfall (400 mm). Vegetation cover under rotational grazing was 60 % against 35 % found in continuous grazing. Crude protein values did not show differences between both grazing systems. However, protein values showed differences between seasons and animal species (P<0.01). Goats collected more protein than sheep, with higher values in summer (12.0 %) and lower in winter and spring (5.3 and 4.3 %, respectively). Ashes, acid detergent fiber and neutral detergent fiber were also evaluated. Diet protein content was not affected for the big difference in plant species number between both grazing systems. It is concluded that the small ruminant grazing selectivity played an important role in this matter.

Continuous grazing favored strawberry clover (Trifolium fragiferum L. ‘Salina’), and rotational grazing (5‐field; 1‐week grazing, 4‐week recovery) favored Ladino clover (T. repens L.) in a sward containing Ladino clover, ‘Salina’ strawberry clover, orchardgrass (Dactylis glomerata L), and perennial ryegrass (Lolium perenne L.). A 2‐field rotation (I‐week, I‐week) favored strawberry clover but had less influence on botanical composition than either 5‐field rotation or continuous grazing. Continuous grazing resulted in a higher percentage of plant cover than did 5‐field rotational grazing. Yields of beef per unit area were similar under the three systems. Water infiltration increased progressively during the 4 years of the experiment, and final infiltration rates were 2 to 3 cm/hr in both continuous and rotationally grazed pastures.

Quality and Botanical Composition of Cattle Diets under Rotational and Continuous Grazing Treatments

Some Effects of a Rotational Grazing Treatment on Quantity and Quality of Available Forage and Amount of Ground Litter

Effect of cattle grazing on range perennial grasses in the Mendoza plain, Argentina

As part of the Cicerone Project’s farmlet experiment, conducted on the Northern Tablelands of New South Wales, Australia, between July 2000 and December 2006, this study assessed the effects of varying soil fertility, pasture species and grazing management on the botanical composition of three 53-ha farmlets subjected to different management strategies. Starting with the same initial conditions, the farmlets were managed to reach different target levels of soil phosphorus (P) and sulfur (S); Farmlet A aimed at 60 mg/kg of Colwell P and 10 mg/kg S (KCl40) whereas Farmlets B and C both aimed at 20 and 6.5 mg/kg of P and S, respectively. Pastures were renovated on six out of eight paddocks on Farmlet A, but only one paddock of each of Farmlets B (typical management) and C (intensive rotational grazing) was renovated. Flexible rotational grazing was employed on Farmlets A and B (each of eight paddocks) while Farmlet C used intensive rotational grazing over its 17 major paddocks, which were further subdivided into 37 subpaddocks. This paper focuses on the botanical composition dynamics observed across all three farmlets and the explanatory variables associated with those changes. Eight assessments of botanical composition were carried out at approximately annual intervals across each of the 37 major paddocks distributed across the farmlets and the results for each of 49 species were aggregated into seven functional groups for analysis. The strongest correlation found was a negative curvilinear relationship between sown perennial grasses (SPG) and warm-season grasses (WSG). The most significant factors affecting the functional group changes were soil P, sowing phase, paddock and date. These factors led to significant increases in SPG and correspondingly lower levels of WSG on Farmlet A compared with Farmlet B. Farmlets B and C experienced similar, declining levels of SPG, and increasing levels of WSG suggesting that intensive rotational grazing did not lead to substantial changes in botanical composition, compared with flexible rotational grazing, in spite of the fact that intensive rotational grazing had much longer grazing rests and shorter graze periods than the other two farmlets. Soil P levels were also significantly associated with levels of cool-season annual grasses, legumes and herbs, especially on Farmlet A. In general, the largest differences in botanical composition were between Farmlet A and the other two farmlets; these differences were most closely associated with those plants categorised as sown, introduced, C3 pasture species. The levels of legume were generally low on all farmlets, due largely to the dry seasons experienced over most of the trial. Efforts to increase the legume composition on all farmlets were more successful on Farmlet A than on the other two farmlets due, presumably, to higher soil fertility on Farmlet A. Farmlet C, with its long rest periods and short graze periods, had a small proportion of legumes, due to the competitive effects of the accumulated tall grass herbage between grazings. The ‘typical’ management of Farmlet B also resulted in low levels of legume as well as increased ‘patchiness’ of the pastures and increased numbers of thistles.

Management‐intensive rotational grazing is used by many farmers seeking to balance profitability, environmental stewardship, and quality of life. Productivity of pastures in much of the upper Midwest is limited to April through October, so promoting high quality forage production during the grazing season and for winter storage is critical to dairy and beef farm profitability. We conducted an experiment on pastures dominated by Kentucky bluegrass (Poa pratensis L.), orchardgrass (Dactylis glomerata L.), meadow fescue [Schedonorus pratensis (Huds.) P. Beauv.], perennial ryegrass (Lolium perenne L.), and white clover (Trifolium repens L.) to compare forage production, forage quality, and root production under management‐intensive rotational grazing, continuous grazing, haymaking, and land with no agronomic management. Rotational paddocks were grazed by cow‐calf pairs monthly for ∼2 d and then allowed to rest for ∼28 d. Plots designated for haymaking were harvested two times per growing season. Potential utilizable forage, quantified by incorporating the estimates of refused and nonutilized biomass, and relative forage quality were significantly greater under management‐intensive rotational grazing when compared to the other treatments. Root production in the surface 15 cm was significantly lower under both grazing treatments compared to the undefoliated control site. The perception of improved production has been used to advocate for rotationally grazed over continuously grazed systems in subhumid pasture, but experimental results have been equivocal. Our results point to managed grazing as a viable alternative to continuous grazing and haymaking in terms of both forage production and quality but not root production.

Movement Dynamics and Energy Expenditure of Yearling Steers Under Contrasting Grazing Management in Shortgrass Steppe

We investigated the synergic use of optical and biophysical traits to characterize Bromus inermis (smooth bromegrass) pasture lands and assess the combined effects of long-term (15-years) rotational grazing and management strategies of (i) no fertilization (C), (ii) mineral nitrogen (N) fertilization (HF), and (iii) supplemented fertilization through dry distiller grains plus soluble (DDGS; SF)- on forage growth, performance, and quality. We found that fertilization improved pasture’s biomass, specific leaf area, leaf area index (LAI), as well as forage quality. The use of N fertilization did not offer an advantage (e.g., forage quality, yield) over DDGS under both grazed and ungrazed conditions. Optical, proximal sensing techniques allowed the characterization of pasture lands in a non-invasive and time-efficient manner. We tested established vegetation indices (VIs) for their accuracy in identifying and quantifying important physiological and morphological traits. Results showed that the Normalized Difference Vegetation Index (NDVI) and Vogelmann (VOG) were among the best performing indices. Results contribute to our understanding of the impact of long-term fertilization management on Bromus inermis pastures and validate the use of proximal sensing methods. Proximal sensing methods provide direct, non-invasive, and time efficient tool for assessment of the performance and health of vegetation, keys to successful integrative management strategies.