•Accurate spatially-explicit models are needed to target management and conservation strategies in coastal meadows.•Above-ground biomass and grassland structure maps were produced using UAV-derived ...datasets.•Sensor fusion improves biomass prediction accuracies.•Monospecific and continuous grazing led to simplified grassland structure.
Coastal meadows provide a wide range of ecosystem services worldwide. In order to better target conservation efforts in these ecosystems, it is necessary to develop highly accurate models that account for the spatial nature of ecosystem structure, processes and functions. In this study, above-ground biomass was predicted at very high spatial resolution in nine study sites in Estonia. A combination of UAV-derived datasets were used to produce vegetation indices and micro topographic models. A random forest algorithm was used to generate above-ground biomass maps and assess the contribution of each predictor variable. The model successfully predicted above-ground biomass at very high accuracies. Additionally, grassland structural heterogeneity was assessed using UAV-derived datasets and vegetation indices. The results were subsequently related to management history at each study site, showing that continuous, monospecific grazing management tends to simplify grassland structure, which could in turn reduce the supply of a key regulation and maintenance ecosystem services: nursery and reproduction habitat for waders. These results also indicate that UAV-based surveys can serve as reliable grassland monitoring tools and could aid in the development of site-specific management strategies.
•We evaluated the effect of two grazing management strategies on herbage and animal production.•Rotatinuous stocking is a grazing strategy based on animal ingestive behaviour.•This approach ...prioritizes the optimal sward structure to maximize intake rate.•Rotatinuous stocking results in greater herbage and animal production.•Trade-off between forage and animal production is overcome with rotatinuous stocking.
‘Rotatinuous’ stocking is a grazing management strategy based on animal behavioural responses to sward structure which is designed to maximize herbage intake per unit of grazing time. It is an alternative to traditional grazing management practices focusing on pasture use efficiency and maximizing herbage accumulation and harvesting. To investigate this approach, Italian ryegrass (Lolium multiflorum) pastures grazed by sheep were evaluated in 2014 and 2015 under two contrasting grazing management strategies. Paddocks were distributed under a complete randomized block design with four replicates. Grazing management strategies were: traditional rotational stocking (RT), with pre- and post-grazing sward heights of 25 and 5 cm, respectively, and ‘Rotatinuous’ stocking (RN), with pre- and post-grazing sward heights of 18 and 11 cm, respectively. Thirty-two castrated Texel × Polwarth crossbred lambs were randomly allocated to treatments. As a consequence of grazing strategies, the stocking cycles were 12 and 4, with resting periods of 13 and 35 days, respectively, for RN and RT treatments. Herbage production, total herbage harvested, and feed conversion efficiency were 28%, 20%, and 40%, respectively, greater for RN than for RT treatment. Although the stocking rate was lower, the average daily gain per animal and live weigh gain per hectare were 153% and 43%, respectively, greater for the RN treatment. Despite the RN treatment being orientated to maximize herbage intake per unit of grazing time, it results in greater total herbage production and harvesting. We conclude that the ‘Rotatinuous’ stocking strategy is not necessarily reversed by low herbage harvesting efficiency. This innovation in grazing management conciliates high herbage and animal production at the same time.
Agriculture, and livestock production in particular, is criticized for being a contributor to global environmental change, including emissions of greenhouse gases (GHG). Methane (CH4) from grazing ...ruminants accounts for most of livestock's carbon footprint because a large share of them are reared under suboptimal grazing conditions, usually resulting in both low herbage intake and animal performance. Consequently, the CH4 quota attributed to animal maintenance is spread across few or no animal outputs, increasing the CH4 intensity g CH4/kg live weight (LW) gain or g CH4/kg milk yield. In this review, the generalized idea relating tropical pastures with low quality and intrinsically higher CH4 intensity is challenged by showing evidence that emissions from animals grazing tropical pastures can equal those of temperate grasses. We demonstrate the medium-to-high mitigation potential of some grazing management strategies to mitigate CH4 emissions from grazing ruminants and stress the predominant role that sward canopy structure (e.g., height) has over animal behavioral responses (e.g., intake rate), daily forage intake and resulting CH4 emissions. From this ecological perspective, we identify a grazing management concept aiming to offer the best sward structure that allows animals to optimize their daily herbage intake, creating opportunities to reduce CH4 intensity. We show the trade-off between animal performance and CH4 intensity, stressing that mitigation is substantial when grazing management is conducted under light-to-moderate intensities and optimize herbage intake and animal performance. We conclude that optimizing LW gain of grazing sheep and cattle to a threshold of 0.14 and 0.7 kg/day, respectively, would dramatically reduce CH4 intensity to approximately 0.2 kg CH4/kg LW gain, as observed in some intensive feeding systems. This could represent a mitigation potential of around 55% for livestock commodities in pasture-based systems. Our results offer new insights to the debate concerning mitigation of environmental impacts of pastoral ecosystems.
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•C3 or C4 forages can drive similar CH4 intensity under good grazing practices.•Optimizing intake is mandatory for CH4 mitigation in grazing conditions.•Live weight gain thresholds are required to assure low CH4 intensities.•Grazing animals can have CH4 intensities as low as those of some confined animals.•Sound grazing practices could lower CH4 intensity of ruminant by 55%.
One of the variables in the structure of the sward with the most influence on the short-term herbage intake rate by grazing ruminants is the canopy height. The objective of this study was therefore ...to characterise the effect of the canopy height on short-term herbage intake rate using Sorghum bicolor cv BR 501. as a reference. Two experiments were conducted at Research Station of the Federal University of Rio Grande do Sul, Brazil, between December 2009 and April 2010. The treatments in experiment 1 were used to determine the influence of the pre-grazing canopy height on the short-term herbage intake and consisted of six canopy heights (30, 40, 50, 60, 70 and 80cm). The treatments in experiment 2 used the pre-grazing canopy height from experiment 1 that maximised the short-term herbage intake rate to evaluate the influence of the severity of grazing down (16, 33, 50, 67 and 84%) on the herbage intake. Both experiments used a completely randomised block design, with two replicates in experiment 1 and three replicates in experiment 2. Four heifers (24±2months and 306±56.7kg) were used in experiment 1. Three of these animals were used in experiment 2, which were then 26±2months and 339±45.5kg. The short-term herbage intake rate was measured by weighing the heifers pre- and post-grazing, corrected for insensible weight losses. The number of grazing jaw movements (biting and non-biting) was counted automatically using an IGER Behaviour Recorder. In both experiments, the sward measurements included the pre- and post-grazing canopy height, the pre-grazing herbage mass and the vertical distribution of morphological components. In experiment 2, the post-grazing herbage mass was also measured. The results showed that the grazing canopy height that maximised the short-term herbage intake rate was approximately 50cm. The grazing down protocol showed that the short-term herbage intake rate was constant until the depletion of 40% of the optimal pre-grazing canopy height. After this level of depletion, there was a marked reduction in the short-term herbage intake rate. The results show that the best target management height in a Sorghum cv. BR 501 pasture, allowing for high levels of the short-term herbage intake rate, is 50cm. With intermittent stocking, this level should be considered as the pre-grazing canopy height, and the level of herbage depletion should not exceed 40%.
•Model typical of crop livestock systems from subtropics.•Managing mixed oats and annual ryegrass pastures at 20cm lead to overall soil–plant–animal.•Equilibrium between animal performance and ...no-till crop demand for soil cover.
Feeding livestock with cover crops can improve the efficiency and sustainability of integrated crop–livestock systems under no-till. However, no-till systems are based on permanent soil cover by organic material, so grazing livestock can compete for soil cover. Hence, managing stocking rates during the grazing period of the cultivated forage species is a key factor to assure enough herbage mass for maintaining long-term sustainable no-till systems. In this context, the objective of this study was to determine sward management targets for a continuously stocked mixed oat (Avena strigosa)×annual ryegrass (Lolium multiflorum) pasture in rotation with soybean in a no-till integrated crop–livestock system to determine the optimum balance between animal production and herbage mass for soil cover. The effects of sward height management on animal performance and herbage mass covers were evaluated. Treatments corresponded to four sward heights: 10, 20, 30 and 40cm, maintained throughout the experimental period through continuous stocking and variable stocking rate, plus a no-grazing control area. Treatments were arranged in a randomized complete block design with three replications. Herbage mass and animal performance increased linearly with sward height, but weight gain per hectare decreased. Grazing efficiency fitted to a quadratic regression and conversion efficiency a logarithmic model. Equilibrium between grazing and conversion efficiencies was reached on swards managed at 20cm, indicating that this sward height provided enough herbage mass to allow both animal performance and no-till crop demand for soil cover.
•Low and moderate grazing intensities promote a grazing down around 45% of non-limiting pre-grazing sward height.•The sward structure and the forage chemical composition of annual ryegrass sward ...(Lolium multiflorum Lam.) managed under low and moderate grazing intensities in rotational stocking are suitable for sheep grazing in the beginning of the sward reproductive stage.•During grazing down stages in the end of the sward reproductive stage, both grazing intensities studied restricted the sheep's ingestive behavior patterns in the larger spatial and temporal scales in a foraging hierarchy (e.g. bites by feeding station, steps per minute, and grazing time).•Sheep's behavioral response depends on: (i) grazing intensity, (ii) period of sward reproductive stage, and (iii) forage structural composition during grazing down.
Foraging behavior studies have supported innovations in sward management, making pastoral systems more sustainable and competitive. Based on this, we evaluated the sheep's ingestive behavior responses and the changes in sward structure during four stages of grazing down in rotational stocking, indicating the threshold level of grazing down for sheep grazing in the reproductive stage of annual ryegrass (Lolium multiflorum Lam.) managed under two grazing intensities (low and moderate). We found evidence that the two grazing intensities each promoted a grazing down at approximately 45% of the non-limiting pre-grazing sward height. However, during grazing down at the end of the sward reproductive stage, the leaves frequency remained lower than that of inflorescences, indicating a restrictive situation for animals in each of the two grazing intensities evaluated. The sheep's ingestive behavior patterns were constrained by the modifications in sward structure. There was observed a decrease in grazing time and bite rate, and a gradual increase in the number of steps between feeding stations during the grazing down stages. Therefore, sheep's behavioral responses during the grazing down of annual ryegrass depend on: (i) grazing intensity, (ii) period of the sward reproductive stage, and (iii) forage structural and chemical composition during grazing down.
An understanding of the processes involved in grazing behaviour is a prerequisite for the design of efficient grassland management systems. The purpose of managing the grazing process is to identify ...sward structures that can maximize animal forage daily intake and optimize grazing time. Our aim was to evaluate the effect of different grazing management strategies on foraging behaviour and herbage intake by sheep grazing Italian ryegrass under rotational stocking. The experiment was carried out in 2015 in southern Brazil. The experimental design was a randomized complete block with two grazing management strategies and four replicates. The grazing management treatments were a traditional rotational stocking (RT), with pre- and post-grazing sward heights of 25 and 5 cm, respectively, and a 'Rotatinuous' stocking (RN) with pre- and post-grazing sward heights of 18 and 11 cm, respectively. Male sheep with an average live weight of 32 ± 2.3 kg were used. As intended, the pre- and post-grazing sward heights were according to the treatments. The pre-grazing leaf/stem ratio of the Italian ryegrass pasture did not differ between treatments (P > 0.05) (~2.87), but the post-grazing leaf/stem ratio was greater (P < 0.001) in the RN than in the RT treatment (1.59 and 0.76, respectively). The percentage of the non-grazed area was greater (P < 0.01) in post-grazing for RN compared with RT treatment, with an average of 29.7% and 3.49%, respectively. Herbage nutritive value was greater for the RN than for the RT treatment, with greater CP and lower ADF and NDF contents. The total time spent grazing, ruminating and resting did not differ between treatments (P > 0.05), with averages of 439, 167 and 85 min, respectively. The bite rate, feeding stations per min and steps per min by sheep were greater (P < 0.05) in the RN than in the RT treatment. The grazing time per hour and the bite rate were greater (P < 0.05) in the afternoon than in the morning in both treatments. The daily herbage intake by sheep grazing Italian ryegrass was greater (P < 0.05) in the RN than in the RT treatment (843.7 and 707.8 g organic matter/sheep, respectively). Our study supports the idea that even though the grazing time was not affected by the grazing management strategies when the animal behaviour responses drive management targets, such as in 'Rotatinuous' stocking, the sheep herbage intake is maximized, and the grazing time is optimized.
1. The functional response (i.e. the relationship between consumers' intake rate and resource density) is central in plant-herbivore interactions. Its shape and the biological processes leading to it ...have significant implications for both foraging theory and ecology of grazing systems. 2. A type IV functional response (i.e. dome-shaped relationship) of short-term intake rate of dry matter (intake while grazing) has rarely been reported for large herbivores and the conditions that can lead to it are poorly understood. 3. We report a type IV functional response observed in heifers grazing monocultures of Cynodon sp. and Avena strigosa. The mechanisms and consequences of this type of functional response for grazed system dynamics are discussed. 4. Intake rate was higher at intermediate than at short or tall sward heights in both grass species. The type IV functional response resulted from changes in bite mass instead of a longer time needed to encounter and process bites. Thus, the decrease of intake rate of dry matter in tall swards is not explained by a shift from process 3 (potential bites are concentrated and apparent) to process 2 (potential bites are apparent but dispersed, Spalinger & Hobbs 1992). Bite mass was smaller in tall than greater proportion of stem and sheath acting as a physical barrier to bite formation.5. It is generally accepted that potential bites are abundant and apparent in most grassland and meadow systems, as they were in the present experiments. Therefore, a type IV response of intake rate not directly related to digestive constraints may determine the dynamics of intake and defoliation under a much larger set of conditions than previously thought. These results have implications for foraging theory and stability of grazing systems. For example, if animals prefer patches of intermediate stature that yield the highest intake rate, grazing should lead to the widely observed bimodal distribution of plant mass per unit area, even when tall patches are not of significantly lower digestive quality than the pasture average.
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