Grazing Treatments Research Articles

The Effects of Different Grazing Periods on the Functional Traits of Leymus chinensis (Trin.) Tzvelev in a Typical Inner Mongolia Steppe

Plant functional traits are effective indicators and predictors of environmental change, revealing plants’ ecological countermeasures and adaptability through phenotypic plasticity. We conducted a 6-year grazing experiment on typical temperate grassland to assess the impact of different grazing periods on the plasticity and variability of the functional traits of Leymus chinensis and the relationship between traits and individual plant biomass. Our study included four treatments: CK (enclosure), T1 (grazing in May and July), T2 (grazing in June and August), and T3 (grazing in July and September). The results for 13 functional traits indicated that the T3 treatment showed the smallest reduction in individual plant biomass, plant height, leaf area, stem length, and leaf length, making it the most effective type of grassland management and optimal for the maintenance and restoration of L. chinensis traits. Under T1, T2, and T3, the plasticity of stem weight, total leaf weight, total leaf area, and stem length was higher and crucial for regulating individual plant biomass. The results underscore that the changes and plasticity of dominant species under grazing treatments are key to understanding the relationship between ecosystem function and grassland management. This study provides a theoretical basis and data support for the adaptive utilization and restoration management of typical grassland resources.

Integrating grazing and food supplementation in coral restoration to enhance settler survival and growth

Sexual coral propagation faces a significant bottleneck due to high post‐settlement mortality, impeding large‐scale reef restoration. This study assessed the effectiveness of co‐culturing Diploria labyrinthiformis settlers with the herbivorous gastropod Cerithium lutosum and supplementing their diet with a commercially available food source, Reef‐Roids, to enhance settler survival and growth. Settlers were reared for 10 weeks under controlled conditions in one of four treatments: Control (C), Feeding with Reef‐Roids (F), Grazing by C. lutosum (G), and combined Feeding + Grazing (FG). Settlers in the Grazing treatment exhibited the highest survival at 87% after 10 weeks, significantly outperforming those in the Control (43%) and Feeding (48%) treatments. The combined feeding and grazing treatment improved survival rates to 74% and resulted in the highest growth rates, with settlers in this group averaging 11.98 ± 2.38 mm2, approximately 3.4‐fold larger than the control and 2.6‐fold larger than the feeding group. The feeding treatment alone did not significantly enhance survival or growth, underscoring the critical role of grazing in mitigating algal competition and promoting settler development. The results highlight the efficacy of grazing by C. lutosum (G and FG) in improving both survival and growth of coral settlers, substantially surpassing the outcomes of ungrazed treatments (F and C). This study highlights the potential of integrating microherbivores, such as C. lutosum, in ex situ coral nurseries. By regulating algal growth, these grazers minimize the need for labor‐intensive maintenance, offering a scalable and cost‐effective strategy to mitigate the high mortality rates of coral settlers.

Transcriptome Responses in Medicago sativa (Alfalfa) Associated with Regrowth Process in Different Grazing Intensities.

Medicago sativa L. (alfalfa), a perennial legume, is generally regarded as a valuable source of protein for livestock and is subjected to long and repeated grazing in natural pastures. Studying the molecular response mechanism of alfalfa under different grazing treatments is crucial for understanding its adaptive traits and is of great significance for cultivating grazing-tolerant grass. Here, we performed a transcriptomic analysis to investigate changes in the gene expression of M. sativa under three grazing intensities. In total, 4184 differentially expressed genes (DEGs) were identified among the tested grazing intensities. The analysis of gene ontology (GO) revealed that genes were primarily enriched in cells, cellular processes, metabolic processes, and binding. In addition, two pathways, the plant-pathogen interaction pathway and the plant hormone signal pathway, showed significant enrichment in the Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. Protein kinases and transcription factors associated with hormones and plant immunity were identified. The plant immunity-related genes were more activated under high grazing treatment, while more genes related to regeneration were expressed under light grazing treatment. These results suggest that M. sativa exhibits different strategies to increase resilience and stress resistance under various grazing intensities. Our findings provide important clues and further research directions for understanding the molecular mechanisms of plant responses to grazing.

245 The influence of deferment and season of use on beef cattle diet quality and composition following a rangeland wildfire

Abstract Research has shown that forage quality increases after a fire. Greater crude protein content in forage can be beneficial for livestock, and even attract herbivores to recently burned areas. However, there has been little research into how forage quality changes within the first 2 yr after a fire and how it affects livestock diet quality or composition. Therefore, this project was conducted within a burn area of an August 2020 wildfire to evaluate the effect of seasonal deferment and annual rest on diet quality, botanical composition, and foraging efficiency of beef cattle grazing burned rangeland. A randomized complete block design was used comparing June grazing versus September grazing with cow/calf pairs, and no deferment versus a 1 yr deferment of grazing. Sixteen 4-hectare pastures were used, with eight being grazed in 2021 and 2022, and eight only grazed in 2022. Pastures were grazed in either June or September by cow-calf pairs for 2 d at a time. In June, 20 cow/calf pairs were used, and 16 pairs were used in September to account for calf growth/intake. Cattle diet composition and masticate samples were collected during 20-min bite-count periods using six ruminally cannulated cows in each pasture prior to and after 2 d grazing periods. Composition of diets upon pasture entry differed among treatments (P < 0.01) with June diets in greater proportions of forbs than September diets. In addition, June diets with no deferment had greater forb composition than June diets with 1 yr deferment (P < 0.01). Crude protein in June diets were substantially greater than September diets (P < 0.01) and within the June grazing period, greatest for the non-deferred treatment (P < 0.01). June diets had decreased neutral detergent fiber (NDF) concentrations than September diets (P < 0.01) and within the June grazing treatments, the first year after burning was least in NDF content (P < 0.01). There was no difference in ash concentration for all treatments and years (P ≥ 0.07) averaging 16.46% ash content. There was no effect of grazing treatment on grams per bite (P ≥ 0.34) averaging 1.36 grams per bite for pre- and post-grazing treatments. In summary, season of use and timing of grazing following a wildfire has an impact on cattle diet composition and quality with the greatest impact in the spring following a wildfire.

417 Impact of virtual fence technology on yearling steer behavior and performance

Abstract Virtual fencing (VF) has the capacity to transform the landscape of livestock management within extensive rangeland systems. The objective of this study was to evaluate the effect of Vence (Merck & Co., Inc., Rahway, NJ) VF technology on yearling steer behavior and performance. Steers were allocated into one of two grazing systems [continuous grazing (CG) or rotational grazing (RG) managed using VF] across three different stocking rates (light, moderate, and heavy, 0.32, 0.40, and 0.72 animal unit months, respectively) for three grazing seasons. Based on initial body weight, steers were randomly blocked into six pastures (346 ± 39, 273 ± 34, and 319 ± 29 kg, respectively) at the South Dakota State University Cottonwood Field Station (n = 127, 135, and 127, in 2021, 2022 and 2023, respectively). Steers assigned to the CG treatment had free access to the entire pasture for the duration of the grazing season. Steers assigned to the RG treatment were rotated among virtual ‘paddocks’ for the duration of the grazing season. The days spent grazing in each paddock for the RG treatment were determined based on bi-weekly clip plots for biomass estimation. The VF collars were used to track steer location at 5-min intervals; only steers assigned to the RG treatment were managed with VF boundaries and exposed to auditory and electrical cues from the collars. Raw data was downloaded from Vence Herd Manager through an automatic programming interface and cleaned by removing messages that failed to transmit correctly or were outside the bounds of study site pastures. Animal behavior metrics of daily distance traveled (DDT), daily grazing time, daily resting time, and daily walking time were calculated for each individual animal and averaged by pasture using Program R. Steer weights were collected using SmartScales (C-Lock Inc, Rapid City, SD). Average daily gain (ADG) was calculated using a linear model to develop a regression equation for each individual animal using weight as the dependent variable and day of trial as the independent variable. The slope of the regression line was used to estimate ADG. Individual DDT, behavior, and performance metrics were analyzed using a mixed model analysis of variance (ANOVA) to compare the impact of grazing treatment and stocking rate (fixed effects) with year as the random effect. Treatment did not influence (P > 0.05) grazing, walking, or resting behavior. Similarly, no differences were detected in DDT between treatment groups or across different stocking rates. Furthermore, there were no differences (P > 0.05) in ADG across treatment groups. Implementation of VF had no impact on animal behavior or performance, justifying its use in grazing settings; however, financial and cattle finishing aspects still need to be evaluated to determine its overall benefits and costs.

Cover crop grazing length impacts on soil health and crop productivity in US Coastal Plain soils

AbstractIntroducing integrated crop‐livestock systems into row crop production promotes income diversification and potential soil health benefits through cover crop grazing on degraded soils of the southeastern United States, but effects of these practices on crop yields and soil health in Coastal Plain soils are not well established. A 4‐year study was performed to evaluate the effects of grazing a multi‐species winter cover crop on soil health and crop yields under mid‐February, mid‐March, and mid‐April cattle removal dates and a non‐grazed control within an annual cotton (Gossypium hirsutum L.) and peanut crop rotation (Arachis hypogaea L.). Chemical soil health indicators (soil organic carbon and permanganate oxidizable carbon), physical soil health indicators (water‐stable aggregates and penetration resistance), biological soil health indicators (microbial biomass carbon, soil respiration, and arbuscular mycorrhizal fungi colonization), crop yield, and cover crop biomass were evaluated. Cover crop biomass at termination was reduced by 3660, 5250, and 5610 kg ha−1 for the mid‐February, mid‐March, and mid‐April cattle removal treatments compared to the non‐grazed control. No grazing treatment effects were observed for biological soil properties. Soil organic carbon was higher in the non‐grazed treatment than the mid‐April grazing treatment across 0‐ to 30‐cm depth. Penetration resistance across 0‐ to 50‐cm depth and water‐stable aggregates at the 0‐ to 30‐cm depth were both negatively impacted by increased grazing period lengths. Results from this study suggest that longer cover crop grazing periods have little effect on biological and chemical soil health indicators in the short term but can negatively impact some physical soil health indicators.

Assessing supplementing strategies for beef cattle in a bale grazing system using grass hay during variable winter conditions

IntroductionBeef cattle in the Northern Great Plains of the United States of America are normally kept in open dry lot pens in winter. Practices such as bale grazing, swath grazing, stockpiling, and corn residue grazing, can be used to extend the grazing season and minimize dry lot use. Extending the grazing season has several advantages over dry lot use but arguably the most important benefit is cost savings due to lower labor and input costs. Strategies selected to supplement cattle in extended grazing systems should maintain cost savings while providing required nutrients to cattle. This study was conducted to evaluate supplementing strategies for beef cattle in a bale grazing system using grass hay during variable winter conditions. The study was conducted across variable winter conditions that are encountered in winters in the US Northern Great Plains.MethodsThe study extended over four years. Each year, non-lactating pregnant beef cows (n = 64, year 1; n = 80, year 2, 3, 4) were divided into eight groups of similar average body weight and randomly assigned to one of four bale grazing treatments as follows: a) bale grazing grass hay, b) bale grazing grass hay treated with a liquid supplement, c) bale grazing grass hay and alfalfa hay, and d) bale grazing grass hay and plus 1.8 kg corn DDGS/head/day. Animal performance was assessed from two-day body weights and body condition scores taken at the start and end of the study. Data analysis considered the fixed effects of treatment, year, and treatment x year interaction.ResultsFinal BW tended (P = 0.09) to be greatest following corn DDGS supplementation and lowest when grass hay was offered. The treatment strategy x year interaction (P = 0.026) for ADG showed that corn DDGS supplementation resulted in positive ADG across the years regardless of environmental conditions. Liquid or alfalfa hay supplementation resulted in positive ADG when environmental conditions were favorable. Final BCS (P = 0.005) and BCS change (P = 0.004) were greater following corn DDGS supplementation, intermediate following alfalfa hay or liquid supplementation and lowest when grass hay was fed. Supplementation costs ranged from $1.33 to $1.90/head/day, the highest cost occurred with corn DDGS supplementation mainly due to cost of corn DDGS and labor required to deliver corn DDGS to cattle on pasture.DiscussionAlfalfa hay or molasses-based liquids increased diet CP content but did not supply adequate energy in severely cold winters. Despite relatively higher supplement costs, high energy supplements such as corn DDGS may be required in severely cold winters where cattle require extra energy. Supplement selection should consider supplement effectiveness to meet animal nutrient requirements particularly in adverse winter conditions such as those encountered in the US Northern Great Plains.

Grazing and selenium influence community stability by increasing asynchrony and sedge, forbs stability in alpine meadow of Qinghai-Tibet Plateau

Grazing is a major driving force of biodiversity, functions and stability of alpine meadows. In selenium-deficient alpine meadows, moderate selenium supplementation can promote plant growth and increase selenium content within the food web. However, the combined effect of grazing and selenium (Se) addition on the stability of alpine meadow communities within selenium-deficient soil is still unclear. Therefore, we conducted a three-year experiment in an alpine meadow of Qinghai-Tibetan Plateau (QTP), with two stocking rates (0 and 6 sheep months ha−1) and six levels of Se addition (0, 5, 10, 20, 40 and 80 g ha−1) to explore how grazing and Se addition affect community stability and its relationship with species richness, species asynchrony and functional group stability. Results showed that the community stability, species richness and biomass response ratio of the community increased gradually with the increase in the selenium application under grazing and enclosure treatments, reaching the maximum values at 20 g ha−1. However, when the selenium addition exceeded 20 g ha−1, the above mentioned indexes were decreased gradually, especially under grazing. Structural equation model showed that grazing and selenium addition indirectly affected the temporal stability of sedges and forbs, thus influencing the temporal stability of the community. Results of this study indicated that the alpine meadow can maintain high species diversity and community temporal stability under moderate grazing combined with selenium addition, providing a scientific basis for selenium-enriched grazing management in alpine meadows.

Grazing period management affects the accumulation of plant functional groups, and soil nutrient pools and regulates stoichiometry in the desert steppe of Northwest China

To understand how nutrient cycling and sequestration are influenced by different grazing periods, the C:N:P stoichiometry features of the plant–soil interface in the desert steppe were measured and evaluated. The 5-year seasonal grazing experiment employed four grazing period treatments: traditional time of grazing (TG), early termination of grazing (EG), delayed start of grazing (DG), and delayed start and early termination of grazing (DEG). Additionally, fenced off desert steppe served as the control. The grazing periods each had a differing impact on the C:N:P stoichiometry in both plant functional group and soil depth comparisons. Compared to the EG, DG, and DEG treatments, the TG treatment had a more significant impact on the C, N, and P pools of grass, as well as the C:P and N:P ratios of forbs, but had a reduced effect on the C:P and N:P ratios of legumes. In contrast to plants, the DG treatment exhibited greater advantages in increasing C pools within the 0–40 cm soil layer. Furthermore, in the 10–20 cm soil layer, the C:P and N:P ratios under the EG treatment were significantly higher, ranging from 8.88% to 53.41% and 72.34%–121.79%, respectively, compared to the other treatments (TG, DG, and DGE). The primary drivers of the C, N, and P pools during different grazing periods were above-ground biomass (AGB) and litter biomass (LB). Both lowering the plant C:P and N:P ratios and considerably raising the plant P pool during different grazing periods greatly weakened the P limitation of the desert steppe environment. It is predicted that delayed start grazing might be a management strategy for long-term ecosystem sustainability, as it regulates above-ground nutrient allocation and has a positive effect on soil C and N pools.

Linkage between soil stoichiometric imbalance and microbial carbon use efficiency in desert steppe under different grazing intensities.

Long-term grazing alters soil resource availability and microbial biomass stoichiometry in grassland ecosystems. Exploring the relationship between soil stoichiometric imbalance and microbial carbon use efficiency (CUE) in grazed desert steppe can help understand soil carbon dynamics from a microbial perspective. Based on a long-term grazing platform in Stipa breviflora desert steppe of Inner Mongolia established in 2004, taking heavy, moderate and light grazing intensities, using no grazing as a control, we measured soil available nutrients, microbial biomass and associated enzyme activities for their acquisition, and calculated soil microbial CUE using ecological stoichiometry. The results showed that grazing inhibited soil microbial CUE by 1.0%-10.3%. Soil C:N imbalance was significantly increased by 20.6% in the moderate grazing treatment, while both C:P imbalance and N:P imba-lance were significantly increased by 20.7% and 25.2% in the heavy grazing treatment, indicating that soil microbial communities were more susceptible to N and P limitation. Soil microbial communities maintained their stoichiometric balance by regulating the threshold of elemental stoichiometry ratios and the production of extracellular enzymes. Structural equation modelling (SEM) results indicated that stoichiometric imbalance indirectly affected microbial CUE by altering the threshold of elemental stoichiometry ratios, microbial biomass stoichiometry, and enzyme stoichiometry.

Risk for Endoparasites Among Production Stages of Female Goats With Notes on Sustainable Parasite Control For Smallholder Flocks

The risk of parasitism in different groups of small ruminants depends on intrinsic, environmental, and management factors. Although there are different views regarding the sex-related risk of endoparasites in small ruminants, females are undoubtedly the most affected group in the flock. Moreover, whether the greater sex-specific risk of parasitic infection observed in female goats in field situations is associated with their production or other intrinsic factors is still under scrutiny. In this paper, cross-sectional epidemiological data collected from selected small ruminant flocks were analysed to determine the distribution, risk, and burden of endoparasites in young, nonpregnant, pregnant, and lactating female goats. There was a higher incidence of gastrointestinal parasites (88.4%, 95%CI= 83.01-92.19) than blood protozoa (54.0%, 95%CI= 46.85-60.92), with a significant difference among the groups. A higher risk of gastrointestinal parasites was observed in lactating (OR = 46.667, P = 0.001) and pregnant (OR = 9.167, P = 0.003) groups. A greater risk of blood protozoan infection was also observed in the pregnant (OR = 5.971, P = 0.0104) and lactating (OR = 3.600, P = 0.0528) groups. A significant increase in the mean faecal egg count of the lactating (2.72 ± 0.76) and pregnant (2.34 ± 0.97) groups (P < 0.05) was accompanied by a significantly lower mean PCV in the lactating group (23.48 ± 4.838) than the kids (29.44 ± 6.13), or nonpregnant (27.80 ± 5.525) groups (P < 0.05). Thus, the pregnant and lactating female goats may experience a greater exposure risk and burden of endoparasites. Therefore, female goats may be selectively targeted for implementing nutritional management, controlled grazing, and selective anthelmintic treatment during pregnancy and lactation to save cost and minimise excessive use of anthelmintic.

Grazing affects ecosystem traits by regulating plateau pika activities at the landscape scale

The mechanism underlying the effects of livestock grazing on grassland ecosystem traits has been greatly discussed. However, as a common small burrowing mammal on the Tibetan Plateau grasslands, the plateau pika's (Ochotona curzoniae) influence on alpine grassland ecosystem traits has rarely been investigated, especially beyond the plot scale. In this study, we flew an unmanned aerial vehicle (UAV) over a grassland landscape under grazing and nongrazing treatments. Mounted visible spectral remote sensing, in combination with field surveys, was utilized to explore how livestock and pika grazing modify grassland ecosystem traits at the landscape scale on the Tibetan Plateau (TP). Using object-oriented classification and partial least squares regression, we retrieved the pika burrow distribution and grassland ecosystem traits. Then, the relationships among livestock grazing, pika burrowing and ecosystem traits were evaluated. The results indicated that livestock grazing reduces the alpine meadow community height by 0.13 cm and the species number by 0.25 while increasing the vegetation coverage by 9.69 % and the aboveground biomass (AGB) by 10.07 g/m2. A lower statue grassland community with greater coverage caused by livestock grazing promotes pika burrowing. Pika burrow density increases 100/ha per 1.70 % increase in vegetation coverage, a 1.87 g/m2 increase in AGB or a 0.08 m decrease in community height. Under livestock grazing, both community structure and nutrients are more strongly associated with pika burrow density. The structural equation model demonstrated that livestock grazing regulates pika burrow density by moderating structural value and subsequently affecting nutritional value. Pika burrowing activity explains 40 % of the total variation in nutritional value. Our findings revealed an intrinsic linkage between mammal activities and alpine grassland ecosystems, which can provide guidelines for grassland management through pika population control by adjusting grazing intensity on the TP.

The impact of sheep grazing on shrub communities at the Afrikaner and Hereford grazing trials at Grootfontein in the Eastern Upper Karoo

In the Nama-Karoo, grazing by livestock is an important driver of Karoo shrub composition. Many different breeds of livestock are farmed in the Nama-Karoo, and the stocking rate varies greatly over the region. In this study we examine how grazing by dorper and merino sheep applied at three stocking rates affected two Karoo shrublands on a long-term grazing trial at Grootfontein in the eastern Karoo. The effects of grazing treatment on shrub communities at two sites of the Afrikaner-Hereford grazing trial differed greatly and were measurable after ten years of rest. At the sandier, grassier Afrikaner site, heavy grazing by dorper sheep had a significant effect on shrub composition, density and cover, whereas the effect of grazing treatment was less pronounced at the Hereford site. Lenient grazing by merino sheep resulted in a vastly different community compared to all other grazing treatments. Individual Karoo shrub species responded differently to grazing treatment. Overall shrub recruitment has faltered for all but three species, and populations were dominated by intermediate-sized and large individuals. Results indicate that grazing management, animal type and stocking rate are important determinants of Nama-Karoo rangeland composition and structure with evidence of a legacy effect longer than ten years.

Effects of Sheep Grazing and Nitrogen Addition on Dicotyledonous Seedling Abundance and Diversity in Alpine Meadows

Seedling is a crucial stage in the growth and development of plants, and the expansion and persistence of plant populations can be achieved through seed regeneration. Sheep grazing, fertilization, light, soil moisture, vegetation diversity and biomass, and litter all have potential impacts on species regeneration. We measured vegetation diversity, annual net primary productivity (ANPP), litter, ground photosynthetically active radiation (PAR), and soil moisture of alpine meadows under sheep grazing and nitrogen addition treatments, and studied their effects on the dicotyledonous seedling abundance and diversity using linear regression models (LMs) and structural equation models (SEMs). We found that sheep grazing reduced ANPP, increased vegetation diversity and PAR, and decreased soil moisture. Fertilization increased ANPP and litter, decreased vegetation diversity and PAR, but had no effect on soil moisture. Sheep grazing and fertilization both reduced the abundance of dicotyledonous seedlings, and simultaneously fertilization can reduce the diversity of dicotyledonous seedlings, while sheep grazing had no effect on the diversity of dicotyledonous seedlings. LMs showed that vegetation diversity, ANPP, and litter, rather than light and soil moisture, affected dicotyledonous seedling abundance and diversity. SEMs revealed that sheep grazing and fertilization indirectly influenced seedling regeneration through vegetation diversity rather than ANPP and litter. Our research will increase our understanding of the dicotyledonous plant regeneration process in alpine grasslands and facilitate the development of strategies for management and protection of alpine grassland.

A longitudinal study of tick infestations and management practices in young stock smallholder dairy cattle in the Tanga region, Tanzania

A longitudinal study involving cohorts of young stock animals (<3 years old) kept on smallholder dairy farms in the Tanga region, Tanzania, was conducted to identify and quantify tick infestations and describe on-farm tick management practices. A total of 549 young stock were followed for 23 months, and 3127 grazing and acaricide treatment observations were obtained. Tick counts were low in the present study, and while more than 30% of animals had a tick on one occasion, most animals had no ticks at most examinations. The most commonly encountered spp. were R. appendiculatus, Boophilus spp., A. variegatum and R. evertsi. Most animals were zero-grazed, a management system that significantly limits animal exposure to ticks; however, grazed calves were more than three times more likely to carry R. appendiclatus and Boophilus spp. ticks than zero-grazed calves were (OR [odds ratio] = 4.4, P < 0.001; 3.6, P < 0.001). There were no significant differences among sampling rounds in the numbers of animals carrying R. appendiculatus ticks (likelihood ratio test P = 0.520). Hand spraying was the common method used, acaricides that require on farm dilution were most commonly used, and most farmers used this method at concentrations considerably less than those recommended by the manufacturer, most likely due to poor understanding, high cost (tempting them to over dilute) and weak extension/veterinary services. Variation in acaricide treatment frequency was not associated with variations in tick attachment, suggesting that most farms were under a strong acaricide regime or at irregular intervals or with tick-building resistance. Our findings suggest that geographic variations in vector densities might partly influence the extent of infection caused by tick-borne pathogens. The applicability of this study to large and extensive cattle production systems is recommended to widen the scope of tick management practices while generating additional data that will inform national tick and tick-borne disease control policy reform in Tanzania.

Effects of Different Grazing Treatments on the Root System of Stipa krylovii Steppe

Plants’ root properties are closely related to their ecological adaptability. This study aimed to clarify the differences in root properties of Stipa krylovii under different grazing disturbances. The morphological characteristics of root length, root surface area, root volume, root tip number, specific root length, and specific surface area of S. krylovii were compared under no grazing, light grazing, moderate grazing and heavy grazing conditions. The ecological adaptability to grazing pressure was also examined. Results showed that the underground biomass density decreased with the increase in grazing intensity. Grazing disturbance can lead to changes in plant community characteristics, and roots adapt to changes in these environmental factors by adjusting their distribution. Among the six root configuration parameters, those under light grazing were significantly higher than those under the other grazing types. The root length and root surface area were concentrated in the range of 0–2 mm. Mild grazing and moderate grazing were conducive to fine root penetration and contact with soil. Moderate grazing disturbance was beneficial to grassland vegetation productivity and played an important role in the stability and sustainable utilization of grassland ecosystem.

Grazing increases the positive feedback of legumes while decreasing the negative feedback of grass

AbstractHerbivore grazing affects plant growth and community structure in grasslands. This effect could be directly through foraging and dung/urine return or indirectly through plant–soil feedbacks (PSFs). Addressing the grazing effect on the feedback of plants can explicate the causes of community changes in the grazing system. However, how grazing and PSF interact to affect plant growth remains unclear. Here, we conducted a classic PSF experiment. In the conditioning stage, two native plant species (a grass Bromus inermis and a legume Medicago sativa) were planted in the field with four simulated grazing treatments (ambient, mowing, dung/urine addition, and mowing + dung/urine addition) in a meadow grassland of northern China. In the feedback stage, B. inermis and M. sativa were planted in the soils (both unsterilized and sterilized) from each treatment in the field experiment. Plant biomass of M. sativa showed positive feedback while B. inermis showed negative feedback across all the simulated grazing treatments. Simulated grazing (mowing and dung/urine addition) increased the positive feedback of M. sativa, while decreasing the negative feedback of B. inermis. The addition of dung/urine to the soil was found to have a significantly stronger impact on plant growth feedback compared to the effect of mowing. Dung/urine addition enriches the soil with higher levels of available nitrogen and phosphorus. Our results suggested that legume plants should have positive PSFs while grass should have negative feedback, which might be amplified by grazing because of the dung/urine fertilization effect. Our study improves the understanding of PSF effects on plant growth and community change in grazed grassland.

Heavy grazing reduces soil bacterial diversity by increasing soil pH in a semi-arid steppe.

In a context of long-term highly intensive grazing in grassland ecosystems, a better understanding of how quickly belowground biodiversity responds to grazing is required, especially for soil microbial diversity. In this study, we conducted a grazing experiment which included the CK (no grazing with a fenced enclosure undisturbed by livestock), light and heavy grazing treatments in a desert steppe in Inner Mongolia, China. Microbial diversity and soil chemical properties (i.e., pH value, organic carbon, inorganic nitrogen (IN, -N and -N), total carbon, nitrogen, phosphorus, and available phosphorus content) both in rhizosphere and non-rhizosphere soils were analyzed to explore the responses of microbial diversity to grazing intensity and the underlying mechanisms. The results showed that heavy grazing only deceased bacterial diversity in the non-rhizosphere soil, but had no any significant effects on fungal diversity regardless of rhizosphere or non-rhizosphere soils. Bacterial diversity in the rhizosphere soil was higher than that of non-rhizosphere soil only in the heavy grazing treatment. Also, heavy grazing significantly increased soil pH value but deceased NH4+-N and available phosphorus in the non-rhizosphere soil. Spearman correlation analysis showed that soil pH value was significantly negatively correlated with the bacterial diversity in the non-rhizosphere soil. Combined, our results suggest that heavy grazing decreased soil bacterial diversity in the non-rhizosphere soil by increasing soil pH value, which may be due to the accumulation of dung and urine from livestock. Our results highlight that soil pH value may be the main factor driving soil microbial diversity in grazing ecosystems, and these results can provide scientific basis for grassland management and ecological restoration in arid and semi-arid area.

The effects of grazing on flowering and fruiting phenology in South Brazilian subtropical grasslands

In subtropical grasslands, characterized by the coexistence of species with different physiology, for example C3 and C4 grasses, studies on the reproductive patterns of plants at the community level are scarce. Most available studies are limited to plant-pollinator interactions, and do not include grasses, even though knowledge on phenology of this species group is highly relevant, e.g., for grazing management or ecological restoration. In this study, we monthly evaluated flowering and fruiting in Brazilian subtropical grasslands under different grazing intensities (high, moderate, low, very low, ungrazed) over one year. To estimate the effect of the seasonal variation on the phenology of functional groups (C3 grass, C4 grass, monocots, dicots, shrubs) we used circular statistics. The highest flowering activity occurred in October and November, while fruiting peaked in March and April. Shrubs had the highest number of flowers and fruits, and C4 grasses contributed the largest number of fruiting species. The flowering peak of most functional groups occurred in October, except for C4 grasses and shrubs that peaked in February and November, respectively. Fruiting of C3 grasses peaked in December, C4 grasses and shrubs were most abundant in April and dicots, and monocots peaked in October. Grazing treatments differed considerably in flowering and fruiting patterns for all species groups. Monocots and dicots herbs showed high flowering activity under intense grazing. C3 grasses presented highest peaks in moderate and low grazing intensities, while C4 grasses peaked in very low grazing, and shrubs showed the highest peaks in ungrazed plots. Flowering and fruiting occurred throughout the year in our study system, with clear variation among functional groups in response to climatic and management patterns. Our results can guide seed collection in the field or vegetation cutting for hay transfer, and thus should lead to improvements in the ecological restoration of subtropical grasslands.

89 Improving cattle grazing efficiency with multi-functional cover crops

Abstract Grazing cool-season cover crops provides a sustainable way of extending the grazing season and reducing the impact row-crop farming systems on the environment. Cover crops promote soil health; however, the impacts of grazing cover crops on soil health in the Southeast are not well understood. The objective of the current study was to determine the effects of different cover crop mixtures on a cotton (Gossypium hirsutum)-peanut (Arachis hypogaea) cropping system. The experiment consisted of 18 paddocks, planted in mixtures of grass [‘Coker’ oat (Avena sativa)], grass + legume [‘Dixie’ crimson clover (Trifolium incarnatum)], or grass + legume + brassica [(‘T-raptor’ brassica (Brassica napus × B. rapa)] planted at the Wiregrass Research and Extension Center (Headland, AL). Paddocks were randomly allocated to grazed or not grazed (n = 3). Grazed paddocks were grazed with yearling beef steers (266 ± 44 kg) using the put and take method to maintain a forage alloance of 1 kg DM per kg BW. Forage samples were collected every 2 wk, for biomass, botanical compositions, and nutritive value. Paddocks were grazed from 17 Jan – 22 Mar 2023 (65 d) and steer BW were taken at the beginning and end of the grazing season for calculation of average daily gain Data were analyzed using Proc Glimmix of SAS 9.4 (SAS Institute, Cary, NC) with forage sampling date considered a repeated measure. No difference in steer average daily gain was detected among grazed treatments (1.5 kg/d; P > 0.44). Cover crop (forage) biomass was also not different among all grazed and ungrazed treatments (1,097 kg DM/ha; P = 0.56). According to the results, grazing cool-season annual cover crops may reduce the supplementation required to maintain cattle through the winter months in the Southeast.