Sward Height Research Articles

Características agronômicas, estruturais e bromatológicas do capim Piatã em lotação intermitente com período de descanso variável em função da altura do pasto

<p>Objetivo-se avaliar a influência das diferentes alturas de pastejo sobre as características agronômicas, estruturais e bromatológicas da Brachiaria brizantha cv. Piatã manejada sob lotação intermitente. Avaliou-se três alturas do dossel forrageiro (30, 45 e 60 cm) ao longo de duas estações de crescimento (Meio e Final da estação). Adotou-se o delineamento em blocos ao acaso, com parcelas subdivididas, onde as parcelas foram alocadas as alturas e nas subparcelas as estações de crescimento. Os valores de altura atenderam o protocolo experimental apresentando médias de 35,2; 43,5 e 59,4, respectivamente para 30, 45 e 60cm de altura. O período de descanso foi variável no decorrer das alturas e proporcionou diferentes ciclos de pastejo, com PD médio de 34, 39 e 54 dias, respectivamente, para as alturas estudadas. A maior produtividade de MST obtida por ciclo foi na altura de 60cm, com média de 4612,51 kg ha-1 e, 3566 kg ha-1 para altura de 30 cm. No entanto nas alturas de 30 e 45 cm foram obtidos três ciclos de pastejo e somente dois para a altura de 60 cm, totalizando com isso, 12,4, 10,7 e 9,2 t MS ha-1 no período. Na relação folha/colmo não houve diferença nas alturas estudadas. O número de perfilho não sofreu alteração com as diferentes alturas, sendo observada a superioridade do número de perfilhos no meio da estação de crescimento. O aumento na altura do pasto não proporcionou alteração no teor de PB e na digestibilidade e aumento nos teores de FDA, apenas foi alterado FDN na altura de 60 cm.</p>

A mobile system for rearing meat chickens on pasture

The effect of grazing on the productive performance and meat quality was evaluated for chickens (Ross 308, n = 192). Chickens were kept in two pens on wooden shavings (2 × 96) from one day of age. On day 23 in the original pen until the end of the experiment at 6 weeks of age. Both groups were fed the same pelleted feed ad libitum. For the pasture-reared group, the moveable shelter was moved twice daily around the pasture with a predominance of grass species. The herbage intake of chickens was indirectly assessed by compressed sward height measurement after each cage movement, which employed a rising plate-meter. In the pasture, chickens preferred grass over clover. There was no significant effect of grazing observed on chicken body weight. The mortality of chick - ens in the grazing group was lower than that in the control group. Pasture treatment improved meat flavour by 9% (P = 0.014), produced breast meat with significantly higher ( P = 0.009) redness, and almost doubled the concentra - tion of α-tocopherol ( P < 0.001). There were no significant effects of grazing on the dry matter, fat, cholesterol or pH of the meat. The production of TBARS in the breast meat of the pasture group after storage at 4°C for 5 days was lower ( P = 0.013) than that in the breast meat of the control chickens. Although the differences between K, Ca, P, Mg, and N concentrations in pasture and soil before and after grazing reached 20%, these differences were not significant.

Little grazer species effect on the vegetation in a rotational grazing system

To maintain and enhance phytodiversity of complex permanent swards, the choice of livestock is still being debated. In this study, vegetation composition, diversity and sward structure of permanent grassland were investigated in response to cattle, sheep or mixed grazing on two sward types differing in composition. The study was conducted in the Solling Uplands in Lower Saxony, Germany, in a triplicate randomized block design. The experimental site belongs to the plant association Lolio-Cynosuretum and is moderately species-rich. One half of the paddocks was treated with herbicides to achieve grass-dominated, species-poor swards (2007: 6.9±1.5speciesm−2, means±sd) in contrast to the diverse controls (10.3±2.9speciesm−2). Paddocks were grazed rotationally in three grazing cycles per year from 2007 to 2011; the vegetation was analyzed from 2007 to 2012. Vegetation composition showed a clear effect of herbicide-treatment, but was not significantly influenced by grazers within or after five years of grazing. With respect to vegetation composition and sward structure, there was no indication of complementary grazing between cattle and sheep in mixed stocking. The effects of grazers in this study were relatively minor and not consistently found. Sward structure, measured as coefficient of variation of sward height, was more heterogeneous in the second grazing cycle 2011 under cattle grazing in contrast to sheep grazing. In addition, the cattle-grazed diverse swards contained more species than the sheep-grazed ones in 2012. These results point toward a slight advantage of cattle grazing for the diversity of European grasslands in common agricultural practice.

Seasonal and interannual variations in feeding station behavior of cattle: effects of sward and meteorological conditions

A feeding station is the area of forage a grazing animal can reach without moving its forefeet. Grazing behavior can be divided into residence within feeding stations (with bites as benefits) and movement between feeding stations (with steps as costs). However, relatively little information has been reported on how grazing animals modify their feeding station behavior seasonally and interannually in response to varying environmental conditions. The feeding station behavior of beef cows (Japanese Black) stocked on a tropical grass pasture (bahiagrass dominant) was monitored for 4 years (2010 to 2013) in order to investigate the association of feeding station behavior with meteorological and sward conditions across the seasons and years. Mean air temperature during stocking often exceeded 30°C during summer months. A severe summer drought in 2013 decreased herbage mass and sward height of the pasture and increased nitrogen concentration of herbage from summer to autumn. A markedly high feeding station number per unit foraging time, low bite numbers per feeding station and a low bite rate were observed in summer 2013 compared with the other seasons and years. Bite number per feeding station was explained by a multiple regression equation, where sward height and dry matter digestibility of herbage had a positive effect, whereas air temperature during stocking had a negative effect (R2=0.658, P<0.01). Feeding station number per minute was negatively correlated with bite number per feeding station (r=–0.838, P<0.001). It was interpreted that cows modified bite number per feeding station in response to the sward and meteorological conditions, and this largely determined the number of feeding stations the animals visited per minute. The results indicate potential value of bite number per feeding station as an indicator of daily intake in grazing animals, and an opportunity for livestock and pasture managers to control feeding station behavior of animals through managements (e.g. fertilizer application, manipulation of stocking intensity and stocking time within the day).

English

Thus study was conducted with the objective of evaluating production and forage characteristics of Signalgrass ( Brachiaria decumbens cv. Basilisk) deferred at different initial heights and nitrogen doses. Three initial sward heights (low - 10 cm, medium - 20 cm and high - 30 cm), three nitrogen doses (40, 80 and 120 kg/ha) and a control treatment, of no fertilization were evaluated. The experimental design utilized was of completely randomized blocks with three replications, in a subdivided-plot arrangement. There was no interaction between sward initial height and nitrogen dose for the variables analyzed. The Signalgrass deferred at an elevated initial height presented greater masses of forage, live stem, dead stem and dead leaves; higher percentage of dead stem and falling rate; and lower number of vegetative tillers, percentage of live leaves and live leaf/live stem ratio. Elevation in the nitrogen dose increase along with the number of live and vegetative tillers; masses of forage, live stem, dead stem, dead leaves and live leaves; percentage of live stem; and live tissue/dead tissue ratio; and reduced the percentage of dead leaves and the live leaf/live stem ratio. Signalgrass can be deferred at low and medium initial heights and varied nitrogen doses, according to the objectives and possibilities of the farmer.

Can animal performance be predicted from short-term grazing processes?

Despite all the biotic and abiotic factors affecting foraging by ruminants, there is a common and fundamental process, which is bite gathering. We hypothesised that because the mechanics of bite formation dominate the foraging process, changes in short-term bite mass are reflected in longer-term animal performance across a wide range of sward conditions. We focus at the meal level of foraging, using experiments in which the effect of abiotic factors and digestive constrains are minimised, making intake rate the main currency. We estimated bite mass across a wide range of structural challenges to large-herbivore foraging in a long-term experiment with heterogeneous native grasslands. A conceptual model was developed for average daily gain, where energy gain and energy costs were proximate causal variables. Energy gain was a function of diet quality and components of daily intake rate, where bite mass was the main component estimated. In turn, components of intake rate were determined by sward structure and bodyweight. Energy costs were a function of bodyweight and abiotic conditions. Finally, sward structure, bodyweight and abiotic conditions were determined by experimental treatments, seasons and years. Then, the conceptual model was translated into statistical models that included variables measured or estimated, and coefficients representing all links in the conceptual model. Weight gain was a function of bite mass, forage characteristics, and animal and abiotic conditions. Models were set up to test whether forage and stocking conditions affected monthly gain beyond the effects through bite mass, after correcting for abiotic factors. Forage mass, height and disappearance did help predict monthly gain after bite mass was included in the model, which supported our hypothesis. However, stocking treatments and season had significant effects not incorporated in bite mass. Although the model explained 77.9% of liveweight gain variation, only 35.2% was due to fixed effects, with 10.8% accounted by bite mass and its interactions. Concomitant experiments showed that sward structure (first with sward height and the second with tussock cover) does determine bite mass and short-term intake rate in the complex native grasslands we studied. Yet, other temporal varying components of monthly gain not correlated with bite mass, temperature or wind, added most of the observed variation in monthly animal performance. Part of the model failure to account for variation in performance may be related to a significant and temporally variable grazing of tussocks. We used a bite mass model that assumed no tussock grazing. In light of these results and a parallel experiment, we conclude that tussock grazing must be incorporated in future versions of the model.

Sheep performance on perennial ryegrass cultivars differing in concentration of water-soluble carbohydrate

High-sugar perennial ryegrass cultivars (HSG) selected for higher concentrations of water-soluble carbohydrate may enhance animal production and reduce emissions of methane and nitrogen. Assessing the effects on economic output and environmental footprint is most robust when related to production per unit of land. Average daily gain (ADG) and liveweight gain per hectare (LWG/ha) of sheep grazing a high-sugar perennial ryegrass cultivar, a diploid perennial ryegrass and a tetraploid perennial ryegrass were compared during measurement periods conducted in spring (84 days duration), autumn (99 days) and late springsummer (160 days). Continuous variable stocking was used, and stocking rate adjusted to maintain a target sward surface height of 6 cm. Average daily gain was higher (P=0.003) on the HSG than on either control in late spring-summer and higher on the tetraploid control than on the HSG or the diploid control in autumn (P=0.04), but the higher ADGs did not translate to significantly higher LWG/ha. These results can inform farmers on cultivar choice and support analysis of methane and nitrogen emissions on an intensity basis for inventory and regulatory purposes. Key words: water-soluble carbohydrate, perennial ryegrasses, high-sugar ryegrass, average daily gain, liveweight gain

Grazing management in an integrated crop-livestock system: soybean development and grain yield

Grazing livestock in integrated crop-livestock systems can cause impacts in the subsequent crop cycle. Aiming to investigate how grazing could affect soybean, the 9th crop cycle of a pasture/soybean rotation was assessed. Treatments were grazing intensities (10, 20, 30 and 40 cm of sward height) applied since 2001 in a mixed of oat and annual ryegrass; and an additional no grazing area as control. Treatments were arranged in a completely randomized block design with three replicates. Grazing affected soybean population and the mass of individual nodules (P 0.05). Soybean yield showed differences among treatments, but no difference was found between grazed and non-grazed areas. Grazing intensities impact the coverage and frequency of weeds (P>0.05). In conclusion, grazing intensity impacts different parameters of soybean yield and development, but only the grazing intensity of 10 cm can jeopardize the succeeding soybean crop.

Using post-grazing sward height to impose dietary restrictions of varying duration in early lactation: its effects on spring-calving dairy cow production

The objective of this study was to investigate the immediate and carryover effects of imposing two post-grazing sward heights (PGSH) for varying duration during early lactation on sward characteristics and dairy cow production. The experiment was a randomised block design with a 2×2 factorial arrangement of treatments. A total of 80 spring-calving (mean calving date – 6 February) dairy cows were randomly assigned, pre-calving, to one of the two (n=40) PGSH treatments – S (2.7 cm) and M (3.5 cm) – from 13 February to 18 March, 2012 (P1). For the subsequent 5-week period (P2: 19 March to 22 April, 2012), half the animals from each P1 treatment remained on their treatment, whereas the other half of the animals switched to the opposing treatment. Following P2, all cows were managed similarly for the remainder of the lactation (P3: 23 April to 4 November, 2012) to measure the carryover effect. Milk production, BW and body condition score were measured weekly, and grass dry matter intake (GDMI) was measured on four occasions – approximately weeks 5, 10, 15 and 20 of lactation. Sward utilisation (above 2.7 cm; P1 and P2) was significantly improved by reducing the PGSH from 3.5 (0.83) to 2.7 cm (0.96). There was no effect of PGSH on cumulative annual grass dry matter (DM) production (15.3 t DM/ha). Grazing to 2.7 cm reduced GDMI by 1.7 and 0.8 kg DM/cow in P1 and P2, respectively, when compared with 3.5 cm (13.3 and 14.0 kg/cow per day, respectively). Cows grazing to 2.7 cm for both P1 and P2 (SS) tended to have reduced cumulative 10-week milk yield (−105 kg) and milk solids yield (−9 kg) when compared with cows grazing to 3.5 cm for both periods (MM; 1608 and 128 kg/cow, respectively). Treatments that alternated PGSH at the end of P1, SM and MS had intermediate results. There was no interaction between P1 and P2 treatments. There was also no carryover effect of early lactation grazing regime on milk and milk solids production in P3, given the reduction in early lactation milk yield. The results indicate that the diet of dairy cows should not be restricted by imposing a severe PGSH for all of the first 10 weeks of lactation, cows should graze to 3.5 cm for at least 5 of these weeks.

Density-dependent diet selection and body condition of cattle and horses in heterogeneous landscapes

For some decades, grazing by cattle and horses is used as a management tool to achieve different nature management goals. For managers there are still questions to be answered about the effects of herbivore densities on their performance, vegetation development and biodiversity. This study examines the effect of density on diet composition, diet quality and body condition of cattle and horses. We expressed density as the ratio between consumption and net primary production of the preferred grasslands. Over a period of one year, we studied sward height and diet composition, diet quality and body condition of free ranging cattle and horses in two different study areas with different ratios between consumption and production. Our results showed that the amount of preferred high quality grasses in the diet of cattle and horses was lower when herbivore density was higher. As a result diet quality was lower and as a result of that body condition was affected. In October body condition of cows was lower and in March body of cows and mares was lower in the high density area. A striking difference between cattle and horses was that during the growing season and at high densities, the amount of preferred grasses in the diet of cattle decreased whereas that of horses increased. This was most likely caused by sward height which became probably too low for cattle. As cattle prefer grass heights of 9–16cm, grass heights lower than those make it difficult for cattle to achieve a sufficient instantaneous intake rate. This means that in homogeneous areas and at high herbivore densities, horses can outcompete cattle. In this paper the effects of density dependent diet selection on vegetation development and conservation management are discussed.

Acúmulo de forragem e estrutura do dossel do capim-Xaraés submetido a intensidades de cortes

Objetivou-se com o presente trabalho avaliar o acúmulo de forragem e a estrutura do dossel do capim-Xaraés submetido a cinco alturas de resíduos (10; 20; 30; 40 e 50 cm) com intervalo de corte baseado na interceptação luminosa (IL) pelo dossel durante a rebrotação (95% de IL). O experimento foi conduzido no Setor de Forragicultura do Centro de Ciências Agrárias e Ambientais da Universidade Federal do Maranhão (UFMA), em Chapadinha, no período de março a novembro de 2011. Utilizou-se o delineamento inteiramente casualizado, com cinco repetições. O período de descanso baseado na estratégia de 95% de IL variou em função das alturas de resíduo e época do ano. Houve efeito das alturas de cortes para a produção de forragem, a densidade populacional de perfilhos, o número de perfilhos vivos, altura do dossel e densidade volumétrica de forragem. Apenas a relação folha/colmo e a taxa de acúmulo de forragem não foram influenciadas pelos fatores estudados, no período chuvoso de 2011. No período da seca, os pastos de capim-Xaraés foram afetados de forma negativa para todas as características avaliadas, independente das alturas de resíduo. De maneira geral, intensidades de cortes mais drásticas (10 cm), promovem maior produção de forragem, maior DPP, maior número de perfilhos mortos e maior densidade, no entanto, resulta em menor número de cortes e maior intervalo entre corte. O inverso ocorre com intensidades de cortes mais lenientes (40 e 50 cm).

Assessment of Beetle and Bug Diversity in Extensively Managed Cattle Farms of Varying Cattle Density, Sward Height, and Surrounding Land Use

Livestock that is extensively managed can have higher diversity and abundance of insects in comparison to intensively managed livestock, although data are more equivocal within a gradient of extensively managed pastures. Additionally, biodiversity on farms is vulnerable to degradation of the surrounding landscape and changing patterns of land use. We monitored Coleoptera and Hemiptera on grass-fed cattle farms in North Carolina to determine effects of cattle and land use patterns on biodiversity. We found differences among farms in sward height, densities of several insect families and insect diversity that were related to management but not to cattle density. Sward height was more strongly related to the insect community than surrounding land cover patterns. However, both sward height and land cover patterns were related to insect diversity patterns, suggesting that maintenance of biodiversity is not solely affected by agricultural practices on farms.

A multi-sensor approach for predicting biomass of extensively managed grassland

Leaf area index (LAI), ultrasonic sward height (USH) and common vegetation indices (VI) derived by spectral radiometric reflection data were collected on an experimental field site with three sward types comprising a pure stand of reed canary grass (Phalaris aruninacea), a legume grass mixture and a diversity mixture with thirty-six species in an extensive two cut management system. Sensor measurements and biomass samplings of 0.25m2 subplots were conducted biweekly between May and October in 2009 and 2010. Different combinations of the sensor response values were used in multiple regression analysis to improve biomass (BM) predictions compared to exclusive sensors. Wavelength bands for sensor specific NDVI-type vegetation indices were selected from the hyperspectral data and evaluated for the biomass prediction as exclusive indices or in combination with LAI and USH. In the set of tested parameters, ultrasonic sward height was the best to predict biomass in single sensor approaches (R2 0.73–0.76). Inclusion of LAI improved the model performance and reduced the prediction accuracy by up to 30% for complex swards, while inclusion of vegetation indices resulted only in minor improvements compared to exclusive USH. LAI acted complementary to USH in a combined prediction model, correcting for overestimations of biomass in high swards. Prediction models using exclusive LAI were barely suited to predict biomass accurately (R2 0.36–0.44) but improved significantly when combined with waveband selected VIs (R2<0.8). Combining all three sensors did not significantly improve the model performance.

Carbon and nitrogen reserves in marandu palisade grass subjected to intensities of continuous stocking management

SUMMARYPlant organic reserves and sward leaf area index (LAI) influence plant growth, persistency and herbage accumulation in grazed swards. The present study was conducted to describe patterns of variation in herbage accumulation and carbohydrate and nitrogen (N) reserves in shoot and root of marandu palisade grass subjected to intensities of continuous stocking management throughout the year. Treatments corresponded to four levels of grazing intensity – severe (S), severe/moderate (S/M), moderate (M) and lenient (L) – and were implemented in the field using bands of sward surface height (SSH – 10, 20, 30 and 40 cm ± 10%, respectively) maintained through continuous stocking and variable stocking rate. Total N concentration was higher in the shoot relative to the root compartment during autumn, early and late spring. On the other hand, the concentration of non-structural carbohydrates (NSC) and soluble N was higher in the root compartment, regardless of grazing intensity and season of the year. When taking into account the pool of C and N reserves, the shoot compartment represented the main storage organ, since it corresponded to the largest pool of NSC (averages of 0·102 ± 0·0038 and 0·201 ± 0·0088 kg/m2 for root and shoot, respectively) and soluble N (averages of 2·7 ± 0·26 and 5·3 ± 0·59 kg/m2 for root and shoot, respectively). During late spring, the time of active plant growth, there was a clear contrast in herbage accumulation and sward LAI among grazing intensities, particularly between the severe and lenient grazing treatments. The results show that even with larger pools of soluble N and NSC in the shoot compartment, herbage accumulation was limited by the reduced leaf area of swards subjected to the severe grazing treatment, indicating that under continuous stocking growth seems to be sustained by current assimilates instead of organic reserves. Therefore, targets of grazing management for maximizing herbage accumulation throughout the year should provide adequate combinations between quantity and quality of sward leaf area. This condition was obtained in the severe/moderate and moderate grazing intensities, and corresponded to sward heights between 20 and 30 cm for marandu palisade grass.

Effect of rotationally grazing perennial ryegrass white clover or perennial ryegrass only swards on dairy cow feeding behaviour, rumen characteristics and sward depletion patterns

The effect of sward type, grass only (GO) or grass white clover (GWc), on lactating dairy cow feeding behaviour, herbage depletion rate and rumen function was investigated in rotationally strip-grazed swards at a daily herbage allowance of 17kg dry matter (DM)/cow/day, in two experiments. In 2011, eight rumen-cannulated cows were blocked into two groups and allocated to each sward type for a 14-day period in a change-over design (2 sward types×2 periods) on three occasions: late spring, summer, and autumn. Feeding behaviour, rumen pH and rumen volatile fatty acids and ammonia contents were measured. Following a continuous design, in 2012 feeding behaviour and herbage depletion rate measurements were undertaken at similar times to those in 2011 over 2–3 weeks in late spring, summer and autumn. Twenty-six (spring) and 36 (summer and autumn) cows were used. Grazing sward height (GSH) was measured five times/day. The percentage of grazed vegetative units, and the extended tiller height, free leaf lamina, tiller DM weight and tiller leaf DM weight of perennial ryegrass (ryegrass) tillers were estimated four times/day. During late spring, summer and autumn, sward white clover content (DM basis) was 7.5%, 8.8% and 30.9%, respectively, in 2011, and 18.0%, 29.7% and 30.6%, respectively, in 2012. In 2011 cows had similar grazing times on both sward types. Cows on GWc spent less time ruminating than cows on GO. Cows had similar total volatile fatty acids on both swards but the isoacids and d-lactic acid percentages, ammonia content and rumen pH were higher in autumn for cows grazing GWc. In 2012, cows on GWc grazed for longer in late spring, ruminated for less time in summer and for less time at night in autumn compared to cows grazing the GO sward. Both sward types had similar post-grazing sward heights and sward height depletion rates, except during morning grazing in autumn, when GWc had a greater sward height depletion rate. A similar percentage of grazed ryegrass tillers was observed between sward types, but the percentage of ryegrass grazed was greater than the percentage of white clover grazed in the GWc swards. The ryegrass tillers in the GWc swards were smaller than those in the GO swards but had similar depletion rates. The GWc swards influenced cow feeding behaviour and rumen characteristics with increased effect in autumn because of an increase in white clover content and a decrease in ryegrass quality.

Wildlife Habitat Quality (Sward Structure and Ground Cover) Response of Mixed Native Warm-Season Grasses to Harvesting

Agricultural intensification in America has replaced native warm-season grasses (NWSG) with introduced forages causing wildlife habitat loss and population declines for the northern bobwhite (Colinus virginianus) and similar ground-nesting birds. Reintroducing NWSGs onto managed grasslands to reverse grassland bird population declines lacks information about appropriate multi-purpose management. Post-season nesting habitat quality of mixed NWSGs (indiangrass (IG, Sorghastrum nutans), big bluestem (BB, Andropogon gerardii) and little bluestem (LB, Schizachyrium scoparium)) responding to previous-year(s) harvest intervals (treatments, 30-, 40-, 60-, 90 or 120-d) and duration (years in production), were assessed on late-spring-early-summer re-growths. Yearly phased harvestings were initiated in May on sets of randomized plots, ≥90-cm apart, in five replications (blocks) to produce one-, two-, and three-year old stands by the third year. Sward heights and canopy closure were recorded a day before harvest, followed a week after by visual estimates of ground cover of plant species and litter. Harvesting increased post-season grass cover and reduced forbs following a high rainfall year. Harvested plot swards showed no treatment differences, but were shorter and intercepted more sunlight. Similarly, harvest duration increased grass cover with no year effect but reduced forbs following a high rainfall year. One- or two-year full-season harvesting of similar stands may not compromise subsequent bobwhite nesting-cover provided post-season harvesting starts after the breeding cycle is completed.

Long term defoliation by cattle grazing with and without trampling differently affects soil penetration resistance and plant species composition in Agrostis capillaris grassland

There are no long-term experimental studies dealing with plant community responses to trampling. Here we report the results for soil penetration resistance and plant species changes in mesotrophic temperate Central European grassland after 12-years of grazing management with and without trampling by cattle. Five grazing treatments (intensive and extensive grazing; cut for hay in June followed by intensive or extensive grazing; and intensive grazing with no trampling under permanent electric fencing) with two replicate blocks have been applied since 1998. Species richness, species composition, sward height, nutrient availability in soil and soil penetration resistance were recorded and evaluated. For statistical analysis we used one way ANOVA and RDA with the Monte Carlo test. Long term grazing by large herbivores had a significant effect on soil penetration resistance with the lowest values in the ‘not trampled’ treatment. Legumes, particularly Trifolium repens, and short forbs (especially Veronica serpyllifolia) were supported by intensively defoliated and trampled treatments, whereas tall forbs (mainly Aegopodium podagraria, Hypericum maculatum) prevailed under the extensively managed treatments. The cover of tall and short graminoids was not dependent on applied treatments. The ‘not trampled’ treatment had the highest prevalence of bryophytes (domination of Rhytidiadelphus squarrosus) and was also the richest in a number of vascular plant species; however, it also had the lowest evenness index. Long-term defoliation by grazing animals without trampling does not lead to the creation of typical pasture swards. Species forming pasture communities are essentially dependent on regular defoliation by grazing and regular trampling by hooves, which causes a high degree of soil compaction as well as sward disruption.

Early weaning and concentrate supplementation strategies for lamb production on Tifton-85 pasture

The influence of early weaning and concentrate supplementation strategies on sward characteristics, forage chemical composition and lamb productivity were evaluated in four production systems on Tifton-85 pasture: suckling lambs not supplemented until slaughter; suckling lambs supplemented with concentrate in creep feeding until slaughter; early-weaned lambs not supplemented until slaughter; and early-weaned lambs supplemented with concentrate until slaughter. Structural, morphological and productive characteristics of pasture were measured. The forage was chemically analyzed to estimate its composition. Lambs average daily gain and productivity were calculated. Sward height, forage and morphological components mass were lower in systems without weaning. Forage production was higher in systems with supplementation. Higher levels of neutral and acid detergent fiber were observed in forage ingested by lambs in creep feeding and by weaned and unsupplemented lambs. Average daily gain was higher for lambs in creep feeding (275 g/d) and lower for the weaned and unsupplemented animals (57 g/d). Productivity was higher for weaned and supplemented lambs (21 kg lamb body weight, BW gain/ha/d). Lower productivity was observed in systems without supplementation (5 kg lamb BW gain/ha/d on average). Ewes modify the sward conditions improving the pasture characteristics and the quality of forage produced. Changes in sward conditions affect the chemical composition of forage ingested by lambs. Early weaning may be an alternative to maximize pasture utilization in small areas. Concentrate supplementation may increase lamb performance and productivity in grazing systems. If the objective is to improve lamb individual performance, creep feeding should be used.

Ingestive behavior of goats under four grazing conditions

This study aimed to assess the sward characteristics and the ingestive behavior of mature goats grazingAruana grass (Panicum maximum cv. Aruana) and limpograss (Hemarthria altissima cv. Florida) under lowand high sward heights. The structural and morphological characteristics of the pasture were assessed, aswell as the ingestive behavior of the animals for 24 hours. The animals had free access to the four swardconditions during the trial period. The forage allowance (FA) showed minimum value (P=0.0002) of 3.9%BW in DM/day for low Aruana and maximum value of 12.5% BW in DM.day-1 for high limpograss. The leaf allowance(LA) showed a similar response to the FA, with a minimum (P=0.0012) of 1.7% BW in DM.day-1 forlow Aruana and maximum of 3.1% BW in DM.day-1 for high limpograss. Grazing time was longer (P&lt;0.0001)in high Aruana and high limpograss, in which the leaf mass was similar (high Aruana = 1282 kg DM.ha-1)or superior (high limpograss = 1773 kg DM.ha-1) to the average leaf mass of the pasture (1335 kg DM.ha-1).It was concluded that mature goats graze for longer periods in high-height swards with higher forage andleaf masses. The criteria chosen for pasture areas to be explored are based on these characteristics, underwhich goats sought to maximize the intake of high quality forage. Grazing activity followed a similar patternof other domestic herbivores (cattle, sheep and horses), but goats did not interrupt this activity during the hottest hours of the day. The activities of rumination and rest occurred for prolonged periods and withhigher frequency during night and late night.

Evaluation of Aminopyralid Applied PRE to Control Western Ragweed (Ambrosia psilostachya) in Oklahoma Pastureland

Western ragweed is problematic in Oklahoma pasture and rangeland. There are no labeled PRE herbicides for western ragweed control in pastures to allow ranchers the flexibility of extending the spray season or the ability to spray before emergence of sensitive crops in bordering fields. Field studies were conducted in four locations during a 2-yr period to determine the effects of applying aminopyralid PRE for control of western ragweed. Good to excellent control of western ragweed was obtained when aminopyralid rates of 89 g ae ha−1 or greater were applied PRE. Control was season long and equal to that obtained with a formulated mixture of 2,4-D and aminopyralid applied POST at a rate of 457 + 57 g ae ha−1. Sward height at time of PRE application had little to no effect on the efficacy of the treatment, but time after application before a significant rainfall event did influence the aminopyralid rate needed to achieve acceptable PRE control.