Sown Pastures Research Articles

Evolving Dairy Cattle Systems in Chile: Structural Shifts and Adaptation Strategies.

This study examines the structural and geographical changes in Chile's dairy cattle systems from 1997 to 2021, using data from agricultural censuses. It focuses on variables like animal stocks, herd sizes, pasture utilization, and stocking rates, analyzed through descriptive statistics, multivariable analysis, and geographical mapping. The findings show a significant decrease in dairy farms (-69%) and dairy cattle stocks (-25.4%), with regional disparities: southern farms increased in importance while central farms declined. There is a trend towards intensification, with higher stocking rates and larger herd sizes. Grassland utilization shifted, with a decrease in natural pastures and an increase in improved and sown pastures. The study identifies four typological groups based on stocking rates, dimensions, and pasture use, reflecting distinct evolutionary paths influenced by climate change, land use, economic dynamics, and technology. Geographical analyses highlight regional variations. This research provides insights into the dynamics of Chile's dairy farming sector and its sustainability challenges and opportunities amidst changing environmental and socioeconomic conditions.

Grazing reduced greenhouse gas fluxes in Inner Mongolia grasslands: A meta-analysis

Grazing exerts a significant influence on greenhouse gases (GHGs) fluxes within temperate grasslands. While previous studies have explored the impact of varying grazing intensities on GHGs fluxes in meadow steppe, typical steppe, and desert steppe, there remains a knowledge gap regarding how grazing intensities affect GHGs fluxes across different grassland types and seasonal variations. In this study, we conducted a meta-analysis of Inner Mongolia grasslands involving 38 published reports and aggregating 143, 160, and 118 records for the CO2, CH4, and N2O, respectively. Our results demonstrated that grazing reduced annual mean CO2 emission, CH4 uptake, and N2O emission by 15.29%, 10.56%, and 24.73%, respectively (P < 0.05). Specifically, during the freeze-thaw period, grazing induced a decrease of 28.06% and 58.41% in CH4 uptake and N2O emissions, respectively, compared to ungrazed treatments (P < 0.05). Further dissecting the impact, we found that grazing reduced CO2 emissions in desert steppe, typical steppe, and meadow steppe by 20.28%, 15.54%, and 11.79%, respectively. In addition, grazing decreased CH4 uptake in typical steppe by 15.14% and decreased N2O emission in typical steppe, meadow steppe, and sown pasture by 20.25%, 24.18%, 52.91%, respectively. Crucially, the alteration in plant biomass due to grazing-induced changes underlying drivers that govern the responses of GHGs fluxes. These results furnish compelling evidence that grazing, particularly in non-growing season, holds the potential to mitigate grassland GHGs fluxes in temperate grasslands. Our results can deepen the understanding of the grazing effects on GHGs and offer valuable insights for refining grazing management strategies in pastoral regions.

Transformation of tall-tussock grasslands and soil water dynamics in the Flooding Pampa

Cow-calf production is the main practice within marginal agricultural lands of the world, like the Flooding Pampa of Argentina, where it promotes the transformation of native tall-tussock grasslands Paspalum quadrifarium into native short-grass grasslands or sown pastures. The effect of these land use changes on water dynamics are not well understood, especially in regions subjected to marked interannual drought and flooding cycles. Here we measured soil properties (infiltration rate, bulk density and soil organic matter), rainfall interception by the canopy, and soil moisture during two years with different annual rainfall. Then, we parameterized a hydrological model (HYDRUS) for inferring consequences of soil water fluxes on water regulation. Infiltration rate was significantly higher in native tall-tussock grasslands than native short-grass grasslands and sown pastures, bulk density was significantly lower in native tall-tussock grasslands than native short-grass grasslands and sown pastures, and soil organic matter was significantly higher in native tall-tussock grasslands than sown pastures. Simulated water dynamics during years of low annual precipitation (summer rainfall deficit), show that transpiration and evaporation from native short-grass grasslands represented 59 % and 23 % of total water balance, whereas transpiration and evaporation from native tall-tussock grasslands represented 70 % and 12 %, respectively. This result reflects the high productive capacity of native tall-tussock grasslands under dry conditions. In contrast, under high annual precipitation (excess during fall and winter), transpiration and evaporation from native short-grass grasslands represented 48 % and 26 % of total water balance, whereas in native tall-tussock grasslands represented 35 % and 9 %, respectively. These results suggest a low capacity of native tall-tussock grasslands to evacuate water excess, especially during fall and winter. The observed differences in water fluxes between native tall-tussock grasslands and native short-grass grasslands are important to understand water dynamics under different climatic conditions and could be useful for adaptation to climate change through ecosystem-based management.

Rangeland resilience to droughts: Changes across an intensification gradient

AbstractAimThe intensification of livestock systems generates structural and functional changes in native grassland, which alter their capacity to respond to disturbances. Our objective was to evaluate the resilience to an extraordinary consecutive‐droughts event, across an intensification gradient of livestock systems. Our prediction was that sites with more intensive management (less diverse) will have lower resilience (as resistance and/or recovery) to drought.LocationSouth‐central region of Uruguay.MethodsWe evaluated the resilience (as resistance and recovery) to consecutive droughts, across an intensification gradient of livestock systems. We analyzed the effect of diversity on resilience at two scales: (1) regional — an observational experiment with real commercial farms, where we compared three systems with an increasing level of intensification that determine changes in diversity, (2) patch — we carried out a manipulative experiment with different grazing management intensities determined by the level of biomass removal and fertilization. In both experiments, resistance and recovery were calculated from the Normalized Difference Vegetation Index.ResultsThe most intensified and less diverse management (sown pastures) had significantly lower resistance than native and overseeded grassland. Also, it showed the lowest recovery rate, and its productivity did not reach previous values after the drought's end. The grazing intensification gradient at the plot scale did not show clear differences among treatments both for resistance and recovery. However, resistance of the individual plots showed a positive significant association not only with species richness and diversity, but also with evenness and diversity of functional groups.ConclusionOur research supports the insurance hypothesis by demonstrating that farms with greater biodiversity (less intensive management) have higher resistance to drought. We found that species richness is not enough to account for the effect of diversity on resilience. Our results emphasize the importance of preserving grassland biodiversity to maintain resilient ecosystems in the face of climate change.

A dynamic simulation model to assess farm-level effects of pasture intensification strategies on beef herd outputs and carbon footprints in acid soil savannas of Eastern Colombia

The neotropical savannas of Eastern Colombia (Llanos) are subjected to changes in land use associated with intensification of beef production and there is limited knowledge on the long-term impacts of these change processes. Furthermore, the effects of spatial and temporal intensification at farm level via the introduction of sown pastures on beef herd outputs, their greenhouse gas (GHG) emissions and the resulting carbon (C) footprints in contrasting savanna landscapes of of the Llanos are unknown. This study was aimed to assess the consequences of gradual system intensification via introduction of sown tropical pastures in two contrasting landscapes, the tillable, flat savannas and the highly dissected rangelands, of the well-drained Eastern savannas of Colombia, in terms of cow-calf production and GHG emissions and the resulting C footprints. A dynamic model was developed to simulate the gradual introduction of two types of tropical pastures in a region with dissected and steep slopes and limited tillable areas where cattle would also have access to Serrania savanna and sown pastures, versus one located in the Plains that are fully transformed over time with the exclusion of native rangelands. Marked changes in herd demography, animal outputs, and emissions were found over time. The C footprint of all systems varied over time depending upon the length of time that pastures contributed to soil organic carbon accumulation and the balance between savanna and sown pasture areas at a whole farm level. In conclusion, the dynamics of the systems subject to intensification were marked and were dependent on the temporal and spatial deployment of sown forage resources. Therefore, generalizing the trends for the region as a whole result in uncertainty. Nevertheless, examination of simulated prototypes may shed light on the expected trends and provides guidance for decision-making

The carbon footprint of beef production from cull cows finished on sown pastures in the savannas of the Colombian Orinoquía

Neotropical savannas of the Colombian Orinoquia are largely dedicated to year-round beef production. There is evidence of sustainable animal production in this savanna environment, but little is known of the links among animal lifetime performance, greenhouse gas emissions, and soil organic carbon (SOC) accumulation at the system level. The main objective of this study was to estimate C footprint of beef production from Brahman (Bos indicus) cull cows finished on contrasting C4-grass-based pastures in the Orinoco basin. Long-term individual variations of liveweights and reproductive performance were used in an Excel® dynamic model to estimate dry matter intake, methane (CH4) emissions and carcass traits, and C footprint at the farm gate. Values from the developed database were computed for cows born and raised on the savanna, bred on Brachiaria decumbens, and later finished on B. humidicola [Scenario (SCE) 1, SCE 2]; B. decumbens (SCE 3); Andropogon gayanus + Melinis minutiflora + Stylosanthes capitata (SCE 4); and A. gayanus + S. capitata (SCE 5) pastures. We estimated C footprints of SCE 1, SCE 3, and SCE 5 using published values of the rates of emission of CH4 and nitrous oxide from the soil, feces, and urine; and accumulation of SOC in soil during the fattening period. The majority of the estimated overall C footprint values at the system level were negative due to expected net SOC accumulation during the fattening period. Depending on the expected quality of management, systems ranged from near equilibrium in C balance to net increases in SOC accumulation.

Nitrogen utilisation, energy utilisation and methane emissions of sheep grazing in two types of pasture

Livestock grazing plays a significant role in maintaining grasslands and promoting animal production globally. To understand the livestock performance in sown pasture (SP) vs native pasture (NP) is important to ensure more effective grassland-livestock interactions with minimal environmental impact. A 2 (treatment) * 2 (period) Latin Square design experiment was conducted with 10 growing Hu sheep ♂ × thin-tailed Han sheep ♀ rams grazed perennially SP vs NP in an inland arid region of China. The objectives were to evaluate the effects of grazing management on nutrient digestibility, nitrogen (N) and energy utilisation and methane (CH4) emission. The N intake, N retained and energy intake (gross energy (GE), and digestible and metabolisable energy) of sheep grazing in SP were significantly increased compared with those grazing in NP. There were significant linear relationships between DM intake (DMI) (g/kg BW or g/kg BW0.75) or CH4 (g/kg BW or g/kg BW0.75) emissions and forage nutrient and GE concentrations within each grassland type. The linear regression analysis indicated that forage CP or ether extract concentration was a good predictor for DMI (g/kg BW or g/kg BW0.75) (R2 = 0.756 or 0.752), and CH4 emission could be predicted using forage nutrient and GE concentrations (R2 = 0.381–0.503). These results suggest that DMI and CH4 emissions per unit metabolic BW were accurately predicted by multiple-factor combinations of forage nutrients, including ether extract and CP paired with GE. The present output could provide useful information for the development of sustainable sheep grazing systems in the inland arid regions of the world.

Supplement feed efficiency of growing beef cattle grazing native Campos grasslands during winter: a collated analysis.

Supplementing growing cattle grazing native subtropical Campos grasslands during winter improves the low, even negative, average daily weight gain (ADG) typical of extensive animal production systems in Uruguay. Nonetheless, to render the practice profitable, it is crucial to control supplement feed efficiency (SFE), that is, the difference in ADG between supplemented and control animals (ADGchng) per unit of supplement dry matter (DM) intake. Little has been studied specifically on how SFE varies in these systems. The objective of this study was to quantify the magnitude and variation in SFE of growing beef cattle grazing stockpiled native Campos grasslands during winter and assess putative associations with herbage, animals, supplements, and climatic variables. We compiled data from supplementation trials carried out in Uruguay between 1993 and 2018, each evaluating between one and six supplementation treatments. The average ADG of unsupplemented and supplemented animals were 0.13 ± 0.174 and 0.49 ± 0.220 kg/animal/day, respectively. In both cases, ADG decreased linearly as the proportion of green herbage in the grazed grassland was lower, but the ADG of unsupplemented animals was further reduced when winter frosts were numerous. Estimated SFE were moderately high, with an average of 0.21 ± 0.076 ADGchng/kg DM, resulting from average ADGchng of 0.38 ± 0.180 kg/animal/day in response to an average supplementation rate of 1.84 ± 0.68 kg supplement DM intake/animal/day (0.86% ± 0.27% body weight). No association was found between SFE and supplementation rate or type (protein vs. energy-based; P > 0.05), but forage allowance negatively affected it, and herbage mass positively affected it, yet in a smaller magnitude, suggesting that a balance is needed between the two to maximize SFE. Weather conditions during trials affected SFE (P < 0.05), with greater SFE in winters with lower temperatures and more frosts. Daytime grazing time was consistently lower in supplemented animals compared to their unsupplemented counterparts, whereas ruminating time during the day was similar, increasing as the proportion of green herbage decreased. Herbage intake estimated from energy balance suggested the existence of some substitution effect. This agrees with the moderately high SFE and with the total digestible nutrients-to-protein ratio of these subtropical humid grasslands being higher than in semi-arid rangelands and dry-season tropical pastures but lower than in sown pastures.

Modeling Pinus radiata D. Don growth and pasture production under different land uses and climate scenarios

Yield-SAFE is a biophysical model to predict long-term production according to light and water availability in agricultural, forest, and agroforestry systems. The Yield-SAFE model should be calibrated and validated for the highest number of tree species and crops to be used as a management tool that takes into account climate change. This study aimed to calibrate and validate the Yield-SAFE model for Pinus radiata D. Don and sown pasture (Dactylis glomerata L.) to estimate the production in (1) forest systems, (2) agricultural systems, and (3) silvopastoral systems established in Galicia (NW Spain) under different conditions of climate: (i) reference “current” climate from 1961 to 1990, (ii) climate from 2021 to 2050, and (iii) climate from 2051 to 2080. The Yield-SAFE model can now be used to assess the long-term productivity of P. radiata D. Don and D. glomerata L. under different land uses and climate conditions. The Yield-SAFE model simulated similar tree and pasture growth in all scenarios of climate because the inter-annual variation of climate was small. However, tree growth estimated with the Yield-SAFE model was higher in the silvopastoral systems than in the forest systems, indicating that land use had more impact on land productivity than climate. Therefore, in regions such as Galicia, the Yield-SAFE model could be used as a tool to support the land use change in an agroforestry context, whilst also including climate scenarios which is considered a valuable solution to mitigate the effect of climate change.

Precipitation controls the annual net primary productivity in sown pastures across a precipitation gradient in dry subtropical Chaco

Exotic pasture species are increasingly replacing native vegetation in subtropical areas because of their potential to increase forage yields. However, there is a scarce analysis of the relationship between forage yield and mean annual precipitation across regional gradients. We analyzed at a regional scale the temporal relationship between the aboveground net primary productivity (ANPP) and the precipitation for different sown grasses for several growing seasons across Dry Chaco, Argentina. We compiled biomass harvest data for seven cultivars of Megathyrsus maximus and Cenchrus ciliaris at eight different sites across a gradient of mean annual precipitation (MAP; 200 mm–1100 mm). We found positive relationships between ANPP and precipitation for most of the cultivars. The strong relationship between annual ANPP and MAP found implies that the high temporal variability in MAP translates into ANPP variability. The regional slope between annual ANPP and MAP was 11.12 kg DM.ha−1.year−1.mm−1. The ratio between the temporal and the spatial models ranged from 0.26 to 1.35. Precipitation use efficiency ranged between 3.9 and 24.1 kg DM.ha−1.year−1.mm−1. These models are robust enough to estimate the ANPP of specific pastures from MAP data. This represents a breakthrough, in grazing systems planning and defining conservation policies for natural resources.

Relationship between orchardgrass (Dactylis glomerata) dominance and the soil chemical characteristics of nonallophanic Andosol under cutting and cattle grazing

AbstractSoil acidity affects botanical compositions and pasture production, but the relationship between orchardgrass persistence and the soil nutrients in acidic soils with different management methods is understudied in production fields. Here, using exchangeable acidity (y1) as an indicator of exchangeable aluminum (Al), we conducted a survey to investigate the relationship between orchardgrass dominance and the soil characteristics in sown pastures under different management practices. The botanical composition and soil chemical conditions were investigated in six orchardgrass–tall fescue mixed pastures (two cutting meadows and four cattle grazing pastures) from June 18 to July 17, 2018. Six‐ and three‐line transects were fixed in each meadow or pasture, respectively, and five measurement locations were set along each transect at 10‐m intervals. Each location had three square plots (20 × 20 cm) for the vegetation survey and three consecutive soil sampling plots (4‐cm diameter) adjacent to the middle square plot. The dominant plant species in each plot was recorded, and soil samples were collected at 0‐ to 5‐cm depth to measure y1 and major soil nutrients. The y1 ranged from 3.55 to 25.83 in the cutting meadows, which was wider than in the grazing pastures (1.85–16.29). In the cutting meadows, the dominance frequency of orchardgrass increased with the rise in y1, whereas that of tall fescue decreased in cutting meadows. No significant relationship was found between dominance frequencies and y1 in the grazing pastures. Although concentration of some soil nutrients varied with y1, these nutrients were not related to the dominance frequencies of orchardgrass for either management strategy. These results suggest that orchardgrass declines are prevented at high exchangeable Al sites by the non‐establishment of less Al‐tolerant plant species under cutting conditions.

The effects of protein supplementation and pasture maintenance on the growth, parasite burden, and economic return of pasture-raised lambs.

The objective of this experiment was to evaluate the impact of protein supplementation and pasture contamination with gastrointestinal nematodes on the mitigation of parasitic infection in grazing lambs. We hypothesized that there would be no difference between protein supplementation and newly sown pasture in evaluating lamb growth and health parameters associated with parasitism. Furthermore, we questioned if there would be an interaction between protein supplementation and pasture type. A total of 192, 60-d-old lambs (28.3 ± 5.1 kg) were randomly assigned to one of four treatments: 1) new pasture without supplementation (NN); 2) new pasture with supplementation (NS); 3) established pasture without supplementation (EN); and 4) established pasture with supplementation (ES) and grazed for 112 d. Lambs were supplemented at a rate of 1% body weight/d. Supplemented lambs had greater body weight (BW) and average daily gain (ADG) when compared with non-supplemented lambs (P < 0.04). Additionally, lambs on newly sown pasture demonstrated greater BW and ADG when compared with lambs grazing on established pasture (P < 0.05). For lamb health, lambs in the EN treatment group had the greatest FAMACHA eye scores and lowest packed cell volume (PCV) over the course of the 112-d grazing period (P < 0.05). Moreover, NS and ES treatment lambs demonstrated similar FAMACHA eye scores when compared with NN treatment lambs; however, NN treatment lambs showed lower PCV when compared with NS and ES treatment lambs (P < 0.05). In evaluating fecal egg counts (FEC), lambs on new pasture or given supplement demonstrated lesser FEC when compared with those lambs on established pasture or not given supplement (P < 0.05). Sixty-four lambs were harvested to evaluate total abomasum nematode counts which demonstrated that Haemonchus contortus represented approximately 80% of total nematodes. Furthermore, based upon gross margin analysis, lambs given a protein rich supplement on pasture had a 9.3 kg increase in lamb BW whereas newly sown pasture had a 1.3 kg increase in lamb BW. A protein rich supplement given to lambs grazing pastures contaminated primarily with H. contortus or placing lambs on newly sown pasture increases lamb BW and improves parasite resiliency. Selection of parasite management strategies may be influenced by cost of production and market opportunities.

Effects of cutting frequency and fertilizer-N application on growth and production on guinea grass (Panicum maximum Jacq) sown pasture

A study was conducted to determine the effects of cutting frequency and fertilizer-N rates on growth and production of guinea grass (Panicum maximum Jacq). The experiment was conducted in Nsukka, Nigeria. Treatments comprised four levels of fertilizer N (0, 150, 300 and 450 kg N ha ') and four cutting intervals (3, 6, 9 and 12 weekly intervals). Plant height, tiller number and herbage dry matter yields were significantly increased by 6%, 44% and 53%, respectively, during the establishment year when fertilizer-Nrate was increased from 0 to 450 kg N ha'. The extent of weed cover was significantly (P &lt; 0.05) reduced by 33% in 2000 when fertilizer-N rate was increased from 0 to 450 kg N ha'. Increase in interval between cuts from 3 to 12 weeks significantly (P &lt; 0.05) increased plant height in all the years. Plant height was increased (P &lt; 0.05) by 28% 34% and 28% in 2001, 2002 and 2004, respectively, when fertilizer N was increased from 0 to 450 kg ha'. Application of Nat 450 kg ha produced similar plant heights in 2001 with the 300 kg N ha' but differed from the 150 kg N ha'. Increase in nitrogen application progressively increased (P&lt;0.05) plant height in 2002 and 2004. &#x0D; Key words: , , ,

Long-term land use change in Australia from native forest decreases all fractions of soil organic carbon, including resistant organic carbon, for cropping but not sown pasture

Soil organic matter (SOM) performs an essential function in soil fertility, biomass and crop productivity, environmental sustainability, and climate change mitigation. We examined how land use change from native forest to either pasture [sown buffel (Cenchrus ciliaris cv. Biloela)] or cropping [primarily wheat (Triticum aestivum L.) and sorghum (Sorghum bicolor L.)] affected total soil organic C (SOC) stocks as well as stocks of three SOC fractions, particulate organic C, humus organic C and resistant organic C. Furthermore, for the cropping system, we also examined whether the use of a ley pasture phase could reverse the loss of SOC. It was found that land use change from native forest to pasture decreased SOC stocks by 12.2 % and soil total N (STN) stocks by 24.6 % during the land development to pasture establishment (≤ 1.75 y), although there were no significant (P > 0.05) changes thereafter up to 33 y and final values were generally similar to initial values. Furthermore, stocks of the three SOC fractions did not change with time in this pasture system. In contrast to these modest changes following conversion to pasture, for land use change to cropping, SOC decreased by 48 % at 0−0.1 m and 38 % (from 54 to 33 Mg ha−1) at 0−0.3 m, due mainly to insufficient C inputs to maintain SOM at steady state. Moreover, stocks of all three SOC fractions decreased with time, including the resistant organic C fraction, indicating that this fraction was not recalcitrant under cropping. The biomass C inputs by crops, mainly as root biomass, were not sufficient to reverse or slow down the rate of decrease of SOC in this soil. However, the introduction of pasture during the last 4 y indicated that the decreases in the stocks of SOC could be arrested by a ley pasture phase.

Sustainability of beef production from brigalow lands after cultivation and mining. 3. Pasture rundown, climate and grazing pressure effects

Context The Acland Land System overlying the Walloon sandstone coal deposits in southern Queensland is generally marginal for cropping but well suited to grazing, and thus cultivated land is commonly returned to pasture. Rehabilitation of these lands after open-cut coal mining seeks to be safe, stable and self-sustaining to satisfy requirements for ecologically sustainable development. Aims The present paper evaluates the sustainability and economic viability of beef production on (a) lands retired from cultivation and then rehabilitated with sown pastures after open-cut coal mining at the New Acland mine site, and (b) similar nearby pasture lands that were not mined but were also retired from cultivation. Methods The GRASP grazing systems model was modified and calibrated with short-term (5-year) grazing trial data (soil, pasture and cattle observations), and then used with long-term (60-year) weather data to estimate effects of land type, pasture rundown, climate and grazing pressure on productivity and economic returns. The productivity of three rehabilitated sites and 15 unmined sites were evaluated, including pastures on six commercial properties. Key results Estimates of long-term mean annual growth of pastures on unmined lands retired from cultivation on three land types (Mountain Coolibah, Brigalow Uplands and Poplar Box) were 3398, 2817 and 2325 kg/ha respectively. Pasture growth was greater on rehabilitated lands; 3736 kg/ha on the site most typical of rehabilitated lands and a mean of 4959 kg/ha across three sites. Seasonal conditions had large effects on cattle liveweight gain (133–213 kg/head per year during the trial); however, pasture growth was the main driver of beef production and economic returns per hectare. In GRASP, potential nitrogen uptake was used to influence key pasture growth processes and accounted for 64% of variation in observed annual growth. The short-term lift and subsequent rundown in productivity typically associated with sown pastures was estimated to have increased mean annual pasture and cattle productivity during the 2014–2018 trial period by up to 17% and 25% respectively. Estimates of long-term mean annual beef production and economic returns for the unmined lands were less than estimated for rehabilitated lands and were 139 kg/head.year (45 kg/ha.year) and AU$154/adult equivalent. Conclusions Rehabilitated lands were found to be sustainable for beef production at grazing pressures up to 30% utilisation of annual pasture growth, and comparable with grazing systems on native and sown pastures in good condition. Pastures on unmined lands retired from cultivation had reduced productivity. Implications Overgrazing is a significant and on-going residual risk to sustainable production. Grazing regimes need to continually adjust for changes in novel landscapes, pasture condition and climate. The methods used in the present study could be applied more generally.

Mature herbs as supplements to ruminant diets: effects on in vitro ruminal fermentation and ammonia production

Context High concentrations of crude protein in ruminant diets may lead to excessive production of ruminal ammonia, which may stress the animal’s metabolism and impact nitrogen efficiency. This may become a problem in zero-concentrate feeding systems when pasture grass is rich in crude protein. Polyphenols such as tannins may protect part of dietary protein from ruminal degradation and thus inhibit ammonia formation. Aims The present study screened mature herbs for their potential to mitigate ruminal ammonia formation in cattle, when provided as a supplement to a forage diet. Methods Thirty-five temperate-climate, herbaceous meadow plant species (including three legumes) that appear in biodiverse natural and sown pastures were investigated for their effects on ruminal ammonia production. Aboveground material was harvested during ripening of the seeds and analysed for nutrient and phenol concentrations. Net energy and protein absorbable at the duodenum were calculated. Incubations (24 h) with cattle rumen fluid following the in vitro Hohenheim Gas Test protocol were performed to compare the effects of the test plants on ruminal gas and ammonia formation. Test plants replaced one-third of a basal mixture consisting of 57% Lolium perenne L. and 43% Medicago sativa L. (air-dry-matter basis). Results were compared with those obtained with the basal mixture alone. Key results According to regression analysis, ammonia concentration after incubation was negatively related to concentrations of total extractable phenols and total tannins in feed mixtures, whereas the relationship was weakly positive with dietary crude protein. In 23 and 19 of the test diets, respectively, in vitro gas production (indicating ruminal organic matter digestibility) and ammonia concentrations in the incubation medium after 24 h were significantly lower than with the basal mixture alone. Incubations containing Galium verum L., Leontodon hispidus L., Lotus corniculatus L., Onobrychis viciifolia Scop., Plantago lanceolata L., Sanguisorba minor Scop. and Scabiosa columbaria L. maintained gas production and estimated in vitro organic matter digestibility while at the same time lowering ammonia concentrations. Conclusions Seven mature herbs of a screening of 35 proved to have potential for positive effects on ruminal protein utilisation without impairing fermentation. Implications These herbs are of particular interest as dietary supplements for dairy cows grazing protein-rich pastures.

Effects of Grazing in a Sown Pasture with Forestland on the Health of Japanese Black Cows as Evaluated by Multiple Indicators

ABSTRACT The objective of the present study was to evaluate the effects of extensive grazingin a sown pasture with forestland on the health of beef cows by measuring multiple indicators. Ten Japanese Black beef cows were used in this experiment. Five of the ten cows were grazed for two months on a 1.8 ha field. The remaining cows were fed under confinement conditions. Behavioral assessments showed that grazing increased sternum lying with rumination of the cows. The grazing cows did not show any abnormal behaviors. There was a tendency for the numbers of red blood cells and lymphocytes to be lower in grazing cows than in confined cows, whereas the number of neutrophils in grazing cows was significantly higher than that in confined cows. In addition, grazing cows had a higher total antioxidant capacity and glutathione peroxidase activity than confined cows. These results suggest that extensive grazing in a sown pasture with forestland increases natural behaviors, decreases circulating red blood cells and lymphocytes and enhances neutrophil circulation, antioxidant enzyme activity, and antioxidant capacity.

Pest insects in natural and sown pastures of Paraguay

Paraguayan livestock production is based mainly on the use of natural and sown pastures as basic cattle feed. Several genera of harmful insects reported in forage grasses can cause damage to both yield and quality of forage. A review of the insect collection of the Plant Protection Area of the Faculty of Agrarian Sciences, National University of Asunción was carried out, in order to prepare a list of insects with incidence in grasses. Then random sampling of different species of Poaceae showing insect damage in open areas of paddocks grazed by cattle was carried out during 2014‒2017 in all Regions of Paraguay. Thirteen different genera and species of pastures were collected and 20 species of insects were identified in the following orders: Hymenoptera (Formicidae family: 5 species); Isoptera (Termitidae: 3 species); Hemiptera (Cercopidae: 6 species; Lygaeidae: 1 species); Lepidoptera (Noctuidae: 2 species); and Orthoptera (Acrididae: 3 species). The most common forms of damage observed in pastures were: leaf consumption (25%), leaf cutting (25%) and leaf yellowing-drying (35%).

Adaptation strategies based on the historical evolution for dairy production systems in temperate areas: A case study approach

Dairy production systems are heterogeneous as they are influenced by farm location and structure, markets, environmental conditions, and the producers' preferences and peculiarities. A typology of the existing dairy systems in Chile was developed with the objective of identifying homogenous groups that would allow for the characterization of adaptation strategies to changing environmental, social, technological, political and economic variables. Multivariate analyses were performed on data from official surveys carried out in 2009, 2011, 2013, and 2015. Six groups (I-VI) were identified representing 26.9%, 21.5%, 21.6%, 14.6%, 6.8% and 8.6% of the population surveyed. Group I was the largest, and it included non-specialized commercial dairies. Group II clustered semi-extensive, medium to large dairies that rely mostly on high yielding improved pastures. Group III included small, semi-extensive commercial farms that make a more intense use of pastoral resources, such as sown pastures and improved native grasslands. Groups IV, V, and VI corresponded to specialized dairies, highly market-oriented, that use annual forages to supplement intensively managed and planned pastures, but that differ in size and some management strategies. The observed temporal changes and adaptations over time were closely linked to farm size, intensity in the use of various technologies, the number and the breed of the dairy cows, and the presence of other agricultural activities in the property. The effect of variable prices of milk and system inputs differed by group. Given the social and economic importance of dairies throughout Central and Southern Chile, a number of interventions are proposed, including technical modifications, extension initiatives, and changes in policies.

Quantifying perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.) seed germination responses to water potential and temperature with a hydrothermal time model

ABSTRACT In New Zealand, a commonly sown pasture combination is perennial ryegrass with white clover. The hydrothermal time model (HTT) was used to quantify germination under different temperature (T) and water potential (WP) conditions for white clover ‘Nomad’ and perennial ryegrass ‘Stellar AR1’. Seeds were germinated in vitro under a range of T × WP combinations, and HTT models were fitted to germination time course data. Rapid germination of white clover under optimum T and WP was reflected by a much lower value for its HTT constant compared with perennial ryegrass (10.8 vs 80.7 MPa °C d). However, the lower base water potential for perennial ryegrass (−1.29 vs −0.495 MPa) and a higher threshold temperature for thermoinhibition (21.8 vs 18.3°C), meant that predicted perennial ryegrass germination was more resilient in warm dry conditions. HTT models can be used to assist decisions about the timing of perennial ryegrass and white clover sowing.