Plant Pathology Commons^™

Leaching Losses Of N, P And K From Grazed Legume Based Swards: Some Preliminary Results, E. R. Dixon, A. C. Stone, D. Scholefield, D. J. Hatch

IGC Proceedings (1977-2023)

There is increasing interest in sustainable agricultural systems because of environmental concerns. Animal production which utilises mixed grass and legume swards could be an effective measure in increasing the efficiency of nutrient utilisation, and investigation into different legume species is necessary. Leaching losses of N, P and K from 3 legume species under grazing by sheep were measured using Teflon-coated suction cups. The experiment took place on the UK site of the EU-funded, multi-site experiment – LEGGRAZE.

Nitrogen Leaching From Cattle, Sheep And Deer Grazed Pastures In New Zealand, Keith Betteridge, Sterwart F. Ledgard, Coby J. Hoogendoorn, M. G. Lambert, Z. A. Park, Des A. Costall, P. W. Theobald

IGC Proceedings (1977-2023)

The impacts of intensified grazing in New Zealand are being reflected in declining quality of groundwater, streams and lake water. Manipulation of ratios of grazing animal species may be one way farmers can reduce nitrogen (N) emissions to ground water. The present research quantifies nitrate and ammonium leaching losses from rotationally grazed sheep, cattle and deer pastures in a common environment.

Relationships Between Biodiversity And Production In Grasslands At Local And Regional Scales, A. Hector, M. Loreau

IGC Proceedings (1977-2023)

Key points

1. Experimental manipulations of plant species diversity in unfertilised prairies and meadows has revealed that increasing diversity often leads to increased productivity (range of observed relationships varies from flat to log-linearly positive); driven by a combination of facilitation, niche-partitioning and sampling/selection effects.

2. The longer-term effects of diversity on ecosystem stability are not as clear and in need of further work.

3. Recent applied work, and a new review of the grassland literature, both show the potential for biodiversity to increase productivity under realistic field conditions.

4. The longer-term feedback of grazers on biodiversity gradients is unknown, and …

Utilizing Perennial Grass Species’ Population Patterns To Detect Looming Desertification Tipping Points In Semi-Arid Regions, F. Munyebvu-Chambara, W. C. Nesongano, M. C. Bilton, A. Linstädter

IGC Proceedings (1977-2023)

Namibia is one of the global dryland regions facing desertification threats due to overgrazing and recurrent drought. This has disastrous effects on forage provision and consequently on local livelihoods. Unfortunately, the mechanisms underlying sudden shifts of rangeland ecosystems towards a desertified state are still poorly understood. The ability to predict desertification tipping points with the aid of suitable ecological indicators is critical to ensure sustainable management of rangeland resources, which are a backbone of rural livelihood in drylands worldwide. Accordingly, we aimed to identify key perennial grass species that can be used as early-warning indicators for desertification tipping points; and …

Evaluation Of Herbage Intake Estimation Methods For Dairy Cattle Grazing On Semi-Extensive Pastures, S. Perdana-Decker, E. Velasco, J. Werner, U. Dickhoefer

IGC Proceedings (1977-2023)

Available empirical and mechanistic models to estimate total dry matter intake (DMI) and pasture dry matter intake (PDMI) of grazing lactating dairy cows have mainly been developed under intensive grazing conditions. The objective was to evaluate the adequacy of such existent models for use under semi-extensive grazing conditions, characterised by semi-natural grassland and less intensive resource use. Feed intake of lactating cows was measured on three commercial organic dairy farms in South Germany during one or two 6-d-periods/farm in 2019. Each period, DMI was determined in 10 or 20 cows per farm from their daily faecal output measured using titanium …

Dairy Cattle Genetics By Environment Interaction Mismatch Contributes To Poor Mitigation And Adaptation Of Grazing Systems To Climate Change Actions In The Peruvian High Andes: A Review, V. M. Velez Marroquin, J. Manhire, R. Garcia Ticllacuri, J. L. Bernal Madrid, C. S. Pinares-Patino

IGC Proceedings (1977-2023)

The high Andes of Peru includes fragile ecosystems. Nevertheless, it plays important ecosystem functions (e.g., biodiversity, water supply for the lowlands, CO₂ sinks in soil, etc). More than 80% of the livestock population of Peru is farmed in this area, supporting the livelihood of approximately 1’400,000 poor families, who are vulnerable to climate change (CC). Climate change in the high Andes is occurring at accelerated rates, compared to lowlands regions. Prevalent factors in the high Andes, such as hypoxia, high UV radiation, climatic extremes, large variation between maximum and minimum temperatures, seasonality in rainfall (determining highly seasonal forage growth) …

Pasture Management Relevant Behaviour Of Yaks (Bosgrunniens), O. Kaufmann, A. Tolebekova

IGC Proceedings (1977-2023)

After a decline in yak populations in Central Asia, efforts have been made for several years to rebuild them. In that context, the ecological demands of the alpine landscape must be taken into account. The aim of the studies was to analyse the behaviour of yak cows in short time intervals and to deduce which sub-areas the yaks prefer more or less strongly, which altitudes in the mountains the animals visit in the course of a year, which distances they cover in summer and winter and which factors influence their grazing behaviour. The investigations were carried out on yaks in …

Seasonality And Grazing Management Effect On Growth And Nutritional Composition Of Herbage On Semi-Natural Grasslands Grazed By Dairy Cows In Southwest Germany, E. Velasco, S. Perdana-Decker, J. Werner, U. Dickhoefer

IGC Proceedings (1977-2023)

Natural and semi-natural grasslands represent an attractive forage source for cows in organic dairy farming. Throughout the grazing season, however, diverse factors such as climatic conditions, botanical composition, as well as grazing and herd management, can influence growth and nutritive value of forage on grasslands. We aimed at investigating the influence of seasonality and grazing management in forage growth and nutritional quality in seven commercial organic dairy cattle farms during the grazing season 2019 in South Germany. Therefore, forty exclusion cages (1 m²) were installed on pastures, which were under three different grazing systems: rotational, short-grass, and continuous …

On Farm Riparian Grazing Demonstration, J. T. Green Jr., M. H. Poore, S. P. Morgan

IGC Proceedings (1977-2023)

Two farm demonstrations were designed to show effects of periodic grazing of riparian areas. Sites were monitored for vegetative cover, degree of treading or hoof prints and dung deposition within three m of stream edge following grazing by beef cattle. A fenced enclosure was established along a 350 m stream reach on Farm-1, and eleven permanent stations were monitored following six graze periods over 12-months. Farm-2 involved grazing of two 0.13 ha paddocks, each of which contained a 22 m stream reach. On Farm-1 the cover improved following riparian exclusion, and evidence of treading in the 11 stations declined following …

A Chance-Constrained Linear Model For Beef Policy Analysis, Claudio F. Machado, S. T. Morris, C. Dake, A. Macdonald, I. M. Brookes, F. Di Croce, F. Gonzalez, N. J. Auza

IGC Proceedings (1977-2023)

A simple linear model to evaluate different bull beef policies (BBP) by incorporating the stochastic nature of pasture yield from a database with separate chance constraints (ChC) was developed. A 100 ha farm was used, and the model was run with five different BBP and set to different levels of pasture yield risk to maximise production.ha^-1.year^-1. Summer was the most risky season, and the optimum mix of policies changed at different levels of risk. Chance constraint represents an interesting and simple alternative to include pasture variation into a linear model.

Sources Of Error For Ultrasonic Measurements Of Steer Compositional Traits In Grazing Studies, Glen E. Aiken, F. M. Rouquette Jr., A. H. Brown Jr.

IGC Proceedings (1977-2023)

Real-time ultrasound technology has potential use for measuring compositional traits in grazing studies. Sources of error with this application must be identified for designing experiments with adequate precision to determine treatment effects. A study was conducted to evaluate breed type (Angus x Brahman, AB; Simmental x [Angus x Brahman], SAB; Simmental x [Brahman x Hereford], SBH), initial body weight, and initial ultrasonic measures as sources of experimental error in the analyses of external fat (EF) depths and longissimus dorsi (ribeye) areas (LDA). Steers were ultrasonically scanned at the initiation and conclusion of a grazing study that examined stocking rate effects …

Vegetation Changes In Southeast Australian Temperate Grasslands, D. L. Garden, T. P. Bolger

IGC Proceedings (1977-2023)

In temperate areas of southeast Australia, the combined effects of tree clearing, grazing, application of fertilizer and the introduction of exotic species have modified the original grasslands. This paper describes these changes and attempts to explain them in terms of ecological principles derived from North American grasslands. Stability of the original grasslands appears to have been due to the lack of disturbance and the slow rates of nitrogen (N) cycling within them. Increased N cycling after disturbance has allowed invasion of species better adapted to higher N status, particularly exotic annual grasses and weeds. The present composition of grasslands, in …

Influence Of Grassland Management And Grazing By Different Farm Animals On Animal Performance And Flora Alterations, W. Jentsch, H.-D. Matthes, A. Admasu, H. Möhring

IGC Proceedings (1977-2023)

The objectives of this study were to test the possibilities of using different farm animals for landscape care on extensive pasture, taking into account their particular performance, and to analyse alterations of the flora in consequence of grazing by different animals and various pasture management. Salers had the highest (836g/d) and Galloways (584g/d) the lowest live weight gain as compared with the other breeds (771g/d). Lambs had higher live weight when grazing together with cattle and horses (mixed grazing) than under one species grazing. The number of legume increased and that of grass decreased. Following 3 years the grazing animals …

Orchardgrass Pastures For Early-Weaned Beef Calves, J. C. Waller, H. A. Fribourg, C. Dixon, A. E. Fisher, B. V. Conger

IGC Proceedings (1977-2023)

Orchardgrass (Dactylis glomerata) grown alone or with ladino white (Trifolium repens) and red (T. pratense) clovers, provides a high quality March to June pasture. However, many beef producers have their cows calving in January-March, thus producing offspring that are too young to utilize spring forage well. As an alternative, some producers have their cows bred so that calves are born in autumn (September-November). By spring, these calves are old enough to consume pasture forage. The few earlier studies on early weaning of fall-born calves consist of drylot feeding of high quality hay or concentrates. …

Management Of Meadow Fescue Pasture For High-Producing Dairy Cows In Northern Japan, K. Sudo, K. Ochiai, T. Ikeda

IGC Proceedings (1977-2023)

The objective of this study was to establish an intensive grazing system of meadow fescue (Festuca elatior L.) pasture for high-producing dairy cows in some areas of Japan where soil freezes in winter. Plant succession of meadow fescue pastures that had been grazed at different plant heights and milk production from cows grazed on meadow fescue pasture compared to that from cows grazed on perennial ryegrass pasture were surveyed over a five year period. Succession of meadow fescue pasture depended on the management of plant height before grazing use. Milk production from cows grazed on meadow fescue pasture was …

Nitrogen Flow To Duodenum Of Steers Grazing On Orchardgrass And Meadowfescue Pastures, Masaaki Hanada, Y. Aibibula, Meiji Okamoto

IGC Proceedings (1977-2023)

This experiment was conducted to evaluate nitrogen flow to the duodenum of steers grazing on orchardgrass (Dactylis glomerata L., OG) or meadowfescue (Festuca elatior L., MF) pasture. Holstein steers fitted with cannulas in the rumen and duodenum were used. Nitrogen content and in vitro dry matter digestibility of herbage did not differ between OG and MF pastures. Herbage nitrogen intake of steers grazing on OG and MF pastures averaged 229 and 271 g/day, respectively. Nitrogen flows to the duodenum of steers grazing on orchardgrass and meadowfescue pastures averaged 187 and 195g/d, respectively. Microbial nitrogen flow to the duodenum …

Intake Estimation Of Rams Under Grazing Condition In A Deferred Pastures Of Panicum Coloratum By Two Techniques, C. M. Ferri, M. A. Brizuela, N. P. Stritzler, H. J. Petruzzi

IGC Proceedings (1977-2023)

The goal of this study was to quantify the organic matter intake (OMI) of Pampinta rams grazing in a Panicum coloratum cv Verde differed pasture. The OMI was compared by two methods: a) the difference between the forage measured in pre and post-grazing condition, and b) the faecal production:digestibility ratio of the diet, estimated by total faecal gathering, and from the quantity of total faecal N in g per 100 g^-1 of OMI and the concentration of total faecal N, respectively. The OMI estimated by difference between the forage measured in pre and post-grazing was 9 % higher (P …

Effect Of Five Different Rest Periods On Tiller Regrowth Of Ryegrass, R. W. Coelho, W. R. Ocumpaugh

IGC Proceedings (1977-2023)

Five rest periods were imposed from April to May on a mixed pasture of two ryegrass (Lolium multiflorum Lam.) varieties and white clover (Trifolium repens L.). The rest period starting dates were: April 4, April 18, May 2, May 16, and May 30, for rest periods 1, 2, 3, 4, and 5, respectively. The total area allocated to the experiment was 1.1 ha, which was divided into 22 pastures. The experimental design used was a split-plot. Rest period was assigned to the main plot, grass to the subplot and legume to the subsubplot. The pastures were “mob-grazed” by …

Contract Grazing Of Young Beef Cattle On Ryegrass In The Southeastern Usa, David I. Bransby

IGC Proceedings (1977-2023)

The objective of this study was to evaluate contract grazing (in which the landowner grazes cattle owned by someone else for a specified fee) as an alternative to traditional ownership of the cattle, in order to improve profitability of grazing young beef cattle on annual ryegrass under limited availability of operating capital in the southeastern USA. Production data from a two-year grazing experiment were used as a basis for an economic analysis which assumed market prices for the beef industry in the region. Return/ha over animal and pasture costs was $312.20 for contract grazing, and $477.50 for purchased cattle. However, …

Horses Grazing Management To Promote Distribution Of Lotus Tenuis (Waldst. Et Kit) In A Temperate Grassland, O. E. Ansín

IGC Proceedings (1977-2023)

In a temperate grassland of the Argentine Pampa, the birdsfoot trefoil (Lotus tenuis Waldst. et Kit) distribution was analyzed as a consequence of the grazing method used. In a plot of 40 ha occupied by native grassland an area of 16 ha was implanted with reed canary grass (Phalaris aquatica L.) and L. tenuis. This area was divided into two parts that contained the same pasture and native grassland surfaces, being grazed by horses. One, under continuous grazing and another one, under a controlled grazing. In the continuous grazing the whole year the animals had permanently access …

Transgenic Maize Hybrid Crop Residues: Nutritive Value And Their Effects On Performance Of Grazing Beef Cows, S. K. Barnhart, J. R. Russell, M. J. Hersom, D. E. Farnham

IGC Proceedings (1977-2023)

Several maize (Zea mays) hybrids, including three transgenic hybrids containing Bacillus thuringiensis (Bt) enzymes (Bt-maize hybrids), were planted in a field study. Mature, midgestation, beef cows (Bos tarus) strip-grazed post-harvest residues as paddocks over 126 days. Body condition-scores and weights were monitored. Forage yield, weathering losses and forage composition were monitored on grazed and ungrazed areas. Forage selection and intake were estimated. Grain yields, dropped grain, initial crop residue concentrations of dry matter (DM), organic matter (OM) and in vitro digestible organic matter (IVDOM) yields were similar among hybrids. Hybrids varied in infestation of maize borers, …

Effects Of Different Levels Of Energy Supplementation On Growth Of Grazing Holstein Heifers, L. P. Novaes, C. E. Polan

IGC Proceedings (1977-2023)

Growth of Holstein heifers was studied for 1987 grazing season to evaluate pasture-drylot systems for raising dairy replacements. Orchardgrass (Dactylis glomerata L), tall fescue (Festuca arundinacea Schreb), bluegrass (Poa pratensis L) and white (Trifolium repens L) and red clover (Trifolium pratense, L) were the principal components of the grass-legume mixture in six paddocks of 1.5 ha each. Carrying capacity was estimated at six animals/ha (3.1 animal units) and excess forage was harvested as hay to control forage growth and quality. Grazing days were 140 days. None or 2.0 kg/d …

Supplementation Of Dairy Cows Under Alfalfa Grazing Conditions With Ground Corn, A. R. Castillo, L. A. Romero, O. R. Quaino, E. A. Comeron, M. C. Gaggiotti

IGC Proceedings (1977-2023)

Two trials were carried out during the Autumn of 1991 and 1992 to investigate the effects of corn supplementation on lactational performance of dairy cows under alfalfa grazing. Forty two multiparous Holstein cows with 30-60 days in milk were used in a randomized continuous design with covariance analysis. The treatments were 0.0, 3.5 and 7.0 kg.day^-1 of corn grain supplementation (T1, T2 and T3 respectively) in 1991 and 0.0, 3.0, 6.0 and 9.0 kg.day^-1 (T1, T2, T3 and T4 respectively) in 1992. Six cows per treatment were used divided in 3 cows per grazing paddock. Dry matter (DM) …

Determination Of N-Alkanes At Different Stratum Heights In A Pasture Of Panicum Maximum Cv. Mombaça, T. C. M. Genro, L. R. L. De S. Thiago, Ê. R. Prates, M. Herrero, V. Sabatel

IGC Proceedings (1977-2023)

The aim of this experiment was to determine n-alkane levels in the stem + leaf sheath and leaf blade components of a pasture of Panicum maximum cv. Mombaça, harvested in 20 cm stratified layers. This pasture was under rotational grazing for intensive beef production throughout the year. The grazing system was based on the use of 16 paddocks with a 2-day grazing period followed by a 30-day resting period. Profiles of n-alkanes were determined in samples harvested in three separate periods: in the middle of the dry season (August 97; PERIOD 1), at the beginning of the wet season (November …

Duration Of Regrowth Of Ryegrass (Lolium Perenne) Swards: Effects On Rumen Fermentation Of Lactating Dairy Cows, P. Chilibroste, S. Tamminga, H. Boer

IGC Proceedings (1977-2023)

The relative importance of duration of sward regrowth and rumen fill and fermentation on the control of grazing time and intake rate during the first grazing session of the day were studied. Four lactating dairy cows were allowed to graze ryegrass (Lolium perenne) swards, with five different regrowth periods after mowing (6, 9, 16, 22 and 30 d). The cows were allowed to graze until they stopped voluntarily. Samples of rumen liquid were taken at approximately 0, 30, 60, 120 and 240 min after the grazing session was finished. Concentration of volatile fatty acids (VFA) followed a significant …

Prediction Of Dry Matter Intake Based On Ruminal Degradation From Milking Cows Grazing Coast-Cross Grass, T. T. Berchielli, J. P. G. Soares, L. J. M. Aroeira, C. L. Furlan, A. K. D. Salman, R. N. Da Silveira, E. B. Malheiros

IGC Proceedings (1977-2023)

Dry matter intake (DMI) of coast-cross grazing by crossbred Holstein-Zebu and Zebu lactating cows was calculated using in vitro dry matter digestibility from extrusa (four esophageal fistulated cows) and fecal output estimate with mordent chromium. Pasture was rotationally grazed with three days grazing period and 27 days resting period, adopting a stocking rate of 1.6 and 3.2 cows/ha, during the dry and rainy season respectively. Voluntary DMI was estimated from degradation characteristics using different equations. Predicted coast-cross DMI varied with models. The prediction of tropical forages dry matter intake from equations based in ruminal degradation parameters needs further investigation before …

Prescribed Fire And Cattle Grazing To Manage Invasive Grasses For Cattle And Wildlife, C. H. Walther, J. Alfonso Ortega‐S., H. L. Perotto-Baldivieso, S. Rideout-Hanzak, D. B. Wester

IGC Proceedings (1977-2023)

Invasive grasses are in most cases introduced species able to outcompete native species. Buffelgrass (Cenchrus ciliaris), Guineagrass (Urochloa minima), and Old World bluestems (Dichanthium spp.) are typical examples of invasive species in southeastern United States. However, native grasses such as tanglehead (Heteropogon contortus) can become invasive and dominant in absence of cattle grazing just like any invasive species. Tanglehead and Kleberg bluestem (Dichanthium ischaemum) increased (p < 0.05) from 1.4 and 1.8% in 1999 to 2.7 and 3.6% in 2002 and then to 8.1 and 9.4% in 2009, respectively. Monocultures of invasive species have very little value for wildlife, and in the case of mature tanglehead its palatability for cattle is very low. Prescribed fire may be used to improve palatability of tanglehead for cattle, and cattle grazing may be used to improve plant species richness for wildlife. To evaluate the effects of prescribed fire and cattle grazing on cattle preference and the botanical composition of a plant community dominated by tanglehead, we burned 3 patches of approximately 0.5 ha in a pasture of 107 ha in October 2016. Two months before the prescribed burning was executed, 10 mother cows were placed in the pasture to graze continually. We fitted GPS collars on 8 cows and location readings were collected every 10 minutes. GPS recordings indicate that cattle used burned patches 4.5 times more after burning compared to before burning. Percent forage utilization of tanglehead was 52% in the burned patches compared to 6% in the control areas. Plant species richness increased from 2.53 to 8.33 plant species per 0.25 m², before and after burning, respectively, an increase of 330%. Prescribed fire and cattle grazing are valuable tools to increase tanglehead palatability and …

Nutrient Return From Plant Litter And Cattle Excretion Grazing On N-Fertilized Grass Or Grass-Legume Pastures In North Florida, Liza Garcia, D. M. Jaramillo, José C. B. Dubeux Jr., Lynn E. Sollenberger, João M. B. Vendramini, N. Dilorenzo, E. R. S. Santos, M. Ruiz-Moreno, L. M. D. Queiroz

IGC Proceedings (1977-2023)

Nutrient recycling via plant litter and livestock excreta is an important ecosystem service provided by grasslands. This study determined nutrient return via these pathways in three grazing systems. The experiment was conducted from May to October (2016 and 2017) and treatments were: 1) Nitrogen fertilized bahiagrass (Paspalum notatum Flügge) pastures (112 kg N ha^-1) during the warm-season, overseeded with a mixture (56 kg ha^-1 of each) of ‘FL 401’ cereal rye (Secale cereale, L.) and ‘RAM’ oat (Avena sativa, L.) during the cool-season (BGN); 2) Ecoturf Rhizoma peanut (Arachis glabrata Benth.)/bahiagrass …

Legumes As A Strategy For Reducing Greenhouse Gas Emissions Of Forage-Livestock Systems, N. Dilorenzo, José C. B. Dubeux Jr., L. Garcia, R. D. Guevara, S. Lagrange, J. Macadam, J. J. Villalba

IGC Proceedings (1977-2023)

Incorporation of legumes into forage systems has been a widely adopted strategy to increase pasture productivity and forage nutritive value, while reducing N inputs. Considering the population growth, and the diminishing land resources for food production, the need to increase the food supply will have to be balanced with the environmental impact of these systems, particularly their carbon footprint. Enteric methane production represents the largest source of greenhouse gas emissions from livestock. Certain forage legumes have evolved plant secondary compounds, such as tannins and other polyphenols, which have been associated with reductions in enteric methane emissions. Studies were conducted at …

Risk Of Climate-Related Impacts On Global Rangelands – A Review And Modelling Study, C. M. Godde, R. B. Boone, A. Ash, K. Waha, L. Sloat, P. Thornton, D. Mason-D’Croz, D. Mayberry, M. Herrero

IGC Proceedings (1977-2023)

Climate change threatens the ability of global rangelands to provide food, support livelihoods and deliver important ecosystems services. The extent and magnitude of potential impacts are however poorly understood. In this study, we review the risk of climate impacts along the rangeland systems food supply chain. We also present results from biophysical modelling simulations and spatial data analyses to identify where and to what extent rangelands may be at climatic risk. Although a quantification of the net impacts of climate change on rangeland production systems is beyond the reach of our current understanding, there is strong evidence that there will …