Physical Sciences and Mathematics 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 (1997-2023)

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 (1997-2023)

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 (1997-2023)

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 (1997-2023)

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 (1997-2023)

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 (1997-2023)

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 (1997-2023)

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 (1997-2023)

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 (1997-2023)

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 (1997-2023)

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 (1997-2023)

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 …