Physical Sciences and Mathematics Commons^™

Environmental Clustering Of New Zealand Dairy Herds, J. R. Bryant, N. López-Villalobos, J. E. Pryce, C. W. Holmes

IGC Proceedings (1993-2023)

Previous studies have found that milk yield (a proxy for feeding level) and temperature-humidity index (THI) are important factors in explaining genotype x environment (G x E) interactions, indicating differences between the abilities of genotypes to forage or consume concentrates effectively or to cope with thermal stress (Ravagnolo and Misztal, 2000; Zwald et al., 2003). The objective of this study was to quantify and cluster (CL) herd environments within New Zealand (NZ) based on production levels, a summer heat load index (HLI) and geographical location.

Risk-Efficiency Assessment Of Haying, A. J. Romera, J. Hodgson, S. T. Morris, S. J. R. Woodward, W. D. Stirling

IGC Proceedings (1993-2023)

Pastoral livestock farms are complex, dynamic systems subject to many forms of external disturbance. Farm Management strategies are therefore typically designed to minimize system variation. The objective of this study was to explore the impacts of different haying policies, in terms of expected profit and risk, for cow-calf farms in the Salado Region of Argentina.

Irish Dairy Farming: Effects Of Introducing A Maize Component On Grassland Management Over The Next 50 Years, A. J. Brereton, N. M. Holden

IGC Proceedings (1993-2023)

Typical management of Irish dairy units is based on a low-cost spring-calving strategy with 90% of annual feed derived from grass grown on the farm. Almost 70% of feed is from grazed grass managed by rotational grazing, the remainder is conserved forage and concentrates. The objectives of the work were to examine how the management system has to be modified when part of the dairy unit land is allocated to maize silage instead of grass silage production, and to examine how climate change over the next 50 years will impact on grass and maize management within the production system.

Lucerne Crown And Taproot Biomass Affected Early-Spring Canopy Expansion, E. I. Teixeira, D. J. Moot, A. L. Fletcher

IGC Proceedings (1993-2023)

Leaf area index (LAI) quantifies canopy expansion in crops and is used in lucerne (Medicago sativa L.) simulation models to predict daily PAR interception (PAR i). This then drives yield through radiation use efficiency (RUE) (Gosse et al., 1984). In perennial crops, like lucerne, the level of biomass stored in crown and taproot may affect canopy expansion in subsequent regrowth cycles (Avice et al., 1997). In temperate regions the impact of this is likely to be greatest in early-spring, when low temperatures delay development. The objective of the current research was to identify whether contrasting levels of winter biomass in …

Autumn Root Reserves Of Lucerne Affected Shoot Yields During The Following Spring, D. J. Moot, E. I. Teixeira

IGC Proceedings (1993-2023)

Frequent grazing affects shoot yield of lucerne (Medicago sativa L.) by limiting radiation interception (Teixeira et al., 2005b) and the accumulation of endogenous reserves (C and N) in perennial storage organs like crowns and taproots (Teixeira et al., 2005a). In temperate regions, the impact of low level of perennial reserves is particularly evident during early-spring, when lucerne regrowth resumes after an overwintering period. The analysis of lucerne yield can be fragmented into its yield components of plant population, shoots per plant and yield per shoot (Volenec et al., 1987). The objective of this research was to quantify …

Milk Production Performance Based On Grazed Grassland In Switzerland, P. Thomet, H. Menzi

IGC Proceedings (1993-2023)

A common feature of profitable dairy systems is the use of large amounts of low cost feed. One approach to improve the competitive ability of the dairy production therefore is to promote grazing (Dillon et al., 1995). A comparison of the actual feeding costs on typical Swiss dairy farms showed that hay and grass silage were four times and concentrates seven times more expensive than grazed grass. A maximum utilisation of grazed grass can be achieved with a seasonal production system, which synchronises the cow’s feed requirements with pasture growth. This strategy was implemented and consistently optimised on an …

Extending The Grazing Season With Turnips, P. Thomet, S. Kohler

IGC Proceedings (1993-2023)

A comparison of the actual feeding costs on 86 typical Swiss dairy farms confirmed that the production of hay and grass silage is very expensive with costs from the field to intake in the range of 20-25 Euro cents/kg of dry matter (DM). Options to extend the grazing season for dairy cows in the late autumn and early winter, and hence reduce winter feeding costs, would therefore be welcome (Penrose et al., 1996). The aim of the study was to compare the DM production potential of summer-seeded turnips with other brassicas and Italian ryegrass and to test whether dairy cows …

The Effect Of Inclusion Of A Range Of Supplementary Feeds On Herbage Intake, Total Dry Matter Intake And Substitution Rate In Grazing Dairy Cows, S. J. Morrison, D. C. Patterson, S. Dawson, C. P. Ferris

IGC Proceedings (1993-2023)

The milk production potential of dairy cows has increased substantially over the past two decades. This development presents new challenges for managing dairy cows during grazing, particularly where the objective is to maximise the proportion of energy in the diet derived from forage. The objective of the current study was to explore supplementation strategies to maintain high total forage intakes from grazed grass supplemented with alternative forage supplements in dairy cows during the grazing season. A second objective of the study was to examine the effect of supplement on substitution rate (SR) and milk yield response.

White Clover Soil Fatigue: An Establishment Problem On Large And Intensive Dairy Farms, K. Søegaard, K. Møller

IGC Proceedings (1993-2023)

In recent years a new constraint, clover soil fatigue, has appeared for the establishment of white clover (Trifolium repens) in Denmark. Increasing dairy farm size has led to more intensive use of clover in crop rotation schemes in the grazing areas located at convenient distances from stables. It has become common practice to establish new clover/grass in the fields just after ploughing clover/grass swards, and soil fatigue is becoming more common. On fatigued land the clover plants emerge, then become stunted and eventually disappear within the same year. The problem tends to cover the full field area. Obviously, …

Effect Of Farm Grass Cover At Turnout On The Grazing Management Of Spring Calving Dairy Cows, M. O'Donovan, L. Delaby, P. Defrance

IGC Proceedings (1993-2023)

Early spring grazing is an objective for most Irish dairy farmers. If more grass is included in the diet of the cow in early lactation, the profitability of the farm system can be increased. Post turnout, dairy cow feeding management varies with the amount of farm grass cover (FC) available. Experiments on the consequences of different FC at turnout require large resources and all scenarios cannot be accounted for. Consequently, a decision support system, Pâtur’IN (Delaby et al., this volume), was used to describe the effects of various FC at turnout on grazing management in spring.

What Supplementation Type For Spring Calving Dairy Cows At Grass In Autumn?, M. O'Donovan, E. Kennedy, T. Guinee, J. J. Murphy

IGC Proceedings (1993-2023)

In spring-calving herds the requirement for conserved forages for indoor feeding is very limited but these feeds may have a role to play as buffer feeds in the spring and autumn periods when grass supply is less than required or as alternatives to concentrates on pasture for cows in early lactation. The objective of this experiment was to compare alternative forages and concentrates as buffer feeds on pasture with spring-calving cows in the autumn.

Manipulation Of Grass Growth Through Strategic Distribution Of Nitrogen Fertilisation, M. Stettler, P. Thomet

IGC Proceedings (1993-2023)

The objective of this study was to evaluate possibilities and limits of manipulating the grass growth of pastures by different nitrogen (N) application strategies with the aim to better synchronise grass supply and feed demand. In Switzerland, the use of N is strongly restricted by legislation. An efficient and well allocated N fertilisation is therefore important.

A Comparison Of Three Systems Of Milk Production With Different Land Use Strategies, L. Shalloo, P. Dillon, J. J. Murphy

IGC Proceedings (1993-2023)

Under the Luxemburg agreement FAPRI-Ireland (Breen & Hennessey 2003) projects that milk price will decrease by 5.0 to 5.5 c/l because of reductions in support for butter and skimmed milk powder. These changes mean that many dairy farmers need to reappraise their systems of milk production and consider necessary adjustments that will ensure viability in the longer term. The objective of this study was to model three different systems of milk production in scenarios where quota, cow numbers or land was restricted.

Project Opti-Milk: Optimisation And Comparison Of High Yield And Low Input Milk Production Strategies On Pilot Farms In The Lowlands Of Switzerland, H. Menzi, T. Blaettler, P. Thomet, B. Durgiai, S. Kohler, R. Staehli, R. Mueller, P. Kunz

IGC Proceedings (1993-2023)

Compared to other European countries milk production costs in Switzerland are high. Therefore Swiss milk producers must drastically reduce their costs. The high yield strategy (HY) and the full grazing (FG) or low-cost strategy appear most promising, at least for the lowland regions. Although the basic knowledge is available for both strategies, they have been applied very little in Switzerland in a consistent and optimised form.

Assessment Of Grass Production And Efficiency Of Utilisation On Three Northern Ireland Dairy Farms, A. J. Dale, P. D. Barrett, C. S. Mayne

IGC Proceedings (1993-2023)

Recent research has shown that grazed grass can be an expensive forage for milk production, particularly if herbage production is low or utilisation is inefficient. There is very limited data on the level of herbage grown and utilised on commercial farms. The objective of this project was to quantify grass production and efficiency of utilisation on farm to substantiate the potential of grazed grass for profitable milk production.

The Effect Of Grassland Management On Bovine Nitrogen Efficiency, N. J. Hoekstra, R. P. O. Schulte, E. A. Lantinga, P. C. Struik

IGC Proceedings (1993-2023)

Nitrogen (N) losses through grazing bovines are at the heart of the current debate on environment and agriculture. N utilisation of grazing bovines is predominantly determined by the form and amount of energy and protein in their diet, which in Ireland consists mainly of grazed grass. The two main problems of grazed grass with respect to animal N utilisation are 1) the imbalance between total N content and energy content, and 2) the lack of synchronisation between the release of N and carbohydrates in the rumen. It was hypothesised that both the balance and synchronisation of N and energy in …

The Effect Of Stocking Rate And Initial Grass Height On Herbage Production And Utilization, And Milk Production Per Unit Area Under Set Stocking By Lactating Dairy Cows, H. Nakatsuji, T. Endo, S. Bawm, T. Mitani, M. Takahashi, K. Ueda, S. Kondo

IGC Proceedings (1993-2023)

In our previous study with lactating dairy cows (Nakatsuji et al., 2004), annual herbage production and utilization, and milk production per unit area under set stocking was not always lower than under rotational grazing at the same stocking rate (6 cows/ha). Furthermore, there was a possibility that set stocking could increase pasture utilization and milk production over rotational grazing when cows were grazed at adequate stocking rate and at the appropriate initial date of grazing. The purpose of the present study was to evaluate the effect of stocking rate and initial grass height on herbage production and utilization, and …

Better Dairy Farm Management Increases The Economic Return From Phosphorus, J. D. Morton

IGC Proceedings (1993-2023)

Some 60% of New Zealand dairy farms on allophanic and sedimentary soils have soil Olsen phosphorus (P) levels to 75 mm depth above the target range for near-maximum pasture production of 20-30 µg/ml (Roberts & Morton 1999). For an economic response in milksolids (MS) production from high Olsen P, the pasture needs to be capable of high production, and the extra pasture grown be converted to milk. This paper seeks to justify this contention and outline some of the farm management practices required to achieve it.

The Effect Of Two Magnesium Fertilisers, Kieserite And Mgo, On Herbage Mg Content, M. B. O'Connor, A. H. C. Roberts, R. Haerdter

IGC Proceedings (1993-2023)

Supplementing Mg to dairy cows is widely practised in New Zealand. Various methods are used including drenching, pasture dusting, water trough treatment and adding to hay, silage and other feedstuffs (Young et al., 1979). Fertiliser Mg (calcined magnesite, MgO) is widely used to maintain soil Mg status but research has shown that using fertiliser Mg to achieve good soil, pasture and animal Mg status requires large inputs of Mg (120 kg/ha) and maintaining blood serum Mg status in dairy cows tends to be short-lived without further animal supplementation (O’Connor et al., 1987). The objective of these experiments was …

The Effect Of Closing Date And Type Of Utilisation In Autumn On Grass Yield In Spring, E. Mosimann, M. Lobsiger, C. Hofer, B. Jeangros, A. Lüscher

IGC Proceedings (1993-2023)

Due to the low cost of grazed grass, most dairy farmers extend the grazing period in autumn. However, delaying the closing date may reduce the grass yield in the following spring (Roche et al., 1996; O’Donovan et al., 2002). The objective of this experiment, conducted in the Swiss lowlands, was to quantify the effects of closing date and type of utilisation in autumn on grass yield in the following spring.

Field Testing Of A Turnip Growing Protocol On New Zealand Dairy Farms, J. P. J. Eerens, P. M. S. Lane

IGC Proceedings (1993-2023)

Summer droughts are a regular occurrence in central North Island districts of New Zealand, which causes pastures to wilt, lose their nutritive value and stop growing. The resulting summer feed gap depresses farm productivity (Clark et al., 1996). Turnips optimally sown mid-late October (more often sown in November or even December) are grown to fill this feed gap. Recorded average yields of 7.4 t dry matter (DM)/ha are below the economic breakeven point of 8-10 t DM/ha (Clark et al., 1996). A turnip growing protocol was developed from published data (Eerens & Lane 2004) and tested on commercial …

Effect Of Different Phosphorous Sources And Levels On The Productive Behaviour Of A Lotus Pedunculatus Cv. Grasslands Maku Oversown Pasture, R. E. Bermúdez, W. Ayala

IGC Proceedings (1993-2023)

The organic meat production protocol of Uruguay (INAC, 2003) requires that the animals graze pastures that receive no chemical fertilisers. The oversown legume pastures in Uruguay used to be fertilised with soluble phosphorous (P) sources that are not accepted by the protocol. The relative efficiency of different P sources would be useful data for farmers. This information is not available for the acid soils of the eastern region of Uruguay. Lotus pedunculatus cv. Grasslands Maku is one of the most adapted legumes to be included in this type of pasture, as the sown area has increased in the last few …

Labour Input Associated With Grassland Management On Irish Dairy Farms, B. O'Brien, K. O'Donovan, J. Kinsella, D. Ruane, D. Gleeson

IGC Proceedings (1993-2023)

The issues of labour and work organisation (working hours, working conditions) must be seriously addressed on Irish dairy farms if dairy farming is to have a viable future. The objective of this study was to quantify the annual labour input per cow on Irish dairy farms, with a specific focus on the task of grassland management, and to establish monthly patterns of labour utilisation over a two-year period for a range of herd sizes.

Factors Affecting Italian Ryegrass (Lolium Multiflorum L.) Seed Distribution, R. D. Williams, P. W. Bartholomew

IGC Proceedings (1993-2023)

Italian ryegrass (Lolium multiflorum L.) can be a productive and high-quality cool-season forage in the Southern Great Plains of the U.S.A, if it is managed to produce sufficient seed for effective reestablishment without compromising forage yield. Before the re-seeding dynamics of Italian ryegrass can be modeled an understanding of seed production, seed-shed, and seed dispersal is necessary. Here two factors affecting Italian ryegrass seed dispersal and distribution are examined – wind and cultivation practice (mowing and raking).

Practical Application Of A One-Parameter Approach To Assess The Accuracy Of Two Different Estimates Of Diet Composition In Sheep, C. Elwert, M. Rodehutscord

IGC Proceedings (1993-2023)

The composition of ingested herbage mixtures can be estimated using the alkane technique (Dove & Moore, 1995). Until now, the accuracy of the estimates is assessed by linear regression of estimated and actual proportions of the dietary components. The authors presented an approach to compare actual and estimated diet compositions using only one parameter named Distance (D; Elwert & Rodehutscord, 2005), thus enabling a statement regarding the similarity of estimated and known diet composition. In a feeding trial with sheep, diet composition was estimated using two different levels of information. The accuracy of the two estimates was assessed and compared …

Effects Of Rumen Fill On Intake And Milk Production In Dairy Cows Fed Perennial Ryegrass, A. V. Chaves, A. Boudon

IGC Proceedings (1993-2023)

Physical limitation often limits dry matter intake (DMI) of high producing cows or cows fed high forage diets. The extent to which DMI is regulated by distention in the rumen depends upon the cow’s energy requirement and filling effects of the diet offered (Allen, 2000). The objective here was to challenge middle lactation dairy cows with rumen fill (rumen inert bulk – RIB) feeding ryegrass fresh cut (indoors) or grazed to determine whether RIB affects intake and milk production.

Use Of Alkanes To Estimate Dry Matter Intake Of Beef Steers Grazing High Quality Pastures, G. Scaglia, H. T. Boland, I. Lopez-Guerrero, R. K. Shanklin, J. P. Fontenot

IGC Proceedings (1993-2023)

Pastures remain the most important source of nutrients for ruminant livestock and nutrition is critical to optimize animal production. The daily quantity of dry matter that is consumed by an animal is a critical measurement to make nutritional inferences about feed and subsequent animal response. Researchers are facing the dilemma that, while estimates of individual animal performance are readily obtained, it is still difficult to estimate the herbage intake of individual animals. The objectives of this experiment were to estimate forage intake in beef steers grazing tall fescue (Festuca arundinacea Schreb.) and alfalfa (Medicago sativa)/tall fescue pastures …

Iterated Jump Graphs, Fran Herr, Legrand Jones Ii

Rose-Hulman Undergraduate Mathematics Journal

The jump graph J(G) of a simple graph G has vertices which represent edges in G where two vertices in J(G) are adjacent if and only if the corresponding edges in G do not share an endpoint. In this paper, we examine sequences of graphs generated by iterating the jump graph operation and characterize the behavior of this sequence for all initial graphs. We build on work by Chartrand et al. who showed that a handful of jump graph sequences terminate and two sequences converge. We extend these results by showing that there are no non-trivial repeating sequences of jump …

Objectives And Benefits Of Molecular Breeding In Forage Species, T. Lübberstedt

IGC Proceedings (1993-2023)

1. The amount of resources and information provided by forage crop genomic programs has dramatically increased during the past few years.
2. Trait-based forward genetic procedures such as mapping and expression profiling have successfully provided new candidate genes or genome regions affecting forage quality. Respective information can easily be transferred across related forage species.
3. Since several genes in major biochemical pathways related to forage traits have been isolated, gene-based reverse genetic approaches (transformation, association studies) are promising.
4. Most genetic experiments are conducted under simplified "artificial" conditions such as on single-spaced plants. Therefore, transferability of respective genetic information to breeding practice needs to …

Both Grass Development Stage And Grazing Management Influence Milk Terpene Content, G. Tornambé, A. Cornu, N. Kondjoyan, P. Pradel, M. Petit, B. Martin

IGC Proceedings (1993-2023)

Terpenes are a wide group of molecules originating from plants’ secondary metabolism. Forage terpenes vary according to the botanical composition and in particular to the proportion of plants such as Apiaceae, Lamiaceae or Asteraceae. These molecules are considered effective milk markers for the presence of diversified forages in dairy cow diets. The variation in terpene content in the milk of grazing cows would depend on the period of development of terpene-rich plants and on the grazing management, whereby cows do or do not have the opportunity to choose and to modify the botanical composition of the ingested grass. The aim …