Concentrate Supplementation of Pasture for Beef Production

End of Project Report* Unsupplemented cattle offered a high grass allowance (18 kg (DM)/head/day), achieved 0.97 of the DM intake of a positive control offered concentrates ad-libitium. At a low grass allowance (6 kg/DM/head/day), there was no effect of supplementary concentrates on grass intake. At a medium (12 kg/DM/head/day), and high grass allowance, supplementary concentrates reduced grass intake by 0.43 and 0.81 kg/DM respectively per kg/DM concentrate offered. * Supplementary concentrates increased complete diet digestibility even though offering supplementary concentrates also increased total DM intake. Complete diet digestibility was higher than the additive values of the grass and concentrates. This would imply that the supplementary concentrates increased the grass DM digestibility. * Increasing the grass allowance increased plasma urea concentration; supplementary concentrates increased total dietary nitrogen intake and reduced plasma urea concentration. These findings suggest that the concentrate supplement enabled greater utilisation by rumen micro-organisms of the degradable nitrogen supplied by the grass. * Supplementing with concentrates increased carcass growth by 116 g/kg concentrate DM eaten whereas increasing the grass allowance increased carcass growth by 38 g/kg/DM grass eaten. The carcass weight response to concentrates of grazing animals was twice that of animals offered concentrates ad-libitum which gained 57 g carcass per kg concentrate DM eaten. * The relationship between carcass gain (Y) (kg/day) and supplementary concentrates (X) (kg/day) was quadratic (P< 0.001) and was best described by the equation: Y = -0.0099X2 + 0.1364X + 0.2459 (R2 = 0.60). The relationship between carcass gain (Y) (kg day-1) and grass intake (X) was also quadratic (P< 0.01) and was best described by the equation: Y = -43X2 + 275X + 133 (R2 = 0.48). Although there was a much larger (double) carcass growth response to supplementary concentrates than to additional grass DM eaten, increasing grass intake significantly increased carcass fat scores whereas offering supplementary concentrates did not. This would imply that relative to concentrates, autumn grass led to a change in the partitioning of energy from muscle towards subcutaneous fat. * As a strategy for increasing the performance of cattle grazing the type of autumn grass used in this study, offering supplementary concentrates offers more scope to improve animal performance than altering grass allowance. * The carbohydrate source of the three concentrates formulated to differ in rate of degradability did not alter rumen fluid pH, volatile fatty acid (VFA) concentration or the rate of grass DM or N degradation when grass supply was considered to be limiting or liberal. The autumn grass was apparently capable of buffering the effects of concentrate DM degradation rate which varied by up to two fold. * The rumen fluid parameters were more influenced by the pat-tern of grass intake than type of concentrate offered. Hence, there was no effect of concentrate type on animal performance.European Union Structural Funds (EAGGF

Nanomaterials for Space Exploration Applications

Nano-engineered materials are multi-functional materials with superior mechanical, thermal and electrical properties. Nanomaterials may be used for a variety of space exploration applications, including ultracapacitors, active/passive thermal management materials, and nanofiltration for water recovery. Additional applications include electrical power/energy storage systems, hybrid systems power generation, advanced proton exchange membrane fuel cells, and air revitalization. The need for nanomaterials and their growth, characterization, processing and space exploration applications is discussed. Data is presented for developing solid-supported amine adsorbents based on carbon nanotube materials and functionalization of nanomaterials is examined

Low electrical resistivity carbon nanotube and polyethylene nanocomposites for aerospace and energy exploration applications

An investigation was conducted towards the development and optimization of low electrical resistivity carbon nanotube (CNT) and thermoplastic composites as potential materials for future wire and cable applications in aerospace and energy exploration. Fundamental properties of the polymer, medium density polyethylene (MDPE), such as crystallinity were studied and improved for composite use. A parallel effort was undertaken on a broad selection of CNT, including single wall, double wall and multi wall carbon nanotubes, and included research of material aspects relevant to composite application and low resistivity such as purity, diameter and chirality. With an emphasis on scalability, manufacturing and purification methods were developed, and a solvent-based composite fabrication method was optimized. CNT MDPE composites were characterized via thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Raman spectroscopy, and multiple routes of electron microscopy. Techniques including annealing and pressure treatments were used to further improve the composites' resulting electrical performance. Enhancement of conductivity was explored via exposure to a focused microwave beam. A novel doping method was developed using antimony pentafluoride (SbF 5 ) to reduce the resistivity of the bulk CNT. Flexible composites, malleable under heat and pressure, were produced with exceptional electrical resistivities reaching as low as 2*10 -6 Ω·m (5*10 5 S/m). A unique gas sensor application utilizing the unique electrical resistivities of the produced CNT-MDPE composites was developed. The materials proved suitable as a low weight and low energy sensing material for dimethyl methylphosphonate (DMMP), a nerve gas simulant

Reducing The Cost of Beef Production by Increasing Silage Intake.

End of Project ReportGrass silage must support the predictable, consistent and profitable production of quality animal produce within environmentally sustainable farming systems. This can be quite a challenge for a crop that is so strongly influenced by the prevailing variable weather conditions, and the many interactions of the latter with farm management practices. Research and scientific progress must therefore continue to provide improved technologies if grass silage is to fulfil the above requirements. Yield, quality (including effects on intake, feed conversion efficiency, growth, meat quality, etc.), conservation losses, inputs and eligibility for EU financial supports determine the cost of providing cattle with silage, and this can have a major impact on the cost of producing milk or beef. Consequently, there has been an emphasis in the research reported here to add new information to the existing framework of knowledge on thes

Maximising Output of Beef Within Cost Efficient, Environmentally Compatible Forage Conservation Systems.

End of Project ReportA comprehensive research programme showed the potential benefits of replacing a productive old permanent grassland pasture dominated by indigenous species with new perennial or Italian ryegrass swards, when each was managed intensively, conserved as silage and fed to beef cattle. Ancillary experiments showed how the silage systems could be modified to improve productivity. However, they also showed that under a less intensive regime, replacing this old permanent pasture by ryegrass reseeds would be difficult to justify.European Union Structural Funds (EAGGF

Optimisation of Nutrient Supply for Beef Cattle Fed Grass or Silage.

End of Project ReportSince forage forms a large part of growing ruminant rations in Ireland, the trust of this project was to examine the effect of ensilage on ruminal digestion of grass and to examine ruminal microbial protein and intestinally absorbable protein supplied by grass and/or clover. A range of in vitro and in vivo techniques were employed and strategies used by commercial beef producers to optimise cattle growth (and nutrient supply) were also documented. To accomplish the aims of this project, a range of methodology developments/ modifications in vitro and in vivo was carried out. From in vitro methodology development it was concluded that : (i) Compared with fresh silage, drying per se may give artifically higher rates of dry matter (DM) digestion. (ii) Greater experimental precision can be obtained by ensuring a greater substrate surface area to reaction volume ratio in each reaction vessel. (iii) For studies where the rate of digestion is of greatest importance, pre-incubation of frozen inoculum in a nutrient medium best simulated the cellulolytic activity of unfrozen inoculum. In studies that require large volumes of inoculum for extended work, freezing directly is justified. (iv) Neutral detergent extraction altered in vitro digestion characteristics of silage. The residue after washing with water at 70°C has a high residual fibre concentration and is more representative of the structural components of silage ingested by ruminants. (v) A semi-continuous culture system developed at Grange Research Centre can successfully model in vitro ruminal digestion of fibre and starch-based diets in a controlled environment. From in vivo methodology development it was concluded that : (i) Oven drying at 60°C and correction for loss of volatiles gives a good estimation of DM concentration of ruminal particulate digesta. This procedure has the added advantage that drying at 60°C allows the residual materials to be analysed for fibre fractions without concern for heat damage which can occur at a higher drying temperature. (ii) A naso-ruminal sampling device can be used to measure the relative patterns of fermentation of contrasting diet types when in situ for up to 7 days. (ii) Application of a vacuum to withdraw samples had no negative effect on ruminal fluid variables. From in vitro studies on grass digestion, it was concluded that : (i) Ensiling of grass decreased the apparent extent of digestion of cell walls when in the presence of the whole plant and that this largely reflected an increase in the lag time before digestion commenced. (ii) Ensiling of grass did not negatively affect the digestion of isolated cell walls. (iii) There is a negative impact of ensiling on microbial protein production from the water soluble carbohydrate fraction of grass. (iv) Supplementation with the water soluble fraction of grass significantly improved the apparent extent of digestion for ensiled forages when compared with the supplementation of the post-ensiling fraction in a batch culture system. (v) There is a negative impact of maturity on the pattern of cell wall fermentation and that this impact can be decreased by ensiling method. From studies on herbage digestion in vivo it was concluded that : (i) Grass silage type had a greater effect than the rate of concentrate fermentation on ruminal microbal protein synthesis. (ii) Harvesting time had a bigger impact on nutrient supply from herbage than sward type (grass or grass/clover). (iii) Increasing clover content in the herbage decreased the biological value (g nitrogen retained/kg absorbed) of dietary protein. Diverse stratgies were used on commercial beef farms to optimise nutrient supply and animal growth. Average animal performance on individual farms was not better than would be typically recorded in a research environment. There was scope on many of the farms to improve technical performance and to decrease the costs of production.European Union Structural Funds (EAGGF

Intake and Growth of Steers Offered Different Allowances of Autumn Grass and Concentrates

The aim of this experiment was to quantify the relationship between autumn grass supply and concentrate supplementation level on grass intake and animal performance. One hundred and ten continental steers (567kg) were assigned to ten treatments in a three grass allowances: (6, 12 and 18kg dry matter (DM) per head daily) by three concentrate levels: (0, 2.5 and 5kg/head/daily) factorial design with a positive control group offered concentrates ad-libitum. Grass allowance was offered daily and concentrates were fed individually. The experiment began on August 22 and all animals were slaughtered after a mean experimental period of 95 days. Grass allowance increased (P\u3c 0.001) complete diet digestibility only in the absence of concentrates and supplementary concentrates increased (P\u3c 0.001) complete diet digestibility only at the low grass allowance. Both offering animals supplementary concentrates (P\u3c 0.001) and increasing daily grass allowance (P\u3c 0.001) increased their carcass growth rate. Grazed grass supported only one third the carcass growth rate of supplementary concentrates per kg of DM eaten. As a strategy for increasing the performance of cattle grazing autumn grass, offering supplementary concentrates offers more scope than altering grass allowance

Grazing and ensiling of energy-rich grasses with elevated sugar contents for the sustainable production of ruminant livestock (Acronym: SweetGrass)

End of Project ReportPermanent grassland dominates the Irish landscape and for many decades perennial ryegrasses have been the main constituent in seed mixtures for grassland. The main attractions in favour of perennial ryegrass swards are that they: x produce high yields in response to fertiliser nitrogen x have a high digestibility when harvested at the appropriate growth stage x are relatively easy to preserve as silage due to their superior content of sugar x persist as permanent swards where favourable management practices prevail If the phenotype of perennial ryegrass were to be improved, one potentially desirable trait would be an elevated concentration of water-soluble carbohydrates (WSC). This could confer benefits in terms of: x further increase the probability of achieving a lactic acid dominant fermentation during ensilage. This could reduce the requirement for traditional acid- or sugar-based additives, improve the likelihood of a positive response from additives based on homofermentative lactic acid bacteria or alternatively eliminate the need for any or the currently available conventional additive. If its effect was to improve silage preservation this should positively impact on dry matter (DM) recovery, improve animal productivity and potential product quality, and reduce N loss to the environment. x improve the opportunity to produce silage with an elevated concentration of WSC. In circumstances where little or no supplementary concentrate feedstuffs were offered with silage, higher residual WSC could enhance silage intake and digestion, thereby improving animal productivity and reducing urinary loss of N. x produce a grass with higher intake characteristics during grazing, resulting in improved or more efficient animal production. x better synchronise or balance the supply of a rapidly fermentable carbon source (e.g. WSC) with soluble N compounds in the rumen of cattle or sheep. This could be important with grazing animals in spring and particularly in autumn when grass N content can be relatively high. Improved synchronisation or balance could potentially improve animal productivity and reduce urinary loss of N.European Union Fifth Framework funded project (QLK5-CT-2001-0498

Effects of fertiliser nitrogen rate to spring grass on apparent digestibility, nitrogen balance, ruminal fermentation and microbial nitrogen production in beef cattle and in vitro rumen fermentation and methane output

peer-reviewedThe effects of two fertiliser nitrogen (N) application rates - 15 (LN) or 80 (HN) kg N/ha - to Lolium perenne dominant swards in spring, on grass dry matter (DM) intake, digestion, rumen fermentation, microbial N production and N-balance in beef cattle, and in vitro fermentation and methane production were studied. Sixteen Charolais steers with a mean live weight (s.d.) of 475 (18.4) kg, were used in a completely randomised block design experiment and offered zero-grazed grass harvested 21-d post N application. The same grass was incubated in an eight-vessel RUSITEC in a completely randomised block design experiment. The HN treatment had a 540 kg/ha higher grass DM yield, and a 20 g/kg DM higher crude protein (CP) concentration compared to LN. There was no difference (P > 0.05) in DM intake, or in vivo DM, organic matter (OM) and N digestibility between treatments. Rumen fermentation variables pH, lactic acid, ammonia (NH3) and total volatile fatty acid (VFA) concentration were similar (P > 0.05) for both treatments. Nitrogen intake was 19 g/d higher (P  0.05) between treatments. The quantity of N retained and N-use efficiency did not differ (P > 0.05) between LN and HN. Plasma urea concentration was 1 mmol/L greater (P  0.05) between HN and LN. In vitro methane and total gas output were not different (P > 0.05) between treatments. Reducing fertiliser N application rate to grass in spring reduced total and urinary N excretion, which has environmental benefits, with no effects on in vitro methane output.The author (Alan O’Connor) was in receipt of a Teagasc Walsh Fellowship, and financial support was provided by the Department of Agriculture, Food and the Marine Research Stimulus Programme (Excess N, 11/S/105)

Yield of binary- and multi-species swards relative to single-species swards in intensive silage systems

peer reviewedBinary- and multi-species sown mixtures may increase herbage yield and/or reduce inorganicnitrogen (N) requirement compared to perennial ryegrass (PRG) (Lolium perenne L.)swards. A split-plot design was used to compare yields of binary- and multi-speciesmixtures to single-species swards of three grasses and red clover managed for intensivesilage production under varying N application rates. Perennial and Italian (Loliummultiflorum Lam.) ryegrasses had greater annual yields when grown as single speciesreceiving 360 kg N/ha per year than in binary mixtures with red clover (Trifoliumpratense L.) receiving 0 kg N/ha per year, whereas timothy (Phleum pratense L.) producedequally high yields in both situations. When no inorganic N was applied, the annualdry matter yield of Mix 1 (10,738 kg/ha; PRG, timothy, red clover and white clover(Trifolium repens L.) and Mix 2 (11,679 kg/ha; PRG, timothy, red clover, ribwort plantain(Plantago lanceolata L.) and chicory (Cichorium intybus L.)) was greater than thatof a PRG sward (PRG/0N; 5,885 kg/ha) and derived more from the contribution of legumesthan herbs. This yield advantage of mixtures declined as inorganic N input increased,as did the legume and herb proportions in the multi-species swards. When averagedacross rates of inorganic N input, Mix 2 had a greater annual yield than Mix 1 (12,464vs. 11,893 kg/ha). Mix 2 receiving no inorganic fertiliser N and both Mix 1 and Mix2 receiving 120 kg N/ha per year matched the annual yield achieved by PRG receiving360 kg N/ha per year. Our results indicate that the yield performance of binary- andmulti-species grassland swards should be measured in situ rather than predicted fromsingle-species swards of constituent species