Alternatives to formic acid as a grass silage additive under two contrasting ensilability conditions

peer-reviewedThe effects of formic acid and four alternative additives on silage fermentation, in-silo DM losses and aerobic stability were compared in an experiment using both difficultto- ensile (DIFF) and easier-to-ensile (EASI) herbages. Both were ensiled in laboratory silos with either no additive or following the application of formic acid (FA; 850 g/kg) at 3 mL/kg herbage, Add-SaFeR® (ATF1) and GrasAAT® (ATF2), both based on ammonium tetraformate, at 4 mL/kg herbage, an antimicrobial mixture (MIX; potassium formate, sodium disulfite and sodium benzoate) at 3 g/kg herbage, or Ecosyl (LAB; Lactobacillus plantarum) at 3 mL/kg herbage. There were four replicates per treatment and the silos were stored for 132 days. DIFF silage made without additive was poorly fermented. All additives increased the extent and improved the direction of DIFF silage fermentation, and reduced in-silo losses. However, MIX did not reduce butyric acid concentration and increased the extent of aerobic deterioration. LAB had a smaller effect on fermentation and in-silo losses than FA. With EASI silages, all additives restricted the extent of fermentation and improved fermentation quality, with the latter effect being smaller than for DIFF silages. LAB promoted a particularly homolactic fermentation but subsequently increased aerobic deterioration. In both DIFF and EASI silages additive treatment improved in vitro digestibility. It is concluded that only ATF1, ATF2 and MIX were as effective as FA at improving silage preservation and reducing in-silo losses with both DIFF and EASI herbages. However, ATF1 and ATF2 were superior in reducing the apparent extent of proteolysis and MIX was slightly less effective at reducing the activity of saccharolytic Clostridia

A note on the fermentation characteristics of red clover silage in response to advancing stage of maturity in the primary growth Corrigendum

Corrigendum to Irish Journal of Agricultural and Food Research, Volume 51, Number 1, 2012, pages 79–84. Available at http://hdl.handle.net/11019/324Corrigendu

A note on the evaluation of the acid-insoluble ash technique as a method for determining apparent diet digestibility in beef cattle.

peer-reviewedThe objective was to determine if the acid-insoluble ash (AIA) method provided accurate estimates of in vivo apparent digestibility compared with the standard total faecal collection (TFC) method. Twelve steers, mean live weight 328 (s.d. 27.3) kg, were offered one of three diets based on whole-crop wheat (WCW) or a grass silage (GS) diet in a 4 × 4 latin square design. Apparent dietary digestibility was determined simultaneously using AIA and TFC methods. Agreement between the two methods depended on diet type, with acceptable agreement (a difference between the methods of 0.06), observed with the WCW-based diets. However, the strength of the agreement was weakened with the inclusion of GS. Agreement statistics were found to be a useful tool for assessing the relationship between the two methods of measurement.This study was funded by the Irish Department of Agriculture, Fisheries and Food (Research Stimulus Fund 05 224)

Evaluation of mix specification and PFA as a cement replacer in concretes used in silage storage structures.

End of Project ReportsAt present, concrete for silage storage structures is specified by the Irish Farm Development Service (DAFF, 1992) in terms of a characteristic 28 day crushing strength of 40 N/mm2 and a minimum cement content of 350 kg/m3. In addition, the maximum aggregate size used must not exceed 20 mm and the slump of the unplasticised concrete must not exceed 75 mm. There is no stipulation on the maximum water to cement ratio to be used. This specification represents a high strength concrete for agricultural use and has been upgraded to this level in an attempt to improve the material’s resistance to corrosion by silage effluent. A cement content of 350 kg/m3 is regarded as a relatively high cement content and may promote thermal cracking in the structures (Blackledge, 1990). This would result in a concrete which would be more susceptible to attack by corrosive effluent. A system of carrying out accelerated durability tests on concrete specimens under controlled conditions has been developed by Teagasc and University College Dublin (O’Donnell, C., 1993). Trials carried out by O’Donnell, indicated that cement content had little influence on the durability of concretes exposed to silage effluent for the ranges of mixes examined, but the use of excess water resulted in marked increases in deterioration. The present study aims to further examine the effect of (i) cement content and (ii) the use of PFA as a cement replacer

A note on the conservation characteristics of baled grass silages ensiled with different additives.

peer-reviewedThe effects of contrasting conventional silage additives on chemical composition, aerobic stability and deterioration, and mould development in baled silage were investigated. Herbage from a grassland sward was wilted for 24 h and treated with acid (formic or sulphuric), sugar (molasses), bacterial (Lactobacillus plantarum, L. plantarum + Serratia rubidaea + Bacillus subtilis, or L. buchneri) or sugar + bacterial (molasses + L. plantarum) additives prior to baling and wrapping. Silage made without an additive preserved well and had a low incidence of mould growth, and the effects of additives were minor or absent. It is concluded that little practical benefit was realised when conventional additives were applied to wilted, leafy, easy-to-ensile grass prior to baling and ensilage

Quantification of nutrient supply in forage-based diets for beef cattle

End of Project ReportIntroduction Cattle rearing systems in Ireland are predominantly grass-based as 80% of agricultural land is dedicated to grassland (silage, hay and pasture) (CSO, 2007). Feed costs represent the largest single variable cost in beef production in Ireland. Grazed grass is generally the cheapest source of food available for beef (and milk) production provided that the environment and management permit high yields of high quality herbage to be utilised (McGee, 2000). Environmental legislation and the rules of environmental schemes such as the European Union (EU) Rural Environmental Protection Scheme are progressively restricting the application of fertilizer Nitrogen (N), and many grazing systems are becoming more extensive. Over 80% of all farms in Ireland make grass silage (O’Kiely et al., 1998) and it accounts for 87% of total grass conserved (Mayne and O’Kiely, 2005). The deficiencies in nutrient supply to beef cattle from grass silage are usually overcome by supplementing with concentrates (McGee, 2005), which are primarily cereal-based (Drennan et al., 2006). However, diverse types of concentrates containing a variety of feed ingredients, particularly non-cereal by-products are available and frequently fed as supplements to grass silage or as highconcentrate diets. The relatively small amount of information available on feeding these contrasting concentrates to beef cattle is inconsistent. Moreover, there has been an increased use of other ensiled forages such as maize and whole-crop cereals. These forages have high intake potential and can reduce the concentrate feeding level, while maintaining or increasing performance of beef cattle (Keady, 2005). With increasing costs of beef production and increasing constraints of environmental regulations, efficient utilisation of consumed nutrients by cattle is imperative in providing sustainable production and income to farmers. Feed evaluation systems are used to match the dietary nutrient supply with animal requirements for a specific level of production (Dijkstra et al., 2007). These systems are important in order to optimise the efficiency of feed utilisation, to improve animal performance and to reduce nutrient losses to the environment (Dijkstra et al., 2007). Although the reticulo-rumen is central to the profile of nutrients available for absorption, yet quantitative knowledge of the rates of passage and the digestion of nutrients in the rumen is limited compared with that on degradation rates (Dijkstra et al., 2007). There is a lack of information that adequately characterises the supply of nutrients from forages and feedstuffs specific to Ireland, especially for fresh grass-based diets of which, there are very few studies reported in the literature. This shortcoming impedes our ability to capitalise on the merits of evolving feeding systems. This project aimed to: 1. Increase the knowledge and advance the understanding on rumen digestion and nutrient flow from the rumen of the main forages / forage-based diets offered to beef cattle in Ireland. 2. Evaluate strategies for optimal utilization of nutrients consumed by cattle

The effect of water-soluble carbohydrate concentration and type on in vitro rumen methane output of perennial ryegrass determined using a 24-hour batch-culture gas production technique

peer-reviewedThe objective of this study was to examine the effects of water-soluble carbohydrate (WSC) concentration and type on the in vitro rumen methane (CH4) output of perennial ryegrass (PR) using a 24-hour batch-culture gas production technique. Dried and milled PR was incubated either alone (PR-O) or with added sucrose (PR-S), inulin (PR-I), or sucrose plus inulin (PR-S+I; sucrose:inulin ratio of 1:4) in sealed glass bottles [0.5 g total substrate dry matter (DM) per bottle] at 39 °C for 24 hours with buffered rumen fluid. The WSC types were added (except for PR-O) so that the WSC concentration in each fermentation bottle at the start of the incubation was either 180 (i.e., PR-O), 225, 270, 315, or 360 g/kg of total substrate DM incubated. There were linear decreases in CH4 output per gram of DM disappeared (CH4/ivDMD) and per mmol of total volatile fatty acid output (CH4/tVFA) with increasing WSC concentration in the incubated substrate. The WSC type had no effect on in vitro rumen CH4 output. It is concluded that since CH4/ivDMD and CH4/tVFA were reduced by increasing the concentration of WSC incubated with PR, it would be worthwhile to undertake in vivo experiments to examine these effects on in vivo CH4 emissions per unit of animal product.Funding for this study was provided under the National Development Plan through the Research Stimulus Fund administered by the Department of Agriculture, Food & the Marine (RSF no. 07 517)

A note on the chemical composition and in vitro digestibility of contrasting stover components of maize grown in climatically marginal conditions and harvested at differing maturities.

peer-reviewedThis study evaluated the nutritive value of three contrasting components of maize stover (leaf, upper stem, lower stem) at three harvest dates. The leaf component had a greater in vitro dry matter digestibility (DMD) and a lower NDF concentration, compared to the stem components. Delaying harvest reduced the in vitro DMD of the stem components to a greater extent than leaf, reflecting lower increases in the NDF and lignin concentrations in leaf tissue. The stem components of maize stover had a lower nutritive value than the leaf component, and had a larger decrease in digestibility with delayed harvest.Funding for this study was provided under the National Development Plan through the Research Stimulus fund administered by the Department of Agriculture, Food and the Marine (RSF 07 501

Conservation characteristics of baled grass silages differing in duration of wilting, bale density and number of layers of plastic stretch-film

peer-reviewedThe effects of duration of wilting, bale density and number of layers of plastic stretchfilm used to wrap bales on the conservation characteristics of baled grass silage was investigated. Grass from the primary growth of a Lolium perenne dominant sward was wilted for 24, 48 or 72 h. For each duration of wilting, 54 cylindrical bales (1.2 m nominal diameter) were made with the baler at a high or low density setting for alternate bales. Bales were wrapped with 2, 4 or 6 layers of plastic stretch-film and stored outdoors for 295 days. Two layers of plastic stretch-film resulted in inferior preservation, lower digestibility and extensive mould growth and deteriorated silage. Substantial improvement occurred to each of these characteristics from applying four layers of stretch-film (P<0.05), while six layers of stretch-film brought little further improvement. When four or six layers of stretch-film were used, extensive wilting restricted fermentation and improved the standard of preservation with the apparently difficult-to-preserve herbage used in this experiment. However, under the anaerobic conditions provided by four or six layers of stretch-film neither progressive wilting nor bale density had a major effect on digestibility, or the extent of surface mould growth or deteriorated silage. It can be concluded that a minimum of four layers of conventional black plastic stretch-film were required to achieve suitably anaerobic conditions, and that the additional benefits from six layers were small. Once anaerobic conditions were achieved, extensive wilting improved the conservation characteristics of baled grass silage made from a difficult-to-preserve crop, whereas bale density had little impact

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