Survival of \u3ci\u3eEscherichia coli\u3c/i\u3e 0157:H7 Added to Grass at Ensiling and Its Influence on Silage Fermentation

Escherichia coli can cause health problems in humans and livestock. It is frequently found in faeces and soil, both of which can contaminate grass harvested for silage-making. To determine the survival of E. coli 0157:H7 during ensilage, and its influence on ensilage, unwilted precision-chop grass was ensiled in laboratory silos with the following additive treatments: (a) no additive, (b) E. coli 0157:H7 (Ec - non-infectious strain, at log10 4.5 colony forming units (cfu) g-1), formic acid (FA), and (d) Ec + FA. Silos were stored at 15oC. Three silos per treatment were opened on days 0, 2, 5, 9, 19 and 180 of ensilage. Silages made without additive or with formic acid underwent contrasting but rapid, lactic acid dominant fermentations. Formic acid restricted fermentation, reducing (P\u3c 0.001) buffering capacity and the concentration of lactic acid and increasing (P\u3c 0.001) the concentration of water soluble carbohydrates. Counts of indigenous Enterobacteria were initially high (log10 8.1 cfu g-1) but declined rapidly in the early stages of ensilage and were not detected by day 19 of ensilage. Formic acid increased (P\u3c 0.05) the initial rate of decline in enterobacterial numbers. No indigenous E. coli 0157 were found on the ensiled grass. Inoculation with E. coli 0157:H7 increased (P\u3c 0.001) the numbers of this organism but they declined rapidly and were absent by day 5 of ensilage. The addition of formic acid accelerated (P\u3c 0.001) this rate of decline. The added E. coli did not alter (P\u3e 0.05) silage fermentation pattern

Aerobic Stability of Grass Silage Mixed with a Range of Concentrate Feedstuffs at Feed-Out

Mixing supplementary concentrates with silage at feed-out could shorten aerobic stability or increase the rate or extent of aerobic deterioration of silage. This experiment quantified such possible effects by twelve contrasting feedstuffs. Four samples (each 6 kg) of unwilted, precision-chop, well preserved grass silage (216 g dry matter (DM) kg-1 and pH 4.0) were incubated at 20oC for 6 days in polystyrene containers alone or with the addition of 400 g (solid ingredients were milled) of wheat grain, barley grain, maize grain, molasses beet pulp, citrus pulp, molasses, soybean meal, maize gluten, sunflower meal, rapeseed meal, dry distillers grains or sunflower oil. Daily temperature profiles were recorded. Silage alone was unstable under aerobic conditions, with an accumulated daily temperature rise during 5 days aerobiosis of 57oC. None of the added ingredients altered (P\u3e 0.05) any of the indices of aerobic deterioration. For the treatments as listed above, the interval until temperature rise commenced was 2.0, 2.0, 2.0, 2.3, 2.0, 2.0, 2.3, 2.0, 2.3, 2.0, 2.0, 2.0 and 2.0 (s.e.m. 0.11) days, the interval until the maximum temperature was reached was 3.8, 3.5, 4.5, 3.5, 4.0, 3.3, 3.5, 3.8, 4.3, 4.0, 3.8, 3.8 and 3.5 (s.e.m, 0.44) days and the accumulated temperature rise to day 5 was 57, 58, 57, 54, 58, 59, 50, 57, 53, 61, 52, 51 and 58 (s.e.m. 3.1)oC. It is concluded that mixing the above feedstuffs with grass silage did not alter the aerobic deterioration of grass silage

Efficient Beef Production from Temperate Grasslands in North-Western Europe

Ireland’s cool temperate maritime climate is conducive to grass growth and, as a result, ruminant livestock systems have evolved that maximise both grazed pastures and conserved grassland forage as winter feed. Most Irish pastures are permanent, capable of achieving high herbage production (Keating and O’Kiely 2000) and, accordingly, supporting intensive livestock production systems. Most male progeny from the 1.1 million Irish dairy herd are reared as steers, typically slaughtered at 24-26 months of age. Approximately 85% of dairy calves available for beef production are spring-born, usually in February/March (AIMS 2011). The progeny of Holstein-Friesian (Ho/Fr) sires account for 0.5-0.6 of the calf crop, with 0.6 and 0.4 of the remainder being sired by early-maturing (EM; e.g. Aberdeen Angus, Hereford) or late-maturing (LM; e.g. Limousin, Belgian Blue, Charolais) sires, respectively. This paper summarises some of the main grassland-based steer beef production systems applicable to Ireland

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

Application of Meta-Analysis and Machine Learning Methods to the Prediction of Methane Production from In Vitro Mixed Ruminal Micro-Organism Fermentation

peer-reviewedIn vitro gas production systems are utilized to screen feed ingredients for inclusion in ruminant diets. However, not all in vitro systems are set up to measure methane (CH4) production, nor do all publications report in vitro CH4. Therefore, the objective of this study was to develop models to predict in vitro CH4 production from total gas and volatile fatty acid (VFA) production data and to identify the major drivers of CH4 production in these systems. Meta-analysis and machine learning (ML) methodologies were applied to a database of 354 data points from 11 studies to predict CH4 production from total gas production, apparent DM digestibility (DMD), final pH, feed type (forage or concentrate), and acetate, propionate, butyrate and valerate production. Model evaluation was performed on an internal dataset of 107 data points. Meta-analysis results indicate that equations containing DMD, total VFA production, propionate, feed type and valerate resulted in best predictability of CH4 on the internal evaluation dataset. The ML models far exceeded the predictability achieved using meta-analysis, but further evaluation on an external database would be required to assess generalization ability on unrelated data. Between the ML methodologies assessed, artificial neural networks and support vector regression resulted in very similar predictability, but differed in fitting, as assessed by behaviour analysis. The models developed can be utilized to estimate CH4 emissions in vitro

Effect of dietary restriction and subsequent re-alimentation on the transcriptional profile of bovine ruminal epithelium

peer-reviewedCompensatory growth (CG) is utilised worldwide in beef production systems as a management approach to reduce feed costs. However the underlying biology regulating the expression of CG remains to be fully elucidated. The objective of this study was to examine the effect of dietary restriction and subsequent re-alimentation induced CG on the global gene expression profile of ruminal epithelial papillae. Holstein Friesian bulls (n = 60) were assigned to one of two groups: restricted feed allowance (RES; n = 30) for 125 days (Period 1) followed by ad libitum access to feed for 55 days (Period 2) or (ii) ad libitum access to feed throughout (ADLIB; n = 30). At the end of each period, 15 animals from each treatment were slaughtered and rumen papillae harvested. mRNA was isolated from all papillae samples collected. cDNA libraries were then prepared and sequenced. Resultant reads were subsequently analysed bioinformatically and differentially expressed genes (DEGs) are defined as having a Benjamini-Hochberg P value of <0.05. During re-alimentation in Period 2, RES animals displayed CG, growing at 1.8 times the rate of their ADLIB contemporary animals in Period 2 (P < 0.001). At the end of Period 1, 64 DEGs were identified between RES and ADLIB, with only one DEG identified at the end of Period 2. When analysed within RES treatment (RES, Period 2 v Period 1), 411 DEGs were evident. Genes identified as differentially expressed in response to both dietary restriction and subsequent CG included those involved in processes such as cellular interactions and transport, protein folding and gene expression, as well as immune response. This study provides an insight into the molecular mechanisms underlying the expression of CG in rumen papillae of cattle; however the results suggest that the role of the ruminal epithelium in supporting overall animal CG may have declined by day 55 of re-alimentation.SMW received financial assistance from Science Foundation Ireland (SFI) contract no 09/ RFP/GEN2447

Conservation efficiency and nutritive value of silages made from grass-red clover and multi-species swards compared with grass monocultures

peer reviewedBinary grass-clover and multi-species swards can increase herbage yields or facilitate reduced inputs of inorganic fertiliser nitrogen (N) compared with perennial ryegrass monocultures. However, the efficiency of the ensilage process and the nutritive value of silage produced from multi-species swards has not been documented. Replicate samples from grass-red clover binary mixture and multi-species mixture swards were ensiled in laboratory silos to assess the ensilability, fermentation characteristics, conservation losses and silage nutritive value compared with grass monocultures produced using inorganic N fertiliser. The results suggest that assessment of the ensilability and subsequent ensilage characteristics of binary and multi-species mixtures should be based on direct sampling from such mixtures rather than being predicted from values obtained from monocultures of constituent species. Under favourable ensiling conditions, unwilted binary mixtures and multi-species mixtures are satisfactorily preserved as silage, comparable to a perennial ryegrass monoculture receiving inorganic N fertiliser. However, when ensiled under more challenging crop conditions the mixtures exhibited a greater requirement for their preservation to be aided, compared with the perennial ryegrass monoculture. Despite the application of inorganic N reducing the legume content of multi-species mixture swards, it had relatively little effect on herbage ensilability or silage preservation. For all species treatments, silage nutritive values were primarily dependent on the pre-ensiling values, although herbage digestibility values declined during ensilage where the ensilage process was inefficient. The current study suggests that in order to be satisfactorily preserved as silage, binary grass-clover and multispecies swards have a greater requirement for an adequate rapid field wilt and/or effective preservative application compared with perennial ryegrass produced using inorganic fertiliser N