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

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

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

Influence of Real Atmospheric Conditions on Free Propagation of Aircraft Noise

The propagation of sound in the atmosphere is influenced by meteorological conditions. During computation a detailed description of meteorological conditions takes a lot of time but principally the needed meteorological data are not available in most cases. That is why the sound propagation calculation of common tools, like the German AzB or the Integrated Noise Model, is based on standardised meteorological conditions. The main objective of this study is to quantify the noise level differences between common propagation and propagation considering real weather conditions. Therefore the two important sound propagation effects for free sound propagation (atmospheric attenuation and geometrical spreading) are investigated for sources in higher altitudes. A ray-tracing algorithm is used to model the refractions of sound due to wind, wind gradients, and temperature gradients. The atmospheric attenuation is calculated by ISO 9613-1. The used meteorological conditions based on the parameters, i.e. temperature, wind, and relative humidity, from one year radiosonde measurements taken at the meteorological observatory Lindenberg in Germany. All in all, for long-term periods all these calculated average sound pressure levels and the levels calculated for standardised atmospheric conditions are similar in size. Furthermore, common noise calculations overestimate the meteorological influence on sound propagation slightly

Mycotoxin occurrence on baled and pit silages collected in Co. Meath

Recent studies of baled silages produced in Ireland have identified considerable filamentous fungal contamination. Many of these fungi are toxigenic, capable of producing secondary metabolites, namely mycotoxins. Mycotoxins are potentially detrimental to livestock health and some can pose a risk to consumers of animal products. Baled (n=20) and pit (n=18) silages from a sample of farms (n=38) in Co. Meath were examined to assess the occurrence of mycotoxins and ascertain whether sampling position within the pit silos (feed face vs. 3 m behind the feed face) has an effect on mycotoxin content or other chemical compositional variables. Of the 20 mycotoxins assayed, baled silages contained [mean of positive values (no. of values in mean)] mycotoxin concentrations (μg/kg dry matter) of beauvericin 36 (2), enniatin (enn.) A 9.3 (3), enn. A1 54 (8), enn. B 351 (9), enn. B1 136 (10), mycophenolic acid (MPA) 11,157 (8) and roquefortine C (Roq. C) 1037 (8) and pit silages contained beauvericin 25 (2) enn. A1 18 (2), enn. B 194 (9), enn. B1 57 (3), MPA 287 (6), Roq. C 3649 (6) and zearalenone 76 (1). There was no difference (P>0.05) observed in the mycotoxin concentrations between baled and pit silages, and 11 of the 20 mycotoxins assayed were below the limits of detection. The position of sampling had no effect on the mycotoxin concentration detected in pit silages. It is concluded that mycotoxin concentrations detected in these pit and baled silages in Co. Meath did not exceed EU regulation or guidance limits, and that similar chemical composition and mycotoxin concentration values occurred at the pit silage feed face and 3 m behind this feed face