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Xie S.,National University of Ireland | Xie S.,Teagasc | Wu G.,Tsinghua University | Lawlor P.G.,Teagasc | And 2 more authors.
Bioresource Technology | Year: 2012

Anaerobic co-digestion of the solid fraction of separated pig manure (SPM) with dried grass silage (DGS) was evaluated in three identical continuously stirred tank reactors (CSTRs) at 35±1°C. The feedstock contained 20% DGS in CSTR1, 30% DGS in CSTR2 and 40% DGS in CSTR3 on a volatile solids (VS) basis. Organic loading rates (OLR) of 1.0, 1.5, 2.0 and 3.0kgVS/m 3/d were studied and it was found that the OLR affected the digester performance more than the DGS proportion in the feedstock. Tripling the OLR increased volumetric methane yields by 88% and decreased specific methane yields by 38%. At the OLR of 3kgVS/m 3/d, post-methane production potentials of digestates ranged from 38% to 41% of total methane production potentials of the feedstock. An energy yield estimation on a 654-sow pig unit showed that 268-371MWh/a electricity and 383-530MWh/a heat would be generated. © 2011 Elsevier Ltd. Source


Xie S.,National University of Ireland | Lawlor P.G.,Teagasc | Frost J.P.,Hillsborough Co. | Wu G.,Tsinghua University | Zhan X.,National University of Ireland
Bioresource Technology | Year: 2012

Hydrolysis and acidification of grass silage (GS) was examined in leaching bed reactors (LBRs) under organic loading rates (OLRs) of 0.5, 0.8 and 1.0kg volatile solids (VS)/m 3/day. The LBRs were run in duplicate over five consecutive batch tests (Batch tests 1-5) to examine the effects of pH, leachate dilution and addition of inoculum on the process of hydrolysis and acidification. The highest GS hydrolysis yields of 52-58%, acidification yields of 57-60% and VS removals of 62-66% were obtained in Batch test 4. Increasing OLRs affected the hydrolysis yield negatively. In Batch test 4, the reduction of lignocellulosic materials was up to 74.4% of hemicellulose, 30.1% of cellulose and 9.3% of lignin within 32days. Cellulase activity can be used as an indicator for the hydrolysis process. Methane production from the LBRs only accounted for 10.0-13.8% of the biological methane potential of GS. © 2012 Elsevier Ltd. Source


Xie S.,National University of Ireland | Frost J.P.,Hillsborough Co. | Lawlor P.G.,Teagasc | Wu G.,Tsinghua University | Zhan X.,National University of Ireland
Bioresource Technology | Year: 2011

Dried grass silage (GS) was pre-treated at different NaOH loading rates (1%, 2.5%, 5% and 7.5% by volatile solids (VS) mass in grass silage) and temperatures (20°C, 60°C, 100°C and 150°C) to determine effects on its bio-degradability in terms of the hydrolysis yield and degradation of ligno-cellulosic materials for biogas production. At 100°C and the four NaOH loadings, up to 45% of the total COD was solubilised and up to 65.6%, 36.1% and 21.2% of lignin, hemicellulose and cellulose were removed, respectively; biological methane production potentials obtained were 359.5, 401.8, 449.5 and 452.5ml CH 4/g VS added, respectively, being improved by 10-38.9% in comparison with untreated GS. VS removals following anaerobic digestion were 67.6%, 76.9%, 85.3%, 95.2% and 96.7% for untreated GS and GS treated at the four NaOH loadings, respectively. 100°C and the NaOH loading rate of 5% is recommended as a proper GS pre-treatment condition. © 2011 Elsevier Ltd. Source


This study investigated the performance and instrumental meat quality of finishing beef steers offered grass silage (GS), grass silage:maize silage (GS:MS) and grass silage:lupins/triticale silage (GS:LT). The lupins/triticale silage was grown as either two separate crops in the same field and harvested together (LT1) or grown and harvested as a mixture (LT2). The silages were offered to eighty continental cross beef steers, initial live weight 530 ± 47.7. kg and 18 ± 1.6 months of age and were supplemented with 3 or 6. kg concentrates fresh/head/d. Silage was fed ad libitum with the mixtures offered at a ratio of 60 GS:40 maize silage (MS), LT1 or LT2 on a dry matter (DM) basis and concentrates were offered once (3. kg) or twice (6. kg) daily on top of the silage. Animals were slaughtered in three batches after 100, 117 and 124. d on experiment. The LT1 and LT2 produced yields of 8.7 and 7.5. kg. DM/ha and the silages were poorly fermented as demonstrated by high ammonia-N concentration (182 and 173. g/kg total N), low lactic acid (9. g/kg DM) and high pH (5.0 and 4.7). Silage type had no significant effect on slaughter live weight, liveweight gain, carcass gain, forage DM intake (DMI), total DMI or feed efficiency expressed as kg. DMI/kg. liveweight gain or kg. DMI/kg. carcass gain. Silage type had no effect on carcass characteristics or instrumental meat quality. The results of this study demonstrate that offering lupins/triticale silage in combination with high quality grass silage (D-value greater than 700) at a ratio of 60 grass silage:40 LT1 or LT2 on a DM basis had no effect on animal performance, carcass characteristics or meat quality parameters relative to high quality grass silage offered alone or in combination with maize silage. © 2011. Source


Donaldson C.J.,Hillsborough Co. | Donaldson C.J.,Queens University of Belfast | O'Connell N.E.,Queens University of Belfast
Applied Animal Behaviour Science | Year: 2012

The aim of this trial was to determine the influence of aerial perches on welfare and production parameters in free-range laying hens. Five commercial free-range houses, each containing between 7000 and 8000 birds, were used. Each house and range area was split in half to create two treatments. In half of the house the birds had access to aerial perches (P) and in the other half they did not (NP). Perches were provided from the start of the lay cycle at 16 weeks of age, and remained in place until the end of the lay cycle (at approximately 74 weeks). Behavioural observations took place over two day periods at intervals between 17 and 70 weeks of age. During day 1, tests of fearfulness and observations of aggressive and feather pecking behaviours were performed. In addition, twenty birds per replicate were randomly selected and weight, body condition, feather coverage and resistance to handling were measured. The use of the range area by birds was assessed on day 2. The percentage of eggs laid out of nest boxes ('floor eggs') was recorded continuously on three of the farms, and egg quality was assessed from a sample of eggs every 10 weeks across the production cycle on all farms. Access to aerial perches significantly reduced the level of aggression in the slatted and litter areas of the house (P<0.05). P birds had a significantly lower flight distance from the observer than NP birds (P<0.05). In addition, NP birds resisted more to being handled than P birds (P<0.01). P birds were heavier (P<0.01) and had a greater body condition score (P<0.05) than NP birds. There was no effect of treatment on feather coverage (P>0.05), egg quality parameters (all P>0.05), or the proportion of floor eggs (P>0.05). In conclusion, these results suggest that the provision of aerial perches in commercial free-range farms leads to welfare benefits in terms of reduced fearfulness and aggression, and improved body condition. © 2012 Elsevier B.V. Source

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