A whole farm BEEF systems Greenhouse gas Emissions Model (BEEFGEM) was developed to determine the effect of varying management practices on greenhouse gas (GHG) emissions from pastoral beef production systems. BEEFGEM simulates two categories of GHG emissions: firstly, the direct GHG emissions of methane, nitrous oxide and carbon dioxide from on-farm livestock production activities and secondly, indirect GHG emissions associated with inputs used on the farm and GHG emissions associated with nitrate leaching and ammonia volatilisation. The aim of this work was to investigate the effect of alternative production systems at farm level on GHG emissions. Greenhouse gas emissions were modelled for five contrasting beef production systems, one based on average farm conditions in Ireland and four based on research farm conditions. Both direct and total GHG emissions per hectare increased with increasing stocking rate for all scenarios tested. However, increasing stocking rate led to a reduction in GHG emissions per kg beef carcass, albeit with higher levels of production efficiency. At moderate stocking rates, increasing stocking rate further resulted in an increase in GHG emissions per kg beef carcass. Cattle production systems finishing males as bulls had lower GHG emissions than production systems finishing males as steers and thus, the lowest GHG emissions per kg beef carcass were achieved for bull beef production systems at moderate stocking rates which had direct and total system GHG emissions of 15.7 and 18.9 kg CO(2)e/kg beef carcass, respectively. Bull beef production systems at high stocking rates were most profitable. The highest GHG emissions were for the scenario representing average farm conditions in Ireland with direct and total emissions of 19.0 and 23.1 kg CO(2)e/kg beef carcass, respectively. This was also the least profitable scenario. (C) 2011 Elsevier B.V. All rights reserved.

The objective of this study was to determine the effect of dietary dl-malic acid (MA) supplementation on feed intake, methane (CH(4)) emissions, and performance of mid lactation Holstein-Friesian cows at pasture. Twenty-four (6 primiparous and 18 multiparous) mid- to late-lactation cows (206 +/- 65 d in milk) grazing a mixed-species grass sward were blocked on parity, days in milk, and pretrial milk yield, and randomly allocated within block to 1 of 2 dietary treatments offered twice daily at milking in 2 equal portions (6 kg/d in total): a control concentrate (0 g/d of MA) and a concentrate supplemented with MA (480 g/d of MA) over a 6-wk period. Cows were allowed a 3-wk acclimation period followed by a 5-d CH(4) measurement period. Enteric CH(4) emissions were estimated using the sulfur hexafluoride tracer gas technique, and herbage intake was measured using the n-alkane technique. Dietary supplementation with MA did not affect voluntary intake of herbage or total dry matter intake, body weight gain, milk yield, fat-corrected milk yield, or daily CH(4) production. These results suggest that there is little benefit to be gained from the dietary supplementation of dairy cows at pasture with MA at least within the inclusion rates used in this study.

A previously developed model, the Pastoral Milk Emission Model (PME Model) was used to simulate both on-farm and off-farm greenhouse gas (GHG) emissions (consisting of methane (CH4), nitrous oxide (N2O) and carbon dioxide (COD) under two contrasting pastoral based milk production systems. There were two primary objectives to this study. Firstly within the production systems studied, to identify the effect simple management changes may have on GHG emissions and farm profitability so that financially viable whole farm GHG mitigation strategies could be developed. The potential effect these management changes could have on national GHG emissions was quantified. The second objective was to determine what effect the characteristics of the production system may have on the uncertainty surrounding the emission of GHGs.The two contrasting production systems were the standard production procedures recommended for Kilinaley, (County Clare, Ireland) and Moorepark (County Cork, Ireland), with grazing seasons of 149 and 250 days per year respectively. The management scenarios tested were changes in pasture quality, pasture utilisation, N application rates, silage quality, level of concentrate supplementation and calving date.Stochastic budgeting revealed that emissions of GHGs were greater at Kilmaley than Moorepark whatever the level of risk/uncertainty. Simple fanning system changes, regardless of location, generally resulted in small changes in both on-farm and total GHG emissions (between-5.8 and +5.1%). However silage quality demonstrated a site specific interaction. Tailor designed whole farm GHG mitigation strategies were developed by combining all identified management changes, which simultaneously reduced GHG emissions and increased farm profitability. Relative to the standard production systems at Moorepark and Kilmaley, on-farm and total GHG emissions were 6.65% and 8.42% and 11.40% and 11.64% respectively. Farm profitability increased at both sites. Projecting these potential reductions onto the national dairy herd revealed that significant reductions in GHG emissions are possible. Relative to 2005 national emissions the implementation of the standard systems would achieve a reduction of 3.46%, this would increase to 4.04% for the tailor designed strategies. Additional reductions in GHG emissions would be achieved through a lowering of inputs within the farm supply chain.Sensitivity analysis revealed differences between systems with regards to source strength, however regardless of the system, source strength was always greatest for enteric CH4, confirmation that considerable efforts should be made to control this GHG source. However differences do exist between systems which suggests that national mitigation strategies must consider regional production systems if GHG reductions are to be maximised. This work has also highlighted the need for more data on indirect GHG emissions derived from leached N. (C) 2007 Elsevier B.V. All rights reserved.

Two experiments were conducted to determine the effects of Yucca schidigera extract (YE) on firstly, dry matter intake (DMI), milk production and milk composition in lactating Holstein Friesian cows and secondly on DMI and GEI and rumen fermentation parameters of ruminally fistulated Holstein Friesian steers. Three levels of YE supplementation were studied in both experiments. In Experiment 1, 33 early lactating dairy cows that were 69 days in milk (S.D.±39) at commencement of the trial were fed YE at either 0, 25 or 50 g/head/day in a randomised block design while in Experiment 2, the three fistulated steers were fed YE at 0, 15 and 28 g/head/day within a latin square design. The lower levels of YE supplementation fed in Experiment 2 were designed to provide similar inclusion rates within the diet as in Experiment 1 after allowing for the higher DMI within Experiment 1. All animals in both trials were offered ad libitum a total mixed ration (TMR) supplemented with concentrates containing the YE. The dairy cows were group housed by diet, however when milk and intake measurements were conducted (days 12 to 18 and days 54 to 60 post commencement of the feeding of the experimental diets) the animals were housed in individual tie up stalls, whereas for Experiment 2 all animals were individually stall fed for the duration of the trial. Feeding YE had no effect on milk yield or composition, however DMI decreased linearly (P<0.06) in response to increasing YE dietary inclusion within Experiment 1. No effects of YE supplementation on total tract digestibility were identified in either experiment, however comparisons between treatments revealed that total volatile fatty acid (VFA) concentration in rumen fluid were lower at for both YE25 and YE50 relative to the control, and rumen protozoa numbers were also linearly (P<0.01) reduced. Although feeding YE to early lactation Holstein Friesian cows had no effect on milk production or digestibility and had only elicited limited responses in rumen fermentation characteristics it would appear to lead to an increase in the efficiency of converting feedstuffs to milk (as comparisons between individual treatments revealed a significant increase following YE supplementation relative to YE0) due to a reduction in voluntary DMI.

An experiment was conducted to establish the effects of feeding refined soy oil (RSO) or whole soybeans (WSB) containing soy oil on DMI, animal performance, and enteric methane (CH4) emissions in young bulls. Thirty-six Charolais and Limousin cross-bred, young beef bulls (338 +/- 27 kg of BW, 218 +/- 17 d of age at the beginning of the experiment) were blocked by BW, age, and breed before being assigned in a randomized complete block design to 1 of 3 experimental treatments (n = 12). The experimental period lasted for 103 d, with enteric CH4 output recorded for 2 periods of 5 consecutive days on d 37 to 41 and d 79 to 83. The 3 dietary treatments consisted of a barley/soybean meal-based concentrate with 0 g/d of RSO; oil from WSB as 6% of DMI (WSB treatment); and oil from RSO as 6% of DMI (RSO treatment). Each diet had a 10:90 forage:concentrate ratio, using barley straw as the forage source. Diet affected DMI (P < or = 0.001) and GE intake (P < 0.05 during the CH4 measurement periods), with the WSB treatment producing the lowest values. The addition of WSB decreased ADG (P < 0.05) compared with the RSO treatment. The WSB treatment also decreased (P < 0.05) average daily carcass gain (ADCG). Both the RSO and WSB concentrates decreased (P < 0.05 to P < 0.001) daily enteric CH4 output when expressed in terms of liters per day, liters per kilogram of DMI, percentage of GE intake, liters per kilogram of ADG, and liters per kilogram of ADCG. Diet had no effect (P = 0.557) on ruminal protozoal numbers. The reductions in enteric CH4 were achieved at relatively high oil inclusion levels. Such oil levels have previously been reported to decrease DMI of high-forage diets, although no effect on DMI was noted with the low-forage diets fed in this experiment. This impact on DMI of high-forage diets may limit the range of diets for which this CH4 reduction strategy may be applicable. The inclusion level of WSB in the current experiment (27%) was beyond the palatability threshold of the bulls used and resulted in a marked decline in intake and performance. Therefore, WSB may have a role to play in ruminant diets, but only at a reduced inclusion rate.

An experiment was conducted to establish the effect of feeding either refined coconut oil (CO) or copra meal containing CO to beef heifers on DMI, animal performance, enteric CH4 emissions, diet digestibility, and the fatty acid profile of the resulting meat. Forty-one Charolais and Limousin crossbred beef heifers (474 +/- 29 kg; 661 +/- 89 d of age) were blocked by BW before being assigned in a randomized complete block design to 1 of 3 experimental treatments (n = 12) or to a pretrial slaughter group (n = 5) used to determine the initial carcass weight. The experimental period lasted for 93 d. Enteric CH4 output was recorded for 2 periods of 5 consecutive days from d 14 to 18 and from d 70 to 74. The 3 dietary treatments were 1) control, a barley/soybean meal-based concentrate with 0 g of CO/ d; 2) RCO, a barley/soybean meal-based concentrate with 250 g of CO/d from refined coconut oil; and 3) CM, a copra meal-based concentrate with 250 g of CO/d from copra meal. Each diet had a 50:50 forage: concentrate using grass silage as the forage source. There was no effect of diet on DMI (P = 0.734) or GE intake (P = 0.486). The addition of RCO increased ADG (P < 0.05) compared with the control treatment. The CM treatment decreased (P < 0.05) average daily carcass gain compared with the RCO treatment only. There was a decrease (P < 0.05) in the digestibility of the DM, OM, CP, and GE fractions of the diet only with the CM treatment. Both the RCO and CM concentrates decreased (P < 0.001) daily enteric CH4 output when expressed in terms of liters per day, liters per kilogram of DMI, percentage of GE intake, liters per kilogram of ADG, and liters per kilogram of average daily carcass gain. The RCO treatment produced the greatest numerical response for all measures. Ruminal protozoa numbers on the RCO treatment were lower (P < 0.05) than on the control treatment. The concentrations of the fatty acid methyl esters, lauric (P < 0.001) and myristic (P < 0.002) acids, were increased in muscle when either of the CCO treatments was compared with the controls, but the differences were of a magnitude unlikely to influence human health status. Although the CM concentrate decreased CH4 comparable with the RCO concentrate, decreased performance resulted in an extended finishing time with implications for lifetime CH4 emissions.

Reductions in agricultural greenhouse gas (GHG) emissions are likely to be maximised if a systems approach is taken as opposed to introducing single focus mitigation strategies in isolation. With this in mind the Pastoral Milk Emissions Model (PMEModel) was developed at the University College Dublin to determine the effect of management change on GHG emissions. Such an approach is particularly pertinent to pastoral systems where the ability to introduce novel mitigation strategies is curtailed by agricultural practice. This paper reports the findings of a GHG simulation study based on a long term trial comparing the effects of Holstein–Friesian strain and feeding system on milk production and reproductive performance. These emissions are compared against a standard system as recommended for profitable milk production. The dairy cow strains examined were the High Production (HP) North American strain, a High Durability (HD) North American strain and a New Zealand (NZ) Friesian strain. The two feeding systems were a control feeding system (the standard Moorepark system) and a high concentrate feeding system. Under the pastoral production systems practiced within Ireland GHG emissions were lowest for the NZ type cow and highest for the HP cow whilst increased concentrate use also reduced GHG's.

In some European countries, the majority of annual enteric methane (CH4) emissions by ruminants occur at pasture - a direct result of the predominance of grazing within ruminant production systems. However, there are only limited data available as to the effect of perennial ryegrass cultivar and season of harvest on CH4 production. Using the in vitro gas production technique, the effect of perennial ryegrass cultivar on fermentation characteristics and CH4 production was determined (Experiment 1) and the persistence of these traits throughout the growing season for two cultivars, identified from Experiment 1 as having either a high or low methanogenic potential, was examined (Experiment 2). In Experiment 1, organic matter (OM) digestibility and cumulative total gas production profiles were unaffected by cultivar but, with regard to the kinetics of CH4 production, the asymptote value (A), cumulative CH4 yield at 72 h, and the fractional rate (p) of CH4 production at both time of 0(.)5A (T-2/(1)) (mu CH4T2/(1)) and at 48 h (mu CH(4)48h) were significantly (P < 0(.)05) different. The amount of digested OM, as a proportion of cumulative CH4 production (DigOM/CH4) at 24 and 72 h after commencement of inoculation, revealed that the amount Of Substrate required to produce 1 ml of CH4 also differed significantly between cultivars (P < 0(.)01). In Experiment 2, regrowth number significantly modified the majority of measured samples (P < 0(.)01); cultivar effects were limited to the lag phase of the Cumulative CH4 production curve and DigOM/CH4 at 8 h only (P < 0(.)05). These results suggest that differences exist between cultivars in how OM is partitioned following microbial fermentation and that these differences demonstrate persistency throughout the growing season. in the course of time it may be possible to exploit these differences through cultivar selection and plant breeding programmes, and thereby reduce enteric CH4 emissions within pastoral production systems.

This experiment sought to establish the response to increasing levels of coconut oil (CO) supplementation with a fixed 0·50:0·50 forage:concentrate diet on intake, digestibility and methane (CH4) emissions. Sixteen continental cross beef heifers (mean starting weight 481±36 kg) were assigned randomly to one of four levels of CO; 0 g/day, 125 g/day, 250 g/day or 375 g/day in an incomplete (three periods) multiple (no. =4) Latin-square design experiment (no. =12 per treatment). A linear reduction in CH4 output occurred as the level of CO in the diet increased ( P<0·001) with the greatest reduction at the 375 g/day level (394, 341, 314 and 240 l/day for animals fed 0, 125, 250 and 375 g/day CO, respectively). As the level of CO increased dry-matter (DM) intake (DMI) decreased, however these differences were only statistically significant at the 375 g/day level ( P <0·001). The proportional reduction in CH4 output was greater than the proportional reduction in DMI and hence CH4 l/kg DMI decreased from 39·8 l/kg when no CO was given to 29·7 l/kg when 375 g/day CO was given. The addition of CO to the diet resulted in a significant decline in dry-matter digestibility (DMD) at the 375 g/day level (P<0·05). These data demonstrate that the inclusion of CO at levels from 0·013 to 0·045 of the dietary DM within a 0·50:0·50 silage and concentrate ration reduces CH4 production with no adverse effect on DMI or DMD up to the 250 g/day level (0·027 of dietary DM).

The objective of this study was to determine the potential of increased fiber-based concentrates to reduce methane (CH(4)) production in relation to milk yield from late-lactation dairy cows. The effect of 2 levels of concentrate supplementation (0.87 vs. 5.24 kg on a dry matter basis) on herbage voluntary intake, total dry matter intake, milk yield, milk composition, and CH(4) production were determined by way of a randomized block designed grazing trial using lactating Holstein-Friesian cows (231 +/- 44 d in milk) grazing a mixed-grass sward with a regrowth aged 36 d. Increased concentrate supplementation resulted in a significant increase in total dry matter intake, milk yield, fat-corrected milk (FCM) yield, and daily CH(4) production. However, herbage intake and milk composition were unaffected. Although daily CH(4) production increased with fibrous concentrate use the increase was not as great as that observed for milk yield. The decline in CH(4) production per kilogram of milk was nonsignificant; however, when relating CH(4) production to FCM(FCM at 35 g of fat/kg of milk), a declining trend was identified within increasing concentrate supplementation (19.26 and 16.02 g of CH(4)/kg of FCM). These results suggest that increased fibrous concentrate use at pasture, even at modest levels, could reduce enteric CH(4) production per kilogram of animal product. However, the effectiveness of such a strategy is dependent on the maintenance of production quotas and a subsequent decline in the number of livestock needed to fulfill the specified production level.

A model was developed to determine what effect management practices would have on the production of the greenhouse gases (GHG) within pastorally based dairy production systems typical of those practiced in Ireland. The model simulates two levels of GHG emissions, firstly the on-farm GHG emissions of methane, nitrous oxide and carbon dioxide for example from the pastorally spreading of slurry and secondly, off-farm GHG emissions associated with both inputs brought onto the farm to maintain productivity (for example emissions arising from manufacture of concentrate feeds and fertiliser) as well as from indirect GHG emissions associated with nitrate leaching and ammonia. The aim of this work was to allow the development of effective GHG mitigation strategies at the farm level capable of reducing GHG emissions per litre of milk.Greenhouse gas emissions were modelled for nine farming systems differing in the level of concentrate supplementation (376, 810 and 1540 kg per cow per lactation) and genotype for milk production as assessed by their pedigree index (< 100, 100-200 and 200-300 kg) of milk production. A three-year study to evaluate the influence of cow genetic potential for milk production and concentrate supplementation level oil profitability of pasture-based systems of milk production was used to drive the Moorepark Dairy Systems Model (MDSM). Output from this model then described farm size, feed budgets, animal numbers and farm profitability when annual milk quota was set to 468,000 kg of milk year. Relating GHG emissions to annual milk sales revealed that for these pastorally based systems increasing concentrate usage reduced both on-farm and off-farm emissions, but that increasing the genotype of the dairy cow (i.e., the genetic capacity of the animal to produce milk) will increase both oil-farm and off-farm GHG emissions. Lowest GHG emissions per kilogram of milk were achieved for an intermediate genotype type cow fed within a high concentrate system whilst the highest emissions were associated with high genotype cows fed within a low concentrate system. Maximum profitability was obtained when either a high concentrate feeding regime was combined with high genotype cows or where low concentrate systems were fed to low genotype cows.Relating farm profitability to GHG emissions allowed the identification of scenarios where changing from one management systems to another would achieve a simultaneous reduction in GHG emissions whilst improving farm profitability. By implementing this approach of assessing management induced change oil both GHG emissions arising from the farm together with farm profitability, individual whole farm GHG mitigation strategies could be developed with a high degree of acceptability to the producer. (c) 2005 Elsevier Ltd. All rights reserved.

Maize silage nutritive quality is routinely determined by near infrared reflectance spectroscopy (NIRS). However, little is known about the impact of sample preparation on the accuracy of the calibration to predict biological traits. A sample population of 48 maize silages representing a wide range of physiological maturities was used in a study to determine the impact of different sample preparation procedures (i.e., drying regimes; the presence or absence of residual moisture; the degree of particle comminution) on resultant NIR prediction statistics. All silages were scanned using a total of 12 combinations of sample pre-treatments. Each sample preparation combination was subjected to three multivariate regression techniques to give a total of 36 predictions per biological trait. Increased sample preparations procedure, relative to scanning the unprocessed whole plant (WP) material, always resulted in a numerical minimisation of model statistics. However, the ability of each of the treatments to significantly minimise the model statistics differed. Particle comminution was the most important factor, oven-drying regime was intermediate, and residual moisture presence was the least important. Models to predict various biological parameters of maize silage will be improved if material is subjected to a high degree of particle comminution (i.e., having been passed through a 1mm screen) and developed on plant material previously dried at 60°C. The extra effort in terms of time and cost required to remove sample residual moisture cannot be justified.

The microbial fermentability, ruminal degradability and digestibility of 48 maize silages were determined using in vitro gas production (GP), in situ degradability and in vitro digestibility procedures. The silages were produced from forage maize harvested throughout the summer of 1998, and represent a wide range of physiological maturities. Large variations among samples were observed for all biological parameters, with the exception of in vitro digestibility and the asymptote of in vitro GP. The potential of near infrared reflectance spectroscopy (NIRS) to predict the biological parameters measured was determined by regression of the biological data against the respective spectral profile. NIRS demonstrated only a moderate ability (R2>0.60–0.80) to predict in vitro digestibility, modelled kinetics of gas production (excluding the asymptote of gas production) and the modelled ruminally soluble dry matter (DM) fraction. Calibration statistics for remaining biological parameters were unacceptably poor (R2=0.60).

The effects of rate of inorganic nitrogen (N) fertilization (0, 80 or 160 kg N ha(-1) per regrowth), season of harvest (regrowths 1, 2 and 3) and perennial ryegrass (Lolium perenne L.) cultivar [classified as having either a normal or elevated water soluble carbohydrate (WSC) concentration genotype] on in vitro gas production and digestibility were assessed. Increased N fertilizer application significantly decreased total gas production (TGP), methane (CH4) production and organic matter digestibility (OMD). The results suggest that the decreases in TGP and CH4 production were associated with a restriction in organic matter (OM) fermentation and an altered crude protein (CP) to structural carbohydrate ratio rather than a modification in the stoichiometry of fermentation. Season of harvest only significantly (P < 0.05) altered in vitro OMD and CH4 production at 8 h, despite altering the chemical composition of the herbage. Cultivar effects on all measured in vitro parameters were not significant presumably because the elevated WSC concentration trait was not expressed strongly in the study.

Maize silage consists of a starch and a fibrous fraction, both of which should be considered when assessing nutritive value. The in vitro evaluation of starch disappearance is laborious and costly. The near infrared reflectance spectroscopy (NIRS) technique requires limited sample preparation and is quick to operate once a calibration is established. This study investigated the potential of NIRS to predict maize starch disappearance in vitro.

The in vivo determination of methane (CH4) production requires specialist equipment which is costly to maintain. Whilst the in vitro gas production technique has been demonstrated to show potential to rank diets for their methanongenic potential at maintenance planes of nutrition (Moss and Givens, 1997) no study has investigated this relationship when feedstuffs are fed ad libitum. The objective of this study was to assess the ability of the technique to predict in vivo CH4 production and animal performance from six diets differing in their chemical composition.

Although methane production from enteric fermentation in ruminants has been studied for many years, it is only recently that research has focused on reducing methane production in order to reduce greenhouse gas emissions. Many new and novel strategies are being researched, but this paper focuses on mitigation strategies that could currently be implemented from the knowledge already available.

Intake, animal performance and methane (CH4) output was investigated using 36 finishing Charolais cross heifers (mean starting weight 462 kg, S.D.±16) fed ad libitum over an 11-week period. Six dietary treatments were investigated in a randomised block design experiment with a factorial arrangement of treatments. The six experimental diets consisted of three forage/concentrate (F/C) ratios (0.65:0.35, 0.40:0.60 and 0.10:0.90) supplemented with two levels of coconut oil (0 or 350 g/day). Rumen protozoa numbers were significantly (P<0.001) lower for diets containing coconut oil at the end of the trial. Reducing the F/C ratio resulted in significantly (P<0.001) increased rates of live weight gain (LWG) and carcass gain (CG), but coconut oil had no effect on animal performance. Methane output in litres per day was significantly modified (P<0.001) by both the F/C ratio and level of coconut oil. Maximal CH4 output was recorded on the 0.40:0.60 diet, with coconut oil reducing daily CH4 output regardless of the F/C ratio. Methane output per unit of animal product (per kg of LWG and carcass gain) was significantly reduced by lower F/C ratios and the dietary inclusion of coconut oil (P<0.001 and P≤0.003, respectively). No significant (P>0.05) interaction between the F/C ratio and coconut oil level was identified although coconut oil significantly reduced dry matter intake (DMI), CH4 l/day and LWG on the 0.65:0.35 F/C ratio diet.