Despite only 4.3% of households using wood as the main form of heating in 2008, over half of annual PM2.5 emissions in Sydney came from domestic wood-heaters, which were also identified as a major contributor to secondary particle formation. With average firewood consumption of about 2 tonnes/year, the average brand new wood-heater emits about 20 kg PM2.5 and has estimated health costs (using the NEPC economic analysis estimate of $280/kg for PM2.5 emissions in Sydney) of $5,600 per year. The current AS4013 test bears little resemblance to real-life emissions because it measures laboratory emissions of a perfectly-operated wood-heater. Development of a real-life emissions test stalled in 2007 after the wood heating industry vetoed a recommendation to halve the emissions limit for new heaters as an interim measure while the new test was developed. The Standards Australia committee was put into abeyance for several years. Average real-life emissions of new wood-heaters are currently estimated at 9.8 g/kg, with only slight reductions to 8.2 and 7.0 g/kg for AS4013 test ratings below 2.5 and 1.5 g/kg respectively. In Launceston, education programs on the health effects of woodsmoke successfully reduced pollution and mortality. The main benefits were achieved by persuading families to switch to nonpolluting heating. Even after years of education on correct operation, AS4013- compliant heaters operated by highly-motivated volunteers averaged 9.4 g/kg, a highly unacceptable level of pollution. Woodsmoke was estimated to be an $8 billion health problem in NSW, but three simple measures: 1) not permitting the installation of new wood heaters (until a health-based emissions standard has been developed); 2) requiring existing heaters to be removed before houses are sold and 3) annual licence fees to fund education programs and assist neighbours whose health or lifestyle is adversely affected by a neighbour's smoke would save about $6 billion of the $8 billion health damages for minimal cost. Education programs could garner public support for such measures by explaining that the average new wood-heater emits more PM2.5 pollution per year than 1,000 passenger cars, that woodsmoke caused 16 (softwood) to 3 (hardwood) times more tumours in tests on mice than the same amount of cigarette smoke and that a typical evening burning 15 kg of wood puts out as much PM2.5 as in the smoke of 7,500 cigarettes. Contrary to popular belief, and despite its proximity to open-cut mines and the Bayeswater and Liddell power stations (which generate enough electricity for 3.25 million homes), the largest single source of PM2.5 in Muswellbrook (population 11,791) is domestic wood-heaters. Education could also focus on the fact that Australian woodheaters are estimated to emit 40,000 tonnes of PM2.5 compared to 10,000 tonnes for electricity generation and 7,400 tonnes for mining, that exposure to a daily average PM2.5 pollution of 25 μg/m³ was considered to be equivalent to actively smoking 3 cigarettes, that the UN Environment Program and the World Meteorological Association recommended phasing out log-burning heaters in developed countries to reduce global warming as well as improve health, and that the NSW Chief Medical Officer, Kerry Chant, said that wood-heaters are so detrimental to the health she supported banning and phasing out them out in builtup urban areas.

Domestic space heating in many cold regions of Australia is usually supplied by heaters running on solid wood, gas or electricity. All three fuel sources usually emit large quantities of greenhouse gases. Firewood collection for wood heaters has serious impacts on biodiversity. Wood heaters emit smoke and other gases which cause serious health problems. This research looked at pellet heaters as an alternative home heating option, to see if they could reduce wood smoke pollution, greenhouse gas emissions and biodiversity impacts, using the Northern Tablelands of NSW as a case study. The research looked at existing literature and conducted social surveys to find that pellet heaters are a suitable home heating option with lower emissions and lower impacts on biodiversity than other options. Pellet heaters will be slightly more expensive to purchase and operate, so options for providing incentives for their uptake were examined. There are public benefits from pellet heaters (public health, biodiversity and climate), and so there may be a case for policy intervention to encourage their uptake. Pellet supply was identified as a disincentive to the uptake of the heaters. The research found that there are suitable local sources of waste wood or silvicultural by-products to support pellet manufacture in the region. An efficient pellet plant would need to produce in the vicinity of 50,000 tonnes per year to be viable. Such a plant would over-supply the Northern Tablelands under the most optimistic scenario, so a market would need to be created for pellets outside the region.

There is increasing demand for technologies to measure CH4 production (DMP) of ruminant livestock in inventory and mitigation research. Studies of genetic variation among animals in DMP require these emissions to be measured on thousands of animals which cannot be managed using traditional chamber studies. However, short-term emission measures have been reported to correlate well with DMP. Our study was conducted to determine the usefulness of 1 and 2 h emission measures using chambers in predicting DMP. In our first experiment, Merino sheep (n = 13) were measured for DMP over 22 h using open circuit chambers. On two subsequent days, after overnight fasts, sheep were offered feed for 1 h before return to the chambers for 2 h and their CH4 production determined. DMP estimated from 22 h measurements correlated moderately well with 2 h emission measures (r² of 0.42-0.48) and 1 h measures (r² of 0.39-0.43). In our second experiment, portable static chambers were designed for 1 and 2 h CH4 emission measurements. The portable static chambers retained 98-99% of an injected tracer gas after 2 h showing that gas leakage from the chamber was very low. With a sheep inside a portable static chamber, CO₂ concentration reached 2.2 x 103 ppmv after 2 h, but sheep showed no discomfort and the partial pressure of O₂ in their blood remained above 97% (i.e., safe for animal health). Our third experiment was to validate use of short-term emission measures from portable static chambers as predictors of DMP. Crossbred Dorset and Border Leicester and Merino ewes (n = 40, LW 54 ± 10.9 kg) were measured for three 22 h sessions in open circuit chambers, after which they were measured for 1 h in portable static chambers. Open circuit chamber measurements had high repeatability (i.e., 0.88) and, excluding one sheep with inconsistent eating patterns, the correlation (r) between 1 h portable static chamber measurements and average emissions in the open circuit chambers was 0.71. We conclude that 1 and 2 h measures of CH4 output in portable static chambers are useful for determining genetic differences in CH4 production in groups of ruminants.

Heritability was estimated for a range of visually assessed traits recorded on Merino sheep, together with the phenotypic and genetic correlations among the visually assessed traits and correlations of the visually assessed traits with measured wool production traits and liveweight. Data were derived from four research resource flocks, with a range of 12 958 to 57 128 records from animals with 478 to 1491 sires for the various traits. The estimates of heritability were high for the wool quality traits of handle, wool character and wool colour (0.33–0.34) and the conformation traits of face cover, neck wrinkle and body wrinkle (0.42–0.45), moderate for front leg structure (0.18) and low for back leg structure (0.13). Fleece rot score had low heritability (0.14), while classer grade was moderately heritable (0.20). Estimates of genetic correlations among the visually assessed wool quality traits were low to moderate in size and positive (0.17–0.47). Genetic correlation estimates among the assessed conformation traits were generally very low, except for the genetic correlations between scores for neck and body wrinkle (0.92±0.01) and front and back leg structure (0.31±0.09). Fleece rot score had low positive genetic correlations with neck and body wrinkle scores (0.18±0.05 and 0.15±0.05, respectively) and classer grade (0.26±0.06). Classer grade was slightly positively correlated with the wool quality traits (0.17–0.45) and leg structure traits (0.21–0.25). The genetic correlations among the visually assessed traits were generally neutral to favourable. The visually assessed wool quality traits had low to moderate favourable genetic correlations with mean and coefficient of variation of fibre diameter (0.19 –0.47), but negative correlations with clean wool yield (–0.26 to –0.37). Face cover was unfavourably correlated with staple length (–0.27±0.04) and liveweight (–0.23±0.02). Neck and body wrinkle scores were genetically associated with higher greasy (0.33–0.39) and clean fleece weights (0.19–0.22), greater coefficient of variation of fibre diameter (0.24–0.26) and fibre curvature (0.27–0.28), but with reduced yield (–0.26 to –0.28) and staple length (–0.34 to –0.41). Fleece rot score was genetically correlated with clean fleece weight (0.26±0.05) and coefficient of variation of fibre diameter (0.27±0.04). Classer grade was favourably correlated with greasy and clean fleece weights (–0.41 to –0.43), staple length (–0.29±0.04), liveweight (–0.36±0.03) and coefficient of variation of fibre diameter (0.27±0.03). Most genetic correlations between the visually assessed traits and the measured production traits and liveweight were close to zero and less than 0.2 in magnitude. This study provides accurate values for the parameter matrix required to incorporate visually assessed traits into breeding objectives and the genetic evaluation programs used in the Australian sheep industry, allowing the development of breeding objectives and indexes that optimally combine visually assessed performance and measured production in Merino sheep.

To assess the potential for genetic improvement to help meet the increasing demand for high-yielding beef carcasses, the heritability of muscle score (MS) plus genetic and phenotypic correlations with weight and fatness traits were estimated on 1856 yearlings and 2596 weaners born from 1992 to 2012 in a predominantly Angus herd divergently selected for High/Low MS. In 2005, after noting that some cattle were positive for the 821_del11 myostatin mutation that causes muscle hypertrophy, procedures were modified to create a third group (HighHet) of High animals with one copy of this major gene. This allowed the additive genetic effects of MS to be assessed, and also the effect of the 821_del11 mutation. MS traits were found to be highly heritable ('h'² = 56-63%), with an extremely high estimated genetic correlation of 99% between weaning and yearling MS. Estimated genetic correlations of MS with rib eye muscle area (EMA) in weaners and yearlings adjusted for either age or weight were 53-56%. Genetic correlations of MS with other traits were relatively low: liveweight (yearlings 5%, weaners 20%), rump fat (yearlings -7%, weaners 11%), rib fat (yearlings -17%, weaners -3%). Apart from weaning liveweight, the estimated genetic correlations were not significantly different from zero. MS had smaller estimated genetic correlations with fatness and weight traits than EMA adjusted for age. For yearlings and weaners born from 2010 to 2012, large significant differences were evident in MS of High and Low calves (4.5-point difference for yearlings; 3.4 points for weaners, on a 15-point scale) and significant differences in EMA (yearlings 2.5, weaners 1.5 cm²). In addition, the 821_del11 mutation reduced fatness, increased MS by 1.5-1.9 points and increased EMA by 2.8-3.6 cm². With high heritability, low correlations with weight and fatness in weaners/yearlings, plus other research (Cafe et al. 2012, 2014a) showing no detrimental effect on maternal productivity or meat quality, but improvements in dressing percent, retail meat yield, meat : bone ratio and feedlot feed efficiency, the development of an estimated breeding value for MS could help improve the efficiency and profitability of beef production.

Nitrate supplementation has been shown to be effective in reducing enteric methane emission from ruminants, but there have been few large-scale studies assessing the effects of level of nitrate supplementation on feed intake, animal growth, or carcass and meat quality attributes of beef cattle. A feedlot study was conducted to assess the effects of supplementing 0.25 or 0.45% NPN in dietary DM as either urea (Ur) or calcium nitrate (CaN) on DMI, ADG, G:F, and carcass attributes of feedlot steers (n = 383). The levels of NPN inclusion were selected as those at which nitrate has previously achieved measurable mitigation of enteric methane. The higher level of NPN inclusion reduced ADG as did replacement of Ur with CaN (P < 0.01). A combined analysis of DMI for 139 steers with individual animal intake data and pen-average intakes for 244 bunk-fed steers showed a significant interaction between NPN source and level (P = 0.02) with steers on the high-CaN diet eating less than those on the other 3 diets (P < 0.001). Neither level nor NPN source significantly affected cattle G:F. There was a tendency (P = 0.05) for nitrate-supplemented cattle to have a slower rate of eating (g DMI/min) than Ur-supplemented cattle. When adjusted for BW, neither NPN source nor inclusion level affected cross-sectional area of the LM or fatness measured on the live animal. Similarly, there were no significant main effects of treatments on dressing percentage or fat depth or muscling attributes of the carcass after adjustment for HCW (P > 0.05). Analysis of composited meat samples showed no detectable nitrates or nitrosamines in raw or cooked meat, and the level of nitrate detected in meat from nitrate-supplemented cattle was no higher than for Ur-fed cattle (P > 0.05). We conclude that increasing NPN inclusion from 0.25 to 0.45% NPN in dietary DM and replacing Ur with CaN decreased ADG in feedlot cattle without improving G:F.

Associations between temperament, stress physiology, and productivity were studied in yearling Brahman steers (n = 81). Steers differed in calpain system gene marker status; 41 were implanted with a hormonal growth promotant at feedlot entry. Temperament was assessed with repeated measurements of flight speed (FS) and crush score (CS) during 6 mo of backgrounding at pasture and 117 d of grain finishing. Adrenal responsiveness was assessed with ACTH challenge, with plasma samples collected immediately before and 60 min after challenge. Steers with higher FS and CS had higher prechallenge plasma cortisol, glucose, lactate, and nonesterified fatty acid concentrations. The ACTH-induced cortisol response was unrelated to FS or CS, but glucose remained higher after challenge in flightier steers. The hormonal growth promotant reduced adrenal responsiveness; tenderness genotype had no effect. When temperament assessments and cortisol concentrations before and after challenge were combined in a principal components analysis, four vectors accounting for 38%, 25%, 18%, and 9% of the variation were identified. The first vector had significant loadings on temperament and prechallenge cortisol; increasing scores were associated with increased plasma glucose, lactate, and nonesterified fatty acid and with reductions in BW and feedlot growth rates, carcass fatness, and muscle pH. The second vector loaded only on ACTH-induced cortisol response; increased scores related to increased residual feed intake, number of daily feed sessions, and meat marbling score. The third and fourth vectors had different loadings on FS and CS and appeared to identify different aspects of temperament measured by FS or CS. Fewer associations were found between the third or fourth vectors and productivity traits, possibly because of lower variance accounted for by these vectors. In conclusion, temperament was related to prechallenge cortisol but not to ACTH-induced cortisol response. Principal components analysis separated these traits into separate components, which in turn had different relations with productivity traits. The largest component of temperament was described similarly by FS and CS, but there were smaller components that these described differently. There were some temperament-related differences in the metabolic status of the steers which were not related to the variation in cortisol, suggesting involvement of the sympatho-adrenal-medullary axis in these temperament-related effects.

Feed intake (FI), weight gain (WG), metabolic weight (MW), feed conversion ratio (FCR), residual feed intake calculated by regression (RFI) and feeding standards formulae (RFIS) were recorded on 1481 steers and heifers of tropically adapted and temperate breeds of cattle feedlot finished on a grain based diet for the domestic (liveweight 400 kg), Korean (520 kg) or Japanese (steers only; 600 kg liveweight) markets. Also measured were subcutaneous fat at the rump (P8) and 12/13 rib sites, 12/13 rib eye muscle area and intra-muscular fat (IMF%), time spent eating, eating rate and number of meals per day. Estimated heritabilities of FI, MW, WG, FCR, RFI and RFIS were 0.27, 0.41, 0.23, 0.06, 0.18 and 0.13. RFI and RFIS had very high genetic (0.98) and phenotypic (0.94) correlations, suggesting that they represent very similar traits. RFI had relatively high genetic correlations with rump and rib fat (0.72 and 0.48 adjusted for age; 0.79 and 0.58 adjusted for carcase weight), but lower correlations with IMF% (0.22 and 0.25 adjusted for age and carcase weight, respectively). Selection for lower RFI is therefore possible in feedlot finished cattle, but fatness will also decrease. In this study, selection for reduced fatness was predicted to reduce RFI by more than direct selection. When appropriate, multivariate selection is therefore recommended to achieve increased feed efficiency together with the desired level of fatness, using an index including RFI, on-test weight gain and fat measurements. There were large breed differences for number of meals per day; Brahman cattle ate more frequently than Belmont Red and Santa Gertrudis breeds which ate more often than temperate breed cattle. Within breeds, there was a tendency for more efficient animals to have fewer meals per day.

Estimates of regression coefficients are biased if the independent (or x) variables contain errors (for example, measurement errors). Equations are derived for the amount of bias in bivariate regression where one independent variable contains significant error, but errors in the other are negligible. Results are tabulated for differing amounts of error and a range of correlations (from 0.1 to 0.9) between the two independent variables. The process of estimating residual feed intake (RFI) is used to illustrate biases present in real-life data. RFI is defined as the amount of feed eaten by an animal less what would be expected from the animal's metabolic weight and weight gain. Measurement errors of metabolic weight, especially if calculated from the mean of several weighings, are relatively small. In contrast, errors in weight gain may be substantial. Regression coefficients from fitting the RFI equation using two different estimates of weight gain are compared with equations derived from genotypic regression and feed standards tables. The unadjusted coefficients differ substantially, but are shown to be much more consistent after adjusting for bias using equations derived in this paper.