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Reducing daily methane production (DMP) via selection for lower estimated daily (pasture) feed intake (DFI) has the potential to be more cost effective than direct selection for DMP. Daily feed intake has a high heritability and high genetic correlation to DMP and has a potential lower cost of measurement. This study's main aim was to determine for a breeding nucleus the optimal proportion of randomly selected young male and female cattle in which to estimate DFI. This optimum proportion was determined by modeling the measurement costs and response to selection of Angus cattle on a (standard industry) Angus breeding index (ABI) augmented with DFI and DMP in a combined breeding objective (BO), but without DMP being measured. For the assumed herd structure and considering a 20 yr planning horizon, the highest net present value (NPV) occurred when 64% of males and no females were measured for DFI. The highest breakeven DFI test cost (A$41.51/head) and highest returns on investment (ROI) occurred when 36% of males and no females had DFI estimates. Higher ROI were achieved when all males had DFI estimates before any females had DFI estimates. There was a diminishing increase in rate of genetic gain when moving from 36% to 64% of males with DFI estimates, thus ROI decreased from 29.7% to 23.1%. When 36% of males had DFI estimates (and no females), herd DMP genetic gain was slightly positive as the DMP reduction per generation from male selection (-0.086) was more than offset by the DMP increase per generation from female selection (+0.110). The selection response for DMP only became negative when at least 40% of males had DFI estimates. Having 64% of males with DFI estimates resulted in a predicted genetic decrease in DMP (-0.018 kgCOe/head per yr), compared to an increase of 0.052 kgCOe/head per yr when no animals had DFI estimates. The optimum proportion of males with DFI estimates (36 to 64%) depends on the breeders attitude toward ROI and the value of genetic change for DMP. Sensitivity analysis showed that the economic value (EV), heritability and genetic variance of DFI had a higher impact on the NPV and ROI outcomes than parameters related to ABI and DMP, so future work should focus on obtaining robust estimates for DFI parameters. Higher EV for feed intake and DMP would result in higher percentages of animals being profitably measured for DFI, leading to larger reductions in DMP.

Methane yield values (MY; g methane/kg dry-matter intake) in beef cattle reported in the global literature (expanded MitiGate database of methane-mitigation studies) were analysed by cluster and meta-analyses. The Ward and k means cluster analyses included accounting for the categorical effects of methane measurement method, cattle breed type, country or region of study, age and sex of cattle, and proportion of grain in the diet and the standardised continuous variables of number of animals, liveweight and MY. After removal of data from outlier studies, meta-analyses were conducted on subsets of data to produce prediction equations for MY. Removing outliers with absolute studentised residual values of >1, followed by meta-analysis of data accounting for categorical effects, is recommended as a method for predicting MY. The large differences among some countries in MY values were significant but difficult to interpret. On the basis of the datasets available, a single, global MY or percentage of gross energy in feed converted to methane (Ym) value is not appropriate for use in Intergovernmental Panel on Climate Change (IPCC) greenhouse accounting methods around the world. Therefore, ideally country-specific MY values should be used in each country’s accounts (i.e. an IPCC Tier 2 or 3 approach) from data generated within that country.

Wool colour is not stable and it changes during storage. This study developed wool challenge methods by using a one-week water bath incubation at 40 o C or incubation overnight at a higher temperature to promote colour changes in wool. The study showed that the bacteria present in raw wool play a significant role in colour biodegradation during challenge (storage). A stable wool colour could be obtained for wool specification after a challenge treatment before colour measurement

The clean and ‘as-is’ colours of seven lots of Australian merino fleece wool and three lots of Australian merino skirtings were measured before processing and at various stages during scouring and ...

The changes in colour, after storage for a period of two years, of fifteen lots of merino and crossbred wool of varying types and appraised levels of discoloration are reported. The relationship between incubated colour and clean colour during the two-year period and the effects of storage on staple length and strength, resistance to compression, potassium content, and pH of water extraction were also examined. The effect of dumping method before storage (tripacks, single-dumped bales, and farm bales) on colour change was also assessed. Clean yellowness changed on average by +0.05 (Y − Z) unit per month (r2 = 0.18). This change varied significantly between lots, ranging from −0.01 to +0.11 unit per month. These changes were less than half the rate of change in greasy-colour (Y − Z), which suggests that the yellowness that developed in greasy merino wool, stored for two years at Sydney during 1990–92, was mainly scourable. The change in clean yellowness after two years appeared to be lower (−1.1 (Y − Z) un...

The objective of this study was to assess the impact of using different relative economic values (REVs) in selection indices on predicted financial and trait gains from selection of sires of cows and on the choice of leading Holstein bulls available in the UK dairy industry. Breeding objective traits were milk yield, fat yield, protein yield, lifespan, mastitis, non-return rate, calving interval and lameness. Relative importance of a trait, as estimated by a.h(2), was only moderately related to the rate of financial loss or total economic merit (ΔTEM) per percentage under- or overestimation of REV (r = 0.38 and 0.29, respectively) as a result of the variance-covariance structure of traits. The effects on TEM of under- or overestimating trait REVs were non-symmetrical. TEM was most sensitive to incorrect REVs for protein, fat, milk and lifespan and least sensitive to incorrect calving interval, lameness, non-return and mastitis REVs. A guide to deciding which dairy traits require the most rigorous analysis in the calculation of their REVs is given. Varying the REVs within a fairly wide range resulted in different bulls being selected by index and their differing predicted transmitting abilities would result in the herds moving in different directions in the long term (20 years). It is suggested that customized indices, where the farmer creates rankings of bulls tailored to their specific farm circumstances, can be worthwhile.

Nine lots of wools representing a wide range of types were selected in order to study changes in wool colour during storage. Core samples from each bale in the 9 lots were measured for clean colour both before and after incubation for one week at 40°C and 100% RH in a water bath. The colour of wools which were resistant to yellowing changed little from their original, non-incubated clean colour, while susceptible wools deteriorated to a more stable colour. Wools which were yellow before and after incubation had higher pH and potassium contents. The change in colour of clean wool following incubation was on average one third of the increase in colour after a greasy wool incubation. The clean colour of wools after incubation in the greasy state at 55°C for 16 hours was similar to the clean colour after a blank dyeing. Clean colour measurement after incubation could form the basis of a discoloration propensity test method for certification purposes.

Greenhouse gas emissions (GHG) from broadacre sheep farms constitute ~16% of Australia’s total livestock emissions. To study the diversity of Australian sheep farming enterprises a combination of modelling packages was used to calculate GHG emissions from three sheep enterprises (Merino ewe production for wool and meat, Merino-cross ewes with an emphasis on lamb production, and Merino wethers for fine wool production) at 28 sites across eight climate zones in southern Australia. GHG emissions per ha, per dry sheep equivalents and emissions intensity (EI) per tonne of clean wool or liveweight sold under different pasture management or animal breeding options (that had been previously determined in interviews with farmers) were assessed relative to baseline farms in each zone (‘Nil’ option). Increasing soil phosphorus fertility or sowing 40% of the farm area to lucerne resulted in the smallest and largest changes in GHG/dry sheep equivalents, respectively (–66%, 113%), though both of these options had little influence on EI for either clean wool or liveweight sold. Breeding ewes with greater body size or genotypes with higher fleece weight resulted in 11% and 9% reductions, respectively, in EI. Enterprises specialising in lamb production (crossbred ewes) had 89% lower EI than enterprises specialising in fine wool production (Merino wethers). Thus, sheep producers aiming for lower EI could focus more on liveweight turnoff than wool production. Emissions intensities were typically highest in cool temperate regions with high rainfall and lowest in semiarid and arid regions with low aboveground net primary productivity. Overall, animal breeding options reduced EI more than feedbase interventions.

Raw rumen liquor derived from sheep fed a wheat grain plus limestone diet was 2.5 times more toxic when injected into mice than liquor from sheep fed lucerne chaff. Liquors from transitional diets were of intermediate toxicity. Lactic acid was apparently not the toxic factor and relatively high molecular weight substances are implicated.