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Relationships between temperament and a range of performance, carcass, and meat quality traits in young cattle were studied in 2 experiments conducted in New South Wales (NSW) and Western Australia (WA), Australia. In both experiments, growth rates of cattle were assessed during backgrounding on pasture and grain finishing in a feedlot. Carcass and objective meat quality characteristics were measured after slaughter. Feed intake and efficiency during grain finishing were also determined in NSW. Brahman (n = 82 steers and 82 heifers) and Angus (n = 25 steers and 24 heifers) cattle were used in the NSW experiment. In NSW, temperament was assessed by measuring flight speed [FS, m/s on exit from the chute (crush)] on 14 occasions, and by assessing agitation score during confinement in the crush (CS; 1 = calm to 5 = highly agitated) on 17 occasions over the course of the experiment. Brahman (n = 173) and Angus (n = 20) steers were used in the WA experiment. In WA, temperament was assessed by measuring FS on 2 occasions during backgrounding and on 2 occasions during grain feeding. At both sites, a hormonal growth promotant (Revalor-H, Virbac, Milperra, New South Wales, Australia) was applied to one-half of the cattle at feedlot entry, and the Brahman cattle were polymorphic for 2 calpain-system markers for beef tenderness. Temperament was not related (most P > 0.05) to tenderness gene marker status in Brahman cattle and was not (all P > 0.26) modified by the growth promotant treatment in either breed. The Brahman cattle had greater individual variation in, and greater correlations within and between, repeated assessments of FS and CS than did the Angus cattle. Correlations for repeated measures of FS were greater than for repeated assessments of CS, and the strength of correlations for both declined over time. Average FS or CS for each experiment and location (NSW or WA × backgrounding or finishing) were more highly correlated than individual measurements, indicating that the average values were a more reliable assessment of cattle temperament than any single measure. In Brahman cattle, increased average FS and CS were associated with significant (P < 0.05) reductions in backgrounding and feedlot growth rates, feed intake and time spent eating, carcass weight, and objective measures of meat quality. In Angus cattle, the associations between temperament and growth rates, feed intake, and carcass traits were weaker than in Brahmans, although the strength of relationships with meat quality were similar.

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The establishment and evaluation of an assessment system to accredit sonographers for measuring the carcass traits of subcutaneous fat depths and longissimus muscle area (LMA) on potential breeding animals by real-time ultrasound is described. Repeatability of operators, variation between the animal's left and right sides, and variations in technique were assessed from measurements and repeat measurements of 30 cattle by up to eight operators at three testing sessions. Accuracy of carcass data was determined by repeatability of measurements, variability between measurers, between left and right sides of the carcass, and variation due to handling and dressing procedures. Correlations with carcass data averaged .92 for rump fat, .90 for rib fat, and .87 for LMA. Residual SD averaged .81 mm, .88 mm, and 5.1 cm2. A very experienced sonographer can measure LMA only marginally less accurately than it can be measured on the carcass. In Session 3, the SE between repeat fat measurements for accredited sonographers averaged .43 mm, indicating that fat depths can be measured more accurately, but when comparing measurements from different operators, adjustments may be required for differences in technique, otherwise overall accuracy will be about the same, approximately 1 mm. Scanned rump fat measurements were consistently approximately 20% higher than on the chilled, hanging carcass 24 h after slaughter; after applying the standard correction factor of 1.17, LMA measurements were similar. Scan and carcass rib fat measurements were similar for animals with less than or equal to 10 mm of fat cover, above which carcass measurements tended to be higher.

Methods of estimating components of variance are described and compared. The method of residual maximum likelihood (REML) is used to illustrate some of the many uses of variance components. Particular attention is paid to the analysis of unbalanced data, including recovery of inter‐block information and efficient combination of results from several trials, or series of trials. A powerful and easy‐to‐use computer program, REML, is available for use on most modern minicomputers.

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As with overseas data, the exponential growth rule fits Australian data well. If cycling doubles, the risk per kilometre falls by about 34%; conversely, if cycling halves, the risk per kilometre will be about 52% higher. Policies that adversely influence the amount of cycling (for example, compulsory helmet legislation) should be reviewed.