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SummaryGrowth Performance and carcass quality of 132 steers originating from six beef breeds, Angus (AN), Simmental (SI), Charolais (CH), Limousin (LI), Blonde d'Aquitaine (BL), and Piedmontese (PI), fattened under the same conditions on the same diet, were compared at a target level of 3.5 % intramuscular fat (IMF) in the M. longissimus dorsi. This target level was set on basis ofthe results ofa preliminary study investigating, with 784 persons, the Visual preference of marbling using photographs. The total mix ration, provided at ad libitum access, consisted of maize silage, grass silage and concentrate (52 %, 26 % and 22 % of DM, resp.). Series 1 was performed in a tie-stall bam while a loose-housing system with straw bedding was used in series 2. The animals were assigned to slaughter either when the target IMF content was reached aecording to the estimation with a real-time ultrasound system applied in the live animals or when 15 months of fattening had passed. AN, SI, CH and LI reached 3.5 % IMF on average at final weights of 501 ± 43, 628 ± 60, 693 ± 117 and 668 ± 65 kg, respectively. BL and PI did not reach this target, although the average fattening period was about three times longer for BL and PI than for AN and the final weights were 758 ± 93 and 647 ± 64 kg, respectively. Under the conditions of this experimental approach, daily gains were highest in AN, followed by CH, SI, LI and BL and lowest in PI. The daily feed intake was significantly lower for PI than for CH, SI and AN. The AN expressed the best feed conversion efficiency in terms of DM expenditure per kg gain over the complete fattening period while this efficiency was lowest in the PI group followed by BL. Among the four breeds, which reached the target IMF content, LI steers showed the greatest proportion of premium cuts and the highest lean to fat and lean to bone ratio in the sirloin, followed, in descending order, by CH, SI and AN. However all four groups were graded around 4 in fatness score (high to very high). The present results revealed for all breeds the difficulty to reach the desired extent of marbling and at the same time favourable carcass conformation, carcass size (except AN) and fat cover which meet market demands.

were used (i) to evaluate the precision of the ultrasound-predicted intramuscular fat (USIMF) and its sources of variation using the current Pie QUIP technology and (ii) to develop improved models for predicting USIMF. Steers were slaughtered when they reached the target value of 3.5% USIMF. Hide samples were obtained 3 d before slaughter by shot-biopsy. After slaughter, a sample of the longissimus muscle was used to determine actual chemical intramuscular fat (EEIMF), collagen content and solubility. Among the variables available during a chute-side scanning session, hide thickness and ultrasound subcutaneous fat thickness at the 12th and 13th ribs were shown to be significantly correlated with EEIMF. These two variables were selected as possible independent variables to evaluate the construction of new models. The model with the best fit included USIMF, hide thickness and liveweight and had a standard error of prediction of 0.96%, which is similar to other published technologies. Breed group and collagen-related traits did not influence USIMF estimation. Finally, the revised Pie QUIP technology should be considered as one technology of choice to predict EEIMF content in live animals.

SummaryMeat quality of Angus (AN), Simmental (SI), Charolais (CH), Limousin (LI), Blonde d'Aquitaine (BL), and Piedmontese (PI) steers (n=22 per breed group) was measured in the M. longissimus dorsi (M.l.d.) and the M. biceps femoris, regio glutea (M.b.f.). Animals were fattened in two subsequent series on a forage-based diet until a target level of 3.5% intramuscular fat (IMF) was reached aecording to real-time ultrasound assessments in the live animals or until 15 months of fattening had passed. Series 1 was performed in a tie-stall barn while a loosehousing system with straw bedding was applied in series 2. The actually measured IMF contents in M.l.d. were 3. 35, 3.47, 3.49, 3.48, 2.34 and 2.40 % for AN, SI, CH, LI, BL and PI, respectively. Breed group differences in IMF content were mostly accompanied by a contrary Variation either in muscle water or protein content. Muscle cholesterol levels were similar for all breeds amounting to 47 and 51 mg/100 g on average in M.l.d. and M.b.f, respectively. Early and late postmortem muscle pH was relatively similar among breeds, but water-holding capacity, measured as losses due to drip, ageing, thawing and cooking, was unfavourably high in AN (drip loss excepted) in both muscles. Cooking loss tended to be lowest in PI, drip loss in SI. The AN showed the palest meat. In line with lightness, heme iron contents were clearly lowest in both muscles in the AN steers. There was no relationship found between IMF and shear force among breed groups. No significant differences between breed groups occurred in M.l.d. collagen solubility and shear force. Apart from breed differences, there were several differences noted between fattening series, namely clearly better water-holding capacity and lower shear force of the meat from series 2 (group housing) than from series 1 (tied System). The results indicate that in steers of similar IMF content and raised under the same feeding and management conditions, differences in most M.l.

This study evaluated the effect of heat-induced dehydration on urinary caffeine excretion after the consumption of a strong coffee solution. Following ingestion of coffee (caffeine 4.9+/-0.1 [SE] mg/kg, 3-4 cups), ten healthy males were intermittently exposed to heat in a sauna until they had lost 2.9 % of lean mass. On a separate occasion, they consumed the same amount of coffee but remained quiet and euhydrated (control). Urine flow was reduced 7-fold in dehydration. At these low excretion rates (< 30 ml/h), caffeine concentration was negatively correlated with flow. Peak urinary caffeine (Cmax) was 7.6 +/- 0.4 (SE) microg/ml in dehydration and 7.1 +/- 0.2 microg/ml in the control (p > 0.05). Compared with the control, dehydration delayed Cmax by 1 hour, maintained higher saliva caffeine concentration (6.1 vs 5.2 microg/ml, p < 0.05) and a lower saliva paraxanthine/caffeine ratio (p < 0.001). The 24h-recovery of caffeine in urine was reduced (1.2 vs 2.8% of dose, p < 0.001), however at least 2.6% of dose were lost in sweat. These results suggest that the rise in circulating caffeine due to delayed metabolic clearance was partly opposed by a sizeable elimination in sweat. Therefore, heat dehydration did not lead to higher concentration of caffeine in urine after coffee ingestion.

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