To identify new molecular markers of beef sensory quality, the transcriptomes of Longissimus thoracis muscle from 25 Charolais bull calves were analyzed using microarrays and compared between high and low meat quality groups; 215 genes were differentially expressed according to tenderness, juiciness, and/or flavor. Among these, 23 were up-regulated in the tenderest, juiciest, and tastiest meats, and 18 were highly correlated with both flavor and juiciness (e.g., PRKAG1), explaining up to 60% of their variability. Nine were down-regulated in the same meats, but only DNAJA1 [the results relating to DNAJA1 and its relationship with tenderness have been patented (Genomic marker for meat tenderness; Patent EP06300943.5, September 12, 2006)], which encodes a heat shock protein, showed a strong negative correlation with tenderness that alone explained 63% of its variability. This protein, known for its anti-apoptotic role, could be involved in meat aging. Thus, DNAJA1 could constitute a new marker of beef sensory quality.

Animals are subjected to various events that cause physical exhaustion and psychological stress during transfer to slaughter. This can lead to defective meat quality. Some animals may be better able to withstand the stress of transfer, depending on their previous experience of transport and on their finishing conditions (mixing, farmers' attitudes). The objective of this study was to assess the impact of 1) the conditions of transfer to slaughter (including duration of the journey, waiting time at lairage, etc.); and 2) the bulls' previous history (including experience in transport, mixing during finishing, and the farmers' attitudes) on the reactions of bulls to transfer and on their meat quality. We conducted a survey in commercial conditions. The history of the bulls and the facilities on the farms were noted; farmers were questioned on their attitudes; the bulls' reactions to loading into and unloading from the truck were observed; journey-related data were collected; and cortisol concentration at slaughter and the pH of the LM and the rectus abdominis were measured. Our study confirmed that certain physical factors associated with transport can increase stress and limit the decline of meat pH. These factors include the absence of loading facilities on the farm, transport on a warm day, or a short waiting time at lairage. Social aspects also played a role; the presence of bulls from the same finishing group limited stress and improved the pH decline. Events and management before transfer were also of importance; the farmer awareness of the sensitivity of bulls to humans or to feeding schedules but the absence of a positive attitude toward close contacts with bulls were all likely to limit stress or its consequences on meat pH. Although these results need to be confirmed in controlled experiments, they suggest that good management of beef bulls before and during transfer is essential to meat quality.

The purposes of this study were 1) to assess the effects of 3 high-concentrate diets on enteric CH(4) production, total tract digestibility, and rumen fermentation of beef cattle, and 2) to evaluate, by life cycle assessment, the potential effects of these feeding systems on the environment. Six bulls (age of 12.4 mo and BW of 417 kg at midexperiment) of the Blond d'Aquitaine breed were assigned to 3 dietary treatments in a replicated 3 × 3 Latin square design. Diets consisted of 1) 49% natural grassland hay, 41% ground corn grain, and 10% soybean meal (hay); 2) 63% corn silage, 21% ground corn grain, and 16% soybean meal (CS); and 3) 70% ground corn grain, 16% soybean meal, and 14% wheat straw (CG). Daily CH(4) emission (g/d), measured using the sulfur hexafluoride tracer technique, was similar for the hay and CS diets and was 56% greater than for the CG diet (P < 0.001). This difference between diets was maintained when CH(4) output was expressed by unit of feed intake (P < 0.001) or digested feed (P < 0.001). Gross energy intake loss as CH(4) averaged 6.9% for the hay and CS diets and 3.2% for the CG diet (P < 0.001). Organic matter intake and GE intake did not differ between diets. Organic matter digestibility was less for the hay diet than for the CS and CG diets (P=0.008). Digestibility of NDF was greatest for the hay diet, intermediate for the CS diet, and least for the CG diet (P=0.02), with ADF digestibility being similar between the hay and CS diets and greater than for the CG diet (P < 0.001). The rumen pH at 5 h postfeeding was less for animals fed the CG diet compared with those fed the other 2 diets (on average, 5.1 vs. 5.9, respectively; P < 0.001). Total CH(4) emission (enteric + manure) was least for the CG diet, whereas N(2)O and CO(2) emissions were greatest for the CG diet. Total greenhouse gas emissions were least for the CG diet when C sequestration by grasslands was not taken into account.

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