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The aim of this work was to improve the knowledge on young suckled Salers bull production and to study the effect of forage type and concentrate level on performance, carcass and muscle characteristics as well as on meat quality. Twenty-four Salers male calves of 150 days of age were assigned to six groups: C0 (fed exclusively with hay and dam’s milk and slaughtered at approximately 6 months of age), and HH (hay – high concentrate), HL (hay – low concentrate), GH (cut grass – high concentrate), GL (cut grass – low concentrate) and CP (control pasture: pasture – high concentrate) groups differing in feeds received until slaughter and slaughtered unweaned at approximately 10 months of age. Carcass weights averaged 210 kg at 10 months of age at slaughter. Average daily weight gain (ADWG) in HH and GH groups tended to be higher (P = 0.09) than in HL and GL groups (1354 v. 1248 g/day). ADWG in CP group (1542 g/day) was higher (P < 0.05) than in the other groups. Carcass weight in CP group (230 kg) tended to be higher (P < 0.1) than in HL (198 kg) and GL (200 kg) groups. Carcass muscle weight was higher (P < 0.05) in GH (155 kg) and CP groups (165 kg) than in HL (141 kg) and GL (142 kg) groups. Carcass and offal fatty tissue weights and carcass fatness did not differ between groups. Neither forage type nor concentrate level had significant effect on the area of muscle fibres or on muscle metabolic enzyme activities (namely, lactate dehydrogenase – LDH, phosphofructokinase – PFK, isocitrate dehydrogenase – ICDH, citrate synthase – CS and cytochrome-c oxidase – COX). semitendinosus muscle of CP group presented higher CS enzyme activities (8.10 μmol/min per g) than HH (5.30 μmol/min per g) and GL (4.52 μmol/min per g) groups. Neither total nor insoluble collagen content significantly differed between groups. Lipid content in rectus abdominis muscle was relatively low (average 67.5 mg/g dry matter) and was not affected by diet (P > 0.05). The ratio between n-6 and n-3 polyunsaturated fatty acid content was lower (P = 0.01) in the low-concentrate-fed than in the high-concentrate-fed group (3.95 v. 5.37, respectively). Sensory analysis noted that longissimus thoracis muscle from CP animals was more tender and juicy than that from HH and GH animals (P < 0.05).

International audience; Thirty fattened one humped desert camels were used to examine the effect of season on contractile and metabolic properties of Longissimus thoracis (LT) muscle. Ten camels were slaughtered according to seasons of the year (winter, summer and autumn). Season significantly influenced muscle chemical composition, ultimate pH (pHu) and color. Activities of metabolic enzymes were higher during autumn season compared to summer and winter for phosphofructokinase (+64% compared to both seasons) and for isocitrate dehydrogenase (+35% and +145% in autumn vs. summer and winter, respectively). Quantification of muscle myosin heavy chain isoforms by SDS-PAGE electrophoresis showed only presence of type I and type IIa MyHC in camel muscle and indicated high proportion in winter for type I and in autumn for type IIa with respect to other seasons. Several correlations between different MyHC proportions and enzyme activities were reported. These findings indicated that muscle characteristics in camels are influenced by season.

Twenty-three Charolais steers, slaughtered at 31 months of age and an average live weight of either 674 kg (light group; n =13) or 751 kg (heavy group; n =10) were used to determine the effect of increasing weight at slaughter by genetic selection on meat quality traits. Steers were born to pure-bred Charolais cows from an INRA experimental herd, reared and finished under the same breeding practices. The quality of meat from the M. rectus abdominis excised 24 h postmortem was scored after 14 days ageing between 0 and 10 by sensory analysis using four descriptors: global assessment, initial tenderness, overall tenderness, juiciness and flavor intensity. Shear force measurements were evaluated on raw and broiled meat after 14 days of ageing. The pH, collagen and lipid contents, the collagen solubility, isocitrate dehydrogenase (ICDH), lactate dehydrogenase and cytochrome- c oxidase activities and the proportion of myosin heavy chain isoforms were measured 24 h post-slaughter. The heavy group was characterized by a significantly higher empty live weight (683 vs 614 kg) and carcass weight (before removing external fat: 469 vs 408 kg; after removing external fat: 463 vs 403 kg) at slaughter than the light one but an equivalent fatness score (2.74 on 5). Scores of heavy steer M. rectus abdominis were significantly higher for descriptors of initial tenderness (6.95 vs 6.31) and overall tenderness (6.79 vs 6.22) although the intramuscular fat content was equivalent for light and heavy group samples (16.6% of dry matter on average). Global assessment and flavor intensity were also slightly in favor of heavy group samples (6.49 vs 5.85 and 6.48 vs 6.07), but no differences were found between the two groups in meat juiciness (6.10 on average). Shear force on raw and broiled meat was not significantly different between groups (5.13 and 6.98 daN on average). No significant differences were found between groups on total and soluble collagen contents ( p =0.32 and p =0.49 respectively). The heavy group was associated with a more glycolytic metabolism (LDH enzyme: 620 vs 528 μmol/min/g; p =0.03) and a higher myosin heavy chain IIx proportion (39.1% vs 32.3%; p =0.07) without any modification in oxidative enzyme activities (ICDH and COX; p =0.49 and 0.84).

International audience; Thirty-eight Charolais steers castrated at 2 or 10 months of age were used to study the effect of age at castration on animal performance, muscle characteristics and meat quality traits in two consecutive trials. Steers, were reared at pasture during the summer and at barn with high quality hay during the winter. The slaughter occurred at 26 months of age and 402 kg of carcass weight. ne quality of meat from M. rectus abdominis (RA) and M. triceps brachii (TB) after 14 days of ageing was evaluated by sensory analysis using three descriptors: tenderness, juiciness and flavour. The physicochemical characteristics, such as collagen amount and solubility, intramuscular fat content, p-calpain and 27 K proteasome sub-unit contents, myosin heavy chain isoform (1, Ila and fix) proportions, metabolic enzyme activities (isocitrate and lactate dehydrogenase, cytochrome-c oxydase), fibre area and type (SO, FOG and FG), were also measured. No significant differences in live weights and average daily gains appeared according to castration age. Between birth and weaning, steers castrated at 10 months had a higher weight gain (1056 vs 10 12 g/d), whereas this tendency was reversed after castration. The weight gain of 10-month castrated steers decreased between 10 and 14 months (668 vs 746 g/d) and between 14 and 20 months (918 vs 974 g/d) than the weight gain of 2-month castrated steers. FOG fibres of 10-month castrated steers had a larger area in M. rectus abdominis (3801 vs 2983 mu m 2), whereas the other fibres areas were not affected by castration age. The proportions of FOG fibres in 10-month castrated steers were higher (8.5 vs 8.1 and 22.2 vs 16.7% respectively for RA and TB muscles) whereas the FG fibres proportions were lower (52.2 vs 55.8 and 50.1 vs 54.9% respectively for RA and TB muscles). Castration age had no impact on myosin heavy chain proportions. The oxidative and glycolytic metabolisms were also not affected by castration age. The intramuscular fat content was not modified by castration age. Delaying castration age led to an increase in collagen content (p=0.04) with no impact on collagen solubility (p=0.73). The mu-calpain and the 27 K proteasome sub-unit contents were significantly lower for 10-month castrated steers than for 2-month castrated ones (75 vs 96% and 76 vs 95% respectively). Meat quality traits of tenderness, juiciness and flavour were equivalent for the two groups of steers in the two muscles. (c) 2008 Elsevier B.V. All rights reserved.

International audience; A total of 436 young bulls from fifteen Western European breeds, including beef, dairy and local types from five countries, were studied to assess variability in live weight, live weight gain, body measurements and carcass traits. Animals were logged indoors, and fed a diet based on concentrate and straw offered ad libitum from 9 months of age to slaughter at 15 months of age. The weight, body length, height at withers and pelvis width, of the animals were recorded at 9, 12 and 15 months of age. After slaughter, 15 carcass variables were recorded, including carcass weight, EU classification scores, morphological measurements and dissection data. Data were analysed by GLM, regression and principal component analysis procedures. Significant differences were found between breeds for all variables studied, however, the body size measurements and the carcass traits were more useful to discriminate among cattle breeds, than either live weight or daily gain. With respect to the body size and carcass traits the studied breeds could be grouped as: Specialized beef breeds, comprising Piemontese, Asturiana de los Valles, Pirenaica, Limousin, South Devon, Charolais and Aberdeen Angus, all of which were characterized by high muscularity, wide pelvis and medium height and a low to medium level of fatness. Local and dairy breeds, comprising Jersey, Casina, Highland, Holstein and Danish Red, the latter two breeds were tall animals, while the former three breeds were small in size. In general the group was poorly muscled and tended to have a high or medium level of fat. Intermediate group, Avilena, Marchigiana and Simmental: these breeds were characterized by an intermediate muscle conformation and fatness level and were relatively tall. This study provides a detailed assessment or a wide range of variables in the major breeds, and several minor breeds, that are used in breeding programmes across Europe and elsewhere, and will provide information that will be of use to define breeding strategies to meet the demands of the European beef market. (c) 2007 Elsevier B.V. All rights reserved.

The objectives of the two experiments were to determine the respective effects and interactions of diet type (grass v. maize diets) and physical activity (grazing v. zero grazing) on lipogenic enzyme activities and adipose cell size in subcutaneous, perirenal and intermuscular adipose tissues and on plasma metabolites and hormones in Charolais steers. After weaning, the steers were assigned to two (Experiment 1, n = 24) or three (Experiment 2, n = 24) groups, with steers in Experiment 1 grazed grass or indoors maize-silage-fed and steers in Experiment 2 grazed grass, indoors cut grass- or indoors maize-silage-fed. Both experiments lasted for 23 months. All grass-fed animals were fed grass silage during the two winter seasons. During the two summer seasons, steers fed on grass were rotationally grazed on a perennial rye-grass pasture while steers fed on cut grass were fed indoors on freshly cut grass alone. Steers fed on maize silage were fed maize silage indoors during the entire experiment. All animals were reared for similar body weight and growth rates and slaughtered at the same age (31 to 32 months). Activities of lipogenic enzymes were significantly lower in the three adipose tissue sites of steers fed cut grass compared with maize silage, although there were less-marked effects in intermuscular adipose tissue. Plasma insulin and glucose concentrations were also lower in steers fed cut grass whereas plasma leptin concentration was similar. As body fat content was not affected by nutritional treatment, it is suggested that the decrease in potential lipogenic activity was associated with the nature of the diet and not to differences in available net energy. In other respects, grazed grass compared with eating cut grass did not affect lipogenic enzyme activities but decreased plasma leptin concentrations in the older steers and increased plasma non-esterified fatty acids and glucose concentrations without affecting adipose tissue weight and adipose cell size.

The effects of age and breed on carcass and muscle characteristics of cull cows slaughtered at the same fattening state between 4 and 9 years of age were analysed in four French breeds: Aubrac (AU), Charolais (CH), Limousin (LI), and Salers (SA). Muscle characteristics were determined in three muscles: longissimus thoracis (LT), semitendinosus (ST) and triceps brachii (TB). They included: (1) the % frequency, cross-sectional area and % area of the different fibre types classified according to their contraction rate and metabolic properties (slow twitch oxidative (SO), fast twitch oxidative glycolytic (FOG) and fast twitch glycolytic (FG)), (2) the isocitrate dehydrogenase (ICDH) and lactate dehydrogenase (LDH) activities, representative of oxidative and glycolytic metabolism respectively, and (3) the total and insoluble collagen contents. Whatever the age of the animals at slaughter, the same carcass composition, fibre characteristics (% frequency, area, % area) and metabolic enzyme activities were obtained whatever the muscles considered. In contrast, important differences between breeds were observed in carcass composition (muscle, fat, bone) and enzyme activities. CH cows presented the highest final live weight and LI carcasses were characterized by higher muscle weight, lower fat and bone weights and more glycolytic muscles. Among the muscle characteristics, collagen was the most influenced by age and breed in a breed and muscle dependent manner respectively. AU and LI cows exhibited lower total and insoluble collagen contents than CH and SA cows, particularly at 6 to 7 years of age and for the LT and ST muscles. Thus collagen could explain an important part of the variability in meat quality from cull cows. In conclusion, results of this study provide consistent data on muscle characteristics of cull cows, few studies were available until then.

The effects of age and breed on growth parameters, carcass and muscle characteristics of bulls, slaughtered at 15, 19 and 24 months of age, were analysed in four French breeds: Aubrac (AU), Charolais (CH), Limousin (LI), and Salers (SA). Muscle characteristics were determined in three muscles: longissimus thoracis (LT), semitendinosus (ST) and triceps brachii (TB). They included: (1) the % frequency, cross-sectional area and % area of fibre types, which were classified according to the contractile nature of the fibres and their metabolic properties (SO slow oxidative, FOG fast oxidative glycolytic and FG fast glycolytic); (2) the isocitrate dehydrogenase (ICDH) and lactate dehydrogenase (LDH) activities, representative of oxidative and glycolytic metabolism respectively; and (3) the total and insoluble collagen contents.In the four breeds, the average daily gain and the food efficiency decreased with age (P < 0·001). The carcass characteristics (muscle, fat and bone weights) increased with age (P < 0·001). The increase of muscle carcass weight with slaughter age was in parallel with the increase in cross-sectional area of individual muscle fibres. Oxidative fibre (SO and FOG) areas increased more between 15 and 24 months than glycolytic fibre (FG) area. Differences between muscles in increases in areas of muscle fibres were consistent: the increase was greater for TB than ST and LT. The muscles studied became more slow and more oxidative above 19 months of age, as evidenced by the fact that the SO % frequency (P < 0·001) and % area (P < 0·001) and ICDH activity (P < 0·05) increased, and LDH activity decreased (P < 0·01). Insoluble collagen content decreased between 15 and 19 months (P < 0·001), and both total (P < 0·01) and insoluble (P < 0·001) collagen contents increased from 19 months.So carcass characteristics were modified between 15 and 24 months, and muscle characteristics were especially modified from 19 months of age. In addition, differences in slaughter data between breeds were clear and consistent, whereas those of muscle characteristics were few and not consistent.

Deux lots de genisses Salers conduites en croissance continue (lot CG, n = 9 ) ou discontinue (DG, n = 14) ont ete compares pendant deux annees de croissance post-sevrage. Pendant toute l'experience, les animaux etaient alimentes a volonte. Les ecarts hivernaux de croissance etaient dus a la distribution de foins de qualite distincte. En ete, les genisses restaient a l'etable et recevaient un foin identique de bonne qualite. Les evolutions de la composition corporelle et des caracteristiques musculaires (type et surface des fibres, collagene) susceptibles d'influer sur la qualite de la viande, ont ete estimees apres des abattages en serie. Ce schema experimental a permis de simuler deux types de milieu nutritionnel (pauvre et riche) et d'en etudier l'impact sur l'ingestion, la croissance, la composition corporelle et les caracteristiques musculaires des animaux. Le lot DG a systematiquement realise une croissance compensatrice estivale, bien qu'incomplete, par rapport au lot CG. Du fait d'un abattage final a meme poids vif, environ 700 kg, les animaux DG ont ete abattus en moyenne 56 jours plus tard que les genisses CG. Les differences de gains de poids moyens valent toujours environ 300 g.j - 1 , en faveur respectivement de CG en hiver et de DG en ete. La compensation etait due a une ingestion accrue en ete (entre +6 et +7 %) et a une tendance pour une meilleure efficacite de la croissance des animaux DG. Aucune difference notable de composition corporelle n'a ete observee entre lots apres l'abattage final. Le poids des carcasses etait alors legerement inferieur a 400 kg et celui des tissus adipeux totaux atteignait environ 130 kg (21,5 % du poids vif vide). Le type de croissance n'a pas non plus influe sur les caracteristiques musculaires finales. En conclusion, l'itineraire de croissance de l'animal peut varier en fonction de la disponibilite alimentaire, sans modifier les caracteristiques des carcasses finies a poids constant.

Leptin is an important hormone for the control of food intake and body weight homeostasis in human and rodents. In ruminants, plasma leptin is positively related to body fatness and energy balance or feeding level (Chilliard et al., 2001) and linked to meat quality determinants such as marbling score (Minton et al., 1998). To our knowledge, no information is available on the effects of the nature of dietary forage on this parameter. The objective of the current work was to examine the effects of replacing maize silage with grass on plasma leptin as well as on the activities of five lipogenic enzymes in perirenal and inter-muscular adipose tissues (AT).

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An experiment was conducted with 42 Montbéliard steers to determine if nutritionally induced interrupted growth could influence muscle characteristics of steers and hence meat quality. A restriction/refeeding path was designed in order to induce a discontinuous growth path. At 9 months of age, 21 steers were given a restricted amount of diet for 3 months and were then slaughtered (R steers; no. = 10; intake: 5·28 kg dry matter (DM) per day) or subjected to a 4-month ad libitum refeeding period (R/F steers; no. = 11; intake: 8·99 kg DM per day) with the same diet (11·03 to 11·12 MJ metabolizable energy (ME) per kg DM) prior to slaughter. An additional 21 control steers were offered the same diet but in amounts that allowed them to gain continuously between 9 and 12 months of age, and were then slaughtered (C steers; no. = 10; intake: 7·08 kg DM per day) or maintained on a continuous feeding protocol through to 16 months of age prior to slaughter (C/C steers; no. = 11; intake: 8·07 kg DM per day). M. semitendinosus (ST), m. longisssimus thoracis and m. triceps brachii (TB) were collected for biochemical and histochemical analyses. R steers had a lower average daily gain (ADG; P 0·001), a lower final weight (P 0·01) and a leaner carcass (P 0·01) than C steers. Upon refeeding, R/F steers had a higher ADG than C/C steers (P 0·05) and underwent compensatory growth resulting in compensation of body weight and composition at 16 months. In muscles, glycolytic lactate dehydrogenase activity was lower in R steers (P 0·01) and restored in R/F steers compared with control steers. Among oxidative enzymes, cytochrome-c oxidase activity was higher in the TB of R/F compared with C/C steers (P 0·001) indicating a muscle-specific metabolic adaptation to the feeding level. There was little effect of the nutritional treatment on muscle fibre size and type except for an increase in the frequency of hybrid fibres in R and R/F groups (P 0·05). Total and insoluble collagen content were affected by restriction (P 0·001) in a muscle-specific manner: insoluble collagen content was lower in ST, but total and insoluble collagen contents were higher in TB of R compared with C animals at 12 months of age. No differences were recorded in lipid contents nor in proteasome activities. The data suggest that an alternation of relatively mild nutritional restriction and ad libitumfeeding had only a small effect on muscle characteristics. However, muscles respond differentially to changes in feeding level.

International audience; The 'Organic' product label guarantees a production process that avoids the use of synthetic fertilisers, pesticides and hormones and minimises recourse to pharmaceuticals or veterinary drugs; however, the product's quality remains an issue that needs to be addressed in response to consumer demand. Consequently, this study was conducted to compare the sensory and nutritional qualities of meat and carcasses from pasture-fed lambs reared organically (O) or conventionally (C). Mean lamb growth profile was kept similar between the two treatments to avoid confounding effects with lamb age or weight at slaughter. The experiment was conducted over 3 years (2005 to 2007) with 12 O and 12 C lambs each year. The O and C treatments differed in the level of on-pasture mineral N fertilisation inducing a higher proportion of white clover in the organic pasture than the conventional pasture. Lambs were slaughtered when they attained a fat class of 2 to 3, and carcass and meat quality were evaluated. Lambs were slaughtered at an average weight and age of 35.3 kg and 156 days in the O treatment, respectively, and 35.2 kg and 155 days in the C treatment, respectively. Sensory evaluation indicated that loin chops from the O treatment had a higher level of abnormal fat odour compared with the C treatment. Carcasses from the O treatment had a softer subcutaneous fat one among 3 years (2007) compared to the C treatment. These results are probably due to a higher proportion of white clover in the diet. Organically reared lambs did offer the slight advantage of muscle fatty acid containing a higher level of stearic acid, which may have positive effects in the prevention of cardiovascular disease in humans. This may be the result of a higher rumen bio-hydrogenation of C18: 3n-3 due to differences in the botanical composition between the O and the C pasture. Production system had no effect on the colour characteristics of the meat and subcutaneous fat, except lightness of subcutaneous dorsal fat, which was slightly higher in the O lambs. There were no differences between O and C lambs in terms of colour stability and lipid oxidation of the meat during the 6-day refrigerated storage under gas-permeable film