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The effects on tenderness of extended ageing of longissimus thoracis (LT, striploin) muscle that differed in structure and composition were examined. Spring-born Angus × Holstein-Friesian heifers (n = 48) and Belgian Blue × Holstein-Friesian heifers (n = 48) were slaughtered, within sire breed, at 20 or 25 mo of age. Approximately 48 h post-mortem, LT steaks (2.5 cm) were removed, and either stored at −20°C for chemical analysis or vacuum-packed, stored at 2°C for 7, 14 or 28 d post-mortem and then at −20°C pending Warner–Bratzler shear force (WBSF) analysis. Muscle from Angus-sired heifers had higher (P < 0.001) intramuscular fat (IMF) concentration, lower (P < 0.001) proportion of type IIX muscle fibres and higher (P < 0.001) proportion of type IIA and type I muscle fibres compared to muscle from Belgian Blue-sired heifers. Collagen characteristics did not differ between sire breeds. Later slaughter increased (P < 0.001) IMF concentration and decreased (P < 0.001) total and insoluble concentrations and collagen solubility. There were no interactions between the main effects for WBSF and no difference between sire breeds. Later slaughter and increasing the duration of ageing decreased (P < 0.05) WBSF. Based on threshold WBSF values in the literature, all samples would be considered tender (

peer-reviewed Background Artificial selection for economically important traits in cattle is expected to have left distinctive selection signatures on the genome. Access to high-density genotypes facilitates the accurate identification of genomic regions that have undergone positive selection. These findings help to better elucidate the mechanisms of selection and to identify candidate genes of interest to breeding programs. Results Information on 705 243 autosomal single nucleotide polymorphisms (SNPs) in 3122 dairy and beef male animals from seven cattle breeds (Angus, Belgian Blue, Charolais, Hereford, Holstein-Friesian, Limousin and Simmental) were used to detect selection signatures by applying two complementary methods, integrated haplotype score (iHS) and global fixation index (FST). To control for false positive results, we used false discovery rate (FDR) adjustment to calculate adjusted iHS within each breed and the genome-wide significance level was about 0.003. Using the iHS method, 83, 92, 91, 101, 85, 101 and 86 significant genomic regions were detected for Angus, Belgian Blue, Charolais, Hereford, Holstein-Friesian, Limousin and Simmental cattle, respectively. None of these regions was common to all seven breeds. Using the FST approach, 704 individual SNPs were detected across breeds. Annotation of the regions of the genome that showed selection signatures revealed several interesting candidate genes i.e. DGAT1, ABCG2, MSTN, CAPN3, FABP3, CHCHD7, PLAG1, JAZF1, PRKG2, ACTC1, TBC1D1, GHR, BMP2, TSG1, LYN, KIT and MC1R that play a role in milk production, reproduction, body size, muscle formation or coat color. Fifty-seven common candidate genes were found by both the iHS and global FST methods across the seven breeds. Moreover, many novel genomic regions and genes were detected within the regions that showed selection signatures; for some candidate genes, signatures of positive selection exist in the human genome. Multilevel bioinformatic analyses of the detected candidate genes suggested that the PPAR pathway may have been subjected to positive selection. Conclusions This study provides a high-resolution bovine genomic map of positive selection signatures that are either specific to one breed or common to a subset of the seven breeds analyzed. Our results will contribute to the detection of functional candidate genes that have undergone positive selection in future studies. This study was financially supported by a grant from the Irish Department of Agriculture, Food and Marine Research Stimulus Fund (11/S/112), the Agricultural Science and Technology Innovation Program (No. ASTIP-IAS-TS-6) and the Natural Science Foundation of China (No. 31200927).

International audience; Colour sidedness is a dominantly inherited phenotype of cattle characterized by the polarization of pigmented sectors on the flanks, snout and ear tips. It is also referred to as 'lineback' or 'witrik' (which means white back), as colour-sided animals typically display a white band along their spine. Colour sidedness is documented at least since the Middle Ages and is presently segregating in several cattle breeds around the globe, including in Belgian blue and brown Swiss. Here we report that colour sidedness is determined by a first allele on chromosome 29 (Cs$_{29}$), which results from the translocation of a 492-kilobase chromosome 6 segment encompassing KIT to chromosome 29, and a second allele on chromosome 6 (Cs$_6$), derived from the first by repatriation of fused 575-kilobase chromosome 6 and 29 sequences to the KIT locus. We provide evidence that both translocation events involved circular intermediates. This is the first example, to our knowledge, of a phenotype determined by homologous yet non-syntenic alleles that result from a novel copy-number-variant-generating mechanism

Thirty-six young fattening bulls from three breeds (Belgian Blue, Limousin and Aberdeen Angus) were fattened over 5 months with fattening diets based either on sugar-beet pulp or on cereals. Fattening performance as well as carcass and meat characteristics were measured. There were few relevant effects of the diets on the parameters. The breeds also showed similar fattening features. However, the BB had higher killing-out proportion and their carcasses presented better scores in terms of conformation and fattening. The meat quality of the breeds differed, especially in terms of luminosity, redness and cooking losses. There were also significant influences of breed on the chemical composition of meat; fat content was lowest in Belgian Blue and highest in Aberdeen Angus. Such specificities could help to allocate breeds in appropriate niches in Belgium.

Animal performance, composition and quality of meat from Belgian Blue bulls either fattened indoors (FI) or finished indoors after a previous grazing period were studied during six years. During the grazing period, three intensification managements were tested on a permanent pasture conducted as set stocking. The intensification levels were either high (HN: 140 kg N·ha −1 with 6 bulls·ha −1 ) or moderate with a 33% reduction of nitrogen fertilisation but with the same stocking rate (MN: 93 kg N·ha −1 , 6 bulls·ha −1 ) or low with no nitrogen fertiliser but with a reduced stocking rate (ON, 4 bulls·ha −1 ). The levels of intensification did not affect sward characteristics and chemical composition of the grass. The apparent nitrogen efficiency per ha was larger in the ON plot than in the HN and MN plots (26 vs. 14%). The average daily gain of bulls during the grazing season was similar in the three groups at 1.0 kg·d −1 . The bulls from the FI group were characterised by average daily gains significantly higher than the bulls which were previously grazed and then finished indoors (1.5 vs. 1.2 kg·d −1 ; P < 0.01). The slaughter weight, the carcass composition, the dressing percentage and most of the meat quality parameters were similar between the treatment groups. The inclusion of a grazing period in the fattening system produced a meat which was darker (lower L*, P < 0.01), more red (higher a*, P < 0.05) and had a higher content of linolenic acid (C18:3 n-3) than that of the animals fattened indoors.

International audience; Myostatin plays a major role in muscle growth and development and animals with disruption of this gene display marked increases in muscle mass. Little is known about muscle physiological adaptations in relation to this muscle hypertrophy. To provide a more comprehensive view, we analyzed bovine muscles from control, heterozygote and homozygote young Belgian blue bulls for myostatin deletion, which results in a normal level of inactive myostatin. Heterozygote and homozygote animals were characterized by a higher proportion of fast-twitch glycolytic fibers in Semitendinosus muscle. Differential proteomic analysis of this muscle was performed using two-dimensional gel electrophoresis followed by mass spectrometry. Thirteen proteins, corresponding to 28 protein spots, were significantly altered in response to the myostatin deletion. The observed changes in protein expression are consistent with an increased fast muscle phenotype, suggesting that myostatin negatively controls mainly fast-twitch glycolytic fiber number. Finally, we demonstrated that differential mRNA splicing of fast troponin T is altered by the loss of myostatin function. The structure of mutually exclusive exon 16 appears predominantly expressed in muscles from heterozygote and homozygote animals. This suggests a role for exon 16 of fast troponin T in the physiological adaptation of the fast muscle phenotype.

This paper introduces javelin diagrams as an innovative way for depicting the results of medical decision analyses. The methods were used to determine whether, and at which values, blood lactate in Belgian White and Blue or maximum tidal volumes in Holstein calves should be measured before deciding to treat or not a calf suffering from the bovine respiratory disease complex. The different alternatives depended upon the probabilities of survival with and without treatment and upon the costs associated with a possible death, the test and the treatment. The chosen alternative was the one with the lowest expected costs. From data collected on the treated calves, the expected costs of measuring lactate (198.01 €) and tidal volumes (27.38 €) before deciding to treat or not were lower than the expected costs of directly treating sick Belgian Blue (215.39 €) and Holstein (51.55 €) calves, respectively. The treatment should be applied to sick Belgian Blue calves with blood lactate ≤ 7.8 mmol/L and to Holstein calves with a maximum tidal volume ≥ 1.81 L. At such test values, the treatment expected costs were lower than the expected costs associated with no treatment of calves with other test values. Probabilistic sensitivity analyses showing benefits in treating animals with a positive test (over not treating the animals with a negative test) were mostly invariant to changes in any cost value but were sensitive to uncertainties in probabilities of survival with or without treatment. The javelin diagrams provided a clear visual indication of such results. They depicted how and by how much the benefits were affected by uncertainties in probabilities, they proposed different information values associated with the chosen alternative, and identified directions for further research. clinical decision analysis / javelin diagrams / bovine respiratory disease complex

Beef and dairy products suffer from a negative health image, related to the nature of their lipid fraction. Rumen lipid metabolism involves the presence of saturated lipids in ruminant tissues. Lipolysis, fatty acid biohydrogenation and formation of microbial fatty acids in the rumen and their effects on rumen outflow of fatty acids are discussed. Special emphasis is given to the formation of trans-fatty acids and the possibilities of decreasing biohydrogenation. Small differences in intestinal digestibilities of fatty acids are mentioned, followed by a discussion on transfer of absorbed fatty acids into milk and adipose tissue lipids. The preferential retention of polyunsaturated fatty acids as well as the balance between synthesis and incorporation of fatty acids in tissues is described. Dietary means for the modification of milk fat are listed, with special emphasis on the possibilities for enrichment in polyunsaturated fatty acids and the presence of conjugated linoleic acids. A description of the nature and development of fat depots in beef cattle is followed by a discussion of breed, conformation and feed effects on adipose tissue distribution and fatty acid composition. Special emphasis is given to the very lean Belgian Blue double-muscled breed. The review ends with a consideration of the limits to the modification of ruminant fats, involving considerations of consumer acceptance as well as animal welfare and environmental effects.

Lorsqu’on les compare à des sujets mixtes de la même race, les taurillons Blanc Bleu Belge (BBB) culards réalisent des gains quotidiens moyens au moins aussi élevés tout en consommant moins d’aliments. L’amélioration de l’efficacité alimentaire est expliquée principalement par la composition des gains de poids : la carcasse d’un sujet BBB culard contient au moins 60 kg de muscle en plus et 30 kg de graisse en moins que celle d’un sujet mixte abattu au même poids vif. Lorsque le poids vif augmente, on observe, dans les deux types, une augmentation du rendement à l’abattage et de la proportion de viande maigre dans la carcasse. La composition chimique et les qualités organoleptiques des viandes sont, elles aussi, influencées par le caractère culard. La teneur en gras est réduite et la proportion d’acides gras polyinsaturés est augmentée chez le culard, ce qui constitue un avantage nutritionnel. L’évolution plus rapide du pH post mortem chez le taurillon culard ne peut expliquer que très partiellement les différences observées pour les qualités sensorielles. La couleur plus pâle de la viande est liée en grande partie à sa faible teneur en myoglobine. L’avantage du culard en matière de tendreté, expliqué par une teneur faible en collagène, n’apparaît pas dans un morceau noble de la carcasse à faible teneur en collagène. Enfin, dans la majorité des études disponibles à ce jour, la capacité de rétention d’eau de la viande produite par les culards apparaît peu différente de celle des non culards. Les concentrations de plusieurs métabolites sanguins indiquent une répartition des nutriments favorable au dépôt de protéines et défavorable au dépôt de graisses chez le culard. Lors de l’engraissement, les particularités endocriniennes concernent essentiellement l’hormone de croissance et l’insuline ; elles peuvent expliquer la répartition particulière des nutriments., When compared to animals of the dual purpose type in the same breed, Belgian Blue double muscled bulls exhibit, at least, similar average daily gain with lower feed intake. The higher feed efficiency in the double muscled type is mainly explained by the composition of the weight gains, the muscle content is minimum 60 kg higher and the fat content 30 kg lower than in the dual pur pose type when slaughtered at a similar live weight. In both types, the dressing percentage and the lean meat proportion in the carcass increase with final liveweight. The chemical composition and the sensory characteristics of meat are also influenced by double muscling. The fat content is reduced and the polyunsaturated fatty acids proportion is increased in the double muscled type, resulting in a nutritional advantage. The difference in sensory characteristics could be, only partially explained by the fas ter post mortem pH drop. The paler meat is mainly related to the myoglobin content. The advantage of the double muscled type in terms of tenderness, due to a low collagen content, is not exhibited in a << choice >> cut of the carcass with a low level of collagen, Finally, according to most of the available data, the water holding capacity of meat of double muscled animals seems not very different. The concentrations of several blood metabolites indicate a partition of the absorbed nutrients propitious to protein deposition and unpropitious to fat deposition in double muscled animals. During the fattening period, this specific partition can be related to endocrine characteristics, mainly growth hormone and insulin.

International audience

Suppl. 1; International audience