Meta-análise de parâmetros genéticos relacionados ao consumo alimentar residual e a suas características componentes em bovinos

O objetivo deste trabalho foi estimar, por meio de meta-análise, a herdabilidade (h²) e as correlações genética (r g) e fenotípica (r f) do consumo alimentar residual (CAR), e das suas características componentes, em bovinos de 19 raças ou grupamentos genéticos. Foram utilizados 22 trabalhos científicos publicados entre 1963 e 2011, de oito países, o que totalizou 52.637 bovinos com idades que variaram de 28 dias até a idade de abate. As estimativas de CAR, consumo de matéria seca (CMS), ganho médio diário (GMD) e peso metabólico (PV0, 75) foram ponderadas pelo inverso da variância amostral. A variação da h² de cada característica entre os estudos foi analisada por quadrados mínimos ponderados. Os efeitos de sexo, país e raça foram significativos para h² de CAR e explicaram 67% da variação entre os estudos. Para CMS, os efeitos de país e raça foram significativos e explicaram 96% da variação. As estimativas combinadas de h² foram: 0, 255±0, 008, 0, 278±0, 012, 0, 321±0, 015 e 0, 397±0, 032 para CAR, CMS, GMD e PV0, 75, respectivamente. As estimativas combinadas de correlação genética e fenotípica foram baixas entre CAR e GMD e entre CAR e PV0, 75 (de -0, 021±0, 034 a 0, 025±0, 035), e de média magnitude entre CAR e CMS (0, 636±0, 035 a 0, 698±0, 041) e entre CMS, GMD e PV0, 75 (0, 441±0, 062 a 0, 688±0, 032). O CAR apresenta estimativa de herdabilidade menor que a de suas características componentes

Genetic relationships between carcass cut weights predicted from video image analysis and other performance traits in cattle

peer-reviewedThe objective of this study was to quantify the genetic associations between a range of carcass-related traits including wholesale cut weights predicted from video image analysis (VIA) technology, and a range of pre-slaughter performance traits in commercial Irish cattle. Predicted carcass cut weights comprised of cut weights based on retail value: lower value cuts (LVC), medium value cuts (MVC), high value cuts (HVC) and very high value cuts (VHVC), as well as total meat, fat and bone weights. Four main sources of data were used in the genetic analyses: price data of live animals collected from livestock auctions, live-weight data and linear type collected from both commercial and pedigree farms as well as from livestock auctions and weanling quality recorded on-farm. Heritability of carcass cut weights ranged from 0.21 to 0.39. Genetic correlations between the cut traits and the other performance traits were estimated using a series of bivariate sire linear mixed models where carcass cut weights were phenotypically adjusted to a constant carcass weight. Strongest positive genetic correlations were obtained between predicted carcass cut weights and carcass value (min rg(MVC)50.35; max rg(VHVC)50.69), and animal price at both weaning (min rg(MVC)50.37; max rg(VHVC)50.66) and post weaning (min rg(MVC)50.50; max rg(VHVC)50.67). Moderate genetic correlations were obtained between carcass cut weights and calf price (min rg(HVC)50.34; max rg(LVC)50.45), weanling quality (min rg(MVC)50.12; max rg(VHVC)50.49), linear scores for muscularity at both weaning (hindquarter development: min rg(MVC)520.06; max rg(VHVC)50.46), post weaning (hindquarter development: min rg(MVC)50.23; max rg(VHVC)50.44). The genetic correlations between total meat weight were consistent with those observed with the predicted wholesale cut weights. Total fat and total bone weights were generally negatively correlated with carcass value, auction prices and weanling quality. Total bone weight was, however, positively correlated with skeletal scores at weaning and post weaning. These results indicate that some traits collected early in life are moderate-to-strongly correlated with carcass cut weights predicted from VIA technology. This information can be used to improve the accuracy of selection for carcass cut weights in national genetic evaluations

Caractérisation des aptitudes bouchères et qualités de la viande de trois systèmes de production de viande bovine à partir des races rustiques françaises Salers, Aubrac et Gasconne

National audienceBeef traits, muscle characteristics of the Longissimus thoracis and meat quality attributes were measured on a representative sample of young Salers, Aubrac and Gascon bulls in order to characterise a specific beef production system for each breed. Young Salers bulls were slaughtered at 19 months of age. They got the poorest conformation and their meat the highest collagen and lipids contents with the coarsest muscle fibres. Young Aubrac bulls were fattened at 24 months of age after a 5 month fattening period following a grazing rearing period. They were the leanest and got the highest pigment content. The Gasconne young bulls were slaughtered at the youngest age (16 months) and got the best slaughter yield, the lowest pigment content and the thinnest muscle fibres. Instrumental measures of meat quality showed the Salers young bulls had the darker and tougher meat, with the higher water holding capacity when grilling. The relationships between sensory meat quality attributes and muscle characteristics showed that flavour predominantly depends on intramuscular lipids content while tenderness is related to pH, muscle fibre size and collagen content.Les aptitudes bouchères à l’abattage, les caractéristiques musculaires du Longissimus thoracis et les qualités de la viande d’un échantillon représentatif de jeunes bovins des races Salers, Aubrac et Gasconne ont été mesurées afin de caractériser objectivement un système de production spécifique à chacune de ces races. Les taurillons du système Salers, abattus à 19 mois, présentent des carcasses de moindre conformation, avec de plus fortes teneurs en collagène et en lipides et des fibres musculaires de plus grosse taille. Les jeunes bovins du système Aubrac sont des ’bourrets d’herbe’, c’est-à-dire des mâles entiers engraissés rapidement de 19 à 24 mois après un phase d’élevage à l’herbe. Ces jeunes bovins ont les carcasses et les viande les plus maigres avec la plus forte teneur en pigments. Les taurillons du système Gascon, abattus les plus jeunes à 16 mois, ont le meilleur rendement, une moindre teneur en pigments et les fibres musculaires de plus petite taille. Les mesures instrumentales des qualités de la viande mettent en évidence que les animaux du système Salers ont une viande plus sombre et plus dure, mais une meilleure capacité de rétention de l’eau à la cuisson, que les animaux des deux autres systèmes. L’étude des qualités sensorielles montre que la flaveur dépend prioritairement de la teneur en lipides intramusculaires et que la tendreté peut être mise en relation avec le pH, la taille des fibres musculaires et la teneur en collagène

Synchronous immune alterations mirror clinical response during allergen immunotherapy

BACKGROUND: Three years treatment with either sublingual or subcutaneous allergen immunotherapy has been shown to be effective and to induce long-term tolerance. The GRASS∗ trial demonstrated that two years treatment via either route was effective in suppressing the response to nasal allergen challenge, although was insufficient for inhibition one year after discontinuation. OBJECTIVE: To examine in the GRASS trial the time-course of immunologic changes during two years sublingual and subcutaneous immunotherapy and for one year after treatment discontinuation. METHODS: We performed multi-modal immunomonitoring to assess allergen-specific CD4 T cell properties, in parallel with analysis of local mucosal cytokine responses induced by nasal allergen exposure and humoral immune responses that included IgE-dependent basophil activation and measurement of serum inhibitory activity for allergen-IgE binding to B cells (IgE-Facilitated Allergen Binding). RESULTS: All three of these distinct arms of the immune response displayed significant and coordinate alterations during 2 years allergen desensitization, followed by reversal at 3 years, reflecting a lack of a durable immunological effect. Whereas frequencies of antigen-specific Th2 cells in peripheral blood determined by HLA class II tetramer analysis most closely paralleled clinical outcomes, IgE-antibody dependent functional assays remained partially inhibited one year following discontinuation. CONCLUSION: Two years of allergen immunotherapy were effective but insufficient for long-term tolerance. Allergen-specific Th2 cells most closely paralleled the transient clinical outcome and it is likely that recurrence of the T cell 'drivers' of allergic immunity abrogated the potential for durable tolerance. On the other hand, persistence of IgE-blocking antibody one year after discontinuation may be an early indicator of a pro-tolerogenic mechanism