A comprehensive characterisation of the fibre composition and properties of a limb (Flexor digitorum superficialis, membri thoraci) and a trunk (Psoas major) muscle in cattle

<p>Abstract</p> <p>Background</p> <p>The fibre type attributes and the relationships among their properties play an important role in the differences in muscle capabilities and features. Comprehensive characterisation of the skeletal muscles should study the degree of association between them and their involvement in muscle functionality. The purposes of the present study were to characterise the fibre type composition of a trunk (<it>Psoas major</it>, PM) and a limb (<it>Flexor digitorum, membri thoraci</it>, FD) muscle in the bovine species and to study the degree of coordination among contractile, metabolic and histological properties of fibre types. Immunohistochemical, histochemical and histological techniques were used.</p> <p>Results</p> <p>The fibre type composition was delineated immunohistochemically in calf muscle samples, identifying three pure (I, IIA, and IIX) and two hybrid type fibres (I+IIA, and IIAX). Most of the fibres in FD were types I and IIA, while pure IIX were absent. All fibre types were found in PM, the IIX type being the most frequent. Compared to other species, small populations of hybrid fibres were detected. The five fibre types, previously identified, were ascribed to three different acid and alkaline mATPase activity patterns. Type I fibres had the highest oxidative capacity and the lowest glycolytic capacity. The reverse was true for the IIX fibres, whereas the type IIA fibres showed intermediate properties. Regarding the histological properties, type I fibres tended to be more capillarised than the II types. Correlations among contractile, metabolic and histological features on individual fibres were significantly different from zero (r values varied between -0.31 and 0.78). Hybrid fibre values were positioned between their corresponding pure types, and their positions were different regarding their metabolic and contractile properties.</p> <p>Conclusion</p> <p>Coordination among the contractile, metabolic and histological properties of fibres has been observed. However, the magnitude of the correlation among them is always below 0.8, suggesting that the properties of muscles are not fully explained by the fibre composition. These results support the concept that, to some extent, muscle plasticity can be explained by the fibre type composition, and by the properties derived from their metabolic and histological profiles.</p

Modélisation des performances de reproduction de la population caprine locale dans les régions arides tunisiennes

La présente étude vise à illustrer l’action qualitative et quantitative de facteurs d’aridité et des modes de conduite sur les performances reproductives de la chèvre locale. Un total de 462 mises bas provenant de l'accouplement de 11 boucs et 185 chèvres, ont été recueillies durant la période 1999-2014. Deux caractères ont été choisis pour analyser les performances de reproduction :la taille de la portée et l’intervalle entre deux mises bas successives. Les facteurs fixes inclus dans le modèle sont l’âge et la parité de la chèvre et l’interaction année × mois de mise bas.  Les moyennes de l’IMB et de la TP sont respectivement 13,85 ± 5,20 mois et de 1,33 ± 0,49 chevreaux. Les jeunes femelles ont montré des performances de reproduction relativement plus faibles que celles des chèvres âgées, indiquant des conflits possibles entre les besoins de croissance et la disponibilité alimentaire. Les performances de reproduction de la chèvre locale affichent des valeurs justifiables par les conditions naturelles hostiles. Il semble avoir une augmentation générale du TP à mesure que la parité progresse jusqu'à la cinquième parité. Une large valeur d’IMB a été observée pour la deuxième parité puis elle tend à diminuer. Le cycle reproductif des chèvres est essentiellement soumis aux effets des facteurs qui agissent sur les ressources pastorales et le stress climatique. Ces constations sont capitales pour l’élaboration des procédures d’évaluation et de choix des reproducteurs dans le cadre d’un schéma de sélection

Characterisation of Goats’ Response to Heat Stress: Tools to Improve Heat Tolerance

This chapter aims to review present knowledge about the effects of heat stress on goats, summarising what is known about its measurement, its impact on the performances of the animals, mainly milk traits, the physiological and genetic bases of the animals’ response and the improvement of resilience through selection. A short historic review of the climatic indexes used to measure heat stress, with special emphasis on the temperature humidity indexes, and the main consequences on milk yield and composition are followed by a description of the results of experiments carried out to study the physiological and metabolic consequences of heat stress. The results of the quantitative analyses of the genetic bases of heat stress using norm of reaction models and of the application of omic techniques, particularly transcriptomic and genomic, to understand the complexity of the genetic background of animal’s reaction to thermal stress, constitute the next points. The chapter ends treating the possible ways and difficulties of applying selection to increase resilience to heat stress

Fermentación in vitro de pepsina/pancreatina con inóculos de conejos

The in vitro gas production of pepsin/pancreatin used in the determination of in vitro digestibility was evaluated using different inocula from rabbits (ileal, caecal and soft faeces from rabbits). In experiment 1 were used 3 different ileal and caecal inocula obtained each one from the combination of the digesta of 3 different 70 d old rabbits

Impact du rythme de pesage sur l’évaluation génétique de performances de croissance des chevreaux de la population caprine locale

L’opération la plus importante dans un schéma d’amélioration génétique est le contrôle des performances qui doit être simple, fiable et peu coûteux. L’étude vise à simuler les méthodes alternatives de simplification de l'enregistrement des poids à âge type pour calculer les gains moyens quotidiens (GMQ) des chevreaux locaux et évaluer l'impact de leur utilisation d'un point de vue génétique pour établir la base d’une amélioration future. Un total de 945 chevreaux (531 mâles et 414 femelles), issus de 19 boucs et 285 chèvres, nés entre 1998 et 2014, ont été utilisé dans cette étude. Les paramètres génétiques ont été estimés pour cinq phénotypes : GMQ (1 -30), GMQ (30-60), GMQ (60-90), GMQ (90-120), GMQ (120-150). L’âge de la mère à la mise bas, l’année et mois de naissance et le sexe du chevreau ont été inclus en tant que facteurs fixes, dans le modèle mixte. La simplification à une et deux semaines a conduit à des héritabilités directes et maternelles pour les différents gains moyens quotidiens, similaires à celles obtenues par l'enregistrement de croissance standard. Une réduction du nombre de contrôles à une et deux semaines pourrait donc être adoptée

Objectives, organization and limiting factors of selection programs for indigenous breeds in Spain

Ponencia publicada en ITEA, vol.104En esta ponencia invitada se resumen las principales características de los programas de selección de las razas autóctonas que se están llevando a cabo en España. Se describen para cada una de ellas la población controlada, los caracteres registrados, los objetivos y criterios de selección, la valoración genética de los reproductores, los aspectos organizativos, la utilización de la información por parte de los ganaderos y los factores limitantes del progreso genético. Los más antiguos de estos programa comenzaron al principio de la década de los 80 del pasado siglo, la mayoría lo hicieron al final de dicha década o en la siguiente y unos pocos en la década actual. Debido a esta disparidad de fechas de iniciación y a otros factores estructurales y organizativos, sus niveles de desarrollo y efectividad son muy variables. Entre los factores limitantes de dicho desarrollo y efectividad más frecuentemente citados se encuentran los reducidos tamaños de los núcleos de selección, la reducida implantación de la I.A. y, consecuentemente, el bajo número de sementales en prueba de descendencia y las bajas fiabilidades de las valoraciones genéticas, la escasa utilización por parte algunos de los ganaderos de las valoraciones genéticas de sus animales para elegir la reposición en los rebaños y, en un cierto número de casos, la escasa participación e interés de los mismos.This invited contribution summarizes the most important characteristics of selection programs being applied to Spanish indigenous breeds. Population and traits being recorded, selection objectives and criteria, breeding values estimation, managing aspects, diffusion to and use of genetic information by breeders and constraints to genetic progress are synthetically described for each breed. The oldest programs started at the beginning of the eighties of the last century. Most of them began at the end of the eighties or in the nineties and a few were initiated within present decade. Due to these age differences, and to other structural and managing factors, their developmental and effectiveness levels are very variable. Small number of animals being registered and, therefore, selected, low number of dams inseminated an its consequence on the capacity to sire testing and on the reliability of estimated breeding values, the scanty use that some of the breeders make of the genetic evaluations and the low participation of farmers in the programs, are among the most important factors limiting their development and their effectiveness in terms of genetic progress obtained

Efecto del nivel de fibra soluble y de la relación de omega-6/omega-3 sobre el consumo de agua en gazapos en cebo

El objetivo de este trabajo fue estudiar el efecto entre la fibra soluble y la relación n-6/n-3 sobre consumo de agua en gazapos tras el destete

Efecto del nivel de fibra soluble y de la relación omega-6/omega-3 sobre la composición química corporal y de la canal en conejos en cebo

El objetivo de este trabajo fue estudiar el efecto de la inclusión de diferentes niveles de fibra soluble combi- nados con distintas relaciones de n-6/n-3 sobre la composición química corporal y de la canal de conejos en crecimiento. Para ello, se formularon cuatro piensos (BF_Bn-3, BF_An-3, AF_Bn-3 y AF_An-3) con dos niveles de fibra soluble (BF: 7,8 vs. AF: 14,4% MS) y dos ratios n-6/n-3 (Bn-3: 13,4 vs. An-3: 3,5). Se utilizaron 40 gazapos/pienso destetados a 26 d de edad (460 ± 79,8 g) para determinar la composición corporal y de la canal mediante impedancia bioeléctrica a los 27, 39, 62 y 69 d de edad. Los gazapos de los piensos BF_An-3 y AF_Bn-3 tendieron a pesar más y a tener más energía corporal (P = 0,078 y 0,094). El porcentaje de proteína de la canal disminuyó un 1,16% en los gazapos del pienso BF_An-3 (P = 0,035), respecto a los tratamientos BF_Bn-3 y AF_An-3. El peso vivo a 62 d tendió a ser mayor con los mayores niveles de n-3 (P = 0,073), disminuyendo un 1,2% (P = 0,049) el porcentaje de proteína corporal y aumentando un 2,7% (P = 0,031) el de grasa. Todas estas variables se iguala- ron a 69 d. La energía corporal a 62 d tendió a incrementarse en los gazapos del pienso BF_An-3 (2380 vs. 2353 kJ/100g MS; P = 0,064), mientras que a los 69 días tendió a incrementarse en los de los tratamientos BF_An-3 y AF_Bn-3 (2493 vs. 2463 kJ/100g MS; P = 0,064). El porcentaje de grasa de la canal a los 39 d de edad, de los gazapos del tratamiento BF_An-3 tendió a disminuir respecto al pienso BF_Bn-3 (P = 0,074), mientras que a 69 d los gazapos del tratamiento BF_An-3 tendieron a aumentar su porcentaje de grasa respecto al pienso BF_Bn-3 (P = 0,074)

Use of Maximum Likelihood-Mixed Models to select stable reference genes: a case of heat stress response in sheep

<p>Abstract</p> <p>Background</p> <p>Reference genes with stable expression are required to normalize expression differences of target genes in qPCR experiments. Several procedures and companion software have been proposed to find the most stable genes. Model based procedures are attractive because they provide a solid statistical framework. NormFinder, a widely used software, uses a model based method. The pairwise comparison procedure implemented in GeNorm is a simpler procedure but one of the most extensively used. In the present work a statistical approach based in Maximum Likelihood estimation under mixed models was tested and compared with NormFinder and geNorm softwares. Sixteen candidate genes were tested in whole blood samples from control and heat stressed sheep.</p> <p>Results</p> <p>A model including gene and treatment as fixed effects, sample (animal), gene by treatment, gene by sample and treatment by sample interactions as random effects with heteroskedastic residual variance in gene by treatment levels was selected using goodness of fit and predictive ability criteria among a variety of models. Mean Square Error obtained under the selected model was used as indicator of gene expression stability. Genes top and bottom ranked by the three approaches were similar; however, notable differences for the best pair of genes selected for each method and the remaining genes of the rankings were shown. Differences among the expression values of normalized targets for each statistical approach were also found.</p> <p>Conclusions</p> <p>Optimal statistical properties of Maximum Likelihood estimation joined to mixed model flexibility allow for more accurate estimation of expression stability of genes under many different situations. Accurate selection of reference genes has a direct impact over the normalized expression values of a given target gene. This may be critical when the aim of the study is to compare expression rate differences among samples under different environmental conditions, tissues, cell types or genotypes. To select reference genes not only statistical but also functional and biological criteria should be considered. Under the method here proposed <it>SDHA/MDH1 </it>have arisen as the best set of reference genes to be used in qPCR assays to study heat shock in ovine blood samples.</p

Predisposición a seleccionar animales tolerantes al calor en la ganadería lechera

Publishe