Cent anys de millora genètica del bestiar a Catalunya

En aquest article es recullen les activitats de millora genètica animal a Catalunya des del temps de la Mancomunitat fins als nostres dies. El veterinari Pere Màrtir Rossell i Vilà es presenta com a figura destacada de la zootècnia i la genètica del bestiar, a l'inici del segle xx. En temps més recents, en particular durant els últims vint-i-cinc anys, la millora genètica a Catalunya ha experimentat un importantíssim impuls gràcies a les activitats sinèrgiques d'empreses de millora ramadera, associacions de ramaders i institucions acadèmiques i de recerca, entre les quals podem destacar l'Escola Tècnica Superior d'Enginyers Agrònoms de Lleida, la Facultat de Veterinària de Barcelona i l'Institut de Recerca i Tecnologia Agroalimentàries.En este artículo se recogen las actividades de mejora genética animal en Cataluña desde los tiempos de la Mancomunidad hasta nuestros días. El veterinario Pere Màrtir Rossell i Vilà se presenta como figura destacada de la zootecnia y de la genética del ganado, en los inicios del siglo xx. En tiempos más recientes, en particular durante los últimos veinticinco años, la mejora genética ha experimentado un importantísimo impulso en Cataluña gracias a las actividades sinérgicas de empresas de mejora ganadera, asociaciones de ganaderos e instituciones académicas y de investigación; entre ellas, podemos destacar la Escuela Técnica Superior de Ingenieros Agrónomos de Lleida, la Facultad de Veterinaria de Barcelona y el Instituto de Investigación y Tecnología Agroalimentarias

Statistical analysis in practice

The main statistical methods used in animal experimentation are presented. These include exploratory data analysis, comparison of two or k means, regression and correlation. Selected cases are analyzed by using the R Commander software followed of an explanation of the outputs. Furthermore, some statistical theory is presented to better understand the analyses carried out.Se presentan los principales análisis estadísticos que se llevan a cabo en la práctica de la experimentación animal (descripción cuantitativa y gráfica de los datos, comparación de dos medias, comparación de k medias y análisis de regresión y correlación). Se analizan datos concretos mediante el paquete estadístico R Commander y se explica cómo interpretar los resultados. Asimismo se presentan nociones de estadística que permiten comprender mejor los análisis realizados

Validation of an approximate approach to compute genetic correlations between longevity and linear traits

The estimation of genetic correlations between a nonlinear trait such as longevity and linear traits is computationally difficult on large datasets. A two-step approach was proposed and was checked via simulation. First, univariate analyses were performed to get genetic variance estimates and to compute pseudo-records and their associated weights. These pseudo-records were virtual performances free of all environmental effects that can be used in a BLUP animal model, leading to the same breeding values as in the (possibly nonlinear) initial analyses. By combining these pseudo-records in a multiple trait model and fixing the genetic and residual variances to their values computed during the first step, we obtained correlation estimates by AI-REML and approximate MT-BLUP predicted breeding values that blend direct and indirect information on longevity. Mean genetic correlations and reliabilities obtained on simulated data confirmed the suitability of this approach in a wide range of situations. When nonzero residual correlations exist between traits, a sire model gave nearly unbiased estimates of genetic correlations, while the animal model estimates were biased upwards. Finally, when an incorrect genetic trend was simulated to lead to biased pseudo-records, a joint analysis including a time effect could adequately correct for this bias

Experimental design and statistical methods

This is a course addressed to future researchers in the field of Animal and Food Sciences, but it is also applicable to other experimental sciences (mainly biological). The objective is that the students be able to design properly experiments from a statistical point of view, and also to develop by themselves statistical analyses related to the most common statistical designs

Bayes factors for testing between different structures of random genetic groups : a case study using weanin weight in Bruna dels Pirineus beef cattle

The implementation of genetic groups in BLUP evaluations accounts for different expectations of breeding values in base animals. Notwithstanding, many feasible structures of genetic groups exist and there are no analytical tools described to compare them easily. In this sense, the recent development of a simple and stable procedure to calculate the Bayes factor between nested competing models allowed us to develop a new approach of that method focused on compared models with different structures of random genetic groups. The procedure is based on a reparameterization of the model in terms of intraclass correlation of genetic groups. The Bayes factor can be easily calculated from the output of a Markov chain Monte Carlo sampling by averaging conditional densities at the null intraclass correlation. It compares two nested models, a model with a given structure of genetic groups against a model without genetic groups. The calculation of the Bayes factor between different structures of genetic groups can be quickly and easily obtained from the Bayes factor between the nested models. We applied this approach to a weaning weight data set of the Bruna dels Pirineus beef cattle, comparing several structures of genetic groups, and the final results showed that the preferable structure was an only group for unknown dams and different groups for unknown sires for each year of calving

Probabilidad de detección de pedigrees erróneos mediante polimorfismos bioquímicos en razas caninas españolas

Mediante técnicas convencionales de electroforesis, se realiza un estudio poblacional de once marcadores genéticos sanguíneos -polimorfismos bioquímicos- para un total de 484 individuos, pertenecientes a diez razas caninas españolas. La información aportada a partir de los valores de las frecuencias génicas de los once sistemas polimórficos, nos permite estimar, en cada una de las razas, las probabilidades de detección de errores en el pedigree. Considerando los once polimorfismos conjuntamente, y en el caso de un único individuo analizado por camada, se obtienen unos valores que oscilan entre el 72,02% para la raza Ca de Bestiar y el 83,02% para la raza Mastín Español, con un valor promedio del 78,29% para el conjunto de las razas. La probabilidad de exclusión de falsas filiaciones se incrementa hasta un valor promedio, para las diez razas, del 92,07%, con unos valores extremos del 88,55% para Ca de Bestiar y del 94,68% para Mastín Español, si se analizan cinco descendientes por camada. Se discute asimismo, la relación eficacia/coste de cada uno de los sistemas de detección (electroforesis en gel de almidón, en gel de poliacrilamida y bidimensional) en el protocolo de control de parentesco.A total of 11 genetic loci encoding enzymes and other blood proteins has been assayed by conventional techniques al electrophoresis in 484 indiuiduals, belonging to 10 spanish breeds of dogs. In each breed the information provided by the values of the allelic frequencies in the 11 polymorphic systems can be used to assess the probabilities to detect erroneous pedigrees. Using the whole set of the 11 polymorpbisms, and in the case 011 individual analyzed per litter, the values ranged between 72,02% for the "Ca de Bestiar" breed and 83,02% in the "Mastín Español" breed, with an average al 78,29%. The probabilities to exclude false filiations increase to an average 0192, O7%lar the 10 breeds, from 88,55% in "Ca de Bestiar" to 94,68% in "Mastín Español", if 5 offsprings are used per litter in the analysis. The relationship between the efficiency and the cost of each system ofdetection (electrophoresis in starch gel) in polyacrilamyde gel and bidimensional) in the protocol of control of relationship is also discussed

Effect of fibrous diet and vitamin C inclusion on uniformity, carcass traits, skeletal strength, and behavior of broiler breeder pullets

This experiment studied the effect of broiler breeder nutritional strategies on uniformity, carcass traits, tibia parameters, and behavior during rearing and prebreeder periods (up to 22 wk of age). One-day-old pullets (n = 384) were randomly assigned to 4 treatments arranged as a 2 × 2 factorial, with 2 fiber levels (control vs. fibrous diet, 15% diluted in AMEn and nutrient content) and 2 vitamin C feed inclusions (0 vs. 200 mg/kg). At 6, 15, and 22 wk, blood sampling was carried out (4 birds/replicate) to determine serum alkaline phosphatase (ALP) levels, and behavior was observed by visual scan sampling. At 22 wk, carcass traits, tibia parameters, and intestinal morphology were assessed (2 birds/replicate), and tail- and wing-feather integrity of all birds were scored. Fibrous diet did not modify BW uniformity, mortality, or tibia growth when compared with control diet. Pullets fed the fibrous diet had lower tibia breaking strength, elastic modulus, and ash content values (P < 0.05). They also had lower ALP serum level at 6 and 22 wk (P < 0.05), their breast muscle was less developed (18.5 vs. 19.8%, P < 0.05), and their abdominal fat deposition was higher (1.14 vs. 0.87%, P < 0.05). At 15 and 22 wk, they performed, on average, 97% less grasping feather pecking and 45% less non-food object pecking behaviors, and their wing-feather score was lower (P < 0.05) at 22 wk. Tail- and wing-feather scores of the control treatments were reduced by vitamin C inclusion (tail: 0.30 vs. 1.15, P < 0.05; wing: 0.98 vs. 1.26, P < 0.05) at 22 wk. In conclusion, fibrous diet improves carcass traits (reduces breast muscle and increases abdominal fat deposition), deteriorates bone mineral deposition and thus skeletal strength, and reduces stereotypic behaviors, improving wing-feather integrity. Vitamin C inclusion improves tail- and wing-feather integrity of lower in feed allowance

Pedigree analysis of eight Spanish beef cattle breeds

The genetic structure of eight Spanish autochthonous populations (breeds) of beef cattle were studied from pedigree records. The populations studied were: Alistana and Sayaguesa (minority breeds), Avileña – Negra Ibérica and Morucha ("dehesa" breeds, with a scarce incidence of artificial insemination), and mountain breeds, including Asturiana de los Valles, Asturiana de la Montaña and Pirenaica, with extensive use of AI. The Bruna dels Pirineus breed possesses characteristics which make its classification into one of the former groups difficult. There was a large variation between breeds both in the census and the number of herds. Generation intervals ranged from 3.7 to 5.5 years, tending to be longer as the population size was larger. The effective numbers of herds suggest that a small number of herds behaves as a selection nucleus for the rest of the breed. The complete generation equivalent has also been greatly variable, although in general scarce, with the exception of the Pirenaica breed, with a mean of 3.8. Inbreeding effective population sizes were actually small (21 to 127), especially in the mountain-type breeds. However, the average relatedness computed for these breeds suggests that a slight exchange of animals between herds will lead to a much more favourable evolution of inbreeding. The effective number of founders and ancestors were also variable among breeds, although in general the breeds behaved as if they were founded by a small number of animals (25 to 163)

Diez años de selección de toros jóvenes en el centro de testaje de la raza Bruna dels Pirineus

publishedTomo I . Sección: Sistemas Ganaderos-Economía y Gestión. Sesión: Vacuno carne II. Ponencia nº

Mapping Recombination Rate on the Autosomal Chromosomes Based on the Persistency of Linkage Disequilibrium Phase Among Autochthonous Beef Cattle Populations in Spain

In organisms with sexual reproduction, genetic diversity, and genome evolution are governed by meiotic recombination caused by crossing-over, which is known to vary within the genome. In this study, we propose a simple method to estimate the recombination rate that makes use of the persistency of linkage disequilibrium (LD) phase among closely related populations. The biological material comprised 171 triplets (sire/dam/offspring) from seven populations of autochthonous beef cattle in Spain (Asturiana de los Valles, Avileña-Negra Ibérica, Bruna dels Pirineus, Morucha, Pirenaica, Retinta, and Rubia Gallega), which were genotyped for 777, 962 SNPs with the BovineHD BeadChip. After standard quality filtering, we reconstructed the haplotype phases in the parental individuals and calculated the LD by the correlation -r- between each pair of markers that had a genetic distance &lt; 1 Mb. Subsequently, these correlations were used to calculate the persistency of LD phase between each pair of populations along the autosomal genome. Therefore, the distribution of the recombination rate along the genome can be inferred since the effect of the number of generations of divergence should be equivalent throughout the genome. In our study, the recombination rate was highest in the largest chromosomes and at the distal portion of the chromosomes. In addition, the persistency of LD phase was highly heterogeneous throughout the genome, with a ratio of 25.4 times between the estimates of the recombination rates from the genomic regions that had the highest (BTA18-7.1 Mb) and the lowest (BTA12-42.4 Mb) estimates. Finally, an overrepresentation enrichment analysis (ORA) showed differences in the enriched gene ontology (GO) terms between the genes located in the genomic regions with estimates of the recombination rate over (or below) the 95th (or 5th) percentile throughout the autosomal genome