M. Valera - Academia.edu (original) (raw)

Papers by M. Valera

Journal of Equine Veterinary Science, 2020

Reproduction, Fertility and Development, 2022

Young Horse competitions for show jumping (for animals between 4 and 6 years old) have been devel... more Young Horse competitions for show jumping (for animals between 4 and 6 years old) have been developed in Spain since 2004 to contribute to equine selection programs in jumping performance. A multivariate BLUP Animal Model has been developed to estimate the breeding values in jumping performance of Spanish young horses. Scores obtained during the competition (caused by mistakes and times exceeding the allowed) and final ranking of 486 young animals were considered. The data file had 2,016 racing performances collected from 34 different competitions. The pedigree file had a total figure of 3,280 animals obtained from the Studbook (four generations of ancestors). Age (4, 5 and 6 years old), level of stress, training level, event centre (15 levels), season (3 levels) and rider (158) were included as fixed effect in the model. The random variables were individual additive and rider-horse interaction effects. The heritability of both traits and the breeding value of each one for the parti...

A paper on breed characterization and genetic relationships among Berrenda en Colorado(BC), Berre... more A paper on breed characterization and genetic relationships among Berrenda en Colorado(BC), Berrenda en Negro (BN), Pajuna (P) and Cardena (C) cattle breeds was presented at a previous EAAP meeting. The present paper involves 168 BN animals (23 farms), 262 BC animals (25 farms), 14 C animals (1 farm) and 51 P animals (3 farms); 32 DNA markers were used for the genetic studies. Gene flow among the four breeds and farms within breeds was estimated: values for among breeds are low, (3,78 and 3,29) among C and Berrenda (BN and BC); little higher among P and Berrenda (BN and BC) (6,71 and 6,89); lower limits were found ( 2,91)among P and Berrenda (BN and BC) and the highest between BN and BC (18,42). The values obtained are not determinants for farms with the breed, especially for Berrenda cattle breeds (BN and BC). The results agree with previous ethnologic studies about common breed origins and mating systems in populations. The divergence times among the populations studied were obtai...

Reproduction, Fertility and Development, 2021

Reproductive performance is one of the key factors in livestock production. It is well known that... more Reproductive performance is one of the key factors in livestock production. It is well known that reproductive traits are influenced by several genetic factors, such as the increase of individual inbreeding levels, which are associated with changes in sperm motility and shape in several species. In horses, the increase in inbreeding is a common problem because of the reduction in effective population size and the increase in selection intensity observed in several breeds. However, studies assessing the effect of high levels of inbreeding on the sperm quality of stallions are scarce. In the present study, we aimed to determine the effect of increased inbreeding levels and age on the sperm motility patterns of Purebred Spanish horses (PRE). We performed kinetic characterisation of 557 sperm samples of 82 PRE stallions aged between 3 and16 years, using computer-assisted sperm analysis (Androvision™, Minitube). We evaluated 5 parameters in 6 different fields per sample: curved line velo...

Animal, 2020

Reproductive traits have a major influence on the economic effectiveness of horse breeding. Howev... more Reproductive traits have a major influence on the economic effectiveness of horse breeding. However, there is little information available. We evaluated the use of reproductive traits as selection criteria in official breeding programs to increase the reproductive efficiency of breeding studs, analysing 696 690 records from the pedigree data of eight Spanish horse populations, with different breeding purposes. The reproductive parameters studied in both sexes were age at first foaling (AFF), age at last foaling, average reproductive life and generational interval. In the females, the average interval between foaling (AIF) and interval between first and second foaling were also studied. There were clear differences between sexes and breeds, which may be due to management practices, breeding purposes and the status of the populations, rather than to differences in actual physiological conditions. Riding mares were the most precocious (AFF, 1937.64 to 2255.69 days) and had a more inten...

Journal of Animal Breeding and Genetics, 2018

To obtain a sport horse that excels in the highest levels of competition, breeders must take into... more To obtain a sport horse that excels in the highest levels of competition, breeders must take into account certain genetic and environmental factors that could influence the sport horse's performance, such as the rider-horse interaction (RHI). The main aim of this study was to describe this interaction in a genetic model by modelling it in relation to the horse's age. A total of 31,129 sport results from Spanish Sport Horses were used from a total of 1,101 animals evaluated, and these were grouped in three age levels and had been ridden by 606 different riders. Only riders who had ridden more than one horse (and vice-versa) were considered for the analyses. Five linear models with different random effects were analysed according to the covariates, the homogeneity/heterogeneity of the RHI and the relevant residual random effects. The model of best fit was then selected for the genetic evaluation of the animal. In general, models including the RHI effect (M2, M4 and M5) fitted better than the other models, and the best fit was obtained for M4 (with heterogeneous residual variance). The genetic variance increased constantly with age, whereas heritability showed a response on three intervals. This study revealed the varied evolution of the RHI with age, showing the different "plastic abilities" of this relationship.

The Veterinary Journal, 2018

Twin foaling is associated with chimaerism in several domestic species and is recognised in horse... more Twin foaling is associated with chimaerism in several domestic species and is recognised in horses. In this study, 21,097 purebred Spanish (Pura Raza Español) horse births from the 2015 to 2016 breeding season were investigated for chimaerism. Twin foaled and chimaeric individuals were assessed on the basis of foaling records, short-tandem repeat (STR) parentage test results and a sex-linked STR-based technique. Fourteen twin pregnancies with 23 twin foals born alive were identified (0.066% twin foaling prevalence), including five blood chimaeric cases (21.7%; overall prevalence 0.011%), suggesting that this genetic condition is extremely low in horses. Furthermore, no true chimaeras were detected. This is the first large scale study analysing the occurrence of chimaerism in a horse population and the first assessment of twin foaling in purebred Spanish horses.

Animal Genetics, 2017

Chromosomal abnormalities in the sex chromosome pair (ECAX and ECAY) are widely associated with r... more Chromosomal abnormalities in the sex chromosome pair (ECAX and ECAY) are widely associated with reproductive problems in horses. However, a large proportion of these abnormalities remains undiagnosed due to the lack of an affordable diagnostic tool that allows for avoiding karyotyping tests. Hereby, we developed an STR (single-tandem-repeat)based molecular method to determine the presence of the main sex chromosomal abnormalities in horses in a fast, cheap and reliable way. The frequency of five ECAX-Iinked (LEX026, LEX003, TKY38, TKY270 and UCDE0502) and two ECAY-Iinked (EcaYH12 and SRY) markers was characterized in 261 Purebred Spanish Horses to determine the efficiency of the methodology developed to be used as a chromosomal diagnostic tool. All the microsatellites analyzed were highly polymorphic, with a sizeable number of alleles (polymorphic information content > 0.5). Based on this variability, the methodology showed 100% sensitivity and 99.82% specificity to detect the most important sex chromosomal abnormalities reported in horses (chimerism, Turner's syndrome and sex reversal syndromes). The method was also validated with 100% efficiency in 10 individuals previously diagnosed as chromosomally aberrant. This STR screening panel is an efficient and reliable molecular-cytogenetic tool for the early detection of sex chromosomal abnormalities in equines that could be included in breeding programs to save money, effort and time of veterinary practitioners and breeders.

Equine Veterinary Journal, 2016

Background: Longevity/durability is a relevant trait in racehorses. Genetic analysis and knowledg... more Background: Longevity/durability is a relevant trait in racehorses. Genetic analysis and knowledge of factors that influence number of harness race starts would be advantageous for both horse welfare and the equine industry. Objectives: To perform a genetic analysis on harness racing using number of races as a measure of longevity/durability and to identify factors associated with career length in Spanish Trotter Horses (STH). Study design: Longitudinal study. Methods: Performance data (n = 331,970) on the STH population for harness racing at national level between 1990 and 2014 were used. A grouped data model was fitted to assess factors influencing the risk of ending harness racing career and to estimate the heritability and breeding values for total number of harness races starts as an indicator of horses' longevity and durability. The model included sex, age at first race and first start earnings as time-independent effects, and the calendar year, driver, trainer, racetrack category and season of competition as time-dependent effects. Results: Across the whole dataset, the average number of harness races horses achieved in Spain was 54.7 races, and this was associated with the horses' sex, age at first race and first start earnings, calendar year, driver, racetrack category, and season. The heritability estimated (0.17 AE 0.01) for number of harness race starts indicates that a beneficial response to direct genetic selection can be expected. Main limitations: Data on horses' health status were not available. Conclusions: Horses' total number of harness race starts is a promising tool for genetic analysis and the evaluation of racing longevity and durability. The estimated heritability provides evidence to support the application of genetic selection of total career number of races to improve longevity/ durability of STH.

Journal of Animal Breeding and Genetics, 2015

Docility is very important for cattle production, and many behavioural tests to measure this trai... more Docility is very important for cattle production, and many behavioural tests to measure this trait have been developed. However, very few objective behavioural tests to measure the opposite approach &amp;#39;aggressive behaviour&amp;#39; have been described. Therefore, the aim of this work was to validate in the Lidia cattle breed a behavioural linear standardized scoring system that measure the aggressiveness and enable genetic analysis of behavioural traits expressing fearless and fighting ability. Reproducibility and repeatability measures were calculated for the 12 linear traits of this scoring system to assess its accuracy, and ranged from 85.3 and 94.2%, and from 66.7 to 97.9%, respectively. Genetic parameters were estimated using an animal model with a Bayesian approach. A total of 1202 behavioural records were used. The pedigree matrix contained 5001 individuals. Heritability values (with standard deviations) ranged between 0.13 (0.04) (Falls of the bull) and 0.41 (0.08) (Speed of approach to horse). Genetic correlations varied from 0.01 (0.07) to 0.90 (0.13). Finally, an exploratory factor analysis using the genetic correlation matrix was calculated. Three main factors were retained to describe the traditional genetic indexes aggressiveness, strength and mobility.

* Correlaciones entre efectos genéticos directo encima de la diagonal, correlaciones entre efecto... more * Correlaciones entre efectos genéticos directo encima de la diagonal, correlaciones entre efectos genéticos maternos por debajo. Los errores estándar oscilaron entre 0.001 a 0.07 para efecto directo y entre 0.002 a 0.10 para efecto materno.

Livestock Science, 2008

The breeding scheme of Spanish Purebred (SPB) horses includes the selection of dressage performan... more The breeding scheme of Spanish Purebred (SPB) horses includes the selection of dressage performance as a main objective. Specific characteristics of the gaits are required for dressage aptitude and some could be selected for genetically. The gait of 130 SPB horses was recorded on a treadmill at walk (1.7 m/s). Nineteen biokinematic variables were analysed, 18 were directly measured from the

In the breeding program of breeds such as the Pura Raza Español horse, selection by gait quality ... more In the breeding program of breeds such as the Pura Raza Español horse, selection by gait quality is of great interest because of their use for dressage performance. However, biokinematic analyses are expensive and data processing is time consuming. So, indirect measurements related to movement quality are alternatively used for a precocious selection of the animals. The aim of this study is to estimate the genetic correlations between 13 conformation measurements and 16 biokinematic variables at trot (4 linear, 6 temporal and 6 angular) in order to identify objective selection criteria for locomotion ability. A total of 130 Pura Raza Español horses from 24 studs, aged between 4-7 years old, were measured and their biokinematic variables were obtained in experimental conditions on a treadmill. There were 155 significant genetic correlations between conformation and biokinematic traits. Croup length was the most correlated trait with biokinematic variables at trot (16), and croup width was the least correlated one (7). Forelimb length and forelimb duration were the most correlated with conformation measurements (12), whereas minimal angle of carpus was the least correlated one (5). All the conformation measurements were genetically correlated with biokinematic variables, and through these relationships when trotting, a total of 6 body measurements were selected for the indirect and precocious selection of gait quality, which could be included directly or combined in body indices.

Meat Science, 2009

In some areas, horsemeat may be considered as an alternative to beef. And recent studies have sho... more In some areas, horsemeat may be considered as an alternative to beef. And recent studies have shown that it may be positive from a nutritional point of view. However, little research has been done on the effects that influence horse carcass traits and meat quality. Breed effect has been studied by comparing two Spanish local breeds (Burguete and Hispano-Bretón) reared following the same traditional production system (24months old). Some differences between breeds were observed for carcass quality measurements and colour parameters. Proximate composition was generally not affected by breed. Burguete foals had lower SFA and MUFA and higher PUFA than Hispano-Bretón ones. PUFA/SFA ratio from both breeds was higher than 0.4 and CLA levels were similar to those found in ruminants.

Animal Genetic Resources Information, 2006

ResumenLa raza bovina Pajuna es una raza autóctona andaluza que está al borde de la extinción. Su... more ResumenLa raza bovina Pajuna es una raza autóctona andaluza que está al borde de la extinción. Su aptitud es mixta carne-trabajo y es posiblemente la raza española más rústica, al ser capaz de adaptarse a los medios marginados, aprovechando los escasos recursos de las sierras andaluzas, que no pueden ser utilizados por otras razas más carniceras.El cruzamiento indiscriminado con razas especializadas, la mecanización del campo y la pérdida del hábitat de explotación han llevado esta raza a una situación de inminente desaparición, con sólo 300 animales puros, relegados en la mayoría de los casos a meros vientres para el cruce industrial en vacadas mixtas.En el presente artículo describimos la situación actual y las causas que la han llevado a esta situación, así como las actuaciones de la Asociación de Criadores (GRAPA), creada en el año 2001, dentro de un programa de preservación y recuperación. Estas razones se pueden resumir en la localización de todos los efectivos existentes, el ...

El Caballo Trotador Español (CTE) es una raza equina criada específicamente para la disciplina qu... more El Caballo Trotador Español (CTE) es una raza equina criada específicamente para la disciplina que lleva su nombre. Su programa de mejora incluye como objetivo principal la consecución de un animal que destaque tanto en las competiciones nacionales como internacionales, con una conformación que favorezca su funcionalidad y un temperamento que le haga ansiar la victoria (http://www. mapa. es/ganaderia/pags/equino/seleccion/trotador. pdf).

Animal, 2016

Making a morphological pre-selection of Pura Raza Español horses (PRE) for dressage is a challeng... more Making a morphological pre-selection of Pura Raza Español horses (PRE) for dressage is a challenging task within its current breeding program. The aim of our research was to design an early genetic selection morphological linear traits index to improve dressage performance, using 26 morphological linear traits and six dressage traits (walk, trot, canter, submission, general impression – partial scores – and total score) as selection criteria. The data set included morphological linear traits of 10 127 PRE (4159 males and 5968 females) collected between 2008 and 2013 (one record per horse) and 19 095 dressage traits of 1545 PRE (1476 males and 69 females; 12.4 records of average) collected between 2004 and 2014. A univariate animal model was applied to predict the breeding values (PBV). A partial least squares regression analysis was used to select the most predictive morphological linear traits PBV on the dressage traits PBV. According to the Wold Criterion, the 13 morphological lin...

Asian-Australasian Journal of Animal Sciences, 2015

This study assessed the influence of genetic type (Embden-Anser anser, EE; Toulouse-Anser anser, ... more This study assessed the influence of genetic type (Embden-Anser anser, EE; Toulouse-Anser anser, TT and F1 cross, ET) for meat characteristics (carcass, meat quality and fatty acid (FA) profiles), of domestic geese "Anser anser domesticus" raised in dehesa as an alternative, organic feeding system. Carcass and breast muscle weight (p<0.01) were greater for the ET group at the same live weight. None of the groups showed differences in the production of fatty liver with this type of feeding. Higher values were found for maximum Warner-Bratzler shear force (between 7.62 and 8.87 kg/cm 2), which implies the improvement of this parameter. High levels of oleic FAs were obtained, especially for the TT group. The polyunsaturated/saturated FA ratio was highest for the ET group (p<0.001), reflecting the optimum nutritional values as a component of a healthy consumer diet.