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Open Access
Prediction of rabbit meat and bone weight using measurements and sample cuts
(Institut national de la recherche agronomique (França), 1984) Blasco, A.; Estany Illa, Joan; Baselga, M.
Regression equations predicting dissectable muscle weight in rabbits from external measurements were presented. Bone weight and weight of muscle groups were also carcass predicted. Predictive capacity of external measurements, retail cuts and muscle groups on total muscle, percent muscle, total bone and muscle to bone ratio were studied separately. Measurements on dissected retail cuts should be included in ordcr to obtain good equations for prediction of percent muscle in the carcass. Equations for predicting the muscle to bone ratio using external mcasurcments and data from the dissection of one hind leg were suggested. The equations had generally high coefficients of determination. The coefficient of determination for prediction of dissectable muscle was 0.91, and for percent muscle in the carcass 0.79.
Open Access
Selection response of growth rate in rabbits for meat production
(Institut national de la recherche agronomique (França), 1992) Estany Illa, Joan; Camacho, J.; Baselga, M.; Blasco, A.
Genetic and environmental trends in 2 lines of rabbit (B and R) selected on individual weight gain (WG) from weaning (4 wk) to slaughter (11 wk) were estimated using mixed model methodology. Line B was derived from the California breed and line R was a synthetic of stock of different origin. The data were collected from a single herd and comprised 7 718 individuals in line B and 9 391 in line R, the lines having 12 and 9 generations of selection respectively. Realized responses in the 2 lines were 2.7% and 2.2% of the initial mean per year respectively and showed that selection on WG was effective but was less than expected. Selection on slaughter weight (SW) and effects of selection on other economic traits are discussed. It is concluded that selection on either WG or SW is a simple method for improving growth rate in rabbit sire line stocks.
Open Access
Rumen digestion and urinary excretion of purine derivatives in response to urea supplementation of sodium-treated straw fed to sheep
(Cambridge University Press, 1993) Balcells Terés, Joaquim; Guada, J. A.; Castrillo, C.; Gasa, J.
The present study examined the effect of urea-N supplementation of a N-deficient diet on digestion and metabolism in the rumen. Five Rasa Aragonesa ewes, each fitted with a rumen cannula, were offered alkali-treated barley straw ad lib. alone or supplemented continuously via the cannula with four levels of urea-N (3, 6, 9 and 12g/d). Rumen NH, concentrations increased in response to urea infusion (6128 mgfl; P < 0.001). At the highest level of rumen NH, concentration there was a significant increase, compared with the unsupplemented treatment, in dry matter (DM) intake (8461206 g/d; P < 0.001) and apparent digestibility of DM (0.38443), organic matter (0.38-0.45) and neutraldetergent fibre (0.41-0.49; P < 0.01). Rumen outflow rates of particulate matter and potential DM disappearances, assessed using nylon bags, were not affected by the experimental treatments, although fractional rate of DM disappearance increased significantly with increasing levels of urea infusion (2446per h). Urinary excretion of total purine derivatives increased with N supplementation, although the response was exclusively due to an increase in allantoin excretion (26.9-66.4 mg/kg live weight (W)07’ per d; P < 0,001). Xanthine, hypoxanthine and uric acid excretion rates were constant, averaging 1.8 (SE 0.17); 5.4 (SE 0.21) and 7.2 (SE 0.36) mg/kg W07s per d respectively. The maintenance of a minimum rumen NH, concentration (approximately 50 mg/l) was necessary to avoid significant reductions in DM intake and fermentation rate. Higher levels, however, may further increase microbial N flow at the duodenum, as suggested by the response in urinary allantoin excretion over the range of rumen NH, concentrations.
Open Access
Promoció del gos d'atura
(Diputació de Girona, 1994) Vilaró, Teresa; Parés Casanova, Pere-Miquel
Open Access
Endogenous purine and pyrimidine derivative excretion in pregnant sows
(Cambridge University Press, 1995) Martin-Orúe, S. M.; Balcells Terés, Joaquim; Guada, J. A.; Castrillo, C.
The present experiment was camed out to study the endogenous losses of purine and pyrimidine derivatives from pregnant sows. Three pregnant and three non-pregnant Large White x Landrace sows were fed on a purine-free diet composed of starch, glucose, sucrose and vegetable oil, with casein as the protein source. The experiment began, for the six animals, after diagnosis of pregnancy and was divided into six 12 d periods. Urine was collected during the Arst 3 d of each experimental period by means of a urethral catheter for determination of allantoin, uric acid, xanthine, hypoxanthine and pseudouridine concentrations. In the absence of dietary nucleic acids (NA), allantoin and, as a consequence, excretion of total purine derivatives (PD) decreased significantly to a constant value (128.3 (SE 7.07) ,umol/kg metabolic live weight (W"75) per d), an amount assumed to represent endogenous excretion. Excretion of uric acid (38.7 (SE 2-15) mollkg W0'p7e5r d), hypoxanthine (21.0 (SE 2.58) ymollkg W'75 per d) and xanthine (11-2 (SE 0.83) pmol/kg W@" per d) were not affected by the experimental treatment, although there was a significant decrease in hypoxanthine excretion in pregnant sows (from 25.5 to 5.2 pnol/kg W@75 per d) compared with nowpregnant sows (from 26.7 to 44%/rmol/kg W@75p er d). Creatinine excretion was not affected by pregnancy and was used as an internal urinary marker. Purine excretion, either expressed as pmol/kg WoT5 per d or as the ratio PD:creatinine, was not affected by experimental treatment, although an apparent increase in pseudouridine excretion, a modified unsalvageable catabolite of RNA-pyrimidine, was found in late pregnancy (3.6 v. 5.2 mo1/100 mol creatinine in non-pregnant sows compared with pregnant sows at 102 d collection).
Open Access
Un modelo de simulación como herramienta para la ayuda a la toma de decisiones en explotaciones porcinas
(Asociación Interprofesional para el Desarrollo Agrario, 1997) Pla Aragonés, Lluís Miquel; Pomar Gomà, Jesús; Noguera Jiménez, José Luis
Open Access
Selection for litter size components: a critical review
(BioMed Central, 1997) Perez Enciso, Miguel; Bidanel, J. P.
The measurement of component variables such as the number of ova shed (OR) and its inclusion in a linear index with litter size (LS) or prenatal survival has been suggested in order to accelerate genetic progress for LS. Despite optimistic theoretical predictions, however, in no selection experiment has the advantage of including OR in an index as compared to direct selection for LS been convincingly demonstrated. A literature survey shows no clear evidence of changes in genetic parameters with selection. By contrast, genetic drift may suffice to explain the less than expected usefulness of measuring OR, although it is not necessarily the sole cause. It is shown that an approximate figure of how much can be gained by measuring OR relative to direct selection for LS is given by (1+(J!Ls/(J!oR)1/2 with mass selection, where y is the phenotypic variance. Nonetheless, the size of the experiment needed to test this prediction is likely to be very large.
Open Access
Intraspecific variability of the patterns of the locomotory behaviour in terrestrial iberian anurans
(Universitat Autònoma de Barcelona. Departament de Biologia Animal, Biologia Vegetal i Ecologia, 1997) Sanuy i Castells, Delfí
The variability in the locomotory behaviour between different species of anurans -the first vertebrates that are adapted to terrestrial environment- show the adaptive capacity of the different forms shaped by evolution. Each species adapts to the environment in a specific fashion. One uses the locomotory behaviour for measuring the variability of the patterns. The paths of the species effected in the different experimental situations -naturals and in the laboratory- were quantified, obtaining severa1 parameters that define the path. The Coefficient of Variation of the mean of each variable is utilise for measuring the variability. The work shows the difference between variables, as a consequence of the specific locomotory behaviour and its adaptation of the environment. We also show, the different adaptability that exists when the experimental conditions change, and each species adapts itself in a different way. The variability of the pattern is an instrument to know this different adaptability.
Open Access
Aplicación de la lógica difusa en el análisis e interpretación de resultados productivos de explotaciones porcinas
(Asociación Interprofesional para el Desarrollo Agrario, 1997) Pomar Gomà, Jesús; Noguera Jiménez, José Luis
Open Access
Urinary excretion of purine derivatives as an index of microbial-nitrogen intake in growing rabbits
(Cambridge University Press, 1998) Balcells Terés, Joaquim; Ganuza, J. M.; Pérez, J. F.; Martin-Orúe, S. M.; González Ronquillo, Manuel
Three experiments were carried out to establish a response model between intake and urinary excretion of purine compounds. In Expt 1 the relationship between the intake of purine bases (PB) and the excretion of total purine derivatives (PD) was determined in seven growing rabbits with a mean initial live weight (LW) of 2.03 (SE 0.185) kg, aged 70 d, each fitted with a wooden neck collar to prevent caecotrophagy. They were fed on five experimental diets formulated with different levels of nucleic acids (0.00, 3.75, 730, 11.25, 15.00 g yeast-RNA/kg diet). The relationship between intake of purine (x, pmol/kg W"'75) and total urinary PD excretion b, pmol/kg WO"'), y = 0.56 + 0.67~(r 20 .86; RSD 0.338), indicated that about 70 % of duodenal PB were recovered as urinary PD and that the endogenous contribution was constant and independent of dietary PB supply. Endogenous excretion of PD (allantoin and uric acid) was measured in a second experiment using six rabbits fed on a purine-free diet and fitted with neck collars to avoid caecotrophagy. Basal daily urinary excretion values for allantoin and uric acid were 532 (SE 33.9) and 55 (SE 7.3) pmol/kg W0'7' respectively; xanthine and hypoxanthine were not found in urine samples and therefore the sum of allantoin and uric acid should comprise the total excretion of PD (588 (SE 40.1) pmol/kg W0'75). The xanthine oxidase (EC 1.2.3.2) activity in plasma, liver, duodenum, jejunum and kidney was measured in a third experiment. The activities of xanthine oxidase in duodenal and jejunal mucosa, liver and kidney were: 0.61 (SE 0.095), 0.37 (SE 0.045), 0.035 (SE 0.001) and 0 units/g fresh tissue respectively and in plasma 2.96 (SE 0.094) units/l. The results show that urinary excretion of PD may be a useful tool to estimate duodenal PB input and microbial protein intake once the relationship between PB and N has been established in caecal micro-organisms.
Open Access
Analysis of the displacement of five iberian anuran species in stress conditions
(Universitat Autònoma de Barcelona. Departament de Biologia Animal, Biologia Vegetal i Ecologia, 1998) Sanuy i Castells, Delfí
This study describes the movement paths -in situation of stress- of five anuran species (Alytes obstetricans, Pelobates cultripes, Bufo bufo, Bufo calamita and Bufo viridis balearicus) by trajectometric analysis. Different experimental treatments (artificial vs. natural) and seasonal variations were studied. The path structure reflects specific (phyogenetic) constraints. Each species showed a characteristic pattern of locomotion for different experimental situations and seasons.
Open Access
Excretion of endogenous and exogenous purine derivatives in sheep: effect of increased concentrate intake
(Cambridge University Press, 1998) Pérez, J. F.; Balcells Terés, Joaquim; Cebrián, J. A.; Martin-Orúe, S. M.
The present study examined the endogenous urinary excretion of purine derivatives (PD; allantoin, uric acid and xanthine plus hypoxanthine) in fed animals. Four Rasa Aragonesa ewes fitted with simple cannulas in the rumen and proximal duodenum were used. Animals were given a lucerne (Medicago sativa) hay diet, as sole feed (A) or supplemented, respectively, with 220 (B), 400 (C), and 550 (D) g rolled barley grain/d following a 4 x 4 random factorial design. Duodenal flow of purine bases (PB) was determined by the dual-phase marker system. 15N was infused continuously into the rumen to label exogenous or microbial PB. Duodenal PB flow and urinary excretion of PD increased with digestible organic matter intake showing a constant recovery of duodenal PB. The isotope dilution of PD in urine samples confirmed the presence of an endogenous fraction, originating from tissues, that increased from 115.2 (SE 5.84) pmol/kg @ 75 for the basal diet to 304.2 (SE 7.6) pmol/kg @'75 at the highest level of duodenal PB.
Open Access
Effect of selective recording on estimates of heritability
(Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (Espanya), 1999) Alfonso Ruiz, Leopoldo; Noguera Jiménez, José Luis; Babot Gaspa, Daniel; Estany Illa, Joan
En este trabajo se analiza el efecto de la selección de datos sobre las estimaciones de heredabilidad. Se estimó el valor de heredabilidad del tamaño de camada en una población porcina en la que los datos correspondientes a las cerdas más viejas eran una muestra seleccionada. Las estimaciones se obtuvieron usando distintos conjuntos de datos derivados de toda la información disponible. Esos conjunto de datos se compararon evaluando su capacidad predictiva. Se vio que las estimaciones de heredabilidad obtenidas utilizando todos los datos disponibles correspondían a valores infraestimados. También se simuló un carácter materno y se generó un conjunto de datos seleccionados eliminando aquellos correspondientes a las hembras sin padres conocidos. Distintos modelos, habitualmente empleados cuando no existe selección de registros, se consideraron para estimar el valor de heredabilidad. Los resultados mostraron que ninguno de esos modelos ofrecía estimaciones insesgadas. Sólo los modelos que tenían en cuenta el efecto de la selección sobre la media residual y la media y varianza genéticas ofrecían estimaciones poco sesgadas. Sin embargo, para poder aplicarlos se debe conocer la selección realizada. El problema de la selección de datos es difícil de abordar cuando se desconoce cual es el proceso de selección que se ha realizado en una población.
Open Access
An expression of mixed animal model equations to account for different means and variances in the base population
(Institut national de la recherche agronomique (França), 1999) Alfonso Ruiz, Leopoldo; Estany Illa, Joan
This paper presents a general expression to predict breeding values using animal models when the base population is selected, i.e. the means and variances of breeding values in the base generation differ among individuals. Rules for forming the mixed model equations are also presented. A numerical example illustrates the procedure.
Open Access
Computation of identity by descent probabilities conditional on DNA markers via a Monte Carlo Markov Chain method
(BioMed Central, 2000) Perez Enciso, Miguel; Varona Aguado, Luís; Rothschild, Max Frederick
The accurate estimation of the probability of identity by descent (IBD) at loci or genome positions of interest is paramount to the genetic study of quantitative and disease resistance traits. We present a Monte Carlo Markov Chain method to compute IBD probabilities between individuals conditional on DNA markers and on pedigree information. The IBDs can be obtained in a completely general pedigree at any genome position of interest, and all marker and pedigree information available is used. The method can be split into two steps at each iteration. First, phases are sampled using current genotypic configurations of relatives and second, crossover events are simulated conditional on phases. Internal track is kept of all founder origins and crossovers such that the IBD probabilities averaged over replicates are rapidly obtained. We illustrate the method with some examples. First, we show that all pedigree information should be used to obtain line origin probabilities in F2 crosses. Second, the distribution of genetic relationships between half and full sibs is analysed in both simulated data and in real data from an F2 cross in pigs.
Open Access
Estimación de los efectos del manejo reproductivo y su influencia en la selección del tamaño de la camada en porcino
(Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (Espanya), 2000) Babot Gaspa, Daniel; Noguera Jiménez, José Luis; Alfonso Ruiz, Leopoldo; Estany Illa, Joan
Con datos procedentes de poblaciones de campo (37.920 partos porducidos en granjas de selección y 95.240 partos producidos en granjas de producción) se ha analizado la influencia de la edad al primer parto, de la duración de la lactación, de la duración del intervalo destete-cubrición fértil y del tipo de cubrición fértil sobre el número de lechones nacidos vivos por parto (NV). Además, utilizando datos simulados se ha evaluado el interés de considerar estos factores de manejo en el modelo de evaluación genética para NV. Los factores de manejo analizados influyen de forma significativa (P < 0,05) sobre NV, en magnitud y sentido similar en las poblaciones de selección y de producción. Mediante simulación se comprueba que omitir la influencia de los factores de manejo anteriores en el modelo de evaluación genética no interfiere en la respuesta a la selección, aunque puede conducir a la obtención de predictores sesgados del valor genético.
Open Access
Variación de peso y aporte energético del pasto en vacas de cría en condiciones de montaña: efecto de la época de parto
(Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (Espanya), 2001) Casasús Pueyo, Isabel; Sanz Pascua, Albina; Villalba Mata, Daniel; Bernués, A.; Ferrer, R.; Revilla, Ricardo
Se analizaron las variaciones de peso durante la estación de pastoreo de vacas multíparas de raza Parda Alpina con partos en otoño (n = 152) o primavera (n = 123) durante el período 1989-1996. Los animales pasta- ron en áreas boscosas (900-1.500 m, 0,2 vacas/ha) y en pastos supraforestales (1.500-2.200 m, 1,2 vacas/ha). Las vacas con parto en otoño presentaron mayores recuperaciones de peso en pastoreo que las de primavera (0,661 vs 0,071 kg/día, P < 0,001), diferencia observada tanto en los pastos forestales como en los supraforestales. Las variaciones de peso en pastoreo se relacionaron negativamente con las observadas en estabulación (r = –0,20, P < 0,05) y también con el peso a la salida al pasto (r = –0,32, P < 0,05). La contribución energética del pasto a los aportes recibidos anualmente de la dieta fue similar en ambas parideras (43,6 p. 100 y 42,2 p. 100 en otoño y primavera, respectivamente, NS), aunque la pauta de reparto de la energía hacia las funciones fisiológicas en los distintos períodos de manejo fue diferente.
Open Access
Hypothesis testing for the genetic background of quantitative traits
(BioMed Central, 2001) García Cortés, Luis Alberto; Cabrillo, Carlos; Moreno, Carlos; Varona Aguado, Luís
The testing of Bayesian point null hypotheses on variance component models have resulted in a tough assigmment for which no clear and generally accepted method exists. In this work we present what we believe is a succeeding approach to such a task. It is based on a simple reparameterization of the model in terms of the total variance and the proportion of the additive genetic variance with respect to it, as well as on the explicit inclusion on the prior probability of a discrete component at origin. The reparameterization was used to bypass an arbitrariness related to the impropriety of uninformative priors onto unbounded variables while the discrete component was necessary to overcome the zero probability assigned to sets of null measure by the usual continuous variable models. The method was tested against computer simulations with appealing results.
Open Access
Bayes factors for detection of quantitative trait loci
(BioMed Central, 2001) Varona Aguado, Luís; García Cortés, Luis Alberto; Perez Enciso, Miguel
A fundamental issue in quantitative trait locus (QTL) mapping is to determine the plausibility of the presence of a QTL at a given genome location. Bayesian analysis offers an attractive way of testing alternative models (here, QTL vs. no-QTL) via the Bayes factor. There have been several numerical approaches to computing the Bayes factor, mostly based on Markov Chain Monte Carlo (MCMC), but these strategies are subject to numerical or stability problems. We propose a simple and stable approach to calculating the Bayes factor between nested models. The procedure is based on a reparameterization of a variance component model in terms of intra-class correlation. The Bayes factor can then be easily calculated from the output of a MCMC scheme by averaging conditional densities at the null intra-class correlation. We studied the performance of the method using simulation. We applied this approach to QTL analysis in an outbred population. We also compared it with the Likelihood Ratio Test and we analyzed its stability. Simulation results were very similar to the simulated parameters. The posterior probability of the QTL model increases as the QTL effect does. The location of the QTL was also correctly obtained. The use of meta-analysis is suggested from the properties of the Bayes factor.
Open Access
Relación entre el nivel de grasa e ingestión y la excreción urinaria de nitrógeno y energía, en gazapos en crecimiento-cebo
(Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (Espanya), 2001) Sanz Parejo, Emiliano; Surra Muñoz, Joaquin; Obiols i Vilamú, J. M.; Seguí i Parpal, Antoni
Se determinó la excreción urinaria de nitrógeno (NU, %) y de energía (EU, kcal/100g), en la última semana de vida, de 36 conejos alimentados, desde el destete (a los 28 d) hasta el sacrificio a los dos meses de edad, con tres piensos conteniendo 0, 3 y 6 % de grasa añadida (G0, G3 y G6); y administrados a dos niveles de ingestión: ad libitum (IL) y restringido (IR) al 70 % de IL. El NU y la EU estuvieron influidos positivamente tanto por el nivel de ingestión (P<0,001) como por el % de grasa ingerida (P<0,05). En estos resultados puede estar involucrado el metabolismo tan elevado de las lipoproteínas transportadoras de lípidos, implicadas en el metabolismo de las grasas, ya sean de origen alimentario o de la lipogénesis de novo. La relación entre la EU y el NU aporta valores muy superiores a los que podría corresponder a las materias orgánicas nitrogenadas, por lo que se podría pensar, como posible causa, en la intervención de materia orgánica no nitrogenada. Asimismo, la cuantificación de la EM del pienso se ve afectada por el incremento del valor calórico de la orina, con el nivel de ingestión y/o el 6 % de grasa añadida. Con ello se evidencia la desigualdad entre ED y EM de la grasa en las raciones que las incluya. Asimismo, el hecho de que la movilización grasa —bien sea de origen alimentario o de la lipogénesis— altere la excreción nitrogenada y/o energética a través de la orina, pone de manifiesto la importancia de su consideración, especialmente cuando dicha pérdida puede afectar a los rendimientos de algunas producciones animales.