Individual efficiency for the use of feed resources in rabbits

A Bayesian procedure, which allows consideration of the individual variation in the feed resource allocation pattern, is described and implemented in 2 sire lines of rabbit (Caldes and R). The procedure is based on a hierarchical Bayesian scheme, where the first stage of the model consists of a multiple regression model of feed intake on metabolic BW and BW gain. In a second stage, an animal model was assumed including batch, parity order, litter size, and common environmental litter effects. Animals were reared during the fattening period (from weaning at 32 d of age to 60 d of age) in individual cages on an experimental farm, and were fed ad libitum with a commercial diet. Body weight (g) and cumulative feed intake (g) were recorded weekly. Individual BW gain (g) and average BW (ABW, g) were calculated from these data for each 7-d period. Metabolic BW (g(0.75)) was estimated as ABW(0.75). The number of animals actually measured was 444 and 445 in the Caldes and R lines, respectively. Marginal posterior distributions of the genetic parameters were obtained by Gibbs sampling. Posterior means (posterior SD) for heritabilities for partial coefficients of regression of feed intake on metabolic BW and feed intake on BW gain were estimated to be 0.35 (0.17) and 0.40 (0.17), respectively, in the Caldes line and 0.26 (0.19) and 0.27 (0.14), respectively, in line R. The estimated posterior means (posterior SD) for the proportion of the phenotypic variance due to common litter environmental effects of the same coefficients of regression were respectively, 0.39 (0.14) and 0.28 (0.13) in the Caldes line and 0.44 (0.22) and 0.49 (0.14) in line R. These results suggest that efficiency of use of feed resources could be improved by including these coefficients in an index of selection.     

Full pedigree quantitative trait locus analysis in commercial pigs using variance components

In commercial livestock populations, QTL detection methods often use existing half-sib family structures and ignore additional relationships within and between families. We reanalyzed the data from a large QTL confirmation experiment with 10 pig lines and 10 chromosome regions using identity-by-descent (IBD) scores and variance component analyses. The IBD scores were obtained using a Monte Carlo Markov Chain method, as implemented in the LOKI software, and were used to model a putative QTL in a mixed animal model. The analyses revealed 61 QTL at a nominal 5% level (out of 650 tests). Twenty-seven QTL mapped to areas where QTL have been reported, and eight of these exceeded the threshold to claim confirmed linkage (P < 0.01). Forty-two of the putative QTL were detected previously using half-sib analyses, whereas 46 QTL previously identified by half-sib analyses could not be confirmed using the variance component approach. Some of the differences could be traced back to the underlying assumptions between the two methods. Using a deterministic approach to estimate IBD scores on a subset of the data gave very similar results to LOKI. We have demonstrated the feasibility of applying variance component QTL analysis to a large amount of data, equivalent to a genome scan. In many situations, the deterministic IBD approach offers a fast alternative to LOKI.     

Quantitative trait locus mapping for meat quality traits in an Iberian x Landrace F2 pig population

An experimental F2 cross between Iberian and Landrace pig strains was performed to map quantitative trait loci (QTL) for diverse productive traits. Here we report results for meat quality traits from 369 F2 animals with records for pH 24 h postmortem (pH 24 h), muscle color Minolta measurements L* (lightness), a* (redness), and b* (yellowness), H* (hue angle), C* (chroma), intramuscular fat (IMF) and haematin pigment content measured in the longissimus thoracis. Pigs were genotyped for 92 markers covering the 18 porcine autosomes (SSC). Results of the genome scan show evidence for QTL for IMF (SSC6; F = 27.16), pH 24 h (SSC3; F = 7.73), haematin pigments (SSC4 and SSC7; F = 8.68 and 9.47 respectively) and Minolta color measurements L* (SSC4 and SSC7; F =16.42 and 7.17 respectively), and a* (SSC4 and SSC8; F = 8.05 and 7.36 respectively). No QTL were observed for the color measurements b*, H*, and C*. Alternative models fitting epistasis between QTL were also tested, but detected epistatic interactions were not significant at a genome-wise level. In this work we identify genomic regions related with meat quality traits. Improvement by traditional selection methods is complicated, and finer mapping would be required for their application in introgression programs.     

Testing genetic determinism in rate of hoof growth in pigs using Bayes Factors

Excessive growth and consequent deformity of hooves is a frequent disorder in some purebred pig populations. A test to detect possible genetic determinism related with this phenomenon was performed using the Bayes Factor (BF). Data were available for females from three purebred selection lines: Landrace (561 records), Pietrain (183) and Large White (225). Animals were scored in four categories, according to the overall growth rate of their hooves. A Bayesian analysis was performed separately for each line using a threshold model with a probit approach, and Bayes Factors between models with and without additive genetic effects were computed. Results from the three lines showed that models exhibiting genetic variability were much more probable than those that did not include a genetic component, with BF values of 312, 35 and 40 (and posterior probabilities of 0.99, 0.97 and 0.98), respectively, for the Landrace, Pietrain and Large White lines. Monte Carlo estimates of posterior means of heritabilities were medium to high (0.25, 0.41 and 0.38, respectively), and the highest posterior density region for heritability at 99% did not include zero in any of the three lines. These results allow us to conclude that genetic determinism has an important influence upon the rate of hoof growth in the pig. A potential genetic response can be achieved in the populations analysed, but further studies are needed to determine the genetic architecture of hoof growth disorders in pigs.     

Study of nickel sorption onto biological sludges. possibilities for heavy metals removal treatments

Nickel adsorption onto a sludge wasting from a biological aeration tank is described in this work. This procedure is planned as an alternative method for metal removal from industrial effluents containing heavy metals in low concentrations. Experimental results of equilibrium adsorption and laboratory equipment operation are reported. Equilibrium data of nickel adsorption were fitted to the Freundlich equation. On the basis of this equation, the effect of several parameters such us metal concentration, sludge concentration and metal dosing rate were tested. Nickel removal efficiency is about 80% in the most favourable cases. Aeration during metal-sludge contact was also tested but little enhancing in metal uptake was observed. This analysis can be used to define the best operation conditions in practical cases either for metal or organic matter removal.     

Bayesian analysis of quantitative trait loci for boar taint in a Landrace outbred population

The genetic basis of the main components of boar taint was investigated in intact male pigs in a commercial population. We analyzed fat androsten-one and skatole concentrations from 217 males of an outbred Landrace population. Records were normalized using a logarithm transformation and tested for normality using a Wilk-Shapiro test. Bayesian analysis was then used to map QTL in 10 candidate regions previously selected on chromosomes 1, 2, 3, 4, 6, 7, 8, 9, 10, and 13. The criterion for QTL detection was the Bayes factor (BF) between polygenic models with and without QTL effects. Both traits had considerable genetic determination, with posterior means of total heritabilities ranging from 0.59 to 0.73 for androstenone and from 0.74 to 0.89 for skatole. Positive evidence for a fat skatole QTL was detected on SSC6 (BF = 5.16); however, no QTL for androstenone were found in any of the 10 chromosomal regions analyzed. With the detection of a QTL for the fat skatole concentration segregating in this population, marker-assisted selection or even gene-assisted selection could be used once the causal mutation of the QTL was identified.     

Identification of carcass and meat quality quantitative trait loci in a Landrace pig population selected for growth and leanness

The identification of QTL related to production traits that are relevant for the pig industry has been mostly performed by using divergent crosses. The main objective of the current study was to investigate whether these growth, fatness, and meat quality QTL, previously described in diverse experimental populations, were segregating in a Landrace commercial population selected for litter size, backfat thickness, and growth performance. We have found QTL for carcass weight (posterior P > 0.75), cutlet weight (posterior P > 0.99), weight of ham (posterior P > 0.75), shoulders weight (posterior probability > 0.99), and shear firm-ness (posterior P > 0.99) on pig Chromosome 2. Moreover, QTL with posterior P > 0.75 for fat thickness between the 3rd and 4th ribs (Chromosome 7), rib weights (Chromosome 8), backfat thickness (Chromosomes 8, 9, and 10), and b Minolta color component (Chromosome 7) were identified. These results indicate that commercial purebred populations retain a significant amount of genetic variation, even for traits that have been selected for many generations.     

Viability of Iberian x Meishan F2 newborn pigs. II. Survival analysis up to weaning

Iberian x Meishan F2 piglet's preweaning survivability was analyzed using categorical data regression procedures within the proportional hazards assumption. A frailty sire model was assumed with the litter effect treated as an additional random source of variation. Moreover, the relative birth weight within litter and the litter effect were considered time-dependent covariates that changed their values in the second day of life due to cross fostering carried out to standardize litters. Six variables had a significant effect on survivability: birth weight (P < 0.01), relative birth weight within litter (P < 0.001), rectal temperature 60 min after birth (P < 0.01), type of presentation at birth (P < 0.05), presence of stillbirths (P < 0.001), and presence of mummified fetuses (P < 0.001). Small piglets (<0.98 kg) suffered a high hazard ratio (6.57; P < 0.001), with this variable being clearly lower for the rest of birth weight categories. Piglets that were small in relation to their siblings (relative birth weight within litter) also suffered an increased death risk, with a hazard ratio of 1.81 (P < 0.05), which was similar to animals with posterior presentations at birth (hazard ratio = 1.80; P < 0.05). Piglets with a rectal temperature lower than 35.4 degrees C 60 min after birth showed the highest hazard ratio (7.18; P < 0.01). Furthermore, the presence of mummified fetuses decreased the survivability of the remaining siblings, with a hazard ratio of 2.03 (P < 0.01), as did the presence of stillbirths (hazard ratio = 3.55; P < 0.001). The inclusion of the two random effects allowed us to estimate the mode of the joint posterior density of the sire variance (0.08) and the litter variance (1.98). The estimated heritability of preweaning survival reached a value of 0.03. We conclude that piglet survival involves several systematic influences related to birth weight, thermoregulatory ability, and injuries suffered during gestation and farrowing. The genetic variance was small compared with those generated by the common environment, for which the genetic improvement of piglet survival seems difficult.     

Adipocyte fatty-acid binding protein is closely associated to the porcine FAT1 locus on chromosome 4

We identified 22 polymorphisms in the adipocyte fatty-acid binding protein (FABP4) gene, a strong positional candidate gene for the FAT1 locus in porcine chromosome 4. The most informative polymorphism, an insertion/deletion in intron 1, together with a single nucleotide polymorphism in intron 3, was genotyped in a cross between Iberian and Landrace pigs. After performing QTL, single marker, and haplotype analyses, we showed that there were at least 2 quantitative trait genes in the FAT1 region and that the FABP4 polymorphism was tightly associated to fatness. A comparison of allelic frequencies in a panel of pig breeds suggested that the Del2634C polymorphism was under indirect selection. We also showed that FABP4 is tightly associated to fatness but not growth. Furthermore, a haplotype analysis suggests that there is genetic heterogeneity at the FAT1 locus within the Landrace breed.     

Comparative study of equine bone marrow and adipose tissue-derived mesenchymal stromal cells

Reasons for performing study: Mesenchymal stromal cells (MSCs) represent an attractive source for regenerative medicine. However, prior to their application, fundamental questions regarding molecular characterisation, growth and differentiation of MSCs must be resolved. Objectives: To compare and better understand the behaviour of equine MSCs obtained from bone marrow (BM) and adipose tissue (AT) in culture. Methods: Five horses were included in this study. Proliferation rate was measured using MTT assay and cell viability; apoptosis, necrosis and late apoptosis and necrosis were evaluated by flow cytometry. The mRNA expression levels of 7 surface marker genes were quantified using RT‐qPCR and CD90 was also analysed by flow cytometry. Differentiation was evaluated using specific staining, measurement of alkaline phosphatase activity and analysis of the mRNA expression. Results: High interindividual differences were observed in proliferation in both cell types, particularly during the final days. Statistically significant differences in viability and early apoptosis of cultured AT‐ and BM‐MSCs were found. The highest values of early apoptosis were observed during the first days of culture, while the highest percentage of necrosis and late apoptosis and lowest viability was observed in the last days. Surface marker expression pattern observed is in accordance to other studies in horse and other species. Osteogenic differentiation was evident after 7 days, with an increasing of ALP activity and mRNA expression of osteogenic markers. Adipogenic differentiation was achieved in BM‐MSCs from 2 donors with one of the 16 media tested. Chondrogenic differentiation was also observed. Conclusions: Proliferation ability is different in AT‐MSCs and BM‐MSCs. Differences in viability and early apoptosis were observed between both sources and CD34 was only found in AT‐MSCs. Differences in their osteogenic and adipogenic potential were detected by staining and quantification of specific tissue markers. Potential relevance: To provide data to better understand AT‐MSCs and BM‐MSCs behaviour in vitro.