Selecting optimal hyperspectral bands to discriminate nitrogen status in durum wheat: a comparison of statistical approaches.

Hyperspectral data can provide prediction of physical and chemical vegetation properties, but data handling, analysis, and interpretation still limit their use. In this study, different methods for selecting variables were compared for the analysis of on-the-ground hyperspectral signatures of wheat grown under a wide range of nitrogen supplies. Spectral signatures were recorded at the end of stem elongation, booting, and heading stages in 100 georeferenced locations, using a 512-channel portable spectroradiometer operating in the 325-1075-nm range. The following procedures were compared: (i) a heuristic combined approach including lambda-lambda R(2) (LL R(2)) model, principal component analysis (PCA), and stepwise discriminant analysis (SDA); (ii) variable importance for projection (VIP) statistics derived from partial least square (PLS) regression (PLS-VIP); and (iii) multiple linear regression (MLR) analysis through maximum R-square improvement (MAXR) and stepwise algorithms. The discriminating capability of selected wavelengths was evaluated by canonical discriminant analysis. Leaf-nitrogen concentration was quantified on samples collected at the same locations and dates and used as response variable in regressive methods. The different methods resulted in differences in the number and position of the selected wavebands. Bands extracted through regressive methods were mostly related to response variable, as shown by the importance of the visible region for PLS and stepwise. Band selection techniques can be extremely useful not only to improve the power of predictive models but also for data interpretation or sensor design.

Genetic structure of Eurasian and North American mallard ducks based on mtDNA data.

To elucidate the origin and genetic structure of the domesticated duck in Eurasia and North America, we sequenced 114 duck D-loop sequences and retrieved 489 D-loop sequences from GenBank. In total, 603 ducks including 50 duck breeds/populations from eight countries (China, France, Russia, India, Kazakhstan, Mongolia, Thailand and USA) were used in this study. One hundred and thirty-four haplotypes and 81 variable sites were detected. H49 was the predominant haplotype, which was considered to be the same dominant haplotype found in the previous studies, and was found in 309 birds. The smallest values for both genetic differentiation index (F(ST), 0.04156) and the number of the net nucleotide substitutions between two populations (D(A), 0.00018) were observed between Eurasian domestic ducks and Eurasian mallards. No geography, breed or population clusters were observed in the Eurasian domestic ducks and mallards. Five haplotypes were shared by USA mallards and Eurasian domestic duck/Eurasian mallards. Only one haplotype (H49) was shared by Eurasian domestic ducks and China spot-billed ducks. By combining phylogenetic analyses, haplotype network profile, genetic distances and shared haplotypes, we can draw two major conclusions: (i) Eurasian and North American mallards show a clear geographic distribution pattern; (ii) Eurasian domestic ducks are derived from the Eurasian mallards, not from the spot-billed ducks.

Feed efficiency in the laying duck: appropriate measurements and genetic parameters.

The objective of this study was to characterize residual feed intake (RFI) in common laying ducks by a) adjusting position and duration of the measurement period and b) estimating genetic parameters of RFI. The feed intake (FI), BW, and egg mass laid (EML) were recorded for 64 I444 common ducks at the beginning (-35 wk of age) and the middle (41-48 wk of age) of the laying curve. Much feed wastage was observed at the beginning of the laying curve and led to biased FI data. However, when laying was well-established, weekly and fortnightly FI measurements were well correlated phenotypically (Rp from 0.84 to 0.92 and from 0.91 to 0.94, respectively for weekly and fortnightly FI) with the measurements over the whole 2-mo period. Regarding egg mass laid, phenotypic correlations between the one-week measurements and the measurements over the whole 2-mo period were more variable than those for FI, ranging from 0.74 to 0.94, and similar to whatever was the period of measurement. The RFI was investigated in a second experiment based on 384 common female ducks, for which FI, EML, BW, and BW gain were recorded at 39 wk of age. The RFI was determined by multiple regression of FI on metabolic BW and EML. Heritability values of FI and RFI were 0.34 and 0.24, respectively. In addition, if the heritability values obtained for BW (0.65) and BW gain (0.09) were consistent with studies in chickens, the very low EML estimates (0.06) were unexpected. The RFI was strongly genetically linked to FI (Rg = +0.89) but appeared to be independent from BW. Selection based on RFI should therefore reduce the FI of animals without clearly modifying the other components. Moreover, the correlated responses on reproductive traits seem favorable because lower RFI values increase the number of eggs produced per year as well as the hatchability and fertility rates.

Estimation of genetic parameters and genome scan for 15 semen characteristics traits of Holstein bulls.

A QTL detection experiment was performed in French dairy cattle to search for QTL related to male fertility. Ten families, involving a total of 515 bulls, were phenotyped for ejaculated volume and sperm concentration, number of spermatozoa, motility, velocity, percentage of motile spermatozoa after thawing and abnormal spermatozoa. A set of 148 microsatellite markers were used to realize a genome scan. First, genetic parameters were estimated for all traits. Semen production traits were found to have moderate heritabilities (from 0.15 to 0.30) while some of the semen quality traits such as motility had high heritabilities (close to 0.60). Genetic correlations among traits showed negative relationships between volume and concentration and between volume and most quality traits such as motility or abnormal sperm while correlations between concentration and these traits were rather favourable. Percentages of abnormal sperm were negatively related to quality traits, especially with motility and velocity of spermatozoa. Three QTL related to abnormal sperm frequencies were significant at p < 0.01. In total, 11 QTL (p < 0.05) were detected. However, the number of QTL detected was within the range of expected false positives. Because of the lack of power to find QTL in this design further analyses are required to confirm these QTL.

Evaluating energy efficiency of site-specific tillage in maize in NE Italy.

This paper examine the efficiency of energy use of three conservation tillage practices (SST - sub-soil tillage; MT - minimum tillage; and NT - no tillage) performed within two management zones, previously identified in a field according to the stability of yield variability. Experiments were carried out in 2003 in NE Italy, on a farm near Rovigo, on a 8-ha field with clay soil, in maize (Zea mays, L.). The purpose of the paper is (i) to investigate the energy variability due to these tillage practices performed spatially within two management zones and (ii) to analyze the long-term energetic efficiency for each tillage practice. The energy balance was highest for SST with respect to MT and NT, due to labor and fuel consumption rates. The energy balance was influenced by the spatial pattern of yield, with appreciable differences between practices in terms of both the conversion index of energy for tillage (9.0, 12.6 and 22.8GJha(-1) for SST, MT and NT, respectively) and the energy use efficiency for tillage (8.0, 11.6, 21.8GJha(-1) for SST, MT and NT, respectively). Based on the simulated data and the calibration results, SALUS model proved to be a good tool for analyzing long-term effects of tillage practices on yield. The NT treatment showed the best efficiency over years, due to the low inputs in comparison with the output level.

Experimental Chagas disease in Balb/c mice previously vaccinated with T. rangeli. II. The innate immune response shows immunological memory: reality or fiction?

Trypanosoma cruzi is a real challenge to the host's immune system, because it requires strong humoral and cellular immune response to remove circulating trypomastigote forms, and to prevent the replication of amastigote forms in tissues, involving many regulator and effector components. This protozoan is responsible for Chagas disease, a major public health problem in Latinamerica. We have developed a model of vaccination with Trypanosoma rangeli, a parasite closely related to T. cruzi, but nonpathogenic to humans, which reduces the infectiousness in three different species of animals, mice, dogs and guinea pigs, against challenge with T. cruzi. In a previous work, we demonstrated that mice vaccinated with T. rangeli showed important soluble mediators that stimulate phagocytic activity versus only infected groups. The aim of this work was to study the innate immune response in mice vaccinated or not with T. rangeli. Different population cells and some soluble mediators (cytokines) in peritoneal fluid and plasma in mice vaccinated-infected and only infected with T. cruzi were studied. In the first hours of challenge vaccinated mice showed an increase of macrophages, NK, granulocytes, and regulation of IL6, IFNγ, TNFα and IL10, with an increase of IL12, with respect to only infected mice. Furthermore an increase was observed of Li T, Li B responsible for adaptative response. Finally the findings showed that the innate immune response plays an important role in vaccinated mice for the early elimination of the parasites, complementary with the adaptative immune response, suggesting that vaccination with T. rangeli modulates the innate response, which develops some kind of immunological memory, recognizing shared antigens with T. cruzi. These results could contribute to the knowledge of new mechanisms which would have an important role in the immune response to Chagas disease.

Immune response and Trypanosoma cruzi infection in Trypanosoma rangeli-immunized mice.

The capacity of Trypanosoma rangeli antigens to induce immune response in mice was analyzed and the course of the infection was studied in immunized animals challenged with virulent forms of T. cruzi. BALB/c mice were immunized with supernatant of disrupted epimastigotes of T. rangeli and with epimastigotes (EPI) of T. rangeli fixed with glutaraldehyde. Both of the antigens were emulsified with incomplete Freund's adjuvant (IFrAdj). All of the animals received T. cruzi Tulahuen antigens in the footpad and the skin reactivity was later studied. The mice that received EPI with or without IFrAdj showed significantly higher skin reactivity than controls, both in Arthus (3 hr) and delayed type hypersensitivity (24 hr) reactions. Furthermore, the mice immunized with T. rangeli developed antibodies against T. cruzi detectable through hemagglutination and immunofluorescence tests. When the animals were challenged with trypomastigotes of T. cruzi, only the groups immunized with EPI-IFrAdj had significantly lower parasitemias and greater survival against infection than controls. These results suggest that T. rangeli can induce humoral and cellular immune response against T. cruzi and attenuate the acute period of the infection produced by this parasite. This is the first time that partial resistance to T. cruzi in T. rangeli-immunized mice is reported. These findings may provide a useful tool for future studies directed at the immunoprevention of Chagas' disease.

Pharmacokinetic comparison of 120-hour infusion versus hyperfractionated oral administration of idarubicin.

The aim of this study was to compare the pharmacokinetics of idarubicin (IDA) and its active metabolite idarubicinol (IDOL) after chronic oral and continuous intravenous (i.v.) IDA administration in order to establish the oral doses needed to reach the i.v. equiactive plasma drug exposure. The pharmacokinetic profile of IDA and IDOL was investigated in 23 patients receiving 12 mg/m2 IDA by 120-h i.v. infusion (2.4 mg/m2/day) combined with cyclophosphamide, etoposide and prednisone in comparison to 28 patients receiving oral IDA doses ranging from 2 to 10 mg/day for 21 days in a phase I study. We found that IDA AUC24h/dose/m2 was 4.7-fold greater during i.v. than oral administration, whereas IDOL AUC24h/dose/m2 was only about 2-fold higher after i.v. administration. The metabolic ratio between IDOL AUC24h and IDA AUC24h in plasma was about 3-fold higher after oral administration. Based on these results we were able to estimate that equiactive plasma drug exposure was reached with an approximately 2.5-fold greater oral dose/m2 of IDA than the corresponding i.v. dose.

DL-alpha-difluoromethylarginine inhibits intracellular Trypanosoma cruzi multiplication by affecting cell division but not trypomastigote-amastigote transformation.

DL-alpha-difluoromethylarginine (DFMA), a specific, irreversible inhibitor of arginine decarboxylase (ADC), decreases the capacity of Trypanosoma cruzi to invade and multiply within different types of mammalian host cells in vitro. In this work we found that inhibition of intracellular growth results from selective impairment of amastigote division without appreciable alteration of the capacity of the invading trypomastigotes to transform into the replicative amastigote form. Addition of agmatine, the product of arginine decarboxylation, reversed the inhibitory effect of DFMA. Inhibition of ornithine decarboxylase activity by DL-alpha-difluoromethylornithine present in the medium prior to and during infection did not affect trypomastigote transformation or amastigote replication and did not change the magnitude of the inhibitory effect of DFMA on parasite multiplication. Hence, neither polyamine synthesis via the ornithine decarboxylase pathway nor salvage of host cell polyamines by T. cruzi appeared to be a likely explanation for the normal rate of parasite transformation that was seen in the presence of DFMA. Two clones of T. cruzi, TMSU-1 and TMSU-2, were tested for their degrees of sensitivity to the inhibitory effects of DFMA. Both trypomastigote association with (i.e., binding to and penetration of) myoblasts, and intracellular amastigote multiplication by either clone were found to be significantly (P less than 0.05) but not completely inhibited by DFMA. Therefore, the partial inhibition of T. cruzi infectivity and replication caused by DFMA is unlikely to represent a composite of effects of the drug on DFMA-sensitive and insensitive clones.(ABSTRACT TRUNCATED AT 250 WORDS)

[Chagas disease. Serologic response to crude and semipurified T. cruzi antigens in different clinical groups of patients]. / Enfermedad de Chagas. Reactividad serológica hacia antígenos crudos y semipurificados del T. cruzi en distintos grupos clínicos de pacientes.

The immune response of people infected by the protozoan parasite Trypanosoma cruzi varies in indeterminate or chronic periods of infection, according to the course of the disease. Apparently, the antibody pattern is different in asymptomatic patients than in patients with cardio-myopathy. The study of those differences for clinical purposes depends on the availability of adequate antigenic preparations. We studied the behavior of crude and partially purified antigens of T. cruzi in acute and chronically infected patients. The level of total antibodies was measured by conventional serology (indirect immunofluorescence, IF, and indirect hemagglutination, HA) and the level of antibodies against different fractions of antigens obtained by analytical chroma-tofocusing, by using enzymatic immunoassay (ELISA). Chronic patients were classified according to Kuschnir et al. in: Group 0 (G0) or Group 1 (G1) according to the absence or presence of electrocardiographic alterations. In acute patients, conventional serology was negative in most cases. However, the ELISA performed with the soluble fraction of the lysate of parasites, showed positive results in 60% of patients. By classical serology, the behavior of chronic patients sera was different in the two groups when assayed by IF; G1 showing more elevated titles than G0. On the other hand, by HA the results were similar in both groups. When the sera were studied by ELISA using the different fractions, the fraction collected at pH 4-4.5, named F IV, detected distinct reactivity in some of, but not in all, the patients of G1. In that subgroup, the highest ELISA indes (optical density of sera vs OD of negative controls) was observed. By associating IF plus FIV-ELISA the results became more apparent: 22% of sera showed titles by IF equal or more than 1:128 and ELISA index equal or more than 3.5, whereas only 2% of G0 showed this characteristic and all the sera with index equal or more than 4 belonged to G1. With lesser antibody titles it was not possible to differentiate between the two groups. It can be concluded that the study of the pattern of antibodies by using different antigens and serological methodologies can offer useful information in the different periods of Chagas disease, by adding the higher sensitivity of methods using crude antigens with the more specific and discriminative results obtained by the use of purified or synthetic antigens.

[Neonatal Chagas disease: laboratory diagnosis during the first year of life]. / Enfermedad de Chagas neonatal. Diagnóstico de laboratorio en el primer año de vida.

This paper describes the parasitologic and serologic studies carried out during the first year of life in 721 pediatric patients born to mothers serologically positive for Chagas disease. The search for circulating trypomastigotes was performed by Strout, blood culture and/or Xenodiagnosis. In some cases, amastigotes were also detected in placenta and umbilical cord. Complement fixation test, indirect hemagglutination and indirect immunofluorescence were used to detect Trypanosoma cruzi antibodies. The dosage of total Ig by single radial immunodiffusion was also carried out. The results obtained showed an absolute correlation between parasite detection and the persistence of antibodies after six months of life. In the first group (GI) formed by 8 children, the diagnosis of congenital infection could not be confirmed because the isolation of T. cruzi was obtained only in later studies. In another 8 children grouped in GIII, it was impossible to detect parasitemia, and the diagnosis was reached by the serological positivity after six months of life. Finally, in 684 patients with anti-T. cruzi antibodies at birth, the serology became negative at the age of 3 months (GIV) or 6 months (GV). The methodology employed in this work is accessible to laboratories of medium complexity, and permits the diagnosis of congenital or neonatal chagasic infection with a high degree of reliability. On the other hand, it avoids unnecessary administration of trypanomicide drugs in a number of newborn and infants who have only received maternal antibodies at birth and were not infected by T. cruzi.

Exoantigens of Trypanosoma cruzi. II. Physicochemical properties.

This paper describes the characterization assays of exoantigens of Trypanosoma cruzi. Plasma of acutely infected BALB/c mice was used as source of exoantigens. The antigenic activity was heat stable, soluble in 10% trichloroacetic acid and sensible to sodium metaperiodate. The treatment with neuraminidase did not affect the antigenic activity demonstrable by counterimmunoelectrophoresis with rabbit serum to total homogenate of culture forms of T. cruzi. The treatment with trypsin did not eliminate the precipitating activity of exoantigen, but it caused the breakdown of the molecule, as may be inferred from its behaviour in Sephacryl S 200. These results suggest that exoantigen is composed of peptide and carbohydrate moieties, with the epitopes located in the sugar moieties. It seems that sialic acid is not involved in the active part of the molecule. The molecular weight of exoantigen was estimated at 200 kilodaltons approximately. By affinity chromatography, an immunogenic parasite antigen from plasma of acutely infected mice was isolated.

Isoxazolylnaphthoquinone effects on the growth of Trypanosoma cruzi.

Knowing the need for new drugs against the etiologic agent of Chagas disease and considering the biological properties of naphthoquinones and isoxazoles, the effect of three isoxazolyl-naphthoquinones on the growth of Trypanosoma cruzi was studied. To evaluate the activity of the compounds on epimastigote forms, growth curves with different concentrations of 2-hydroxi-N-(3,4-dimethyl-5-isoxazolyl)-1,4-naphthoquinone-4 -imine (I), N-(3,4-dimethyl-5-isoxazolyl)-4-amino-1,2-naphthoquinone (II), 2-acetyl-N-(3,4-dimethyl-5-isoxazolyl)-1,4-naphthoquinone-imine (III) and Nifurtimox as reference drug were made. The studies on the trypomastigote form were performed on two month old BALB/c mice, evaluating parasitemia on day 13 post infection. The results obtained with epimastigotes showed that all drugs induced alterations in motility, morphology, viability and/or lysis of parasites. For the treatments on trypomastigotes the best results were obtained with (I) which reduced parasitemia compared to untreated controls.

Experimental Chagas disease. Innate immune response in Balb/c mice previously vaccinated with Trypanosoma rangeli. I. The macrophage shows immunological memory: Reality or fiction?

Chagas' disease, caused by Trypanosoma cruzi, is a major vector borne health problem in Latin America and an emerging or re-emerging infectious disease in several countries. Immune response to T. cruzi infection is highly complex and involves many components, both regulators and effectors. Although different parasites have been shown to activate different mechanisms of innate immunity, T. cruzi is often able to survive and replicate in its host because they are well adapted to resisting host defences. An experimental model for vaccinating mice with Trypanosoma rangeli, a parasite closely related to T. cruzi, but nonpathogenic to humans, has been designed in our laboratory, showing protection against challenge with T. cruzi infection. The aim of this work was to analyze some mechanisms of the early innate immune response in T. rangeli vaccinated mice challenged with T. cruzi. For this purpose, some interactions were studied between T. cruzi and peritoneal macrophages of mice vaccinated with T. rangeli, infected or not with T. cruzi and the levels of some molecules or soluble mediators which could modify these interactions. The results in vaccinated animals showed a strong innate immune response, where the adherent cells of the vaccinated mice revealed important phagocytic activity, and some soluble mediator (Respiratory Burst: significantly increase, p ≤ 0.03; NO: the levels of vaccinated animals were lower than those of the control group; Arginasa: significantly increase, p ≤ 0.04). The results showed an important role in the early elimination of the parasites and their close relation with the absence of histological lesions that these animals present with regard to the only infected mice. This behaviour reveals that the macrophages act with some type of memory, recognizing the antigens to which they have previously been exposed, in mice were vaccinated with T. rangeli, which shares epitopes with T. cruzi.

Vaccination with Trypanosoma rangeli induces resistance of guinea pigs to virulent Trypanosoma cruzi.

Chagas' disease, endemic in Latin America, is spread in natural environments through animal reservoirs, including marsupials, mice and guinea pigs. Farms breeding guinea pigs for food are located in some Latin-American countries with consequent risk of digestive infection. The aim of this work was to study the effect of vaccination with Trypanosoma rangeli in guinea pigs challenged with Trypanosoma cruzi. Animals were vaccinated with fixated epimastigotes of T. rangeli, emulsified with saponin. Controls received only PBS. Before being challenged with T. cruzi, parasitemia, survival rates and histological studies were performed. The vaccinated guinea pigs revealed significantly lower parasitemia than controls (p<0.0001-0.01) and a discrete lymphomonocytic infiltrate in cardiac and skeletal muscles was present. In the chronic phase, the histological view was normal. In contrast, control group revealed amastigote nests and typical histopathological alterations compatible with chagasic myocarditis, endocarditis and pericarditis. These results, together with previous works in our laboratory, show that T. rangeli induces immunoprotection in three species of animals: mice, guinea pigs and dogs. The development of vaccines for use in animals, like domestic dogs and guinea pigs in captivity, opens up new opportunities for preventive tools, and could reduce the risk of infection with T. cruzi in the community.

Detailed analysis of the individual feeding behavior of male and female mule ducks.

The feeding behavior of 19 mule ducks (males and females) bred in a group was studied during their growth phase (between 3 and 8 wk of age) using the recording system for waterfowl feeding behavior developed in our lab. The basic feeding behavior data obtained allowed us to confirm on the one hand the reliability of our tool and, on the other hand, to compute food intake traits per day (ADFI, number of visits, and time spent feeding per day), per visit (feed intake per visit, visit duration, and visit feeding rate), and per meal (meal size, meal duration, and meal feeding rate). Daily feed intake increased with age (130 to 248 g/d) while the time spent feeding decreased from 14 to 5.5 min/d. Because the duration of visits remained stable (average 45 s), this reflected a decrease in the number of visits per day. At the same time the feed intake per visit and the feeding rate per visit increased sharply with age. The same trend was observed at the meal level for both the feed intake and the feeding rate. Feed intake did not differ between males and females, but the time spent feeding was significantly greater for females than for males (10.8 and 8.9 min per day and 53 and 37 s per visit for females and males, respectively), leading to significantly greater feeding rate for males (30 g/min) than for females (24 g/min). Grouping visits in meal events minimized the differences between genders as the meals tended to comprise fewer visits for females. Under the hypothesis of a genetic link between feeding behavior during growth and force-feeding ability of ducks, genetic selection of these behavioral traits could be included in breeding programs to improve the force-feeding capacity of mule ducks.

Improving residual feed intake of mule progeny of Muscovy ducks: genetic parameters and responses to selection with emphasis on carcass composition and fatty liver quality.

In France, about 95% of the fatty liver production comes from mule ducks, an infertile hybrid cross between female common ducks (Anas platyrhynchos) and Muscovy drakes (Cairina moschata). As a hybrid, genetic improvement of the performance of mule ducks is achieved by selection of the parental populations. Feed represents two-thirds of the total costs of duck production; thus, the breeders' main concern is to improve the birds' feed efficiency without impairing their capacity to be overfed after the growing period. To obtain insight into this economically important trait, we designed a divergent selection experiment for Muscovy sires on the basis of the residual feed intake (RFI) of their male mule progeny. Residual feed intake represents the fraction of feed intake that cannot be explained by maintenance and production requirements. Data comprised records from generations 0 to 2 with 227 Muscovy sires of 2,016 mule ducks. Growth and fat deposition were measured individually for all mule ducks. Half-sib mule ducks were placed together in 1 small pen, and the feed consumption was recorded for each pen; all half-sibs therefore had the same feed intake estimates. Heritability of RFI was high (0.83 ± 0.42), and after 2 generations of selection, the differences between lines in terms of RFI (contrast of 9.13 g/d, representing 0.76 phenotypic standard deviation; P < 0.0001) and feed conversion ratio (contrast of 0.08, representing 0.28 phenotypic standard deviation; P = 0.0003) were marked. In regard to carcass traits, the low-RFI line (high-efficiency animals) had heavier legs (476 vs. 463 g; P < 0.0001) and magret muscles (268 vs. 262 g; P = 0.001) than the high-RFI line (low-efficiency animals). No differences were observed for either the liver weight or the melting rate between the 2 lines (P > 0.46). Selection on RFI thus improves the feed efficiency of animals without impairing their capacity to produce fatty liver.

Microsatellite mapping of quantitative trait loci affecting meat quality, stress hormones and production traits in Duroc × Large White F2 pigs.

An F2 cross between Duroc and Large White pigs was carried out in order to detect quantitative trait loci (QTL) for 11 meat quality traits (L*, a* and b* Minolta coordinates and water-holding capacity (WHC) of two ham muscles, ultimate pH of two ham and one loin muscles), 13 production traits (birth weight, average daily gain during post-weaning and fattening periods, carcass fat depths at three locations, estimated lean meat content, carcass length and weights of five carcass cuts) and three stress hormone-level traits (cortisol, adrenaline and noradrenaline). Animals from the three generations of the experimental design (including 456 F2 pigs) were genotyped for 91 microsatellite markers covering all the autosomes. A total of 56 QTL were detected: 49 reached the chromosome-wide level (suggestive QTL with a maximal probability of 0.05) and seven were significant at the genome-wide level (with a probability varying from 6 × 10(-4) to 3 × 10(-3)). Twenty suggestive QTL were identified for ultimate pH, colour measurements and WHC on chromosome (SSC) 5, 6, 7, 8, 9, 11, 13, 14, 15 and 17. For production traits, 33 QTL were detected on all autosomes except SSC6, 8 and 9. Seven of these QTL, located on SSC2, 3, 10, 13, 16 and 17, exceeded the genome-wide significance threshold. Finally, three QTL were identified for levels of stress hormones: a QTL for cortisol level on SSC7 in the cortisol-binding globulin gene region, a QTL for adrenaline level on SSC10 and a QTL for noradrenaline level on SSC13. Among all the detected QTL, seven are described for the first time: a QTL for ultimate pH measurement on SSC5, two QTL affecting birth weight on SSC2 and 10, two QTL for growth rate on SSC15 (during fattening) and 17 (during post-weaning) and two QTL affecting the adrenaline and noradrenaline levels. For each QTL, only one to five of the six F1 sires were found to be heterozygous. It means that all QTL are segregating in at least one of the founder populations used in this study. These results suggest that both meat quality and production traits can be improved in purebred Duroc and Large White pigs through marker-assisted selection. It is of particular interest for meat quality traits, which are difficult to include in classical selection programmes.

Genetic parameters of product quality and hepatic metabolism in fattened mule ducks.

Genetic parameters of traits related to hepatic lipid metabolism, carcass composition, and product quality of overfed mule ducks were estimated on both parental lines of this hybrid: the common duck line for the maternal side and the Muscovy line for the paternal side. The originality of the statistical model was to include simultaneously the additive genetic effect of the common ducks and that of the Muscovy ducks, revealing a greater genetic determinism in common than in Muscovy. Plasma metabolic indicators (glucose, triglyceride, and cholesterol contents) were heritable, in particular at the end of the overfeeding period, and heritabilities increased with the overfeeding stage. Carcass composition traits were highly heritable in the common line, with values ranging from 0.15 for liver weight, 0.21 for carcass weight, and 0.25 for abdominal fat weight to 0.32 for breast muscle weight. Heritabilities of technological outputs were greater for the fatty liver (0.19 and 0.08, respectively, on common and Muscovy sides for liver melting rate) than for the pectoralis major muscle (between 0.02 and 0.05 on both parental sides for cooking losses). Fortunately, the processing industry is mainly facing problems in liver quality, such as too high of a melting rate, than in meat quality. The meat quality appraisal criteria (such as texture and cooking losses), usually dependent on pH and the rate of decline of pH, were also very lowly heritable. This study demonstrated that genetic determinism of meat quality and ability of overfeeding is not similar in the common population and in the Muscovy population; traits related to fattening, muscle development, and BW have heritability values from 2 to 4 times greater on the common line than on the Muscovy line, which is relevant for considering different selection strategies.