Millor Fernandes do Rosário

Quantitative trait loci associated with fatness in a broiler-layer cross.

An F(2) population established by crossing a broiler male line and a layer line was used to map quantitative trait loci (QTL) affecting abdominal fat weight, abdominal fat percentage and serum cholesterol and triglyceride concentrations. Two genetic models, the line-cross and the half-sib, were applied in the QTL analysis, both using the regression interval method. Three significant QTL and four suggestive QTL were mapped in the line-cross analysis and four significant and four suggestive QTL were mapped in the half-sib analysis. A total of five QTL were mapped for abdominal fat weight, six for abdominal fat percentage and four for triglyceride concentration in both analyses. New QTL associated with serum triglyceride concentration were mapped on GGA5, GGA23 and GG27. QTL mapped between markers LEI0029 and ADL0371 on GGA3 for abdominal fat percentage and abdominal fat weight and a suggestive QTL on GGA12 for abdominal fat percentage showed significant parent-of-origin effects. Some QTL mapped here match QTL regions mapped in previous studies using different populations, suggesting good candidate regions for fine-mapping and candidate gene searches.

Influência do sistema de criação sobre o desempenho, a condição fisiológica e o comportamento de linhagens de frangos para corte

The objectives of this research were to evaluate the influence of rearing systems (intensive or semi-intensive) on the performance (body weight and feed efficiency), chicken physiological condition under heat stress (rectal temperature, respiratory frequency and hematocrit) and behavioural parameters (frequency in the pasture areas) of broilers lines. To evaluate broilers performance and physiological condition on the ages of 45, 55, 65 and 75 days one experiment was carried out in boxes with 4,5 m2 of inside area and 35 m2 of outside area were 35 broilers were reared in each box. Another experiment was carried out to evaluate the frequency of broilers it the pasture areas from 35 to 75 days of age. One of the evaluated lines did not show adaptation to the semi-intensive rearing system. Significant differences were found in broilers performance and physiological conditions in both systems. In the semi-intensive rearing system the rectal temperature, respiratory frequency, hematocrit and feed efficiency were smaller and body weight larger than in the intensive rearing system. It was concluded that the semi-intensive rearing system provided conditions that increased broilers welfare and positively influenced the physiological conditions and performance of the broilers.

Genotypic characterization of microsatellite markers in broiler and layer selected chicken lines and their reciprocal F1s.

Populacoes experimentais de frangos tem sido desenvolvidas pelo mundo para mapeamento de QTLs, mas a caracterizacao genotipica delas nao e normalmente apresentada. O objetivo deste estudo foi caracterizar genotipicamente duas geracoes F1 reciprocas e suas linhagens parentais com base na estimacao de parâmetros genotipicos. Estas geracoes F1 originaram duas populacoes brasileiras referencias para mapear QTLs. Os parâmetros avaliados foram: conteudo de informacao polimorfica (PIC), heterozigosidades observada e esperada e numero de alelos por loco nos cromossomos 1, 3 e 4. Todos os animais parentais e F1 de ambas as populacoes foram usados, em um total de 83 animais: 14 de uma linhagem de corte (TT) e 14 de uma linhagem de postura (CC), e 55 de suas geracoes reciprocas F1. Tanto as linhagens como as populacoes referencias foram desenvolvidas no Centro Nacional de Pesquisa de Suinos e Aves (EMBRAPA), Brasil. Os genotipos de todos os animais foram obtidos a partir de 34 marcadores microssatelites localizados nos cromossomos 1 (13), 3 (12) e 4 (9). Com base na amostragem realizada, as duas linhagens exibiram um total de 163 alelos, dos quais 31 (31,1%) e 44 (33,0%) foram oriundos exclusivamente de CC e TT, respectivamente, com frequencias alelicas que variaram de 0,03 a 0,82. A heterozigosidade observada foi maior (0,68-0,71) em ambas as geracoes F1 do que em suas linhagens fundadoras devido ao desequilibrio de ligacao. Finalmente, as duas linhagens parentais possibilitaram a obtencao de geracoes reciprocas F1 com valores elevados de PIC (0,50-0,52) e heterozigosidade observada, bem como com um numero satisfatorio de alelos por loco (4,06-4,32). Estes resultados permitirao comparar e selecionar familias e marcadores microssatelites mais informativos em estudos de QTLs, reduzindo os custos de genotipagem.

QTL for percentage of carcass and carcass parts in a broiler x layer cross

An F2 experimental population, developed from a broiler layer cross, was used in a genome scan of QTL for percentage of carcass, carcass parts, shank and head. Up to 649 F2 chickens from four paternal half-sib families were genotyped with 128 genetic markers covering 22 linkage groups. Total map length was 2630 cM, covering approximately 63% of the genome. QTL interval mapping using regression methods was applied to line-cross and half-sib models. Under the line-cross model, 12 genome-wide significant QTL and 17 suggestive linkages for percentages of carcass parts, shank and head were mapped to 13 linkage groups (GGA1, 2, 3, 4, 5, 7, 8, 9, 11, 12, 14, 18 and 27). Under the paternal half-sib model, six genome-wide significant QTL and 18 suggestive linkages for percentages of carcass parts, shank and head were detected on nine chicken linkage groups (GGA1, 2, 3, 4, 5, 12, 14, 15 and 27), seven of which seemed to corroborate positions revealed by the previous model. Overall, three novel QTL of importance to the broiler industry were mapped (one significant for shank% on GGA3 and two suggestive for carcass and breast percentages on GGA14 and drums and thighs percentage on GGA15). One novel QTL for wings% was mapped to GGA3, six novel QTL (GGA1, 3, 7, 8, 9 and 27) and suggestive linkages (GGA2, 4, and 5) were mapped for head%, and suggestive linkages were identified for back% on GGA2, 11 and 12. In addition, many of the QTL mapped in this study confirmed QTL previously reported in other populations.

Avaliação do estresse térmico em condição simulada de transporte de frangos de corte

This experiment aimed to simulate thermal-stress-environment conditions in climatic chamber during the transportation of birds to slaughterhouse to evaluate the influence of these conditions on physiological parameters and carcass conformation in broiler chickens. Thirty chicks with 42 days old were weighted and distributed to transportation crates (10 chicks by crate), and submitted to high stress conditions (35oC and 85% RH) to simulate the transport to the slaughterhouse. At each time of exposition to the stress conditions (0, 30, 60, 90 and 120 minutes), two birds from each crate was withdrawn for further analyses. Body weight, rectal temperature, respiratory frequency and hematocrit value were measured, and after that they were slaughtered to evaluate of carcass conformation (carcass, breast, legs (thighs and drumsticks), back and viscera weights). Physiological and carcass conformation characteristics (body weight loss and legs weight, wings and back weights) differed after be submitted to high stress conditions. The exposition time and the environment conditions of transport affected negatively the metabolism and thermal body equilibrium of broilers.

Síndrome ascítica em frangos de corte: uma revisão sobre a fisiologia, avaliação e perspectivas

Poultry genetic breeding programs which look for maximum weight gain, improved feed conversion, high viability, high carcass yield and low fat deposition may cause some physiologic syndromes, for example caloric stress, sudden death and ascites. Ascites is framed in concept of the multifactorial syndromes, once its manifestation happens when certain genetic and environment factors act together, determining the process. Anatomical and physiological limitations in blood circulation in the lungs give rise to pulmonary hypertension syndrome (PHS), producing great fluid accumulation in abdominal cavity, which is denominated ascites. Ascites causes reduction of blood circulation efficiency, leading broilers to death due to hypoxia, mainly between 30 and 40 days of age. Ascitic broilers have reduced body weight gain as a consequence of feed restriction. Additionally, there is increased abdominal cavity volume and internal organ congestion. Ascites is discussed through this manuscript based on physiological description, evaluation measures and perspectives.

Avaliação de materiais genéticos visando à produção de frango caipira em diferentes sistemas de alimentação

The aim of the current study was to evaluate the performance of experimental and commercial genotypes of chicken recommended for free-range rearing system submitted to two diet programs (conventional and alternative). The experimental design consisted of a randomized design applied until 28 days and a randomized factorial 8x2 design (eight genotypes: Paraiso Pedres, Caipirao da ESALQ, 7 P, Embrapa 041, Label Rouge, Paraiso Pelado, Caipirinha da ESALQ and Carijo Barbada and two diet programs), using two replicates with 30 chickens/box as experimental unit, from 29 to 84 days of age. Average body weight and feed:gain ratio were recorded during three periods: 1) 0-28, 2) 0-56 and 3) 0-84 days and submitted to the analysis of variance. The effect of diet was evidenced for all traits in periods 2 and 3. The effect of genotype was verified for all variables in period 1, but only for average body weight in periods 2 and 3. The interaction genotype and diet was observed for feed:gain ratio in period 2 and for all traits in period 3. Paraiso Pedres and Caipirao from ESALQ presented higher average body weight than the other genotypes in period 1. In period 2, Paraiso Pedres presented the highest average body weight and all genotypes differed for feed:gain ratio. Caipirao from ESALQ, Paraiso Pedres and 7 P presented higher average body weight than the other genotypes and all strains differed for feed:gain ratio in period 3. The full substitution of conventional diet by corn led to a worse chicken performance. Overall performance of the evaluated genotypes was conditioned by genetic and nutrition factors, with the lowest negative effects of substitution of conventional diet by corn on all traits in the Paraiso Pedres genotype.

Investigation of Leptin gene in broiler and layer chicken lines

Leptin, a polypeptide hormone secreted mainly by adipose tissue, plays an important role in feed intake regulation, energy metabolism and reproduction in several species. Its function has been intensively studied in mammals; however, in birds limited information is available. The cDNA sequence for chicken leptin has been reported, and high hepatic expression levels of leptin were associated with fat deposition in selected bird lines. However, controversies still remain concerning to the chicken leptin gene and several authors failed to amplify this gene from genomic DNA or cDNA. In view of this controversy and the importance of this gene, the present study aimed to investigate the leptin gene in a population of birds developed by Embrapa Swine and Poultry Research Center (Brazil). First of all, the sequences of Gallus gallus leptin gene (GenBank AF012727) and Mus musculus (GenBank NM_008493) were aligned with the objective of designing primers in conserved regions among the two species, since 94.6% of similarity is described in the literature in those species. For all four pairs of primers designed, several amplification tests were performed with both DNA and cDNA, but neither unique fragment nor expected band size was ever achieved. The leptin sequence in GenBank does not represent the sequence of the chicken leptin gene.

Genetic linkage maps of chicken chromosomes 6, 7, 8, 11 and 13 from a Brazilian resource population

A linkage map is essential not only for quantitative trait loci (QTL) mapping, but also for the organization and location of genes along the chromosomes. The present study is part of a project whose major objective is, besides from construction the linkage maps, the whole genome scan for mapping QTL for performance traits in the Brazilian experimental chicken population. Linkage maps of chicken chromosomes 6 to 8, 11 and 13 were constructed based on this population. The population was developed from two generations of crossbreeding between a broiler and a layer line. Fifty-one microsatellite markers were tested, from which 28 were informative: 4, 8, 7, 4 and 5 for chromosomes 6, 7, 8, 11 and 13, respectively. A SNP located in the leptin receptor gene was included for chromosome 8. Ten parental, 8 F1 and 459 F2 chickens from five full-sib families were genotyped with these markers. The number of total informative meioses per locus varied from 232 to 862, and the number of phase-known informative meioses from 0 to 764. Marker orders in the chromosomes coincided with those of the chicken consensus map, except for markers ADL0147 and MCW0213, on chromosome 13, which were inverted. The reduced number of phase-known informative meioses for ADL0147 (150) may be pointed out as a possible cause for this inversion, apart from the relative short distance between the two markers involved in the inversion (10.5 cM).

Identification and characterization of microRNAs expressed in chicken skeletal muscle

MicroRNAs (miRNAs, miRs) encompass a class of small non-coding RNAs that often negatively regulate gene expression. miRNAs play an essential role in skeletal muscle, determining the proper development and maintenance of this tissue. In comparison to other organs and tissues, the full set of muscle miRNAs and its expression patterns are still poorly understood. In this report, a chicken skeletal muscle miRNA library was constructed, and the expression of selected miRNAs was further characterized during muscle development in chicken lines with distinct muscling phenotypes. Clone library sequence analysis revealed 40 small RNAs with similarities to previously described chicken miRNAs, seven miRNAs that were never identified before in chicken, and some sequence clusters representing other possible novel miRNAs. Temporal expression profiles of three miRNAs associated with cell proliferation and differentiation (miR-125b, miR-221, and miR-206) in two chicken lines (broiler and layer) revealed the differential steady-state levels of these miRs during skeletal muscle growth and suggests that miR-206 is involved in the muscling phenotype that is observed in growth-selected chicken lines.