Bovine respiratory disease (BRD) is the most common infectious disease of beef and dairy cattle and is characterized by a complex infectious etiology that includes a variety of viral and bacterial pathogens. We examined the global changes in mRNA abundance in healthy lung and lung lesions and in the lymphoid tissues bronchial lymph node, retropharyngeal lymph node, nasopharyngeal lymph node and pharyngeal tonsil collected at the peak of clinical disease from beef cattle experimentally challenged with either bovine respiratory syncytial virus, infectious bovine rhinotracheitis, bovine viral diarrhea virus, Mannheimia haemolytica or Mycoplasma bovis. We identified signatures of tissue-specific transcriptional responses indicative of tropism in the coordination of host’s immune tissue responses to infection by viral or bacterial infections. Furthermore, our study shows that this tissue tropism in host transcriptional response to BRD pathogens results in the activation of different networks of response genes. The differential crosstalk among genes expressed in lymphoid tissues was predicted to be orchestrated by specific immune genes that act as ‘key players’ within expression networks. The results of this study serve as a basis for the development of innovative therapeutic strategies and for the selection of cattle with enhanced resistance to BRD.

The objectives of this study were to estimate genetic parameters and genetic trends and perform principal component analysis for the following traits: body weight adjusted at 210 days of age (W210), one year (W365), and yearling or 450 days of age (W450); weight gain from birth to weaning or 210 days of age (WGBW), from weaning to 365 days of age (WGW365), and from one year to yearling (WGY); and scrotal circumference adjusted at 365 (SC365) and 450 (SC450) days of age of Guzera beef cattle. Variance components were estimated under a two-trait animal model using the restricted maximum likelihood method. The fixed effects included in the model were birth season, contemporary group, and covariable age of dam at calving as linear and quadratic effects. Heritability estimates ranged from 0.10 (WGY) to 0.41 (W450 and SC450). The studied traits could be used as selection criteria because of their sufficient additive genetic variability to respond to the selection process. However, lower selection efficiency is expected for WGBW and WGY. Genetic trends studied were significant for all traits, except WGY. The W365 and W450 traits belonged to the "Genetic Merit Total" index and responded to selection with favorable genetic gain per year. The traits that were not included in the selection index showed favorable positive genetic correlations attributed to the indirect selection processes. The principal component analysis identified two groups of traits. The first group related to body weight and weight gain and the second related to the scrotal circumference, indicating that selection could be applied to one group of traits within each observed group. The genetic gains were attributed in the same direction for the other traits belonging to the groups. Thus, we recommend selecting animals for W365 based on first group, and SC365 based on second.

The aim of this study was to estimate genetic parameters for accumulated productivity (ACP), first calving interval (CI1), second calving interval (CI2), and mean calving interval (MCI) in Nelore beef cattle. The ACP trait is a reproduction index and comprises the total number of calves born per dam, weight of weaned calves, and age of the dam at calving. Genetic parameters were estimated by the average information restricted maximum likelihood method in two-trait analyses. The average heritability estimate for ACP was 0.17 (0.03). For CI1, CI2, and MCI, the heritability estimates were 0.02, 0.02, and 0.06, respectively. Genetic correlations between ACP with CI1, CI2, and MCI were -0.16 ± 0.47, -0.29 ± 0.53, and -0.40 ± 0.27, respectively. Despite of the low heritability estimates obtained in our study, reproduction traits should be further studied and their inclusion in the selection criteria must be evaluated in order to improve the performance of females because these traits are of great economic importance in beef cattle. Accumulated productivity could contribute to decrease the mean calving interval in Nelore cattle.

The availability of dense genomic information has increased genome-wide association studies for the bovine species; however research to assess the effect of single genes on production traits is still important to elucidate the genes functions. On this study the association of IGF1, GH, and PIT1 markers with growth and reproductive traits (birth weight, weaning weight, weight at 12 and 18 months of age, preweaning average daily weight gain, age and weight at first calving, and scrotal circumference at 12 and 18 months of age) were assessed by means of the variance component approach. The phenotypes were adjusted and then analyzed under two animal models, one which considered the polygenic and genotype (IGF1, GH or PIT1 markers) effects (Model 1), and the other which considers only the polygenic effect (Model 2). When the likelihood ratio test and the Bonferroni correction was applied at 5 % significance level, the genetic markers for the IGF1, GH, and PIT1 genes did not influence significantly the traits (p > 0.002). However, evidence of association of IGF1 with birth weight (p = 0.06) and GH with weight at first calving (p = 0.03) and with weight at 12 months of age (p = 0.08) was observed. In conclusion we could not confirm the associations between IGF1, GH, and PIT1 and growth traits that were previously reported in Canchim cattle, and no association was observed between these genes and reproductive traits. Future studies involving functional markers of IGF1, GH and PIT1 genes may help to clarify the role of these genes in growth and reproductive processes.

Apolipoprotein B (APOB) and Adiponectin Receptor 1 (ADIPOR1) are related to the regulation of feed intake, fat metabolism and protein deposition and are candidate genes for genomic studies in birds. In this study, associations of two single nucleotide polymorphisms (SNPs) g.102 (APOB) and g.729 (ADIPOR1) with carcass, bone integrity and performance traits in broilers were investigated. Genotyping was performed on a paternal line of 1,454 broilers. The SNP detection was carried out by PCR-RFLP technique using the restriction enzymes HhaI for the SNP g.729 and MslI for the SNP g.102 . The association analyses of the two SNPs with 85 traits were performed using the restricted maximum likelihood (REML) and Generalized Quasi-Likelihood Score (GQLS) methods. For REML the model included the random additive genetic effect of animal and fixed effects of sex, hatch and SNP genotypes. In the GQLS method, a logistic regression was used to associate the genotypes with phenotypes adjusted for fixed effects of sex and hatch. The SNP g.729 in the ADIPOR1 gene was associated with thickness of the femur and breast skin yield. Thus, the ADIPOR1 gene seems implicated in the metabolism and/or fat deposition and bone integrity in broilers.

Intense selection among broilers, especially for performance and carcass traits, currently favors locomotion problems and bone resistance. Conducting studies relating to development and growth of bone tissue in broilers is necessary to minimize losses. Thus, genetic parameters were estimated for a broiler population's phenotypic traits such as BW at 42 d of age (BW42), chilled femur weight (CFW) and its yield (CFY), and femur measurements: calcium, DM, magnesium, phosphorus, and zinc content; breaking strength; rigidity; length; and thickness. Variance components were estimated through multitrait analyses using the restricted maximum likelihood method. The model included a fixed group effect (sex and hatch) and additive and residual genetic random effects. The heritability estimates we obtained ranged from 0.10 ± 0.05 to 0.50 ± 0.08 for chilled femur yield and BW42, respectively, and indicated that the traits can respond to the selection process, except for CFY, which presented low-magnitude heritability coefficients. Genetic correlation estimates between breaking strength, rigidity, and traits related to mineral content indicated that selection that aims to improve the breaking strength resistance of the femur is highly correlated with mineral content. Given the genetic correlation estimates between BW42 and minerals, it is suggested that in this population, selection for BW42 can be performed with greater intensity without affecting femoral integrity.

ABSTRACT. Intense selection for production traits has improved the genetic gain of important economic traits. However, selection for performance and carcass traits has led to the onset of locomotors problems and decreasing bone strength in broilers. Thus, genes associated with bone integrity traits have become candidates for genetic studies in order to reduce the impact of bone disorders in broilers. This study investigated the association of the RUNX2 and TNFSF11 genes with 79 traits related to performance, carcass composition, organs, and bone integrity in a paternal broiler line. Analyses of genetic association between single-nucleotide polymorphisms (SNPs) and traits were carried out using the maximum likelihood procedures for mixed models. Genetic associations (P < 0.05) were found between SNP g.124,883A>G in the RUNX2 gene and chilled femur weight (additive plus dominance deviation effects within sex) and with performance traits (additive within sex and additive effects). The SNP g.14,862T>C in the TNFSF11 gene presented genetic associations (P < 0.05) with additive plus dominance deviation effects within sex for performance traits. Suggestive genetic associations (P < 0.10) were found with abdominal fat and its yield. Selection based on SNPs g.14,862T>C in TNFSF11 and g.124,883A>G in RUNX2 could be used to improve performance and carcass quality traits in the population studied, although SNP g.14,862T>C was not in Hardy-Weinberg equilibrium because it was not undergoing a selection process. Furthermore, it is important to validate these markers in an unrelated population for use in the selection process.

a b s t r a c tThe aim of this study was to evaluate the allele substitution effects of IGF1, GH and PIT1 markers on the estimated breeding values (EBVs) for birth (BW) and weaning weights (WW), weight at 12 (W12) and 18 (W18) months of age, weight (WFC) and age (AFC) at first calving, and scrotal circumference measured at 12 (SC12) and 18 (SC18) months of age in Canchim beef cattle. Maternal effects were considered for birth (BW maternal ) and weaning (WW maternal ) weight. Regression analyses were carried out considering the EBVs, obtained from multi-trait analyses, and the deviations for each allele studied (four alleles for the IGF1 markers and two for GH and PIT1 markers, respectively). According to the results obtained for IGF1, the substitution effect of the "225" allele was significant (Pr 0.05) and presented higher EBVs for BW, BW maternal , WW, W12, W18, and SC18; and lower EBVs for WW maternal . The allele substitution effect observed for GH gene was significant (P r0.05) on EBVs for AFC and WFC. The "Valine" allele was responsible for lower EBVs for AFC and higher EBVs for WFC. For the PIT1 gene, the substitution effect of the "HinfÀ " allele was significant (Pr 0.05) on the EBVs for WW, WW maternal , AFC, and WFC, respectively. Important allele substitution effects were found for weight and reproduction traits in Canchim cattle. In general, markers on the IGF1 gene are related to higher EBVs for weight, while markers on the GH and PIT1 showed greater influence on the EBVs for age and weight at first calving. Adding molecular markers information on the selection process could result in increased genetic gains in Canchim cattle. Future studies using high-density genotyping platforms may contribute to our understanding of the effects of these genes on traits of economic importance in the Canchim breed. (D.P. Munari). Please cite this article as: Grossi, D.d.A., et al., Allele substitution effects of IGF1, GH and PIT1 markers on estimated breeding values for weight and reproduction traits in Canchim beef cattle. Livestock Science (2015), http://dx.