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Objective The objective of this study was to identify genes associated with 305-day milk yield (MY) and fat yield (FY) that also influence the adaptability of the Thai multibreed dairy cattle population to tropical conditions. Methods A total of 75,776 imputed and actual single nucleotide polymorphisms (SNPs) from 2,661 animals were used to identify genomic regions associated with MY and FY using the single-step genomic best linear unbiased predictions. Fixed effects included herd-year-season, breed regression, heterosis regression and calving age regression effects. Random effects were animal additive genetic and residual. Individual SNPs with a p-value smaller than 0.05 were selected for gene mapping, function analysis, and quantitative trait loci (QTL) annotation analysis. Results A substantial number of QTLs associated with MY (9,334) and FY (8,977) were identified by integrating SNP genotypes and QTL annotations. Notably, we discovered 17 annotated QTLs within the health and exterior QTL classes, corresponding to nine unique genes. Among these genes, Rho GTPase activating protein 15 (ARHGAP15) and catenin alpha 2 (CTNNA2) have previously been linked to physiological traits associated with tropical adaptation in various cattle breeds. Interestingly, these two genes also showed signs of positive selection, indicating their potential role in conferring tolerance to trypanosomiasis, a prevalent tropical disease. Conclusion Our findings provide valuable insights into the genetic basis of MY and FY in the Thai multibreed dairy cattle population, shedding light on the underlying mechanisms of tropical adaptation. The identified genes represent promising targets for future breeding strategies aimed at improving milk and fat production while ensuring resilience to tropical challenges. This study significantly contributes to our understanding of the genetic factors influencing milk production and adaptability in dairy cattle, facilitating the development of sustainable genetic selection strategies and breeding programs in tropical environments.

Objective This study compared five distinct sets of biological pathways and associated genes related to semen volume (VOL), number of sperm (NS), and sperm motility (MOT) in the Thai multibreed dairy population. Methods The phenotypic data included 13,533 VOL records, 12,773 NS records, and 12,660 MOT records from 131 bulls. The genotypic data consisted of 76,519 imputed and actual single nucleotide polymorphisms (SNPs) from 72 animals. The SNP additive genetic variances for VOL, NS, and MOT were estimated for SNP windows of one SNP (SW1), ten SNP (SW10), 30 SNP (SW30), 50 SNP (SW50), and 100 SNP (SW100) using a single-step genomic best linear unbiased prediction approach. The fixed effects in the model were contemporary group, ejaculate order, bull age, ambient temperature, and heterosis. The random effects accounted for animal additive genetic effects, permanent environment effects, and residual. The SNPs explaining at least 0.001% of the additive genetic variance in SW1, 0.01% in SW10, 0.03% in SW30, 0.05% in SW50, and 0.1% in SW100 were selected for gene identification through the NCBI database. The pathway analysis utilized genes associated with the identified SNP windows. Results Comparison of overlapping and non-overlapping SNP windows revealed notable differences among the identified pathways and genes associated with the studied traits. Overlapping windows consistently yielded a larger number of shared biological pathways and genes than non-overlapping windows. In particular, overlapping SW30 and SW50 identified the largest number of shared pathways and genes in the Thai multibreed dairy population. Conclusion This study yielded valuable insights into the genetic architecture of VOL, NS, and MOT. It also highlighted the importance of assessing overlapping and non-overlapping SNP windows of various sizes for their effectiveness to identify shared pathways and genes influencing multiple traits.

Objective This study was to estimate heritabilities, additive genetic correlations, and phenotypic correlations between number of piglets born alive (NBA), litter birth weight (LTBW), number of piglets weaned (NPW) and litter weaning weight (LTWW) in different parities of Landrace (L), Yorkshire (Y), Landrace×Yorkshire (LY), and Yorkshire×Landrace (YL) sows in a commercial swine operation in Northern Thailand. Methods Two models were utilized, a single trait repeatability model (RM) and a multiple trait animal model (MTM). The RM assumed reproductive records from different parities to be repeated values of the same trait, whereas the MTM assumed these records to be different traits. The two models accounted for the fixed effects of farrowing year-season, genetic group of the sow, heterosis, and age at first farrowing, and the random effects of sow, boar, and residual. Results Heritability estimates from RM were 0.02±0.01 for NBA, 0.10±0.01 for LTBW, 0.04±0.01 for NPW, and 0.11±0.01 for LTWW. Heritability estimates from MTM fluctuated across parities, ranging from 0.04±0.01 in parity 2 to 0.09±0.02 in parity 4 for NBA, 0.07± 0.02 in parity 2 to 0.16±0.02 in parity 3 for LTBW, 0.04±0.02 in parity 4 to 0.08±0.01 in parity 1 for NPW, and 0.16±0.02 in parity 1 to 0.20±0.02 in parity 2 for LTWW. Additive genetic correlation estimates from MTM were also variable, ranging from 0.29±0.24 between NBA in parity 1 and NBA in parity 2 to 0.99±0.05 between LTWW in parity 3 and LTWW in parity 4. Conclusion The findings of this study highlight the advantage of using MTM for the genetic improvement of reproductive traits in swine and contribute to the development of sustainable swine breeding programs in Thailand.

DNA methylation and the alternative splicing of precursor messenger RNAs (pre-mRNAs) are two important genetic modification mechanisms. However, both are currently uncharacterized in the muscle metabolism of rabbits. Thus, we constructed the Tianfu black rabbit obesity model (obese rabbits fed with a 10% high-fat diet and control rabbits from 35 days to 70 days) and collected the skeletal muscle samples from the two groups for Genome methylation sequencing and RNA sequencing. DNA methylation data showed that the promoter regions of 599 genes and gene body region of 2522 genes had significantly differential methylation rates between the two groups, of which 288 genes had differential methylation rates in promoter and gene body regions. Analysis of alternative splicing showed 555 genes involved in exon skipping (ES) patterns, and 15 genes existed in differential methylation regions. Network analysis showed that 20 hub genes were associated with ubiquitinated protein degradation, muscle development pathways, and skeletal muscle energy metabolism. Our findings suggest that the two types of genetic modification have potential regulatory effects on skeletal muscle development and provide a basis for further mechanistic studies in the rabbit.

Abstract Fatty acids of intramuscular fat (IMF) in rabbits can influence meat quality, but it is unclear which fatty acids benefit to human health. A rabbit model of weight gain and weight loss was constructed using two rabbit groups and two growth stages. Stage 1 included control group1 fed a commercial diet(CG1) and experimental group1 fed a high fat diet (EG1). Stage 2 include control group2(CG2) and experimental group2 (EG2) both fed a restricted commercial diet. We detected differences in blood biochemical indicators as well as changes in intramuscular adipose cells and intramuscular fatty acid content in control and experiment groups at two stages. High fat induction can make rabbits become obese, have higher concentrations of glucose (GLU), total cholesterol (TC), triglyceride (TG), low density lipoprotein‐cholesterol (LDL‐C) and free fatty acid (FFA), and lower concentrations of insulin (INS). In addition, a high‐fat diet promotes hypertrophy of precursor adipocytes in femoral muscles. Conversely, a restricted diet causes weight loss, decreases the concentration of TG, FFA, and INS in CG2 and EG2, and increases the deposition of unsaturated fatty acids in the femoral muscle. The content of monounsaturated trans oleic acid (C18:1n‐9T) in EG2 was significantly higher than in CG2, whereas oleic acid (C18:1n‐9C) was significantly lower in EG2 than in CG2. The polyunsaturated fatty acids Linolenate (C18:3 n‐3) and cis‐5,8,11,14,17‐Eicosapentaenoate (C20:5 n‐3) increased in CG2 and EG2. The content of Linoleate (C18:2 n‐6) and γ‐Linolenic acid (C18:3 n‐6) significantly increased in CG2. The content of cis‐11,14‐Eicosatrienoic acid (C20:2) decreased significantly in CG2, but increased significantly in EG2.Thus, a high‐fat diet can increase the formation of unhealthy fatty acids. Conversely, weight loss due to a restricted diet leads to an increase in unsaturated fatty acids in the femoral muscle, indicating that it reduces obesity symptoms and it may improve meat quality in rabbit.

Abstract Background Transcription has a substantial genetic control and genetic dissection of gene expression could help us understand the genetic architecture of complex phenotypes such as meat quality in cattle. The objectives of the present research were: 1) to perform eQTL and sQTL mapping analyses for meat quality traits in longissimus dorsi muscle; 2) to uncover genes whose expression is influenced by local or distant genetic variation; 3) to identify expression and splicing hot spots; and 4) to uncover genomic regions affecting the expression of multiple genes. Results Eighty steers were selected for phenotyping, genotyping and RNA-seq evaluation. A panel of traits related to meat quality was recorded in longissimus dorsi muscle. Information on 112,042 SNPs and expression data on 8588 autosomal genes and 87,770 exons from 8467 genes were included in an expression and splicing quantitative trait loci (QTL) mapping (eQTL and sQTL, respectively). A gene, exon and isoform differential expression analysis previously carried out in this population identified 1352 genes, referred to as DEG, as explaining part of the variability associated with meat quality traits. The eQTL and sQTL mapping was performed using a linear regression model in the R package Matrix eQTL. Genotype and year of birth were included as fixed effects, and population structure was accounted for by including as a covariate the first PC from a PCA analysis on genotypic data. The identified QTLs were classified as cis or trans using 1 Mb as the maximum distance between the associated SNP and the gene being analyzed. A total of 8377 eQTLs were identified, including 75.6% trans, 10.4% cis, 12.5% DEG trans and 1.5% DEG cis; while 11,929 sQTLs were uncovered: 66.1% trans, 16.9% DEG trans, 14% cis and 3% DEG cis. Twenty-seven expression master regulators and 13 splicing master regulators were identified and were classified as membrane-associated or cytoskeletal proteins, transcription factors or DNA methylases. These genes could control the expression of other genes through cell signaling or by a direct transcriptional activation/repression mechanism. Conclusion In the present analysis, we show that eQTL and sQTL mapping makes possible positional identification of gene and isoform expression regulators.

Objective The objectives were to compare variance components, genetic parameters, prediction accuracies, and genomic-polygenic estimated breeding value (EBV) rankings for milk yield (MY) and fat yield (FY) in the Thai multibreed dairy population using five single nucleotide polymorphism (SNP) sets from GeneSeek GGP80K chip. Methods The dataset contained monthly MY and FY of 8,361 first-lactation cows from 810 farms. Variance components, genetic parameters, and EBV for five SNP sets from the GeneSeek GGP80K chip were obtained using a 2-trait single-step average-information restricted maximum likelihood procedure. The SNP sets were the complete SNP set (all available SNP; SNP100), top 75% set (SNP75), top 50% set (SNP50), top 25% set (SNP25), and top 5% set (SNP5). The 2-trait models included herd-year-season, heterozygosity and age at first calving as fixed effects, and animal additive genetic and residual as random effects. Results The estimates of additive genetic variances for MY and FY from SNP subsets were mostly higher than those of the complete set. The SNP25 MY and FY heritability estimates (0.276 and 0.183) were higher than those from SNP75 (0.265 and 0.168), SNP50 (0.275 and 0.179), SNP5 (0.231 and 0.169), and SNP100 (0.251and 0.159). The SNP25 EBV accuracies for MY and FY (39.76% and 33.82%) were higher than for SNP75 (35.01% and 32.60%), SNP50 (39.64% and 33.38%), SNP5 (38.61% and 29.70%), and SNP100 (34.43% and 31.61%). All rank correlations between SNP100 and SNP subsets were above 0.98 for both traits, except for SNP100 and SNP5 (0.93 for MY; 0.92 for FY). Conclusion The high SNP25 estimates of genetic variances, heritabilities, EBV accuracies, and rank correlations between SNP100 and SNP25 for MY and FY indicated that genotyping animals with SNP25 dedicated chip would be a suitable to maintain genotyping costs low while speeding up genetic progress for MY and FY in the Thai dairy population.

Objective This research aimed to determine biological pathways and protein-protein interaction (PPI) networks for 305-d milk yield (MY), 305-d fat yield (FY), and age at first calving (AFC) in the Thai multibreed dairy population. Methods Genotypic information contained 75,776 imputed and actual single nucleotide polymorphisms (SNP) from 2,661 animals. Single-step genomic best linear unbiased predictions were utilized to estimate SNP genetic variances for MY, FY, and AFC. Fixed effects included herd-year-season, breed regression and heterosis regression effects. Random effects were animal additive genetic and residual. Individual SNP explaining at least 0.001% of the genetic variance for each trait were used to identify nearby genes in the National Center for Biotechnology Information database. Pathway enrichment analysis was performed. The PPI of genes were identified and visualized of the PPI network. Results Identified genes were involved in 16 enriched pathways related to MY, FY, and AFC. Most genes had two or more connections with other genes in the PPI network. Genes associated with MY, FY, and AFC based on the biological pathways and PPI were primarily involved in cellular processes. The percent of the genetic variance explained by genes in enriched pathways (303) was 2.63% for MY, 2.59% for FY, and 2.49% for AFC. Genes in the PPI network (265) explained 2.28% of the genetic variance for MY, 2.26% for FY, and 2.12% for AFC. Conclusion These sets of SNP associated with genes in the set enriched pathways and the PPI network could be used as genomic selection targets in the Thai multibreed dairy population. This study should be continued both in this and other populations subject to a variety of environmental conditions because predicted SNP values will likely differ across populations subject to different environmental conditions and changes over time.

Abstract Background Meat quality related phenotypes are difficult and expensive to measure and predict but are ideal candidates for genomic selection if genetic markers that account for a worthwhile proportion of the phenotypic variation can be identified. The objectives of this study were: 1) to perform genome wide association analyses for Warner-Bratzler Shear Force (WBSF), marbling, cooking loss, tenderness, juiciness, connective tissue and flavor; 2) to determine enriched pathways present in each genome wide association analysis; and 3) to identify potential candidate genes with multiple quantitative trait loci (QTL) associated with meat quality. Results The WBSF, marbling and cooking loss traits were measured in longissimus dorsi muscle from 672 steers. Out of these, 495 animals were used to measure tenderness, juiciness, connective tissue and flavor by a sensory panel. All animals were genotyped for 221,077 markers and included in a genome wide association analysis. A total number of 68 genomic regions covering 52 genes were identified using the whole genome association approach; 48% of these genes encode transmembrane proteins or membrane associated molecules. Two enrichment analysis were performed: a tissue restricted gene enrichment applying a correlation analysis between raw associated single nucleotide polymorphisms (SNPs) by trait, and a functional classification analysis performed using the DAVID Bioinformatic Resources 6.8 server. The tissue restricted gene enrichment approach identified eleven pathways including “Endoplasmic reticulum membrane” that influenced multiple traits simultaneously. The DAVID functional classification analysis uncovered eleven clusters related to transmembrane or structural proteins. A gene network was constructed where the number of raw associated uncorrelated SNPs for each gene across all traits was used as a weight. A multiple SNP association analysis was performed for the top five most connected genes in the gene-trait network. The gene network identified the EVC2, ANXA10 and PKHD1 genes as potentially harboring multiple QTLs. Polymorphisms identified in structural proteins can modulate two different processes with direct effect on meat quality: in vivo myocyte cytoskeletal organization and postmortem proteolysis. Conclusion The main result from the present analysis is the uncovering of several candidate genes associated with meat quality that have structural function in the skeletal muscle.

Carcass and meat quality are two important attributes for the beef industry because they drive profitability and consumer demand. These traits are of even greater importance in crossbred cattle used in subtropical and tropical regions for their superior adaptability because they tend to underperform compared to their purebred counterparts. Many of these traits are challenging and expensive to measure and unavailable until late in life or after the animal is harvested, hence unrealistic to improve through traditional phenotypic selection, but perfect candidates for genomic selection. Before genomic selection can be implemented in crossbred populations, it is important to explore if pleiotropic effects exist between carcass and meat quality traits. Therefore, the objective of this study was to identify genomic regions with pleiotropic effects on carcass and meat quality traits in a multibreed Angus–Brahman population that included purebred and crossbred animals. Data included phenotypes for 10 carcass and meat quality traits from 2,384 steers, of which 1,038 were genotyped with the GGP Bovine F-250. Single-trait genome-wide association studies were first used to investigate the relevance of direct additive genetic effects on each carcass, sensory and visual meat quality traits. A second analysis for each trait included all other phenotypes as covariates to correct for direct causal effects from identified genomic regions with pure direct effects on the trait under analysis. Five genomic windows on chromosomes BTA5, BTA7, BTA18, and BTA29 explained more than 1% of additive genetic variance of two or more traits. Moreover, three suggestive pleiotropic regions were identified on BTA10 and BTA19. The 317 genes uncovered in pleiotropic regions included anchoring and cytoskeletal proteins, key players in cell growth, muscle development, lipid metabolism and fat deposition, and important factors in muscle proteolysis. A functional analysis of these genes revealed GO terms directly related to carcass quality, meat quality, and tenderness in beef cattle, including calcium-related processes, cell signaling, and modulation of cell–cell adhesion. These results contribute with novel information about the complex genetic architecture and pleiotropic effects of carcass and meat quality traits in crossbred beef cattle.

A high-fat diet (HFD) is widely recognized as a significant modifiable risk for insulin resistance, inflammation, Type 2 diabetes, atherosclerosis and other metabolic diseases. However, the biological mechanism responsible for key metabolic disorders in the PAT of rabbits subject to HFD remains unclear. Here, untargeted metabolomics (LC-MS/MS) combined with liquid chromatography (LC) and high-resolution mass spectrometry (MS) were used to evaluate PAT metabolic changes. Histological observations showed that the adipocytes cells and density of PAT were significantly increased in HFD rabbits. Our study revealed 206 differential metabolites (21 up-regulated and 185 down-regulated); 47 differential metabolites (13 up-regulated and 34 down-regulated), comprising mainly phospholipids, fatty acids, steroid hormones and amino acids, were chosen as potential biomarkers to help explain metabolic disorders caused by HFD. These metabolites were mainly associated with the biosynthesis of unsaturated fatty acids, the arachidonic acid metabolic pathway, the ovarian steroidogenesis pathway, and the platelet activation pathway. Our study revealed that a HFD caused significant lipometabolic disorders. These metabolites may inhibit oxygen respiration by increasing the adipocytes cells and density, cause mitochondrial and endoplasmic reticulum dysfunction, produce inflammation, and finally lead to insulin resistance, thus increasing the risk of Type 2 diabetes, atherosclerosis, and other metabolic syndromes.

Type 2 diabetes and metabolic syndrome caused by a high fat diet (HFD) have become public health problems worldwide. These diseases are characterized by the oxidation of skeletal muscle mitochondria and disruption of insulin resistance, but the mechanisms are not well understood. Therefore, this study aims to reveal how high-fat diet causes skeletal muscle metabolic disorders. In total, 16 weaned rabbits were randomly divided into two groups, one group was fed a standard normal diet (SND) and the other group was fed a high fat diet (HFD) for 5 weeks. At the end of the five-week experiment, skeletal muscle tissue samples were taken from each rabbit. Untargeted metabolomic analysis was performed using ultra-performance liquid chromatography combined with mass spectrometry (UHPLC-MS/MS). The results showed that high fat diet significantly altered the expression levels of phospholipids, LCACs, histidine, carnosine, and tetrahydrocorticosterone in skeletal muscle. Principal component analysis (PCA) and least squares discriminant analysis (PLS-DA) showed that, compared with the SND group, skeletal muscle metabolism in HFD group was significantly up-regulated. Among 43 skeletal muscle metabolites in the HFD group, phospholipids, LCACs, histidine, carnosine, and tetrahydrocorticosteroids were identified as biomarkers of skeletal muscle metabolic diseases, and may become potential physiological targets of related diseases in the future. Untargeted metabonomics analysis showed that high-fat diet altered the metabolism of phospholipids, carnitine, amino acids and steroids in skeletal muscle of rabbits. Notably, phospholipids, LCACs, histidine, carnopeptide, and tetrahydrocorticosteroids block the oxidative capacity of mitochondria and disrupt the oxidative capacity of glucose and the fatty acid-glucose cycle in rabbit skeletal muscle.

The objective of this study was to investigate the effect of the polymorphism in the Myopalladin (MYPN) gene on meat quality traits in the Hyla, Champagne, Tianfu Black rabbit breeds using PCR and DNA sequencing. A novel SNP (g.18497416 G > A) was found at 229 bp in exon 13 of chromosome 18. The three rabbit populations had intermediate levels of genetic diversity according to their polymorphism information content values. The statistical analysis indicated that rabbits with the GG genotype had a significantly greater a*24h and b*24h than rabbits with the AA genotype (p

Objective The objective of this research was to estimate genetic correlations between number of piglets born alive in the first parity (NBA1), litter birth weight in the first parity (LTBW1), number of piglets weaned in the first parity (NPW1), litter weaning weight in the first parity (LTWW1), number of piglets born alive from second to last parity (NBA2+), litter birth weight from second to last parity (LTBW2+), number of piglets weaned from second to last parity (NPW2+) and litter weaning weight from second to last parity (LTWW2+), and to identify the percentages of animals (the top 10%, 25%, and 50%) for first parity and sums of second and later parity traits. Methods The 9,830 records consisted of 2,124 Landrace (L), 724 Yorkshire (Y), 2,650 LY, and 4,332 YL that had their first farrowing between July 1989 and December 2013. The 8-trait animal model included the fixed effects of first farrowing year-season, additive genetic group, heterosis of the sow and the litter, age at first farrowing, and days to weaning (NPW1, LTWW1, NPW2+, and LTWW2+). Random effects were animal and residual. Results Heritability estimates ranged from 0.08±0.02 (NBA1 and NPW1) to 0.29±0.02 (NPW2+). Genetic correlations between reproduction traits in the first parity and from second to last parity ranged from 0.17±0.08 (LTBW1 and LTBW2+) to 0.67±0.06 (LTWW1 and LTWW2+). Phenotypic correlations between reproduction traits in the first parity and from second to last parity were close to zero. Rank correlations between LTWW1 and LTWW2+ estimated breeding value tended to be higher than for other pairs of traits across all replacement percentages. Conclusion These rank correlations indicated that selecting boars and sows using genetic predictions for first parity reproduction traits would help improve reproduction traits in the second and later parities as well as lifetime productivity in this swine population.

Antibiotics have been widely used in livestock to treat and prevent bacterial diseases. However, use of antibiotics has led to the emergence of antibiotic resistant microorganisms (ARMs) in food animals. Due to the decreased efficacy of antibiotics, alternatives to antibiotics that can reduce infectious diseases in food animals to enhance animal health and growth performance are urgently required. Here, we show that animal genetics is associated with the hindgut microbiome, which is related to fat deposition and beta-lactam resistance in the gastrointestinal tract. We investigated the hindgut microbiota structure in 95 postweaning heifers belonging to the unique multibreed Angus-Brahman herd with breed composition ranging from 100% Angus to 100% Brahman. The hindgut microbial composition of postweaning heifers differed among breed groups. The mucin-degrading bacterium Akkermansia known for promoting energy expenditure was enriched in Brahman calves that contained less intramuscular fat content, while butyrate-producing bacterium Faecalibacterium was linearly positively correlated with Angus proportion. Moreover, the higher relative abundance of beta-lactam resistant genes including ampC gene and arcA gene was associated with the greater Brahman proportion. As the first study aimed at understanding changes in hindgut microbiota among beef cattle with linear gradient of breed composition and its association with marbling in meat, our results suggest that the effects of animal genetics on the gut microbiota structure is associated with fat deposition and potentially a factor affecting the gut antimicrobial resistance.

The prohibition of the use of growth-promoting drug additives in feeds was implemented in China in 2020. However, rabbits can experience symptoms of intestinal disease, such as diarrhea and flatulence, when switching from standard normal diets with antibiotics to antibiotic-free diets. The molecular mechanisms related to the occurrence of these diseases as well as associated physiological and metabolic changes in the intestine are unclear. Thus, the objectives of this study were to study the pathogenesis of intestinal inflammation using untargeted metabolomics. This was done to identify differential metabolites between a group of antibiotic-free feed Hyplus rabbits (Dia) whose diet was abruptly changed from a standard normal diet with antibiotics to an antibiotic-free diet, and an antibiotic diet group Hyplus rabbits (Con) that was fed a standard normal diet with antibiotics. Morphological damage to the three intestinal tissues was determined through visual microscopic examination of intestinal Dia and Con tissue samples stained with hematoxylin and eosin (HE). A total of 1969 different metabolites were identified in the three intestinal tissues from Dia and Con rabbits. The level of 1280 metabolites was significantly higher and the level of 761 metabolites was significantly lower in the Dia than in the Con group. These differential metabolites were involved in five metabolic pathways associated with intestinal inflammation (tryptophan metabolism, pyrimidine metabolism, phenylalanine, tyrosine and tryptophan biosynthesis, lysine degradation, and bile secretion). Rabbits in the Dia group developed metabolic disorders that affected the intestinal microbiota and changed the permeability of the intestinal tract, thereby triggering intestinal inflammation, affecting feed utilization, reducing production performance, and activating the intestinal tract self-repair mechanism. Thus, the abrupt transition from a diet with antibiotics to an antibiotic-free diet affected the structure and metabolism of the intestinal tract in Hyplus rabbits. Consequently, to avoid these problems, the antibiotic content in a rabbit diet should be changed gradually or alternative antibiotics should be found.

microRNAs (miRNAs), small non-coding RNA with a length of about 22 nucleotides, are involved in the energy metabolism of skeletal muscle cells. However, their molecular mechanism of metabolism in rabbit skeletal muscle is still unclear. In this study, 16 rabbits, 8 in the control group (CON–G) and 8 in the experimental group (HFD–G), were chosen to construct an obese model induced by a high–fat diet fed from 35 to 70 days of age. Subsequently, 54 differentially expressed miRNAs, 248 differentially expressed mRNAs, and 108 differentially expressed proteins related to the metabolism of skeletal muscle were detected and analyzed with three sequencing techniques (small RNA sequencing, transcriptome sequencing, and tandem mass tab (TMT) protein technology). It was found that 12 miRNAs and 12 core genes (e.g., CRYL1, VDAC3 and APIP) were significantly different in skeletal muscle from rabbits in the two groups. The network analysis showed that seven miRNA-mRNA pairs were involved in metabolism. Importantly, two miRNAs (miR-92a-3p and miR-30a/c/d-5p) regulated three transcription factors (MYBL2, STAT1 and IKZF1) that may be essential for lipid metabolism. These results enhance our understanding of molecular mechanisms associated with rabbit skeletal muscle metabolism and provide a basis for future studies in the metabolic diseases of human obesity.

The objective of this research was to estimate genetic parameters and trends for length of productive life (LPL), lifetime number of piglets born alive (LBA), lifetime number of piglets weaned (LPW), lifetime litter birth weight (LBW), and lifetime litter weaning weight (LWW) in a commercial swine farm in Northern Thailand. Data were gathered during a 24-year period from July 1989 to August 2013. A total of 3,109 phenotypic records from 2,271 Landrace (L) and 838 Yorkshire sows (Y) were analyzed. Variance and covariance components, heritabilities and correlations were estimated using an Average Information Restricted Maximum Likelihood (AIREML) procedure. The 5-trait animal model contained the fixed effects of first farrowing year-season, breed group, and age at first farrowing. Random effects were sow and residual. Estimates of heritabilities were medium for all five traits (0.17±0.04 for LPL and LBA to 0.20±0.04 for LPW). Genetic correlations among these traits were high, positive, and favorable (p

The objective of this study was to investigate the accuracy of imputation from low density (LDC) to moderate density SNP chips (MDC) in a Thai Holstein-Other multibreed dairy cattle population. Dairy cattle with complete pedigree information (n = 1,244) from 145 dairy farms were genotyped with GeneSeek GGP20K (n = 570), GGP26K (n = 540) and GGP80K (n = 134) chips. After checking for single nucleotide polymorphism (SNP) quality, 17,779 SNP markers in common between the GGP20K, GGP26K, and GGP80K were used to represent MDC. Animals were divided into two groups, a reference group (n = 912) and a test group (n = 332). The SNP markers chosen for the test group were those located in positions corresponding to GeneSeek GGP9K (n = 7,652). The LDC to MDC genotype imputation was carried out using three different software packages, namely Beagle 3.3 (population-based algorithm), FImpute 2.2 (combined family- and population-based algorithms) and Findhap 4 (combined family- and population-based algorithms). Imputation accuracies within and across chromosomes were calculated as ratios of correctly imputed SNP markers to overall imputed SNP markers. Imputation accuracy for the three software packages ranged from 76.79% to 93.94%. FImpute had higher imputation accuracy (93.94%) than Findhap (84.64%) and Beagle (76.79%). Imputation accuracies were similar and consistent across chromosomes for FImpute, but not for Findhap and Beagle. Most chromosomes that showed either high (73%) or low (80%) imputation accuracies were the same chromosomes that had above and below average linkage disequilibrium (LD; defined here as the correlation between pairs of adjacent SNP within chromosomes less than or equal to 1 Mb apart). Results indicated that FImpute was more suitable than Findhap and Beagle for genotype imputation in this Thai multibreed population. Perhaps additional increments in imputation accuracy could be achieved by increasing the completeness of pedigree information.

Structural equation models involving latent variables are useful tools for formulating hypothesized models defined by theoretical variables and causal links between these variables. The objectives of this study were: (1) to identify latent variables underlying carcass and meat quality traits and (2) to perform whole-genome scans for these latent variables in order to identify genomic regions and individual genes with both direct and indirect effects. A total of 726 steers from an Angus-Brahman multibreed population with records for 22 phenotypes were used. A total of 480 animals were genotyped with the GGP Bovine F-250. The single-step genomic best linear unbiased prediction method was used to estimate the amount of genetic variance explained for each latent variable by chromosome regions of 20 adjacent SNP-windows across the genome. Three types of genetic effects were considered: (1) direct effects on a single latent phenotype; (2) direct effects on two latent phenotypes simultaneously; and (3) indirect effects. The final structural model included carcass quality as an independent latent variable and meat quality as a dependent latent variable. Carcass quality was defined by quality grade, fat over the ribeye and marbling, while the meat quality was described by juiciness, tenderness and connective tissue, all of them measured through a taste panel. From 571 associated genomic regions (643 genes), each one explaining at least 0.05% of the additive variance, 159 regions (179 genes) were associated with carcass quality, 106 regions (114 genes) were associated with both carcass and meat quality, 242 regions (266 genes) were associated with meat quality, and 64 regions (84 genes) were associated with carcass quality, having an indirect effect on meat quality. Three biological mechanisms emerged from these findings: postmortem proteolysis of structural proteins and cellular compartmentalization, cellular proliferation and differentiation of adipocytes, and fat deposition.

The emergence of infections caused by antimicrobial resistant microorganisms (ARMs) is currently one of the most important challenges to public health and medicine. Though speculated to originate at least partially from the overuse of antibiotics during food animal production, we hypothesized that cattle are exposed to ARMs in the environment. In this cohort study, a herd of beef calves with no previous exposure to antibiotics was followed during the first year of life in order to investigate the rate of colonization by bacteria resistant to the third-generation cephalosporin cefotaxime. Fecal samples were collected from the recto anal junction of cattle at the age of ~3, 6, 9, and 12 months and tested for cefotaxime resistant bacteria (CRB) and the presence of extended spectrum β-lactamases (ESBLs). The colonization dynamics of CRB in calves (n = 188) was evaluated with samples collected from four periods using longitudinal statistical analyses. Colonization by CRB was a dynamic process with over 92% of the calves testing positive for CRB at least once during the first year of life. All isolates subjected to antimicrobial susceptibility test were resistant to at least four different antibiotics and carried multiple variants of the blaCTX-M genes. Metagenomic analysis revealed significant differences in microbiota of the calves with and without CRB colonization at different ages. This study provides evidence that colonization of beef calves by ARMs is a dynamic process that can occur in the absence of veterinary or agricultural use of antibiotics.

Crossbreeding is a common strategy used in tropical and subtropical regions to enhance beef production, and having accurate knowledge of breed composition is essential for the success of a crossbreeding program. Although pedigree records have been traditionally used to obtain the breed composition of crossbred cattle, the accuracy of pedigree-based breed composition can be reduced by inaccurate and/or incomplete records and Mendelian sampling. Breed composition estimation from genomic data has multiple advantages including higher accuracy without being affected by missing, incomplete, or inaccurate records and the ability to be used as independent authentication of breed in breed-labeled beef products. The present study was conducted with 676 Angus–Brahman crossbred cattle with genotype and pedigree information to evaluate the feasibility and accuracy of using genomic data to determine breed composition. We used genomic data in parametric and non-parametric methods to detect population structure due to differences in breed composition while accounting for the confounding effect of close familial relationships. By applying principal component analysis (PCA) and the maximum likelihood method of ADMIXTURE to genomic data, it was possible to successfully characterize population structure resulting from heterogeneous breed ancestry, while accounting for close familial relationships. PCA results offered additional insight into the different hierarchies of genetic variation structuring. The first principal component was strongly correlated with Angus–Brahman proportions, and the second represented variation within animals that have a relatively more extended Brangus lineage—indicating the presence of a distinct pattern of genetic variation in these cattle. Although there was strong agreement between breed proportions estimated from pedigree and genetic information, there were significant discrepancies between these two methods for certain animals. This was most likely due to inaccuracies in the pedigree-based estimation of breed composition, which supported the case for using genomic information to complement and/or replace pedigree information when estimating breed composition. Comparison with a supervised analysis where purebreds are used as the training set suggest that accurate predictions can be achieved even in the absence of purebred population information.

Autogenous proteolytic enzymes of the calpain family are implicated in myofibrillar protein degradation. As a result, the μ-calpain gene and its specific inhibitor, calpastatin, have been repeatedly investigated for their association with meat quality traits in cattle; however, no functional mutation has been identified for these two genes. The objectives of this study were: (1) to assess breed composition effect on tenderness; (2) to perform a linkage disequilibrium (LD) analysis in μ-calpain and calpastatin genes as well as an association analyses with tenderness; and (3) to analyze putative functional SNPs inside the significant LD block for an effect on tenderness. Tenderness measurements and genotypes for 16 SNPs in μ-calpain gene and 28 SNPs in calpastatin gene from 673 steers were analyzed. A bioinformatic analysis identified “putative functional SNPs” inside the associated LD block – polymorphisms able to produce a physical and/or chemical change in the DNA, mRNA, or translated protein in silico. Breed composition had a significant (P < 0.0001) effect on tenderness where animals with more than 80% Angus composition had the most tender meat. One 11-kb LD-block and three LD-blocks of 37, 17, and 14 kb in length were identified in the μ-calpain and calpastatin genes, respectively. Out of these, the LD-block 3 in calpastatin, tagged by SNPs located at 7-98566391 and 7-98581038, had a significant effect on tenderness with the TG-CG diplotype being approximately 1 kg more tender than the toughest diplotype, TG-CG. A total of 768 SNPs in the LD-block 3 of calpastatin were included in the bioinformatic analysis, and 28 markers were selected as putative functional SNPs inside the LD-block 3 of calpastatin; however, none of them were polymorphic in this population. Out of 15 initial polymorphisms segregating inside the LD-block 3 of calpastatin in this population, markers ARSUSMARC116, Cast5, rs730723459, and rs210861835 were found to be significantly associated with tenderness.

Se utilizaron registros de producción de leche ajustada a 305 días, equivalente edad adulta y dos or deñas de la primera lactancia, del Programa Nacional de Mejoramiento Genético en México PNMG (n= 163,885), qu e incluye a la Asociació n Holstein de México (AHM) (n= 43,668) y al Banco Nacional de Información Lechera (BNIL) (n= 120,217). El objetivo del estudio fue el análisis de las tendencias genéticas de poblaciones Hol stein en México. Se utilizó el método del Mejor Predictor Lineal Insesgado para predecir los valores genéticos (VG) d e los animales con un modelo animal usando el programa ASREML, el modelo incluyó el grupo hato-año-estación de part o como efecto fijo, y animal y residuo como aleatorios. Se estimaron los promedios de los VG de los sementa les ponderados por el número de hijas y no ponderados del PNMG, AHM y BNIL. Así como los promedios ponderados de lo s VG de los sementales del PNMG de acuerdo a su país de origen (EUA, Canadá, México y Otros). También se est imaron los promedios de VG y valores fenotípicos (VF) para las vacas en producción. Los VG y VF promedios de la s vacas del PNMG, AHM y BNIL aumentaron entre el 2007 y el 2011. Ganaderos de la AHM escogieron sementales con m ayores VG que los del BNIL. Sin embargo, ganaderos del BNIL utilizaron sementales con altos VG más frecuent emente. Los sementales extranjeros tuvieron VG superiores a los nacionales y fueron más utilizados por los g anaderos.

Se estimaron componentes de varianza y parámetros genéticos para producción de leche total a la primer a lactancia (PL1), producción de leche ajustada a 305 días y a equivalente adulto de la primera lactancia (PL1st d), producción de leche total de las cinco primeras lactancias (PL5) y producción de leche ajustada a 305 días y a equivalente adulto de las primeras 5 lactancias (PL5std). Se utilizaron las bases de datos de la Asociación Holstein de México (AHM; n= 43,668) y del Banco Nacional de Información Lechera (BNIL; n= 120,217). Las varianzas fueron estimad as mediante REML, utilizando un modelo animal simple p ara PL1 y PL1std y un modelo animal de repetibilidad para PL5 y PL5std. Las heredabilidades estimadas fueron desde bajas a moderadas para la primera lactancia (0.17 ± 0.009 a 0.49 ± 0.019) y para las primeras cinco lactancias (0.16 ± 0.006 a 0.41 ± 0.004). Las repetibilidades para PL5 y PL5std tuvieron un rango de 0.32 ± 0.002 a 0.41 ± 0.004. La inclusión de la información del BNIL en las eva luaciones genéticas permitió incorporar datos de producción que no se estaban tomando en cuenta. Esto no solam ente mejoró la precisión de los valores genéticos de los sementales para producción de leche, sino que también p ermitió la predicción de los valores genéticos de animales nacionales y extranjeros con progenies en México.

The objective of this study was to estimate variance components and genetic parameters for lactation milk yield (LY), lactation length (LL), average milk yield per day (YD), initial milk yield (IY), peak milk yield (PY), days to peak (DP) and parameters (ln(a) and c) of the modified incomplete gamma function (MIG) in an Ethiopian multibreed dairy cattle population. The dataset was composed of 5,507 lactation records collected from 1,639 cows in three locations (Bako, Debre Zeit and Holetta) in Ethiopia from 1977 to 2010. Parameters for MIG were obtained from regression analysis of monthly test-day milk data on days in milk. The cows were purebred (Bos indicus) Boran (B) and Horro (H) and their crosses with different fractions of Friesian (F), Jersey (J) and Simmental (S). There were 23 breed groups (B, H, and their crossbreds with F, J, and S) in the population. Fixed and mixed models were used to analyse the data. The fixed model considered herd-year-season, parity and breed group as fixed effects, and residual as random. The single and two-traits mixed animal repeatability models, considered the fixed effects of herd-year-season and parity subclasses, breed as a function of cow H, F, J, and S breed fractions and general heterosis as a function of heterozygosity, and the random additive animal, permanent environment, and residual effects. For the analysis of LY, LL was added as a fixed covariate to all models. Variance components and genetic parameters were estimated using average information restricted maximum likelihood procedures. The results indicated that all traits were affected (p

We used actual and adjusted weights to 120 d and 210 d of age of 72,731 male and female Nellore calves born in 40 PMGRN - Nellore Brazil herds from 1985 to 2005 aiming to compare the effect of different definitions of contemporary groups on estimates of (co)variance and genetic parameters. Four models, each one with a different structure of contemporary group (CG), were compared using the Akaike Information Criterion (AIC), the Bayesian Information Criterion (BIC), and the Consistent Akaike Information Criterion (CAIC). (Co)variance estimates were obtained using a derivative-free restricted maximum likelihood procedure. Estimates of (co)variances and genetic parameters were similar for the four models considered. However, the BIC and CAIC indicated that the most appropriate model for this Nellore population was the one that considered CG to be random, and sex of calf to be fixed and separate from CG, in which CG was defined as the group of calves born in the same herd, year, season of birth (trimester), and undergone the same management.

The objective of this research was to estimate the relative magnitude of effects included in contemporary groups (CG) and their interactions with adjusted and actual 120 d and 210 d weights in 72, 731 male and female Nelore calves born from 1985 to 2005 in 40 herds from PMGRN (Genetic Improvement Program of Nelore). Ten models with different CG structures were compared. The analyses were done using the general linear models (GLM) procedure run in SAS software. All of the effects included in the CG for each model were significant (p < 0.001) for the four traits analyzed. Inclusion of semester or trimester of birth as part of a CG was more appropriate than its use as an independent effect in the model because it accounted for interactions with the other effects in the CG. Calf sex (CS) and dam age at calving (DAC) had similar effects across the models, which suggested independence from other effects in these models. The corresponding age deviation effect had a larger impact on actual weight at 120 d than any other effect in all of the models tested. The use of actual weights in models with no CS effect in CG provides an alternative that would allow better genetic connectedness among CGs and greater accuracy in genetic evaluations.

Se estimaron componentes de varianza y parámetros genéticos para producción de leche total a la primera lactancia (PL1), producción de leche ajustada a 305 días y a equivalente adulto de la primera lactancia (PL1std), producción de leche total de las cinco primeras lactancias (PL5) y producción de leche ajustada a 305 días y a equivalente adulto de las primeras 5 lactancias (PL5std). Se utilizaron las bases de datos de la Asociación Holstein de México (AHM; n= 43,668) y del Banco Nacional de Información Lechera (BNIL; n= 120,217). Las varianzas fueron estimadas mediante REML, utilizando un modelo animal simple para PL1 y PL1std y un modelo animal de repetibilidad para PL5 y PL5std. Las heredabilidades estimadas fueron desde bajas a moderadas para la primera lactancia (0.17 ± 0.009 a 0.49 ± 0.019) y para las primeras cinco lactancias (0.16 ± 0.006 a 0.41 ± 0.004). Las repetibilidades para PL5 y PL5std tuvieron un rango de 0.32 ± 0.002 a 0.41 ± 0.004. La inclusión de la información del BNIL en las evaluaciones genéticas permitió incorporar datos de producción que no se estaban tomando en cuenta. Esto no solamente mejoró la precisión de los valores genéticos de los sementales para producción de leche, sino que también permitió la predicción de los valores genéticos de animales nacionales y extranjeros con progenies en México.

Se utilizaron registros de producción de leche ajustada a 305 días, equivalente edad adulta y dos ordeñas de la primera lactancia, del Programa Nacional de Mejoramiento Genético en México PNMG (n= 163,885), que incluye a la Asociación Holstein de México (AHM) (n= 43,668) y al Banco Nacional de Información Lechera (BNIL) (n= 120,217). El objetivo del estudio fue el análisis de las tendencias genéticas de poblaciones Holstein en México. Se utilizó el método del Mejor Predictor Lineal Insesgado para predecir los valores genéticos (VG) de los animales con un modelo animal usando el programa ASREML, el modelo incluyó el grupo hato-año-estación de parto como efecto fijo, y animal y residuo como aleatorios. Se estimaron los promedios de los VG de los sementales ponderados por el número de hijas y no ponderados del PNMG, AHM y BNIL. Así como los promedios ponderados de los VG de los sementales del PNMG de acuerdo a su país de origen (EUA, Canadá, México y Otros). También se estimaron los promedios de VG y valores fenotípicos (VF) para las vacas en producción. Los VG y VF promedios de las vacas del PNMG, AHM y BNIL aumentaron entre el 2007 y el 2011. Ganaderos de la AHM escogieron sementales con mayores VG que los del BNIL. Sin embargo, ganaderos del BNIL utilizaron sementales con altos VG más frecuentemente. Los sementales extranjeros tuvieron VG superiores a los nacionales y fueron más utilizados por los ganaderos.

A disponibilidade de grandes bases de dados em associações de diferentes raças e cruzamentos de bovinos,e a demanda crescente dos produtores por avaliações genéticas dos animais de raças puras e cruzados têm renovado o interesse na implementação de procedimentos de avaliação genética multirracial. Na maioria das associações de criadores dos Estados Unidos está sendo aplicada a avaliação genética de animais puros e cruzados.O Brasil, com sua enorme população bovina (167 milhões),composta amplamente por Zebu e seus cruzamentos (80%),e muitas grandes e bem estruturadas empresas (várias com dez mil animais ou mais), é provável que possua um expressivo número de bases de dados apropriadas para ser analisado por meio de procedimentos de avaliação genética multirracial. Comumente, no entanto, neste país são usados procedimentos de avaliação genética intra-racial independentemente da composição genética das populações bovinas. Os procedimentos intra-raciais ignoram os efeitos genéticos não-aditivos entre raças, e assumem que os parâmetros genéticos são os mesmos em todos os grupos raciais. Os procedimentos de avaliação genética multirracial incluem ambos os aspectos, assim, eles são preferíveis aos intra-raciais para avaliar geneticamente populações compostas por animais puros e cruzados. Os procedimentos de avaliação genética multirracial produzem predições genéticas aditivas mais acuradas, permitem a comparação direta de animais de diferente composição racial e viabilizam o melhoramento genético aditivo e não-aditivo em populações multirraciais. No entanto, esses procedimentos são computacionalmente mais complexos, requerem maior número de parâmetros genéticos e apresentam problemas de confundimento e multi colinearidade. Neste artigo, caracterizam-se as populações multirraciais, discutem-se modelos de avaliação genética, procedimentos e tarefas para sua implementação, e, quando relevante, apresentam-se comentários gerais sobre a situação multirracial no Brasil. PALAVRAS-CHAVE: Bovinos, cruzamento, avaliação genética, multirracial, predição.

Akirin play an important role not only in innate immune response but also in skeletal myogenesis. The chicken’s Akirin gene family only has Akirin 2. We detected the coding sequences of the Akirin 2 gene in a Chinese indigenous chicken (Langshan chicken) population to investigate the possibility of using this gene for chicken marker-assisted selection. The results of PCR-SSCP and DNA sequence showed that there were no polymorphisms in the six amplified regions of the Akirin 2 gene. In addition, there was no SNP record about the chicken’s Akirin 2 gene by searching in NCBI. Thus, the Akirin 2 gene may not be suitable to be used in chicken as a gene marker for marker- assisted selection.

Com o objetivo de se comparar o ajustamento de modelos com diferentes definições de grupos contemporâneos sobre as estimativas de (co)variâncias e parâmetros genéticos para pesos padronizados e reais aos 120 e 210 dias de idade, analisaram-se dados de 72.731 bezerros Nelore, machos e fêmeas, nascidos de 1985 a 2005 em 40 rebanhos integrantes do PMGRN - Nelore Brasil. Foram comparados quatro modelos incluindo diferentes estruturas de grupos contemporâneos (CG), julgados pelos critérios de informação de Akaike, Bayesiano e modificado de Akaike. As estimativas foram obtidas pelo método da máxima verossimilhança restrita livre de derivadas. As estimativas de (co)variâncias e parâmetros genéticos foram similares entre os modelos, porém os critérios de informação (BIC, CAIC) indicaram que o modelo mais adequado é o que considera o grupo contemporâneo como efeito aleatório, sendo este constituído pela concatenação dos efeitos de rebanho, ano de nascimento, grupo de manejo e efeito sazonal de trimestre de nascimento, e com efeito do sexo do bezerro independente do CG. PALAVRAS-CHAVE: critérios de informação; gado de corte; grupos contemporâneos.

Se utilizaron registros de pesos al nacimiento (18,383) y al destete (9,023) de la población mexicana de ganado Simmental, para estimar varianzas genéticas aditivas directas y maternas, heredabilidades, correlaciones y tendencias genéticas. La información se obtuvo en 434 hatos de socios de la Asociación Mexicana Simmental-Simbrah, entre 1980 y 1999. El grupo contemporáneo se definió como hato- año-estación. Se utilizó un modelo animal de dos caracterí­sticas con efectos aditivos directos y maternos, para estimar varianzas y parámetros genéticos, y predecir valores genéticos. Las heredabilidades para peso al nacimiento fueron 0.40 para el aditivo directo y 0.12 para el aditivo materno, la correlación genética aditiva directa-materna fue -0.63. Para peso al destete las heredabilidades fueron 0.33 para el aditivo directo y 0.19 para el aditivo materno, la correlación aditiva directa-materna fue -0.67. La íºnica correlación entre caracterí­sticas que resultó diferente de cero, fue entre peso al nacimiento directo y peso al destete directo (0.73). Las heredabilidades maternas fueron menores que las directas, y las correlaciones entre los efectos aditivos directos y maternos fueron negativas en las dos caracterí­sticas. Las tendencias genéticas en la población mexicana de Simmental fueron positivas para los efectos genéticos aditivos directos, y negativas para los aditivos maternos. Estas tendencias sugieren que la selección se hizo con mayor énfasis en los efectos genéticos aditivos directos para peso al destete. Debido a la correlación negativa entre los efectos genéticos aditivos directos y maternos, los programas de selección para crecimiento predestete necesitarí­an de un balance adecuado entre estos dos tipos de efecto.

Se utilizaron registros de animales puros y cruzados de las razas Brahman y Simmental provenientes de tres hatos desconectados genéticamente, para estimar componentes de varianza dentro de hato, para efectos directos aditivos y maternos para peso al nacimiento (PN) y al destete ajustado a 205 dí­as (PD205). Los hatos utilizados se encuentran localizados en la región subtropical del estado de Tamaulipas, México. Se estimaron componentes de varianza por medio de procedimientos de máxima verosimilitud restringida con modelos mixtos padre-,madre. El modelo incluyó los efectos fijos de grupo contemporáneo, y el combinado de edad de la madre-sexo de la crí­a-grupo racial de la madre. Los efectos de grupo genético incluyeron los intra-raciales aditivos directos, intra-raciales aditivos maternos, interraciales no aditivos directos e interraciales no aditivos maternos Simmental-Brahman. Los efectos aleatorios fueron el genético aditivo directo, genético aditivo materno y el residual. Los efectos en el modelo variaron de acuerdo a la caracterí­stica y la composición del hato. Los estimadores de heredabilidad fueron: 0.05 +- 0.03 para PN directo, 0.09 +- 0.03 para PN materno, 0.23 +- 0.08 para PD205 directo, 0.11 +- 0.04 para PD205 materno, en el hato 1, 0.84 +- 0.17 para PN directo, 0.63 +- 0.28 para PD205 directo y 0.33 +- 0.22 para PD205 materno, en el hato 2, y 0.03 +- 0.07 para PN directo, 0.15 +- 0.07 para PN materno, 0.22 +- 0.15 para PD205 directo y 0.17 +- 0.10 para PD205 materno, en el hato 3

A disponibilidade de grandes bases de dados em associações de diferentes raças e cruzamentos de bovinos,e a demanda crescente dos produtores por avaliações genéticas dos animais de raças puras e cruzados têm renovado o interesse na implementação de procedimentos de avaliação genética multirracial. Na maioria das associações de criadores dos Estados Unidos está sendo aplicada a avaliação genética de animais puros e cruzados.O Brasil, com sua enorme população bovina (167 milhões),composta amplamente por Zebu e seus cruzamentos (80%),e muitas grandes e bem estruturadas empresas (várias com dez mil animais ou mais), é provável que possua um expressivo número de bases de dados apropriadas para ser analisado por meio de procedimentos de avaliação genética multirracial. Comumente, no entanto, neste país são usados procedimentos de avaliação genética intra-racial independentemente da composição genética das populações bovinas. Os procedimentos intra-raciais ignoram os efeitos genéticos não-aditivos entre raças, e assumem que os parâmetros genéticos são os mesmos em todos os grupos raciais. Os procedimentos de avaliação genética multirracial incluem ambos os aspectos, assim, eles são preferíveis aos intra-raciais para avaliar geneticamente populações compostas por animais puros e cruzados. Os procedimentos de avaliação genética multirracial produzem predições genéticas aditivas mais acuradas, permitem a comparação direta de animais de diferente composição racial e viabilizam o melhoramento genético aditivo e não-aditivo em populações multirraciais. No entanto, esses procedimentos são computacionalmente mais complexos, requerem maior número de parâmetros genéticos e apresentam problemas de confundimento e multi colinearidade. Neste artigo, caracterizam-se as populações multirraciais, discutem-se modelos de avaliação genética, procedimentos e tarefas para sua implementação, e, quando relevante, apresentam-se comentários gerais sobre a situação multirracial no Brasil. PALAVRAS-CHAVE: Bovinos, cruzamento, avaliação genética, multirracial, predição.