Improvement in feed conversion efficiency can improve the sustainability of beef cattle production, but genomic selection for feed efficiency affects many underlying molecular networks and physiological traits. This study describes the differences between steer progeny of two influential Angus bulls with divergent genomic predictions for residual feed intake (RFI). Eight steer progeny of each sire were phenotyped for growth and feed intake from 8 mo. of age (average BW 254 kg, with a mean difference between sire groups of 4.8 kg) until slaughter at 14–16 mo. of age (average BW 534 kg, sire group difference of 28.8 kg). Terminal samples from pituitary gland, skeletal muscle, liver, adipose, and duodenum were collected from each steer for transcriptome sequencing. Gene expression networks were derived using partial correlation and information theory (PCIT), including differentially expressed (DE) genes, tissue specific (TS) genes, transcription factors (TF), and genes associated with RFI from a genome-wide association study (GWAS). Relative to progeny of the high RFI sire, progeny of the low RFI sire had -0.56 kg/d finishing period RFI (P = 0.05), -1.08 finishing period feed conversion ratio (P = 0.01), +3.3 kg^0.75 finishing period metabolic mid-weight (MMW; P = 0.04), +28.8 kg final body weight (P = 0.01), -12.9 feed bunk visits per day (P = 0.02) with +0.60 min/visit duration (P = 0.01), and +0.0045 carcass specific gravity (weight in air/weight in air—weight in water, a predictor of carcass fat content; P = 0.03). RNA-seq identified 633 DE genes between sire groups among 17,016 expressed genes. PCIT analysis identified >115,000 significant co-expression correlations between genes and 25 TF hubs, i.e. controllers of clusters of DE, TS, and GWAS SNP genes. Pathway analysis suggests low RFI bull progeny possess heightened gut inflammation and reduced fat deposition. This multi-omics analysis shows how differences in RFI genomic breeding values can impact other traits and gene co-expression networks.

A pedigreed population containing 71 calves and 8 sires was used to compare sire qualification using three genotyping platforms [14 microsatellite, real-time quantitative PCR, and 100, 200, 500, and 1000 single nucleotide polymorphism (SNP) arrays]. Parentage was also qualified in an unknown-pedigree population containing 8480 calves with 460 sires using SNP arrays. The three platforms qualified the true sire in the known-pedigree population with zero mismatches. The 100 and 200 SNP arrays yielded specificities of 0.92 and 0.99 with a 1% mismatch rate in the knownpedigree population, respectively. In the larger population, SNP panels of the 500 and 1000 highest minor allele frequency SNPs were also evaluated. The 1000 SNP panel qualified paternity to a single sire for 82.1% of calves with 1% or 2% mismatches. Not all commercial sires were genotyped, which accounts for missing paternity for some calves. In this larger population, the 100 SNP array qualified multiple sires to 0.42% of calves and single sires to 80.84% of calves without mismatches. The 200 SNP array assigned unique paternity, and 79.8% of calves were qualified to a sire without mismatches. With a 2% mismatch rate, sire qualifications agreed with the 1000 SNP array. This study highlights the interplay among population size, genotyping error rates, and the specificity and sensitivity of parentage platforms.Key words: SNP parentage panel, sensitivity (parentage), specificity (parentage), Charolais, cattle (beef).Résumé : Une population à pedigree contenant 71 veaux et 8 géniteurs mâles a été utilisée pour comparer la qualification des géniteurs mâles au moyen de trois plateformes de génotypage (14 microsatellites, PCR quantitative en temps réel, ainsi que des réseaux de 100, 200, 500, et 1000 SNPs). La parenté a aussi été qualifiée dans une population de pedigree inconnu contenant 8480 veaux et 460 géniteurs mâles au moyen des réseaux de SNPs. Les trois plateformes ont qualifié le véritable géniteur dans la population à pedigree connu avec aucun écart. Les réseaux à 100 et 200 SNPs ont rendu des spécificités de 0,92 et 0,99 avec un taux d'écart de 1 % dans la population à pedigree connu, respectivement. Dans la plus grande population, les panels de SNPs de 500 et 1000 SNPs de fréquence d'allèles mineurs les plus élevés ont aussi été évalués. Le panel de 1000 SNPs a qualifié la paternité à un seul géniteur pour 82,1 % des veaux avec seulement 1 % à 2 % d'écarts. Tous les géniteurs mâles commerciaux n'ont pas été génotypés ce qui explique la paternité manquante pour certains veaux. Dans cette population plus grande, le réseau à 100 SNPs a qualifié de multiples géniteurs à 0,42 % des veaux et un seul géniteur à 80,84 % des veaux sans écarts. Le réseau à 200 SNPs a assigné une paternité unique et 79,8 % des veaux ont été qualifiés à un géniteur sans écart. Avec un taux d'écart de 2 %, la qualification des géniteurs était en accord avec le réseau de 1000 SNPs. Cette étude souligne l'interdépendance entre la taille de la population, les taux d'éca...

Epizootic bovine abortion (EBA), or “foothill abortion,” is the leading cause of beef cattle abortion in California and has also been reported in Nevada and Oregon. In the 1970s, the soft-shelled tick Ornithodoros coriaceus, or “pajaroello tick,” was confirmed as the disease-transmitting vector. In 2005, a novel Deltaproteobacterium was discovered as the etiologic agent of EBA (aoEBA), recently named Pajaroellobacter abortibovis. This organism cannot be grown in culture using traditional microbiological techniques; it can only be grown in experimentally-infected severe combined immunodeficient (SCID) mice. The objectives of this study were to perform a de novo genome assembly for P. abortibovis and identify and validate potential antigenic proteins as candidates for future recombinant vaccine development. DNA and RNA were extracted from spleen tissue collected from experimentally-infected SCID mice following exposure to P. abortibovis. This combination of mouse and bacterial DNA was sequenced and aligned to the mouse genome. Mouse sequences were subtracted from the sequence pool and the remaining sequences were de novo assembled at 50x coverage into a 1.82 Mbp complete closed circular Deltaproteobacterial genome containing 2250 putative protein-coding sequences. Phylogenetic analysis of P. abortibovis predicts that this bacterium is most closely related to the organisms of the order Myxococcales, referred to as Myxobacteria. In silico prediction of vaccine candidates was performed using a reverse vaccinology approach resulting in the identification and ranking of the top 10 candidate proteins that are likely to be antigenic. Immunologic testing of these candidate proteins confirmed antigenicity of seven of the nine expressed protein candidates using serum from P. abortibovis immunized mice.

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