UNASSIGNED: Identifying molecular mechanisms responsible for the response to heat stress is essential to increase production, reproduction, health, and welfare. This study aimed to identify early biological responses and potential biomarkers involved in the response to heat stress and animal\'s recovery in tropically adapted beef cattle through proteomic analysis of blood plasma.
UNASSIGNED: Blood samples were collected from 14 Caracu males during the heat stress peak (HSP) and 16 h after it (heat stress recovery-HSR) assessed based on wet bulb globe temperature index and rectal temperature. Proteome was investigated by liquid chromatography-tandem mass spectrometry from plasma samples, and the differentially regulated proteins were evaluated by functional enrichment analysis using DAVID tool. The protein-protein interaction network was evaluated by STRING tool.
UNASSIGNED: A total of 1,550 proteins were detected in both time points, of which 84 and 65 were downregulated and upregulated during HSR, respectively. Among the differentially regulated proteins with the highest absolute log-fold change values, those encoded by the GABBR1, EPHA2, DUSP5, MUC2, DGCR8, MAP2K7, ADRA1A, CXADR, TOPBP1, and NEB genes were highlighted as potential biomarkers because of their roles in response to heat stress. The functional enrichment analysis revealed that 65 Gene Ontology terms and 34 pathways were significant (P < 0.05). We highlighted those that could be associated with the response to heat stress, such as those related to the immune system, complement system, hemostasis, calcium, ECM-receptor interaction, and PI3K-Akt and MAPK signaling pathways. In addition, the protein-protein interaction network analysis revealed several complement and coagulation proteins and acute-phase proteins as important nodes based on their centrality and edges.
UNASSIGNED: Identifying differentially regulated proteins and their relationship, as well as their roles in key pathways contribute to improve the knowledge of the mechanisms behind the response to heat stress in naturally adapted cattle breeds. In addition, proteins highlighted herein are potential biomarkers involved in the early response and recovery from heat stress in tropically adapted beef cattle.

Supplementing trace minerals is common in managing bovine respiratory disease (BRD) in post-weaned cattle; however, its influence on host immunity and metabolism in high-risk cattle remains unclear. We aimed to assess the impact of three supplementation programs on liver and serum trace element concentrations and blood gene expression. Fifty-six high-risk beef steers were randomly assigned to one of three groups over 60 days: (1) sulfate-sourced Cu, Co, Mn, and Zn (INR), (2) amino acid-complexed Cu, Mn, Co, and Zn (AAC), or (3) AAC plus trace mineral and vitamin drench (COMBO). Serum and liver biopsies for Cu, Co, Mn, and Zn at d0, d28, and d60 were analyzed from cattle free of BRD (n = 9 INR; n = 6 AAC; n = 10 COMBO). Differences and correlations of mineral concentrations were analyzed via generalized linear mixed models and Spearman\'s rank coefficients, respectively (p < 0.05). Whole blood RNA samples from healthy cattle (n = 4 INR; n = 4 AAC; n = 4 COMBO) at d0, d13, d28, d45, and d60 were sequenced and analyzed for differentially expressed genes (DEGs) via glmmSeq (FDR < 0.05), edgeR (FDR < 0.10), and Trendy (p < 0.10). Serum and liver Cu and Co concentrations increased over time in all groups, with higher liver Cu in COMBO (487.985 μg/g) versus AAC (392.043 μg/g) at d60 (p = 0.013). Serum and liver Cu concentrations (ρ = 0.579, p = 6.59 × 10-8) and serum and liver Co concentrations (ρ = 0.466, p = 2.80 × 10-5) were linearly correlated. Minimal gene expression differences were found between AAC versus COMBO (n = 2 DEGs) and INR versus COMBO (n = 0 DEGs) over time. AAC versus INR revealed 107 DEGs (d13-d60) with increased traits in AAC including metabolism of carbohydrates/fat-soluble vitamins, antigen presentation, ATPase activity, and B- and T-cell activation, while osteoclast differentiation and neutrophil degranulation decreased in AAC compared to INR. Our study identifies gene expression differences in high-risk cattle fed inorganic or amino acid-complexed mineral supplements, revealing adaptive immune and metabolic mechanisms that may be improved by organically sourced supplementation.

UNASSIGNED: Theileria orientalis Ikeda genotype is an emerging cattle disease in the US. Since 2017, when T. orientalis Ikeda was discovered in beef cattle in two counties in Virginia, cattle infections have risen to include ~67% of Virginia counties and 14 states. Consistent with New Zealand studies, many infected herds in Virginia were >90% positive upon initial testing without overt evidence of infection. Central bull tests present a unique opportunity to study the effects of T. orientalis Ikeda infections, as bulls from multiple source herds are consolidated. The objective of this study was to determine if infection with T. orientalis Ikeda affected the average daily gain (ADG), adjusted yearling weight (AYW) and breeding soundness of bulls at two test stations in Virginia over a period of years.
UNASSIGNED: The bulls were fed and housed similarly to compare their growth performance and breeding soundness. For T. orientalis Ikeda testing, DNA was extracted from whole blood for quantitative polymerase chain reaction.
UNASSIGNED: The number of bulls infected with T. orientalis Ikeda at initial delivery to the stations increased significantly over the years studied. Multivariable linear regression models, using Angus bulls from Virginia test stations, indicated no significant effect on ADG or AYW in bulls that became test positive during the test or were positive for the duration, compared to Angus bulls that were negative for the duration. At LOC A, the odds of passing a breeding soundness exam (BSE) were not significantly different for bulls that turned positive during the test or were positive for the duration, compared to bulls that were negative for the duration of the test. At LOC B, bulls that became positive during the test were 2.4 times more likely (95% CI: 1.165-4.995, p = 0.016) to pass their BSE compared to bulls that remained negative throughout the test.
UNASSIGNED: We do not suppose that an obscured infection of T. orientalis Ikeda is protective for bulls to pass a BSE. However, this study demonstrates an obscured infection of T. orientalis Ikeda does not negatively affect weight gain or achievement of a satisfactory BSE rating at the central bull test stations in Virginia.

BACKGROUND: The selection of individuals based on their predicted breeding values and mating of related individuals can increase the proportion of identical-by-descent alleles. In this context, the objectives of this study were to estimate inbreeding coefficients based on alternative metrics and data sources such as pedigree (FPED), hybrid genomic relationship matrix H (FH), and ROH of different length (FROH); and calculate Pearson correlations between the different metrics in a closed Nellore cattle population selected for body weight adjusted to 378 days of age (W378). In addition to total FROH (all classes) coefficients were also estimated based on the size class of the ROH segments: FROH1 (1-2 Mb), FROH2 (2-4 Mb), FROH3 (4-8 Mb), FROH4 (8-16 Mb), and FROH5 (> 16 Mb), and for each chromosome (FROH_CHR). Furthermore, we assessed the effect of each inbreeding metric on birth weight (BW), body weights adjusted to 210 (W210) and W378, scrotal circumference (SC), and residual feed intake (RFI). We also evaluated the chromosome-specific effects of inbreeding on growth traits.
RESULTS: The correlation between FPED and FROH was 0.60 while between FH and FROH and FH and FPED were 0.69 and 0.61, respectively. The annual rate of inbreeding was 0.16% for FPED, 0.02% for FH, and 0.16% for FROH. A 1% increase in FROH5 resulted in a reduction of up to -1.327 ± 0.495 kg in W210 and W378. Four inbreeding coefficients (FPED, FH, FROH2, and FROH5) had a significant effect on W378, with reductions of up to -3.810 ± 1.753 kg per 1% increase in FROH2. There was an unfavorable effect of FPED on RFI (0.01 ± 0.0002 kg dry matter/day) and of FROH on SC (-0.056 ± 0.022 cm). The FROH_CHR coefficients calculated for BTA3, BTA5, and BTA8 significantly affected the growth traits.
CONCLUSIONS: Inbreeding depression was observed for all traits evaluated. However, these effects were greater for the criterion used for selection of the animals (i.e., W378). The increase in the genomic inbreeding was associated with a higher inbreeding depression on the traits evaluated when compared to pedigree-based inbreeding. Genomic information should be used as a tool during mating to optimize control of inbreeding and, consequently, minimize inbreeding depression in Nellore cattle.

Chelated copper (Cu) sources, such as Cu glycinate (CuGly), may be more bioavailable relative to Cu sulfate (CuSO 4 ) when fed to ruminants under antagonistic pressure. The objective of this study was to determine the bioavailability of CuGly (GemStone Cu; Phibro Animal Health) relative to CuSO4 in steers fed a diet supplemented with 0.3% sulfur and 2 mg molybdenum/kg of dry matter (DM). Sixty Angus crossbred steers (n = 12 per treatment) averaging 288 ± 4.85 kg were enrolled in a 90-d study and fed a corn silage-based diet with one of five Cu supplementation strategies, including no supplemental Cu (CON), 5 or 10 mg supplemental Cu from CuSO4/kg DM, and 5 or 10 mg supplemental Cu from CuGly/kg DM. Steers were housed in pens equipped with GrowSafe feed bunks (GrowSafe Systems Ltd., Airdire, AB, Canada), with six steers per pen. Growth performance, liver Cu, and plasma Cu were analyzed in the MIXED procedure of SAS 9.4 (SAS Inst. Inc, Cary, NC) with orthogonal contrasts to compare CON vs. 5 mg Cu/kg DM, CON vs. 10 mg Cu/kg DM, 5 vs. 10 mg Cu/kg DM, and CuSO4 vs. CuGly. Copper indices were regressed against Cu intake and slopes were calculated using the GLM procedure SAS. Dietary Cu supplementation did not affect steer body weights on days 0, 28, 56, or 90 (P ≥ 0.52), average daily gain, dry matter intake, or gain:feed (P ≥ 0.36). Final plasma Cu concentration did not differ between CON vs. 5 mg Cu/kg DM (P = 0.79), CON vs. 10 mg Cu/kg DM (P = 0.65), or 5 vs. 10 mg Cu/kg DM (P = 0.39). Steers receiving CuSO4 tended to have greater final plasma Cu concentrations than those receiving CuGly (P = 0.08). Initial liver Cu concentration averaged 374 mg Cu/kg DM, which is considered highly adequate. No steers reached deficient Cu status by the end of the 90-d period. Control steers had lesser final liver Cu concentrations than supplemented steers (P ≤ 0.04). Steers receiving 10 mg supplemental Cu/kg DM had greater liver Cu concentrations than those receiving 5 mg supplemental Cu/kg DM (P = 0.01). Copper source had no effect on final liver Cu concentrations (P = 0.57) and based on liver Cu and Cu intake the bioavailability of CuGly was similar to CuSO4 (115%; P = 0.27). The initially high Cu status and the fact that cattle did not become Cu deficient may have impacted the relative bioavailability results, and more research is needed to investigate the role initial Cu status and antagonistic pressure play in the bioavailability of chelated Cu sources.

Antimicrobials are used on livestock farms to treat and prevent infectious animal diseases and to promote the growth of livestock. We monitored the prevalence of antibiotic-resistant Escherichia coli (AR-EC) isolates from beef cattle (BC) and dairy cows (DCs) on a livestock farm in Yamagata, Japan. Fecal samples from 5 male BC and 10 male DCs were collected monthly from October 2022 to November 2023. In total, 152 and 884 E. coli isolates were obtained from the BC and DC fecal samples, respectively. Notably, 26 (17.1%) and 29 (3.3%) E. coli isolates in the BC and DC groups, respectively, were resistant to at least one antibiotic. The resistance rates to tetracycline, ampicillin, gentamicin, and chloramphenicol of the isolates were significantly higher than those to the other antimicrobials. The tetracycline resistance genes tetA (70.6%) in DCs and tetB (28%) in BC were identified, along with the blaTEM gene in ampicillin-resistant isolates (BC: 84.2%, DCs: 42.8%). Despite significant variations in the monthly detection rates of AR-EC isolated from BC and DCs throughout the sampling period, the judicious use of antimicrobials reduced the occurrence of AR-EC in both BC and DCs, thereby minimizing their release into the environment.

To date, more than 20 species in the genus Cyclospora have been reported. Among them, Cyclospora cayetanensis has been recognized as the causative agent of human cyclosporiasis, which is characterized by severe intestinal injury and prolonged diarrhea in patients with immune dysfunction. The presence of C. cayetanensis in cattle has been confirmed. To date, however, no surveillance data are available on the occurrence and prevalence of Cyclospora spp. in cattle in Shanxi Province, North China. In the present study, a total of 761 fecal samples collected from cattle in three representative counties (Qi, Jishan, and Shanyin) in this Province were examined for Cyclospora spp. by using a polymerase-chain-reaction-restriction-fragment-length polymorphism (PCR-RFLP) test based on the nuclear small subunit ribosomal RNA (SSU rRNA) gene. The prevalence of Cyclospora spp. in cattle was 2.1%, and region, age, sex, and breed were not identified to be risk factors. Molecular evolutionary analysis based on the SSU rRNA sequences revealed that all 12 of the isolates were relatively distant from the human pathogen C. cayetanensis; seven isolates were grouped with Cyclospora colobi, whereas the others were grouped with cattle Cyclospora spp. reported previously. Though C. cayetanensis was not detected in cattle in the present study, more investigations should be performed in human populations, other animal species, or cattle from other regions of Shanxi Province and other environmental sources from the One Health perspective.

One-carbon metabolites (OCM) are metabolites and cofactors which include folate, vitamin B12, methionine, and choline that support methylation reactions. The objectives of this study were to investigate the effects of moderate changes in maternal body weight gain in combination with OCM supplementation during the first 63 d of gestation in beef cattle on (1) B12 and folate concentrations in maternal serum (2) folate cycle intermediates in maternal and fetal liver, allantoic fluid (ALF), and amniotic fluid (AMF) and (3) metabolites involved in one-carbon metabolism and related metabolic pathways in maternal and fetal liver. Heifers were either intake restricted (RES) and fed to lose 0.23 kg/d, or fed to gain 0.60 kg/d (CON). Supplemented (+ OCM) heifers were given B12 and folate injections weekly and fed rumen-protected methionine and choline daily, while non-supplemented (-OCM) heifers were given weekly saline injections. These two treatments were combined in a 2 × 2 factorial arrangement resulting in 4 treatments: CON-OCM, CON + OCM, RES-OCM, and RES + OCM. Samples of maternal serum, maternal and fetal liver, ALF, and AMF were collected at slaughter on day 63 of gestation. Restricted maternal nutrition most notably increased (./ ≤ 0.05) the concentration of vitamin B12 in maternal serum, 5,10-methylenetetrahydrofolate and 5,10-methenyltetrahydrofolate in maternal liver, and cystathionine in the fetal liver; conversely, maternal restriction decreased (P = 0.05) 5,10-methylenetetrahydrofolate concentration in fetal liver. Supplementing OCM increased (P ≤ 0.05) the concentrations of maternal serum B12, folate, and folate intermediates, ALF and AMF 5-methyltetrahydrofolate concentration, and altered (P ≤ 0.02) other maternal liver intermediates including S-adenosylmethionine, dimethylglycine, cystathionine Glutathione reduced, glutathione oxidized, taurine, serine, sarcosine, and pyridoxine. These data demonstrate that OCM supplementation was effective at increasing maternal OCM status. Furthermore, these data are similar to previously published literature where restricted maternal nutrition also affected maternal OCM status. Altering OCM status in both the dam and fetus could impact fetal developmental outcomes and production efficiencies. Lastly, these data demonstrate that fetal metabolite abundance is highly regulated, although the changes required to maintain homeostasis may program altered metabolism postnatally.
Maternal stresses that occur during pregnancy, such as restricted nutrition, can impact the developmental outcomes of the offspring in a process known as developmental programming. This programming can occur through epigenetics, which involves changes in fetal gene expression and can occur through the addition of methyl groups to DNA. These changes regulate gene transcription in the offspring and can alter offspring health, efficiency, and life-long outcomes. One-carbon metabolites (OCM), which are nutrients like the amino acid methionine and the vitamins B12, folate, and choline, act as intermediates or cofactors for the donation of methyl groups to DNA. This study investigated the effects of differing maternal rates of gain along with OCM supplementation during early gestation on OCM and related metabolite concentrations in the dam and fetus. We found that supplementing OCM to beef heifers increased maternal OCM and related metabolite concentrations and fetal fluid OCM concentrations. We also found that low maternal gain increased maternal serum and liver OCM concentrations. We can conclude from these findings that both maternal rate of gain and OCM supplementation can impact maternal OCM concentrations at day 63 of gestation and further research is needed to see if those maternal impacts will affect the developing fetus or calf later in its life.

Beef is a major global source of protein, playing an essential role in the human diet. The worldwide production and consumption of beef continue to rise, reflecting a significant trend. However, despite the critical importance of beef cattle resources in agriculture, the diversity of cattle breeds faces severe challenges, with many breeds at risk of extinction. The initiation of the Beef Cattle Genome Project is crucial. By constructing a high-precision functional annotation map of their genome, it becomes possible to analyze the genetic mechanisms underlying important traits in beef cattle, laying a solid foundation for breeding more efficient and productive cattle breeds. This review details advances in genome sequencing and assembly technologies, iterative upgrades of the beef cattle reference genome, and its application in pan-genome research. Additionally, it summarizes relevant studies on the discovery of functional genes associated with key traits in beef cattle, such as growth, meat quality, reproduction, polled traits, disease resistance, and environmental adaptability. Finally, the review explores the potential of telomere-to-telomere (T2T) genome assembly, structural variations (SVs), and multi-omics techniques in future beef cattle genetic breeding. These advancements collectively offer promising avenues for enhancing beef cattle breeding and improving genetic traits.

This study evaluated the association between the proportion of Brahman genetics and productivity of Brahman-Angus cows at weaning using a 31-yr dataset containing 6,312 cows and 5,405 pregnancies. Cows were contemporaneously reared and enrolled in yearly breeding seasons under subtropical conditions of North-Central Florida. They were evenly distributed in six-breed groups (G) according to the proportion of Brahman genetics: G0% to 19%, G21% to 34%, G38% (Brangus), G41% to 59%, G63% to 78%, and G81% to 100%. The proportion of cows calving (84.9%) did not differ across the six-breed groups. However, cows in the G81% to 100% weaned fewer calves (90.8%) than cows in the G0% to 19% and G21% to 34% (95.7%, each). The weaning rate of cows in the G38% (94.3%), G41% to 59% (94.2%), and G63% to 78% (93.0%) was intermediate between these three breed groups. The preweaning calf mortality was greater for cows in the G81% to 100% (9.2%) than cows in the G0% to 19% and G21% to 34% (4.3%, each), but intermediate for cows in the G38% (5.7%), G41% to 59% (5.8%), and G63% to 78% (7.0%). Cows in the G81% to 100% also weaned lighter calves (220.6 kg) than cows in the G0% to 19% (245.2 kg), G21% to 34% (250.2 kg), G38% (247.9 kg), G41% to 59% (252.5 kg), and G63% to 78% (245.2 kg). Cows in the G0% to 19% weaned lighter calves than cows with 21% to 78% of Brahman genetics. The 205-d adjusted weaning weight evidenced the less productive results of cows in G0% to 19% and G81% to 100% compared with other genetic groups, as they calved at the fastest and slowest rate, respectively. Thus, the 205-d adjusted weaning weight eliminated this bias. Additionally, younger cows weaned lighter calves; and male calves were heavier at weaning than female calves. Both parity order of cow and calf sex altered the magnitude of the described association between breed group of cows and calf weaning weights. Overall, after adjusting for weaning rate and age of calves at weaning, the number of kilograms produced per cow submitted to reproduction was less for cows in the G0% to 19% (191.1 kg) and G81% to 100 (181.8 kg) compared with cows in the G21% to 34 (197.0 kg), G38 (195.9 kg), G41% to 59 (199.7), and G63% to 78 (196.2). Cows in the G81% to 100% were the least productive. Thus, a proportion of Brahman genetics between 21% and 78% ensured superior productivity of Brahman-Angus cows subjected to subtropical conditions.