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At least 19 recordsLinked to original sources
PubMed2026

A genome-wide assessment of the population structure of thirteen admixed and pure Australian beef cattle breeds.

Knowledge of population structure is a key factor for successful multi-breed genomic prediction, especially in single-step analysis when metafounders are considered. In Australia, current assessments mostly focus on single breeds using a single-step genomic prediction method. However, the effective integration of pedigree, phenotypic, and genomic data in a multi-breed framework still requires further research, especially for combined analyses including admixed and multi-breed populations. This study began with 602,952 genotyped individuals with 8K SNPs in common from 13 beef cattle breeds (Alexandria, Angus, Brahman, Brangus, Charolais, Droughtmaster, Hereford, Kynuna, Limousin, Santa Gertrudis, Shorthorn, Speckle Park, and Wagyu). Due to different numbers of animals being genotyped in each breed, a representative subset of animals was chosen by employing a validated sampling strategy using Gaussian Mixture Models (GMM) complemented by Principal Component Analysis (PCA) within each breed. Subsequently, a specific number of animals in each cluster were randomly selected to capture the entire genetic diversity per breed, with a total of 260 animals from each breed. The first three principal components explained 59.89% of the total variation, with PC1 (33.54%) clearly separating Bos indicus from Bos taurus lineages. Admixture analysis identified stable ancestral components and defined the genetic makeup of both pure and composite populations. The results showed extensive genetic diversity in some breeds and highlighted distinct genetic differences between Bos indicus and Bos taurus breeds. In addition, six composite breeds' admixture levels confirmed their origin and breed history, revealing a directional shift in ancestry proportions by a longitudinal increase in Brahman ancestry within tropical composites over time. Thus, the findings pave the way for more effective utilization of genetic diversity both within and across populations and provide a framework for designing multi-breed genetic evaluations and breeding programs to improve productivity and profitability in Australian beef production.

Animals↗
PubMed2025

Genomic prediction and genome-wide association study for liver abscesses in crossbred beef cattle.

Liver abscesses are a concern in feedlot cattle, and little is known about the role of genetics in their development. This study aimed to estimate genetic parameters and to identify single-nucleotide polymorphisms (SNPs) associated with liver abscesses. Crossbred cattle representing 18 breeds in the U.S. Meat Animal Research Center Germplasm Evaluation Program were phenotyped for liver abscesses at slaughter (n&#x2005;=&#x2005;9,044). Seventeen percent of cattle had liver abscesses. These cattle had genotypes that were imputed to sequence variant genotypes. After filtering and quality control, 340,723 SNPs were used in the analysis. Liver abscess prevalence was modeled with a single-step genomic best linear unbiased prediction (ssGBLUP) threshold model using a Bayesian framework. The model included contemporary group (sex, treatment group, and slaughter date), additive genomic, and residual effects. Genomic heritability was 0.039 (95% highest posterior density&#x2005;=&#x2005;0.005, 0.081), which was very small. To assess prediction quality, a 5-fold random cross-validation structure was used. Method Linear Regression was used to assess accuracy, bias, and dispersion by comparing estimated breeding values (EBV) from full and reduced analyses. Cross-validation metrics showed EBV based on genotypes had 0.05 reliability (SD&#x2005;<&#x2005;0.01) with no bias relative to EBV based on genotypes and phenotypes. For the genome-wide association study, SNP effects were back calculated from the EBV solutions from ssGBLUP. No SNPs were associated with liver abscesses at a Benjamini-Hochberg adjusted 0.05 significance level. Although a large dataset was used, this result was because of the low genomic heritability and imprecise EBV used to calculate SNP effects. Based on these results, environmental factors contribute to most of the variation in liver abscesses. Genetic selection to reduce liver abscesses would be slow because of the low genomic heritability, measurement late in life, and inability to measure breeding animals. A faster approach would be finding additional environmental interventions that maintain animal performance.

Animals↗
PubMed1979

Bacteriological aspects of the disposal of manure from beef cattle.

Manure, collected from cattle housed in yards, was spread on experimental plots at the rate of 120 tonnes per hectare per annum. The manure was applied to 2 plots at 6-monthly intervals while a further 2 plots received monthly applications. Samples of manure soil, run-off and ground waters were examined for their counts of total aerobic bacteria, coliforms, faecal coliforms and for the presence of salmonellae. Comparison of the bacterial counts from samples from the test plots to those of the control plots showed that no change occurred in the levels of coliforms or faecal coliforms over the 3 years of manure application. One hundred and fifty-seven isolations of salmonella were made from the soil and water samples, but only 51 could be attributed to the manure. No difference was observed in the effects of different application frequencies.

Animals↗
PubMed1978

Epidemiology of bovine leukemia in Venezuela.

Approximately 20 thousand bovines of autochtonious and imported breeds, located in different regions of the Country were serologically tested by Immuno-diffusion (I.D.) in agar, using BLV GP60 antigens, for the purpose of determining the prevalence of infection by Bovine Leukemia Virus. Hematologic and histopathologic assays were made with the object of determining variations in hematologic values and the determination of stages of persistent lymphocytosis, and of studying the morphocytological changes that accompany malignant transformations of lymphoid elements, in order to make studies on the incidence of clear tumoral lesions in herds highly affected by Leukemia. From 16 thousand samples of serum, tested by the I.D., 6 thousand were positives (37,5%) pertaining to 150 herds distributed in all 20 states of the Country. The sera correspond to different breeds: dairy cattle, beef cattle, brahman, zebú hybrids, and buffalo. Hematologically, persistent lymphocytosis induced by the BLV was verified, by previously discarding other pathologic stages with transitory lymphocytosis. Factors which explain this high incidence and the spread of the Bovine Leukemia in Venezuela were detected.

Age Factors↗
PubMed2025

Genomic study for pregnancy loss in Brahman cattle.

Reproduction has major influence on productivity of beef cattle operations. Maintaining an animal in the herd for an extended period without producing a marketable product can result in significant economic losses, compromising the efficiency of the production system. Understanding genetic variation's role in pregnancy loss (PL) is crucial for improving reproductive success in cattle. Identifying genomic regions that influence embryo and fetal survival, as well as pinpointing candidate genes associated with PL, can enhance breeding strategies. The objective of this study was to estimate variance components and investigate genetic factors associated with PL in Brahman cattle. Phenotypic records consisted of 29,905 pregnancy (28,691) and abortion (1,214) records from nulliparous, primiparous, and multiparous cows. A total of 921 animals were genotyped using a medium-density SNP chip (&#x223c;52K markers). Variance components were estimated using a threshold model to assess the binary response to PL through a single-step genomic BLUP procedure. The heritability estimate for PL was low (0.11), but the presence of genetic variance suggests that selection for improved reproductive performance is feasible. Genome-wide association analyses identified 17 candidate regions containing 92 genes. Regions on BTA4, 7, 8, 9, 11, 12, 16, 18, 19, 21, 22, and 29 harbored genes associated with embryonic development and implantation, fertilization, G protein-coupled receptors, embryonic brain development, olfactory receptor activity, and calcium signaling. Orthologous genes were also identified in humans (Homo sapiens), rats (Rattus norvegicus), and mice (Mus musculus). The candidate regions reported in this study provide insights for identifying and selecting animals with improved reproductive performance, ultimately enhancing the productivity of Brahman cattle. Moreover, our findings contribute to a better understanding of the genetic and physiological mechanisms underlying pregnancy retention in beef cattle.

Animals↗
PubMed1977

Generalized glycogenosis in beef shorthorn cattle--heterozygote detection.

A preliminary study of acidic alpha-glucosidase in a variety of tissues was carried out in an attempt to develop a test which might be used to detect individuals heterozygous for the genetype associated with generalized glycogenosis in beef Shorthorn cattle. Of the tissues readily available peripheral lymphocytes were chosen as being likely to be the most suitable. It was concluded that, when coupled with genealogical information, assays of alpha-glucosidase in extracts of lymphocytes were useful for identifying heterozygous individuals with a reasonably high degree of probability.

Animals↗
PubMed1975

Occurrence of gastrointestinal parasites in Georgia cattle.

A survey of gastrointestinal nematodes in Georgia cattle was conducted from 1968 through 1973 from actual worm counts from viscera of 145 slaughtered beef cattle or from egg counts made from fecal samples from 3,273 beef and 100 dairy cattle. Beef cattle were grouped as calves, yearlings, and cows. Dairy cattle were grouped as calves, replacement heifers, and cows. Results of fecal examinations positive; 99.5, 99.3, 99.6, and 41.2% of the calves, yearlings, drylot calves, and cows, respectively, were infected with nematodes. Seventy-four percent of the eggs counted were of the Cooperia-Ostertagia - Trichostrongylus complex (C-O-T) and 21% were of the Haemonchus-Oesophagostomum complex (H-O). Sixty-nine percent of the infective larvae recovered from coprocultures made from composite samples were of Ostertagia ostertagi. Moniezia (tapeworm) eggs were seen in 16% of all the samples, more predominantly in the calves (24%) and less in the cows (smaller than 1%). Oocysts of Eimeria spp were detected in 61% of the cattle, more predominantly in younger cattle. All cattle necropsied were infected with O ostertagi. Other nematodes present, in order of decreasing frequency, were Trichostrongylus axei (97%), Haemonchus placei (66%), Cooperia punctata (63%), Cooperia oncophora (61%), Oesophagostomum radiatum (61%), Bunostomum phlebotomum (55%), Trichostrongylus colubriformis (36%), Cooperia pectinata (28%), Trichuris spp (17%), Nematodirus spathiger (9%), and Capillaria bovis (4%). Tapeworms were also recovered from 19% of the cattle at necropsy. Seventy-eight percent of the dairy cattle were positive; 98% of the calves, 80% of the heifers, and 58% of the cows. Cooperia-Ostertagia-Trichostrongylus eggs were detected in 78% and H-O eggs in 38% of the cattle. Eimeria oocysts were detected in 71% of all the dairy cattle, and Moniezia eggs were in 10% of the calves and 7% of the heifers.

Animals↗
PubMed1975

Apparent thiamin status of cattle and its relationship to polioencephalomalacia.

The thiamin status (thiamin concentration in whole blood, plasma, and erythrocytes; erythrocyte transketolase activity) of normal cattle consuming varying diets did not differ from that of cattle with polioencephalomalacia or lead poisoning. Dairy cattle had higher ruminal content of thiamin and lower thiamin destroying activity than did beef cattle. Renal oxalosis was no more frequent in cattle which had polioencephalomalacia than in postnatal calves. In normal beef cattle, approximately 75% of total blood thiamin is in erythrocytes and the remainder in plasma.

Animals↗
PubMed2025

Influence of creatine pyruvate on newly received cattle: insights from metagenomics and metabolomics.

Transport stress is a critical factor affecting the health and growth performance of beef cattle, potentially leading to oxidative stress, inflammation, and metabolic disorders. Creatine pyruvate (CrPyr), as a potential stress alleviator, has unclear mechanisms of action. We monitored the growth of 17 Simmental calves (control, n&#x2009;=&#x2009;8; CrPyr, n&#x2009;=&#x2009;9) over 30 days post-transportation, collecting rumen and blood samples on days 1/4, and 30. This study aims to investigate the effects of CrPyr on the growth performance, rumen microbiome, and metabolome of calves subjected to transport stress. Results showed that CrPyr increased average daily gain and antioxidant capacity, while reducing the level of stress hormones and inflammation. In the 4 days post-transport, CrPyr mainly increases Ruminococcus abundance to boost ruminal nitrogen metabolism, providing substrates for microbial protein synthesis. CrPyr also provides energy for the proliferation of Ruminococcus by regulating ATP synthesis genes (ATPVC) and enriching purine metabolism products. Meanwhile, it strengthens the host's amino acid metabolism, especially aspartate, to enhance antioxidative capacity. By day 30, CrPyr primarily boosts Prevotella abundance to regulate VFA synthesis, supplying host energy. It regulates the ATP synthesis gene ATPF0A and enriches purine metabolism products, supporting Prevotella growth. Increased citric acid and ATP levels further aid host growth. The findings distinctly demonstrate that the mechanisms by which CrPyr alleviates transport stress through the regulation of the rumen microbiome and metabolome, and confirms that its effects are time-dependent. These findings provide a theoretical basis for the development of stress-alleviation strategies based on CrPyr and hold significant implications for enhancing the health and production performance of beef cattle.

Animals↗