Ocular squamous cell carcinoma and infectious keratoconjunctivitis are common ocular pathologies in Hereford cattle with considerable economic impact. Both pathologies have been associated with low eyelid pigmentation, and thus, genetic selection for higher eyelid pigmentation could reduce their incidence. The objective of the present study was to reveal the genetic basis of eyelid pigmentation in Hereford cattle. The analysis included a single-step genome-wide association study (ssGWAS) and a subsequent gene-set analysis in order to identify individual genes, genetic mechanisms and biological pathways implicated in this trait. Data consisted of eyelid pigmentation records in 1,165 Hereford bulls and steers, visually assessed in five categories between 0% and 100%. Genotypic data for 774,660 single nucleotide polymorphism markers were available for 886 animals with pigmentation records. Pedigree information of three generations of ancestors of animals with phenotype was considered in this study, with a total of 4,929 animals. Our analyses revealed that eyelid pigmentation is a moderately heritable trait, with heritability estimates around 0.41. The ssGWAS identified at least eight regions, located on BTA1, BTA3, BTA5, BTA14, BTA16, BTA18, BTA19 and BTA24, associated with eyelid pigmentation. These regions harbor genes that are directly implicated in melanocyte biology and skin pigmentation, such as ADCY8, PLD1, KITLG, and PRKCA. The gene-set analysis revealed several functional terms closely related to melanogenesis, such as positive regulation of melanocyte differentiation and regulation of ERK1 and ERK2 cascade. Overall, our findings provide evidence that eyelid pigmentation is a heritable trait influenced by many loci. Indeed, the ssGWAS detected several candidate genes that are directly implicated in melanocyte biology, including melanogenesis. This study contributes to a better understanding of the genetic and biological basis of eyelid pigmentation and presents novel information that could aid to design breeding strategies for reducing the incidence of ocular pathologies in cattle. Additional research on the genetic link between eyelid pigmentation and ocular pathologies is needed.

Rarámuri Criollo (RC) cattle have been raised by the isolated Tarahumara communities of Chihuahua, Mexico, for nearly 500 years, mostly under natural selection and minimal management. RC cattle were introduced to the United States Department of Agriculture-Agricultural Research Service Jornada Experimental Range (RCJER) in 2005 to begin evaluations of beef production performance and their adaptation to the harsh ecological and climatic conditions of the Northern Chihuahuan Desert. While this research unveiled crucial information on their phenotypic plasticity and adaptation, the genetic diversity and structure of the RCJER population remains poorly understood. This study analyzed the genetic diversity, population structure, ancestral composition, and selection signatures of the RCJER herd using a ~64 K SNP array. The RCJER herd exhibits moderate genetic diversity and low population stratification with no evident clustering, suggesting a shared genetic background among different subfamilies. Admixture analysis revealed the RCJER herd represents a distinctive genetic pool within the Criollo cattle breeds, with significant Iberian ancestry. Selection signatures identified candidate genes and quantitative trait loci (QTL) for traits associated with milk composition, growth, meat and carcass, reproduction, metabolic homeostasis, health, and coat color. The RCJER population represents a distinctive genetic resource adapted to harsh environmental conditions while maintaining productive and reproductive attributes. These findings are crucial to ensuring the long-term genetic conservation of the RCJER and their strategic expansion into locally adapted beef production systems in the USA.

Canine degenerative myelopathy (DM) is a hereditary disease of the spinal cord, characterized by a progressive clinical course, and the death of affected animals. This study aimed to investigate the population distribution of the SODc.118:G˃A mutation responsible for the disease. For this purpose, 131 dogs from both breeds (Pit Bull Terrier, n=64, and Boxer, n=67) were studied. Genomic DNA was extracted from peripheral blood, and the mutation was identified using the PCR-RFLP technique. For each population, the mutant allele frequency, genotypic frequency, and Hardy–Weinberg equilibrium were calculated. The frequency of the DM-related A allele was 0.16 in the Pit Bull Terrier and 0.52 in the Boxer breed. Both populations were in Hardy–Weinberg equilibrium (p > 0.05). The genotypic distribution differed between the two breeds analyzed and also between different populations within each breed (p < 0.05). Simulation of the evolution of the mutant allele frequency under different genetic drift models showed that the variance of the allele frequency increased as the effective population size (Ne) decreased. The frequency detected in the Boxer breed was high, and although it was lower in the Pit Bull Terrier, the allele was still present. These findings support the potential use of genotyping tests for degenerative myelopathy management and provide descriptive population data from dogs of both breeds in Uruguay. A mielopatia degenerativa canina (MD) é uma doença hereditária da medula espinhal, caracterizada por um curso clínico progressivo e pela morte dos animais afetados. Este estudo teve como objetivo investigar a distribuição populacional da mutação SODc.118:G˃A responsável pela doença. Para isso, foram estudados 131 cães de ambas as raças (Pit Bull Terrier, n=64, e Boxer, n=67). O DNA genômico foi extraído do sangue periférico e a mutação foi identificada usando a técnica PCR-RFLP. Para cada população, foram calculadas a frequência do alelo mutante, a frequência genotípica e o equilíbrio de Hardy-Weinberg. A frequência do alelo A relacionado à DM foi de 0,16 na raça Pit Bull Terrier e de 0,52 na raça Boxer. Ambas as populações estavam em equilíbrio de Hardy-Weinberg (p > 0,05). A distribuição genotípica diferiu entre as duas raças analisadas e também entre diferentes populações dentro de cada raça (p < 0,05). A simulação da evolução da frequência do alelo mutante sob diferentes modelos de deriva genética mostrou que a variância da frequência do alelo aumentou à medida que o tamanho efetivo da população (Ne) diminuiu. A frequência detectada na raça Boxer foi alta e, embora fosse menor no Pit Bull Terrier, o alelo ainda estava presente. Esses achados apoiam o uso potencial de testes de genotipagem para o manejo da mielopatia degenerativa e fornecem dados descritivos da população de cães de ambas as raças no Uruguai

The North American Corriente (NAC) is a Criollo-derived cattle breed raised primarily in the Southwestern and Great Plains regions of the United States for rodeo sports and beef production. Despite the substantial practical knowledge surrounding the breed, available information on the genomic makeup of NAC cattle remains limited. To address this gap, a comprehensive genomic analysis of two commercial NAC herds in northeastern New Mexico, United States, was conducted using a ~64 K SNP microarray. A total of 97 NAC cattle were initially sampled; after quality control, relatedness filtering, and population structure analysis, 52 animals were retained for downstream analysis. Population structure and admixture analyses point to a certain degree of genetic differentiation in the NAC population, which could be consistent with a distinct Criollo cattle lineage. This interpretation remains preliminary, however, and would benefit from additional sampling across independent and geographically representative herds. The overlap between functional enrichment results and known quantitative trait loci is consistent with the possibility that some genomic regions associated with movement, fertility, immune response, and carcass and milk traits may have been subject to selection. While informal, anecdotal observations of some of these phenotypic traits have been noted, further research with larger sample sizes and functional validation would be needed before drawing firmer conclusions. This study supports ongoing efforts to genetically characterize, promote, and conserve Criollo cattle populations across the Americas.