ABSTRACT
Food from animal sources (e.g., fish) represents the food group most likely to disseminate diseases to humans. To prevent food contamination and foodborne illnesses, intelligent packaging has been developed to monitor fish freshness by real-time tracking their physicochemical attributes and informing consumers about their conservation state. In this context, we investigated the influence of ionic strength (IS) provided by CaCl2 on the chromatic response of anthocyanin açai extracts incorporated into methylcellulose (MC) within hydrocolloid-based colorimetric sensors for monitoring the freshness of Lambari fish. The color sensitivity of the sensors was modulated by IS in the presence of NH3 volatile and/or TVB-N. Increasing IS led to a plasticizing effect in the MC matrix, which influenced the chromatic properties of anthocyanin in the presence of NH3 and/or TVB-N. The perception of distinct colors by untrained eyes improved from 10 min with the control sensor to 2.5 min for sensors with IS >50 mM. Adjusting the IS to 500 mM with LiCl, CaCl2, or MgCl2 resulted in gray-green, blue, or moss-green colors, respectively, diverging from the control sensor's color (pink and gray) after 10 min of ammonia exposure, confirming salt-induced copigmentation. Color irreversibility in the sensors was achieved when the IS exceeded 250 mM. Through principal component analysis, we statistically validate the efficacy of the sensor in assessing the freshness of Lambari fish. The sensor maintained its color-change capability even after 60 d of storage and was able to classify Lambari fish freshness according to Brazilian and European standards. This study elucidates the interrelation between the structures and properties of natural compounds such as MC, anthocyanin, and CaCl2, providing a method to control the chromatic properties of sensors intended to monitor food quality, safety, and shelf-life.
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This work shows how the tunnel-effect based magnetoresistance (TMR) technology can be used as a competitive sensing method in electrical current and power processors. The sensor is arranged in a Wheatstone bridge topology, and each magnetoresistance was composed of a series connection of 360 magnetic tunnel junction elements with the following structure (thickness in nm): 100 SiO2/5 Ta/15 Ru/5 Ta/15 Ru/5 Ta/5 Ru/20 IrMn/2 CoFe30/0.85 Ru/2.6 CoFe40B20/1.2 MgO/2 CoFe40B20/0.21 Ta/4 NiFe/0.20 Ru/6 IrMn/2 Ru/5 Ta/10 Ru. First, the electrical and thermal characteristics of the sensor were evaluated by analyzing its response to DC current sweeps at various temperatures, controlled using a climatic chamber. Nominal values of current sensitivity S (0.324 mV/A), bridge output offset voltage Vo,s,o (-37.1 mV), bridge input resistance Rinp,bridge (0.958 kΩ), and their thermal behavior were obtained (0.0036 mV/A°C, 0.079 mV/°C, and -0.31 Ω/°C). Second, an instrumentation system is introduced to characterize the sensor, measuring its sensitivity to AC line currents from the mains up to 10 Arms. Finally, an electronic wattmeter was developed showing the relevant quantities of its design. The circuit is able to interface a TMR Wheatstone bridge to an analog processor. Power and current measurements were obtained from a 150 Vrms AC mains 1.5 kW load with resistive and capacitive components, achieving less than 1% deviation over the expected values. The circuit shown can be used to interface these signals to more complex smart digital engines with active or reactive energy processing capabilities, while providing inherent high voltage isolation, thanks to its TMR measurement technology.
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The need to transition to more sustainable agriculture that is adaptable to environmental challenges, reducing dependence on chemical fertilizers and minimizing environmental impact, represents the new paradigm of the moment. In this scenario, studies with the adoption of bioinputs in corn cultivation emerge as a viable option for the sustainability of agricultural activity. Therefore, the objective was to evaluate the effect of doses of neem vegetable cake on the yield components of corn crops. An experimental design was used of randomized blocks was used, consisting of four doses of neem vegetable rendering (3 kg ha-1, 6 kg ha-1, 9 kg ha-1 and 12 kg ha-1) and a treatment control without the presence of organic fertilizer. The result indicates the presence of a significant effect of treatments with the application of neem cake on the main components of corn yield, including grain productivity, suggesting that the high carbon content present in the organic product can induce phytochemical effects and biological changes. in the soil, making it more productive. It was found that, when administering the maximum experimental dose, compared to the control group, there was a significant effect (p≤0.01) of 21.3% on grain productivity, jumping from 2,140 kg ha -1, when did not apply organic fertilizer, to 2,596 kg ha-1 with the application of 12 kg of neem cake per hectare. It is noted that the increase in grain productivity was in the proportion of 38 kg ha-1 of corn for each kilo of neem cake applied. To facilitate interpretation and decision-making, an analysis of the economic viability of neem cake for rainfed corn was also determined, also identifying the maximum experimental dose of 12 kg ha-1, as the most economically viable, providing an increase in profit of around R$ 119.92 per hectare, in relation to the control.
Subject(s)
Azadirachta , Fertilizers , Zea mays , Zea mays/growth & development , Azadirachta/chemistry , Fertilizers/analysis , Agriculture/methods , Random Allocation , Soil/chemistryABSTRACT
Carbon monoxide poisoning is one of the leading causes of mortality and morbidity by poisoning in the world. Signs and symptoms are nonspecific and related to impaired oxygen delivery to tissues, with the brain being the most affected organ due to its high oxygen demand. CO-Hb is a poor indicator of severity and long-term outcome, with clinicians relying more on clinical features such as level of consciousness and need for intubation, organ dysfunction and shock and also pH level. A 45-year-old female was found unconscious in her home with the fireplace lit and smoke all over the house. She was last seen well 18 hours before. She was brought to the emergency department and was admitted to the ICU in coma and cardiogenic shock, with a metabolic acidosis with hyperlactacidemia and a CO-Hb level of 15.5%. Laboratorial investigation revealed hepatic cytolysis, acute renal failure, rhabdomyolysis and a troponin I level of 338 ng/L. ECG showed no acute myocardial ischemia. Echocardiogram revealed diffuse hypokinesia with an ejection fraction of 25%. Head CT scan showed bilateral and symmetrical hypodensities of the globus pallidus. The patient underwent hyperbaric oxygen treatment with full neurological and cardiac recovery, allowing extubation 48 hours after admission. This rare severe case of coma due to carbon monoxide intoxication with globus pallidus injury and cardiogenic shock was successfully treated with hyperbaric oxygen, showing that it can be the right treatment choice in these cases, with an excellent impact on neurological and cardiac outcome.
L'intoxication au CO est une des causes principales de décès par empoisonnement dans le monde. Les signes, non spécifiques, sont dus à l'hypoxie cellulaire et le cerveau est le plus souvent atteint en raison de sa consommation d'oxygène élevée. Le taux d'HbCO est un indice peu fiable de la gravité initiale et du risque de séquelles si bien que l'on préfère se baser sur la clinique (conscience, nécessité d'intubation, dysfonctions d'organe, choc) et le pH sanguin. Une femme de 45 ans a été trouvée inconsciente à son domicile entièrement enfumé, cheminée allumée. Le dernier contact remontait à 18 heures. Elle a été hospitalisée en réanimation en coma et choc cardiogénique, avec une acidose lactique et une HbCO à 15,5%. La biologie retrouvait une cytolyse hépatique, une insuffisance rénale aiguë, une rhabdomyolyse et une troponine I à 338 ng/L. L'ECG ne trouvait pas d'ischémie, l'échocardiographie objectivait une hypokinésie globale et évaluait la fraction d'éjection à 25%. La TDM cérébrale montrait une hypodensité pallidale bilatérale. L'oxygénothérapie hyperbare (OHB) a permis une récupération neurologique et cardiaque complètes, permettant l'extubation à h48. Cette récupération complète après OHB confirme qu'il peut s'agir du traitement idoine des intoxications graves au CO, avec un excellent impact sur les devenirs cardiaque et neurologique.
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OBJECTIVE: Knowing the important repercussions of menopause for women's health and that female longevity can be better understood through studies based on aging biomarkers, studies on the relationship between menopause and telomere shortening may help to better understand this stage of life. This study aimed to analyze what research has been produced regarding the relationship between menopause and telomere length. METHODS: This integrative literature review included searches in PubMed, CINAHL, LILACS, Web of Science and Scopus databases. Four studies were selected for the final sample. RESULTS: The findings of these studies indicate that older age for menopause and longer reproductive life (difference between age at menopause and menarche) are associated with longer telomeres, that is, with longevity. CONCLUSION: The relationship between menopause and telomere length is uncertain. The small number of studies included in this review, and the fact that the results indicate that the relationship between menopause and telomere length may be dependent on the stage of the menopause and race/ethnicity, suggest that additional research focusing on these variables should be carried out.
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The objective of this study was to verify the flight radius and the influence of the climatic season and period of the day on the external activity of Melipona rufiventris bees. The forager bees were released at different distances to evaluate the flight radius. The following were considered for external activities in the four different seasons of the year (Winter, Autumn, Spring, Summer): the entry with no apparent load was considered as nectar/water, entry with defined and opaque mass in the corbicula was considered as pollen, the entry with undefined and shiny mass in the corbicula was considered as resin/clay or bee exit no load and removal of debris, mass trapped by the jaws. Assessments were performed between 6 am and 6 pm each month. M. rufiventris can reach distances of 2 500 meters, however the return decreases as the distance increases. The species performs all activities in and out of the colony during all seasons of the year and periods between 6 am and 6 pm but reduce nectar/water collection and exit from the box without apparent load and with debris between 6:00 am and 10 am in winter. It is concluded that distances greater than 1 500 meters hinder the external activity of bees which is influenced by air temperature, air humidity, time of day, season of the year and food availability.
Subject(s)
Plant Nectar , Radius , Bees , Animals , Seasons , Humidity , WaterABSTRACT
OBJECTIVES: The aims of this article were to analyse the burden of NCDs and their RFs in the Mercosur countries between 1990 and 2019 and to project mortality trends for 2030. STUDY DESIGN: Epidemiological study of time series. METHODS: The present study used data from the Global Burden of Disease study. The absolute number of deaths, mortality rates, disability-adjusted life years, years of life lost, years lived with disability and the burden of premature mortality by NCD attributable to the RFs were evaluated. Projections were made up to 2030. Age-standardised rates were used to draw comparisons by years and by countries. The analysis was conducted using the RStudio software. RESULTS: Between 1990 and 2019, a decrease was found in the premature mortality rates caused by NCDs in all the countries, except for Paraguay, which remained stable. When analysing premature mortality rates due to NCDs up to 2030, it was predicted that none of the countries would achieve the sustainable development goal of a one-third reduction in premature mortality by NCDs. Regarding the impacts of the RFs for NCDs, smoking, dietary risks, high blood pressure (BP) and high body mass index (BMI) were the main risks attributable to premature deaths due to NCDs. CONCLUSIONS: The results showed that mortality rates are declining in Mercosur countries; however, none of the countries are predicted to achieve the sustainable development goal of a one-third reduction in mortality due to NCDs by 2030. In addition to access to adequate treatment, progress is required in public regulation actions to reduce RFs, such as smoking, dietary risks, high BP and high BMI.
Subject(s)
Hypertension , Noncommunicable Diseases , Humans , Sustainable Development , Global Health , Mortality, Premature , Smoking , Global Burden of Disease , Risk Factors , Quality-Adjusted Life YearsABSTRACT
Improving the thermal resilience of magnetic tunnel junctions (MTJs) broadens their applicability as sensing devices and is necessary to ensure their operation under harsh environments. In this work, we are address the impact of temperature on the degradation of the magnetic reference in field sensor stacks based on MgO-MTJs. Our study starts by simple MnIr/CoFe bilayers to gather enough insights into the role of critical morphological and magnetic parameters and their impact in the temperature dependent behavior. The exchange bias coupling field (Hex), coercive field (Hc), and blocking temperature (Tb) distribution are tuned, combining tailored growth conditions of the antiferromagnet and different buffer layer materials and stackings. This is achieved by a unique combination of ion beam deposition and magnetron sputtering, without vaccum break. Then, the work then extends beyond bilayers into more complex state-of-the-art MgO MTJ stacks as those employed in commercial sensing applications. We systematically address their characteristic fields, such as the width of the antiferromagnetic coupling plateau ΔH, and study their dependence on temperature. Although, [Ta/CuN] buffers showed higher key performance indications (e.g.Hex) at room temperature in both bilayers and MTJs, [Ta/Ru] buffers showed an overall wider ΔHup to 200 °C, more suitable to push high temperature operations. This result highlights the importance of properly design a suitable buffer layer system and addressing the complete MTJ behavior as function of temperature, to deliver the best stacking design with highest resilience to high temperature environments.
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PURPOSE: Literature has demonstrated an inverse relation between magnesium (Mg) consumption and development of type 2 diabetes mellitus (T2DM), hypertension (HT), and dyslipidemia. After bariatric surgery (BS), micronutrients deficiencies are common, it being important to ensure appropriate supplementation. There is no recommendation about Mg supplementation and to our knowledge, its effect has not been studied to date. Our aim was to evaluate the effect of Mg supplementation in cardio-metabolic risk factors on post-bariatric patients. MATERIALS AND METHODS: A retrospective observational study of patients with obesity who underwent BS was performed. Data was assessed preoperatively and yearly (4-year follow-up). RESULTS: A total of 3363 patients were included. In the first year of follow-up, 79.8% (n = 2123) of the patients were supplemented with Mg, with evidence of slightly decreased percentages in the following years. Mg deficiency (serum Mg < 1.52 mEq/L) was more common among patients who were not supplemented during each year of follow-up (p < 0.05). Among those who underwent Mg supplementation, the percentage of T2DM, HT, or low-density lipoprotein cholesterol (LDL-C) > 130 mg/dL was significantly lower. In the first year post-surgery, the supplementation group had a lower risk of T2DM (OR = 0.545, p < 0.0001), LDL-C > 130 mg/dL (OR = 0.612, p < 0.0001), and HT (OR = 0.584, p < 0.0001). The OR for having these metabolic comorbidities persisted lower during the 4 years' follow-up. Patients who had Mg deficiency had higher prevalence of T2DM and HT. CONCLUSION: Mg supplementation seems to have a protective effect on the development of T2DM, HT, and LDL-C > 130 mg/dL in post-bariatric patients.
Subject(s)
Bariatric Surgery , Diabetes Mellitus, Type 2 , Hypertension , Obesity, Morbid , Bariatric Surgery/adverse effects , Cholesterol, LDL , Diabetes Mellitus, Type 2/complications , Dietary Supplements , Humans , Hypertension/complications , Magnesium , Obesity, Morbid/surgery , Retrospective Studies , Risk FactorsSubject(s)
COVID-19 , Adrenal Cortex Hormones/adverse effects , Humans , Retrospective Studies , SARS-CoV-2ABSTRACT
Properly quantifying environmental heat stress (HS) is still a major challenge in livestock breeding programs, especially as adverse climatic events become more common. The definition of critical periods and climatic variables to be used as the environmental gradient is a key step for genetically evaluating heat tolerance (HTol). Therefore, the main objectives of this study were to define the best critical periods and environmental variables (ENV) to evaluate HT and estimate variance components for HT in Large White pigs. The traits included in this study were ultrasound backfat thickness (BFT), ultrasound muscle depth (MDP), piglet weaning weight (WW), off-test weight (OTW), interval between farrowing (IBF), total number of piglets born (TNB), number of piglets born alive (NBA), number of piglets born dead (NBD), number of piglets weaned (WN), and weaning to estrus interval (IWE). Seven climatic variables based on public weather station data were compared based on three criteria, including the following: (1) strongest G×E estimate as measured by the slope term, (2) ENV yielding the highest theoretical accuracy of the genomic estimated breeding values (GEBV), and (3) variable yielding the highest distribution of GEBV per ENV. Relative humidity (for BFT, MDP, NBD, WN, and WW) and maximum temperature (for OTW, TNB, NBA, IBF, and IWE) are the recommended ENV based on the analyzed criteria. The acute HS (average of 30 days before the measurement date) is the critical period recommended for OTW, BFT, and MDP in the studied population. For WN, WW, IBF, and IWE, a period ranging from 34 days prior to farrowing up to weaning is recommended. For TNB, NBA, and NBD, the critical period from 20 days prior to breeding up to 30 days into gestation is recommended. The genetic correlation values indicate that the traits were largely (WN, WW, IBF, and IWE), moderately (OTW, TNB, and NBA), or weakly (MDP, BFT, and NBD) affected by G×E interactions. This study provides relevant recommendations of critical periods and climatic gradients for several traits in order to evaluate HS in Large White pigs. These observations demonstrate that HT in Large White pigs is heritable, and genetic progress can be achieved through genetic and genomic selection.
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OBJECTIVE: Failure of dental implants treatment is frequently the result of bacterial colonization of implants followed by diseases like peri-implantitis. Recent studies have been made regarding the surface treatment of implants components, namely abutments that are in the interface of the living tissue with the implant. This work aimed at evaluating the antimicrobial profile of a silane-based coating with TiO2 adapted to an abutment screw, that was also developed as an anti-loosening agent, to prevent adhesion and migration of Gram + and Gram-bacteria, Staphylococcus aureus, and Escherichia coli, respectively. METHODS: Direct contact antimicrobial studies were conducted on coated and uncoated samples by resazurin fluorescent assay and cytotoxicity assessment was done via MTT indirect method on days 1 and 4. Sterilizations studies by FTIR analysis were also performed to understand the ideal balance between sterilization efficacy and coating functionality subjecting the samples to ethylene oxide, gamma irradiation, and autoclave sterilization, before antimicrobial testing. The implant system as a whole was also studied for its ability to block bacterial migration and preventing microleakage as well as an assessment of initial bacterial adhesion evaluated by scanning electron microscopy. RESULTS: Direct contact studies performed on coated samples showed a very high antimicrobial activity, while cytotoxicity assays revealed the coating to be safe and non-leachable. Sterilizations studies showed that the antimicrobial features of the coating were preserved and interchangeable regardless of the sterilization method. The implant system migration studies demonstrated that the implant system works as an efficient barrier for the studied bacteria. SIGNIFICANCE: The acquired results clearly show that it is possible to obtain a highly functional coating with obvious and marked antimicrobial features that together with an abutment that prevents bacterial migration and versatility in sterilization methodology has a very high potential in the dental implant field.
Subject(s)
Anti-Infective Agents , Dental Implants , Anti-Infective Agents/pharmacology , Bacteria , Bone Screws , Dental Abutments , Dental Implant-Abutment DesignABSTRACT
The study of palatal rugae is shown to be scientifically valid to human identification due to the unique number and style of the palatal ridges. Dentures provide an array of data and specifics that allow for the individualization of their wearers. This article describes the identification of edentulous, skeletonized remains through the analysis of the palatal rugae printed on the complete upper denture and subsequent comparison with the palatal rugae of an old complete denture of an unknown missing person. The analyses focus on the form, classification, location, and size of the palatal rugae which, in conjunction with the information obtained from the anthropological examination, resulted in a positive identification of the cadaver. This method has a significant impact on the identification process, particularly when other identification methodologies and techniques cannot be implemented. This case report highlights the importance of palatal rugae in human identification in cases of edentulous cadavers.
Subject(s)
Forensic Anthropology , Palate , Denture, Complete , Denture, Complete, Upper , Humans , Mouth MucosaABSTRACT
Artificial neural networks are notoriously power- and time-consuming when implemented on conventional von Neumann computing systems. Consequently, recent years have seen an emergence of research in machine learning hardware that strives to bring memory and computing closer together. A popular approach is to realise artificial neural networks in hardware by implementing their synaptic weights using memristive devices. However, various device- and system-level non-idealities usually prevent these physical implementations from achieving high inference accuracy. We suggest applying a well-known concept in computer science-committee machines-in the context of memristor-based neural networks. Using simulations and experimental data from three different types of memristive devices, we show that committee machines employing ensemble averaging can successfully increase inference accuracy in physically implemented neural networks that suffer from faulty devices, device-to-device variability, random telegraph noise and line resistance. Importantly, we demonstrate that the accuracy can be improved even without increasing the total number of memristors.
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In this paper we perform nanofabrication of square artificial spin ices with different lattice parameters, in order to investigate the roles of vertex excitation on the features of the system. In particular, the character of magnetic charge distribution asymmetry on the vertices are observed under magnetic hysteresis loop experiments. We then compare our results with simulation using an emergent Hamiltonian containing objects such as magnetic monopoles and dipoles in the vertices of the array (instead of the usual Hamiltonian based on the dipolar interactions among the magnetic nanoislands). All possible interactions between these objects are considered (monopole-monopole, monopole-dipole and dipole-dipole). Using realistic parameters we observe very good match between experiments and theory, which allow us to better understand the system dynamics in function of monopole charge intensity.
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Milk fat composition has important implications in the nutritional and processing properties of milk. Additionally, milk fat composition is associated with cow physiological and health status. The main objectives of this study were (1) to estimate genetic parameters for 5 milk fatty acid (FA) groups (i.e., short-chain, medium-chain, long-chain, saturated, and unsaturated) predicted from milk infrared spectra using a large data set; (2) to predict genomic breeding values using a longitudinal single-step genomic BLUP approach; and (3) to conduct a single-step GWAS aiming to identify genomic regions, candidate genes, and metabolic pathways associated with milk FA, and consequently, to understand the underlying biology of these traits. We used 629,769 test-day records of 201,465 first-parity Holstein cows from 6,105 herds. A total of 8,865 genotyped (Illumina BovineSNP50K BeadChip, Illumina, San Diego, CA) animals were considered for the genomic analyses. The average daily heritability ranged from 0.24 (unsaturated FA) to 0.47 (medium-chain and saturated FA). The reliability of the genomic breeding values ranged from 0.56 (long-chain fatty acid) to 0.74 (medium-chain fatty acid) when using the default τ and ω scaling parameters, whereas it ranged from 0.58 (long-chain fatty acid) to 0.73 (short-chain fatty acid) when using the optimal τ and ω values (i.e., τ = 1.5 and ω = 0.6), as defined in a previous study in the same population. Relevant chromosomal regions were identified in Bos taurus autosomes 5 and 14. The proportion of the variance explained by 20 adjacent single nucleotide polymorphisms ranged from 0.71% (saturated FA) to 15.12% (long-chain FA). Important candidate genes and pathways were also identified. In summary, our results contribute to a better understanding of the genetic architecture of predicted milk FA in dairy cattle and reinforce the relevance of using genomic information for genetic analyses of these traits.
Subject(s)
Cattle/genetics , Fatty Acids/metabolism , Milk/chemistry , Animals , Cattle/physiology , Fatty Acids, Unsaturated/metabolism , Female , Genomics , Genotype , Lactation/genetics , North America , Parity , Polymorphism, Single Nucleotide , Pregnancy , Reproducibility of Results , Selective BreedingABSTRACT
Maraba virus is a member of the genus Vesiculovirus of the Rhabdoviridae family that was isolated in 1983 from sandflies captured in the municipality of Maraba, state of Pará, Amazônia, Brazil. Despite 30 years having passed since its isolation, little is known about the neuropathology induced by the Maraba virus. Accordingly, in this study the histopathological features, inflammatory glial changes, cytokine concentrations, and nitric oxide activity in the encephalon of adult mice subjected to Maraba virus nostril infection were evaluated. The results showed that 6 days after intranasal inoculation, severe neuropathological-associated disease signs appeared, including edema, necrosis and pyknosis of neurons, generalized congestion of encephalic vessels, and intra- and perivascular meningeal lymphocytic infiltrates in several brain regions. Immunolabeling of viral antigens was observed in almost all central nervous system (CNS) areas and this was associated with intense microglial activation and astrogliosis. Compared to control animals, infected mice showed significant increases in interleukin (IL)-6, tumor necrosis factor (TNF)-α, interferon (INF)-γ, MCP-1, nitric oxide, and encephalic cytokine levels. We suggest that an exacerbated inflammatory response in several regions of the CNS of adult BALB/c mice might be responsible for their deaths.
Subject(s)
Meningoencephalitis/complications , Vesicular Stomatitis/complications , Animals , Astrocytes/metabolism , Brazil , Cytokines/analysis , Disease Models, Animal , Flow Cytometry , Male , Meningoencephalitis/pathology , Mice , Mice, Inbred BALB C , Microglia/metabolism , Nitric Oxide/analysis , Vesicular Stomatitis/pathology , VesiculovirusABSTRACT
Milk fat content and fatty acid (FA) composition have great economic value to the dairy industry as they are directly associated with taste and chemical-physical characteristics of milk and dairy products. In addition, consumers' choices are not only based on the nutritional aspects of food, but also on products known to promote better health. Milk FA composition is also related to the metabolic status and physiological stages of cows and thus can also be used as indicator for other novel traits of interest (e.g., metabolic diseases and methane yield). Genetic selection is a promising alternative to manipulate milk FA composition. In this study, we aimed to (1) estimate time-dependent genetic parameters for 5 milk FA groups (i.e., short-chain, medium-chain, long-chain, saturated, and unsaturated) predicted based on milk mid-infrared spectroscopy, for Canadian Ayrshire and Jersey breeds, and (2) conduct a time-dependent, single-step genome-wide association study to identify genomic regions, candidate genes, and metabolic pathways associated with milk FA. We analyzed 31,709 test-day records of 9,648 Ayrshire cows from 268 herds, and 34,341 records of 11,479 Jersey cows from 883 herds. The genomic database contained a total of 2,330 Ayrshire and 1,019 Jersey animals. The average daily heritability ranged from 0.18 (long-chain FA) to 0.34 (medium-chain FA) in Ayrshire, and from 0.25 (long-chain and unsaturated FA) to 0.52 (medium-chain and saturated FA) in Jersey. Important genomic regions were identified in Bos taurus autosomes BTA3, BTA5, BTA12, BTA13, BTA14, BTA16, BTA18, BTA20, and BTA21. The proportion of the variance explained by 20 adjacent SNP ranged from 0.71% (saturated FA) to 1.11% (long-chain FA) in Ayrshire, and from 0.70% (unsaturated FA) to 3.09% (medium-chain FA) in Jersey cattle. Important candidate genes and pathways were also identified, such as the PTK2 and TRAPPC9 genes, associated with milk fat percentage, and HMGCS, FGF10, and C6 genes, associated with fertility traits and immune response. Our findings on the genetic parameters and candidate genes contribute to a better understanding of the genetic architecture of milk FA composition in Ayrshire and Jersey dairy cattle.