92 results on '"T. Duffield"'
Search Results
2. Associations of parity with health disorders and blood metabolite concentrations in Holstein cows in different production systems
- Author
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I.J. Lean, S.J. LeBlanc, D.B. Sheedy, T. Duffield, J.E.P. Santos, and H.M. Golder
- Subjects
parity ,disease ,longevity ,blood metabolites ,Dairy processing. Dairy products ,SF250.5-275 ,Dairying ,SF221-250 - Abstract
ABSTRACT: Data were obtained from studies in Australia, Canada, and the United States using individual cow data from 28,230 Holstein cows to evaluate associations between parity and disease. Our goal was to develop understanding of disease risks for cows of differing parity. We hypothesized that there would be increased risks of disease and changes in metabolite concentrations with increased parity. Parity ≥5 represented 2,533 cows or 9.0%, parity 4 was 9.8% (2,778), parity 3 as 19.0% (5,355), parity 2 as 28.1% (7,925), and parity 1 was 34.1% (9,639) of the sample. Of these cows, 15.5% were in Australia, 14.7% in Canada, and 69.8% in the United States. Lactational incidence (LI) risk of clinical hypocalcemia increased with parity from 0.1% for parity 1 to 13% for parity ≥5 cows. The marked increase suggests profound differences in metabolism with increased parity. The LI of clinical mastitis was 17.4%. The odds of mastitis increased with parity to 2.5 times greater in parity ≥5 than in parity 1. The LI of lameness increased with parity; specifically, the odds of lameness was 5.6 times greater for parity ≥5 than parity 1. Dystocia incidence was 8.7% and greatest for parity 1 cows. The LI of retained placenta was 7.4% and increased with parity, with the odds for parity ≥5 2.3 times greater than for parity 1. The LI of metritis was 10% and of endometritis 14%, with the greatest odds in parity 1. The LI of clinical ketosis was 3.3% with a marked increase in odds with parity. The prevalence of subclinical ketosis was 26.8% with only cows in parity 1 having lower odds than other parities. Parity ≥5 cows had greater odds (odds ratio = 1.7) of respiratory disease than parity 1 cows, which were lesser than other parities. Metabolite concentrations were evaluated in 5,154 Holstein cows in the precalving, calving, and immediate postcalving data sets. Metabolic measures near peak lactation provided 1,906 observations. Concentrations of β-hydroxybutyrate (BHB) and nonesterified fatty acids increased with parity on d 1 to 3 of lactation and at peak lactation. On d 1 to 3 after calving differences in glucose, nonesterified fatty acids, and BHB indicated a greater reliance on mobilized lipid to export energy to peripheral tissues as BHB for greater parity cows. Differences in concentrations among parity groups were marked at times, for example >0.20 mM in Ca for parity 1 and 2 to parity ≥5 and >0.33 mM for all older parities compared with parity 1 for P on the day of calving. The marked increase suggests profound differences in metabolism with increased parity are probably influenced, in part, by increased production. We found marked differences in concentrations of metabolites with parity that are consistent with reduced reproduction, health, and body condition for higher parity cows. These unfavorable differences in metabolism in Ca, P, glucose, and cholesterol concentrations for higher parity cows also complement the often-substantial differences in disease risk with parity and suggest a need to carefully consider the parity structure in study design. Managers and advisors will need to consider methods to reduce risk of health disorders tailored to cows of different ages.
- Published
- 2023
- Full Text
- View/download PDF
3. Increased parity is negatively associated with survival and reproduction in different production systems
- Author
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I.J. Lean, H.M. Golder, S.J. LeBlanc, T. Duffield, and J.E.P. Santos
- Subjects
production ,milk-protein ,parity ,pregnancy ,longevity ,Dairy processing. Dairy products ,SF250.5-275 ,Dairying ,SF221-250 - Abstract
ABSTRACT: We conducted a retrospective meta-analysis based on individual cow data to assess the associations of parity, level of production, and pasture-based or intensively fed systems with fertility. Our goal was to provide understandings of the role of parity in risks for removal and reproductive failure. Multilevel models were used to evaluate the fixed effects of parity, milk, milk solids, milk fat and protein percentage and yield, and production system [intensively fed (n = 28,675) or predominantly pasture fed (n = 4,108)] on reproductive outcomes. The outcomes were the hazard of not being bred (HNBRED), hazard of pregnancy (HPREG), pregnancy to first breeding (PREG1), and odds of becoming pregnant in a lactation (OPAL). The 32,783 cows were in 13 studies conducted in Australia (14.6% of cows), Canada (2.4% of cows), and the United States (83.0% of cows). There were 38.5% of cows in the sample in parity 1, 27.3% in parity 2, 16.7% in parity 3, 9.0% in parity 4, and 8.6% in parity ≥5. Compared with cows of parity 1, parity ≥5 cows had a greater HNBRED [hazard ratio (HR) = 2.45], lesser HPREG (HR = 0.73), and reduced OPAL (odds ratio = 0.36). However, the parity ≥5 cows had similar PREG1 to other parities except for parity 1. This suggests the possibility of a higher proportion of subfertile parity ≥5 cows than for other parities. Associations between parity and reproductive measures were influenced by the different milk production measures, indicating that milk yield and milk component percentages and yields modified the odds or hazards of successful reproduction. All milk production measures had quadratic associations with OPAL, indicating that either low or high production or concentration of solids within a cohort reduced OPAL. This reduced OPAL reflected a greater HNBRED for lower milk yield and milk protein and fat yielding cows. Both milk yield and milk protein percentage had quadratic associations with HPREG. When centered milk yield was categorized into quartiles, small differences in HPREG existed. A more marked association of milk protein percentage occurred with HPREG, with optimal HPREG at approximately 0.5% above group mean milk protein percentage. Milk fat percentage (HR = 0.901), fat yield (kg/d; HR = 0.78), protein yield (kg/d; HR = 0.71), and milk solids yield (kg/d; HR = 0.84) were all linearly associated with reduced HPREG. Difference in production systems did not have substantive effects on PREG1 but did for HNBRED, HPREG, and OPAL. Estimates of associations of parity with reproductive outcomes HNBRED, HPREG, and OPAL were influenced by milk and milk solids yield; older cows had markedly lower reproductive outcomes. Interestingly, for PREG1, there were few differences among parities and differences were less influenced by milk yield and constituent measures. The marked associations of parity with removal for all reasons, deaths and culling, and reductions in HNBRED, HPREG, and OPAL indicate a need to focus on the physiological changes with parity to produce better strategies to support optimal longevity of cows.
- Published
- 2023
- Full Text
- View/download PDF
4. Holstein dairy cows lose body condition score and gain body weight with increasing parity in both pasture-based and total mixed ration herds
- Author
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I.J. Lean, D.B. Sheedy, S.J. LeBlanc, T. Duffield, J.E.P. Santos, and H.M. Golder
- Subjects
Dairy processing. Dairy products ,SF250.5-275 - Abstract
Body condition scoring (BCS) and body weight (BW) are observations associated with labile tissue reserves, health, and reproduction efficiency of dairy cows. The effect of parity (1 through to ≥5) and feeding system (pasture-based and TMR) on BCS and BW were evaluated utilizing raw data sets from 16 retrospective studies that totaled 24,807 Holstein cows across 3 nations (Australia, Canada, and the United States). Linear regression models were used to investigate the 5 outcome variables of precalving BCS, peak milk BCS, change in BCS from precalving to peak milk, and peak milk BW and their respective associations with parity and feeding system. To help control for the influence of calendar time, study treatment protocols when applicable, and genetic change, all outcome variables were center-transformed around each study group mean. Including feeding system as a covariate improved model fit for most outcome variables; however, the relative effect size of parity was generally much greater than feeding system effect size. Parity 2 cows had the lowest precalving BCS of −0.087 [95% confidence interval (CI): −0.107, −0.065] less than the mean, whereas parity 1 cows had the greatest, 0.068 (95% CI: 0.043, 0.092) above mean, regardless of feeding system. Peak milk BCS overall decreased with increasing parity (parity 1 to parity ≥5: −0.13, 95% CI: −0.19, −0.08) and BCS change during the transition period monotonically decreased with increasing parity (parity 1 to parity ≥5: −0.22, 95% CI: −0.26, −0.17). Peak milk BW monotonically increased with increased parity (parity 1 to parity ≥5: 114 kg, 95% CI: 104, 125). A waffle plot was used to present the proportions of cows, by parity, that were partitioned into “low BCS and low BW,” “low BCS and high BW,” “high BCS and low BW,” or “high BCS and high BW” groups. Cows were assigned either a high or low status by being above or below their specific centered study group means, respectively. Considering a null hypothesis of 25% per BCS-BW category, there was a striking change in category from parity 1 cows that were predominantly in the “high BCS and low BW” category (61.2%) to parity ≥5 cows that were predominantly in the “low BCS and high BW” category (55.5%). The study supports studies showing increased weight and change in BCS with increased parity. We highlight the associations among production system, BCS, BW, and parity.
- Published
- 2022
- Full Text
- View/download PDF
5. Characterizing ruminal acidosis risk: A multiherd, multicountry study
- Author
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H.M. Golder, S.J. LeBlanc, T. Duffield, H.A. Rossow, R. Bogdanich, L. Hernandez, E. Block, J. Rehberger, A.H. Smith, J. Thomson, and I.J. Lean
- Subjects
Genetics ,Animal Science and Zoology ,Food Science - Published
- 2023
- Full Text
- View/download PDF
6. Increased parity is negatively associated with survival and reproduction in different production systems
- Author
-
I.J. Lean, H.M. Golder, S.J. LeBlanc, T. Duffield, and J.E.P. Santos
- Subjects
Genetics ,Animal Science and Zoology ,Food Science - Abstract
We conducted a retrospective meta-analysis based on individual cow data to assess the associations of parity, level of production, and pasture-based or intensively fed systems with fertility. Our goal was to provide understandings of the role of parity in risks for removal and reproductive failure. Multilevel models were used to evaluate the fixed effects of parity, milk, milk solids, milk fat and protein percentage and yield, and production system [intensively fed (n = 28,675) or predominantly pasture fed (n = 4,108)] on reproductive outcomes. The outcomes were the hazard of not being bred (HNBRED), hazard of pregnancy (HPREG), pregnancy to first breeding (PREG1), and odds of becoming pregnant in a lactation (OPAL). The 32,783 cows were in 13 studies conducted in Australia (14.6% of cows), Canada (2.4% of cows), and the United States (83.0% of cows). There were 38.5% of cows in the sample in parity 1, 27.3% in parity 2, 16.7% in parity 3, 9.0% in parity 4, and 8.6% in parity ≥5. Compared with cows of parity 1, parity ≥5 cows had a greater HNBRED [hazard ratio (HR) = 2.45], lesser HPREG (HR = 0.73), and reduced OPAL (odds ratio = 0.36). However, the parity ≥5 cows had similar PREG1 to other parities except for parity 1. This suggests the possibility of a higher proportion of subfertile parity ≥5 cows than for other parities. Associations between parity and reproductive measures were influenced by the different milk production measures, indicating that milk yield and milk component percentages and yields modified the odds or hazards of successful reproduction. All milk production measures had quadratic associations with OPAL, indicating that either low or high production or concentration of solids within a cohort reduced OPAL. This reduced OPAL reflected a greater HNBRED for lower milk yield and milk protein and fat yielding cows. Both milk yield and milk protein percentage had quadratic associations with HPREG. When centered milk yield was categorized into quartiles, small differences in HPREG existed. A more marked association of milk protein percentage occurred with HPREG, with optimal HPREG at approximately 0.5% above group mean milk protein percentage. Milk fat percentage (HR = 0.901), fat yield (kg/d; HR = 0.78), protein yield (kg/d; HR = 0.71), and milk solids yield (kg/d; HR = 0.84) were all linearly associated with reduced HPREG. Difference in production systems did not have substantive effects on PREG1 but did for HNBRED, HPREG, and OPAL. Estimates of associations of parity with reproductive outcomes HNBRED, HPREG, and OPAL were influenced by milk and milk solids yield; older cows had markedly lower reproductive outcomes. Interestingly, for PREG1, there were few differences among parities and differences were less influenced by milk yield and constituent measures. The marked associations of parity with removal for all reasons, deaths and culling, and reductions in HNBRED, HPREG, and OPAL indicate a need to focus on the physiological changes with parity to produce better strategies to support optimal longevity of cows.
- Published
- 2021
7. Associations of parity with health disorders and blood metabolite concentrations in Holstein cows in different production systems
- Author
-
I.J. Lean, S.J. LeBlanc, D.B. Sheedy, T. Duffield, J.E.P. Santos, and H.M. Golder
- Subjects
Genetics ,Animal Science and Zoology ,Food Science - Abstract
Data were obtained from studies in Australia, Canada, and the United States using individual cow data from 28,230 Holstein cows to evaluate associations between parity and disease. Our goal was to develop understanding of disease risks for cows of differing parity. We hypothesized that there would be increased risks of disease and changes in metabolite concentrations with increased parity. Parity ≥5 represented 2,533 cows or 9.0%, parity 4 was 9.8% (2,778), parity 3 as 19.0% (5,355), parity 2 as 28.1% (7,925), and parity 1 was 34.1% (9,639) of the sample. Of these cows, 15.5% were in Australia, 14.7% in Canada, and 69.8% in the United States. Lactational incidence (LI) risk of clinical hypocalcemia increased with parity from 0.1% for parity 1 to 13% for parity ≥5 cows. The marked increase suggests profound differences in metabolism with increased parity. The LI of clinical mastitis was 17.4%. The odds of mastitis increased with parity to 2.5 times greater in parity ≥5 than in parity 1. The LI of lameness increased with parity; specifically, the odds of lameness was 5.6 times greater for parity ≥5 than parity 1. Dystocia incidence was 8.7% and greatest for parity 1 cows. The LI of retained placenta was 7.4% and increased with parity, with the odds for parity ≥5 2.3 times greater than for parity 1. The LI of metritis was 10% and of endometritis 14%, with the greatest odds in parity 1. The LI of clinical ketosis was 3.3% with a marked increase in odds with parity. The prevalence of subclinical ketosis was 26.8% with only cows in parity 1 having lower odds than other parities. Parity ≥5 cows had greater odds (odds ratio = 1.7) of respiratory disease than parity 1 cows, which were lesser than other parities. Metabolite concentrations were evaluated in 5,154 Holstein cows in the precalving, calving, and immediate postcalving data sets. Metabolic measures near peak lactation provided 1,906 observations. Concentrations of β-hydroxybutyrate (BHB) and nonesterified fatty acids increased with parity on d 1 to 3 of lactation and at peak lactation. On d 1 to 3 after calving differences in glucose, nonesterified fatty acids, and BHB indicated a greater reliance on mobilized lipid to export energy to peripheral tissues as BHB for greater parity cows. Differences in concentrations among parity groups were marked at times, for example0.20 mM in Ca for parity 1 and 2 to parity ≥5 and0.33 mM for all older parities compared with parity 1 for P on the day of calving. The marked increase suggests profound differences in metabolism with increased parity are probably influenced, in part, by increased production. We found marked differences in concentrations of metabolites with parity that are consistent with reduced reproduction, health, and body condition for higher parity cows. These unfavorable differences in metabolism in Ca, P, glucose, and cholesterol concentrations for higher parity cows also complement the often-substantial differences in disease risk with parity and suggest a need to carefully consider the parity structure in study design. Managers and advisors will need to consider methods to reduce risk of health disorders tailored to cows of different ages.
- Published
- 2021
8. Anesthetic Management for Cesarean Delivery of a Parturient with Impetigo Herpetiformis
- Author
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Adrienne T. Duffield and Kathleen A. Smith
- Subjects
Pregnancy ,business.industry ,General Medicine ,Placental insufficiency ,Perioperative ,medicine.disease ,Hypovolemia ,Anesthesia ,medicine ,Generalized pustular psoriasis ,medicine.symptom ,business ,Airway ,Impetigo herpetiformis ,Rare disease - Abstract
Impetigo herpetiformis (IH), or generalized pustular psoriasis of pregnancy, is an exceedingly rare, generalized pustular skin eruption occurring during pregnancy associated with hypovolemia, sepsis, hypocalcemia, and airway edema. Fetal outcomes are generally poor, and parturients with IH may present with emergent indications for cesarean delivery due to placental insufficiency. We present a case of IH in a 19-year-old G1P0 who underwent successful general anesthesia for cesarean delivery. Her case highlights the anesthetic implications for patients afflicted with this rare disease, including perioperative pain management, airway concerns, considerations for neuraxial anesthesia, and monitoring challenges.
- Published
- 2013
- Full Text
- View/download PDF
9. Plasmon excitation and self‐coupling in a bi‐periodically modulated two‐dimensional electron gas
- Author
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Haroon Ahmed, T Duffield, C. R. Whitehouse, R. J. Wilkinson, D. C. Peacock, J. E. F. Frost, H. P. Hughes, N. Apsley, David G. Hasko, David A. Ritchie, C. D. Ager, and G. A. C. Jones
- Subjects
Number density ,Chemistry ,business.industry ,Scattering ,Physics::Optics ,General Physics and Astronomy ,Charge density ,Grating ,Molecular physics ,Ultrasonic grating ,Optics ,Modulation ,Wave vector ,business ,Plasmon - Abstract
We report far infrared (FIR) studies of plasmons in spatially modulated two‐dimensional electron gases (2DEGs) in AlGaAs/GaAs heterostructures using biased overlaid metal gratings, including interdigitated gratings, both as optical couplers and as spatially modulating gates. Comparison of the experimental results with the predictions of scattering matrix calculations of the FIR response of a modulated 2DEG in the presence of a perfectly conducting lamellar grating allow us to deduce the spatial variation of the number density distribution in the 2DEG as a function of grating bias. For the interdigitated grating gates, the 2DEG can be modulated at a period of twice that of the grating fingers by differentially biasing alternate fingers; 2D plasmon resonances have been observed at half‐integral values of the grating wave vector G, corresponding to the electrically induced periodicity of the 2DEG modulation itself acting as an optical coupler in addition to the metal grating. The observed G/2 plasmon frequencies decrease with increasing amplitude of the 2DEG number density modulation, in quantitative agreement with those obtained from scattering matrix calculations of the optical response of a modulated 2DEG under a perfectly conducting lamellar grating; calculations of the oscillating charge density profiles show that this occurs because, as the modulation amplitude increases, the oscillation becomes localized in regions of low 2DEG number density which are also under one of the sets of grating fingers, and is therefore better screened.
- Published
- 1992
- Full Text
- View/download PDF
10. Critical behaviour of bulk phonons in YBa2Cu3O7-δas observed by infrared absorption spectroscopy
- Author
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J Blunt, T Duffield, P Freeman, Bernd Güttler, H. P. Hughes, Ekhard K. H. Salje, C. D. Ager, and Mark Harris
- Subjects
Superconductivity ,Absorption spectroscopy ,Condensed matter physics ,Mean field theory ,Chemistry ,Condensed Matter::Superconductivity ,Infrared spectroscopy ,General Materials Science ,BCS theory ,Condensed Matter Physics ,Absorption (electromagnetic radiation) ,Spectroscopy ,Spectral line - Abstract
The frequencies and the absorption cross sections of infrared active phonons show anomalies related to the transition between the normal and superconducting phase in YBa2Cu3O7. The excess intensity of the absorption line and the frequency shift of the mode near 585 cm-1 are proportional to each other. Correlating these parameters with the thermodynamic order parameter using hard model spectroscopy leads to an order parameter of the superconducting phase which follows formally mean field theory of the BCS or Landau-Ginzburg type.
- Published
- 1990
- Full Text
- View/download PDF
11. Active DPF Regeneration for 2007 Diesel Engines
- Author
-
Chris Huffmeyer, Randy Johnson, Kendall T. Duffield, John Brian Abel, Jon Joseph Huckaby, Tom Kozakiewicz, Jon Baurley, and Yougen Kong
- Subjects
Diesel fuel ,Diesel particulate filter ,Regeneration (biology) ,Environmental science ,Pulp and paper industry - Published
- 2005
- Full Text
- View/download PDF
12. New committee formed at the University of Guelph to investigate cases of possible abuse of client-owned animals
- Author
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D, Bienzle, A, Abrams-Ogg, C, Bolam, A, Leclerc, S, Weese, T, Duffield, M B, MacDonald, and B, McEwen
- Subjects
Ontario ,Letter ,Legislation, Veterinary ,Animals ,Humans ,Mandatory Reporting ,Animal Welfare - Published
- 2004
13. Short communication: effects of monensin on 3-methylhistidine excretion in transition dairy cows
- Author
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T. Duffield, P. Dick, A. Martin, Brian W. McBride, R. Bagg, J. P. Walton, and Jan C. Plaizier
- Subjects
medicine.medical_specialty ,Nitrogen balance ,Nitrogen ,Sodium ,chemistry.chemical_element ,Ice calving ,Urine ,Biology ,Excretion ,chemistry.chemical_compound ,Pregnancy ,Internal medicine ,Lactation ,Genetics ,medicine ,Animals ,Monensin ,Dairy cattle ,Labor, Obstetric ,Ionophores ,Proteins ,Methylhistidines ,medicine.anatomical_structure ,Endocrinology ,chemistry ,Delayed-Action Preparations ,Animal Science and Zoology ,Cattle ,Female ,Energy Metabolism ,Food Science - Abstract
Urinary 3 methyl-histidine excretion was measured in high yielding dairy cows between 10 and 3 d precalving and between 3 and 9 d postcalving. Cows received a sodium monensin controlled-release capsule or a placebo 3 wk before calving. Monensin did not affect urinary 3 methyl-histidine. Average urinary 3 methyl-histidine excretion was significantly higher postcalving (4.11mmol d –1 ) than precalving (2.48 mmol d –1 ). This increase is assumed to be predominantly due to the negative nitrogen balance in the postcalving period caused by insufficient nutrient intake to meet nutrient requirements, which necessitates catabolism of mainly myofibrillar protein.
- Published
- 2001
14. The effect of tilmicosin administered to ewes prior to lambing on incidence of clinical mastitis and subsequent lamb performance
- Author
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A, Croft, T, Duffield, P, Menzies, K, Leslie, R, Bagg, and P, Dick
- Subjects
Sheep ,animal diseases ,Incidence ,Body Weight ,Sheep Diseases ,Mastitis ,respiratory system ,Anti-Bacterial Agents ,Mammary Glands, Animal ,Animals, Newborn ,parasitic diseases ,Animals ,Female ,Tylosin ,Macrolides ,Research Article - Abstract
The effect of tilmicosin on the incidence of clinical mastitis and subsequent lamb performance was studied in 9 sheep flocks in Ontario. Ewes were treated randomly with either tilmicosin or placebo approximately one month prior to lambing. Outcome was assessed by comparing rates of clinical mastitis, palpable udder abnormalities, and preweaning (50-day) lamb weights between the 2 treatment groups, while controlling for other important variables. Lambs raised by multiparous ewes treated with tilmicosin were significantly heavier than lambs from placebo-treated multiparous ewes at 50 days. Lambs from tilmicosin-treated ewes were on average 0.52 kg heavier than lambs in the placebo group. There was no difference between treatment groups in the weight of lambs from first parity ewes. Tilmicosin treatment resulted in a 43% decrease in palpable udder abnormalities. Incidence of clinical mastitis did not differ between experimental groups. The administration of tilmicosin prelambing, at the time of routine clostridial disease vaccination, may be a beneficial and convenient way to reduce mastitis infection and improve the preweaning gain of lambs.
- Published
- 2000
15. Phonon-order parameter coupling in YBa2Cu3O7- deltaas observed by infrared absorption spectroscopy
- Author
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C. D. Ager, H. P. Hughes, Mark Harris, T Duffield, J Blunt, P Freeman, Bernd Güttler, and Ekhard K. H. Salje
- Subjects
Coupling ,Superconductivity ,Materials science ,Condensed matter physics ,Absorption spectroscopy ,Phonon ,Metals and Alloys ,Phase (waves) ,Infrared spectroscopy ,Condensed Matter Physics ,Condensed Matter::Superconductivity ,Materials Chemistry ,Ceramics and Composites ,Direct coupling ,Electrical and Electronic Engineering ,Spectroscopy - Abstract
Infrared absorption spectroscopy has been used to investigate the complete phonon frequency range (20 cm-1-700 cm-1) at temperatures between 10 K and 300 K. A direct coupling of bulk phonon modes in YBa2Cu3O7- delta with the superconductor order parameter is deduced from the critical temperature dependence in the superconducting low temperature phase (Tc approximately 92 K). The excess intensity and the frequency shift of the mode near 580 cm-1 are shown to be proportional to the square of a BCS-like order parameter in agreement with the predictions of Hard Mode Spectroscopy.
- Published
- 1991
- Full Text
- View/download PDF
16. The association between first DHI milk-test parameters and subsequent displaced abomasum diagnosis in dairy cows
- Author
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T, Geishauser, K, Leslie, T, Duffield, and V, Edge
- Subjects
Quality Control ,Canada ,Milk ,Abomasum ,Animals ,Cattle Diseases ,Humans ,Cattle ,Milk Proteins ,Lipids ,Congenital Abnormalities - Abstract
First Dairy Herd Improvement Corporation (DHI) test milk that was sampled prior to displaced abomasum (DA) diagnosis was used to examine the association between milk yield (kg), fat (%), protein (%), or fat/protein ratio and DA in dairy cows. 27 DA cases were matched to 3 controls per case by herd and calving date. Logistic regression was used to examine the effect of each milk parameter on the odds of DA, adjusting for lactation number and days in milk (DIM) at test. Higher odds of DA diagnosis was found with lower milk yield, higher milk fat percentage, lower milk protein percentage and higher fat/protein ratio. We conclude that milk yield, fat percentage, protein percentage and fat/protein ratio may be used to detect cows at risk for DA. Our findings also indicate that cows diagnosed with DA were energy deficient prior to DA diagnosis.
- Published
- 1999
17. Saturated Mini-Band Transport in Semiconductor Superlattices
- Author
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M. Helm, M.A. Koza, S. J. AllenJr., Rajaram Bhat, G. Brozak, D. M. Hwang, P. Grabbe, C. H. Perry, T. Duffield, and F. De Rosa
- Subjects
Physics ,Nonlinear system ,Condensed matter physics ,law ,Cyclotron ,Cyclotron resonance ,Perturbation (astronomy) ,Semiconductor superlattices ,Landau quantization ,Conductivity ,Magnetic field ,law.invention - Abstract
Strong nonlinear response is an essential feature of narrow band transport. These potentially strong nonlinearities derive from the fact that a perturbation applied to a narrow band will exhaust the spectrum of states and the response will be saturated. The most exciting example is the long sought for but never achieved Bloch oscillation [1]. Here, we describe two different experiments that explore the saturated response of a narrow conduction band. First we discuss the effect of magnetic fields that drive the cyclotron resonance above the top of the mini-band and then, secondly, we document quenching of the narrow band conductivity at temperatures that exceed the mini-band width.
- Published
- 1991
- Full Text
- View/download PDF
18. Shallow donors in extended state GaAs/(Al, Ga) As superlattices
- Author
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Rajaram Bhat, T. Duffield, J. P. Harbison, Maria C. Tamargo, D. M. Hwang, P. Grabbe, S.J. Allen, F. DeRosa, and M. Koza
- Subjects
Condensed Matter::Quantum Gases ,Condensed matter physics ,Chemistry ,Astrophysics::High Energy Astrophysical Phenomena ,Superlattice ,Heterojunction ,General Chemistry ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Condensed Matter Physics ,Magnetic field ,Condensed Matter::Materials Science ,Materials Chemistry ,Physics::Chemical Physics ,Absorption (electromagnetic radiation) - Abstract
We have studied the effect of superlattice structure on the 1s to 2p + transition energy of shallow donors. In a strong magnetic field along the growth direction the transition is inhomogeneously broadened with absorption features that can be correlated with the position of the donor with respect to the barriers and wells. The results compare well with recent theory of donors in superlattices and are potentially important for the determination of donor distributions in superlattices.
- Published
- 1986
- Full Text
- View/download PDF
19. Breakdown of cyclotron resonance in semiconductor superlattices
- Author
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D. M. Hwang, Rajaram Bhat, M.A. Koza, S.J. Allen, T. Duffield, F. DeRosa, and P. Grabbe
- Subjects
Condensed matter physics ,Chemistry ,Cyclotron ,Cyclotron resonance ,Resonance ,General Chemistry ,Landau quantization ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Condensed Matter Physics ,Fourier transform ion cyclotron resonance ,Electron cyclotron resonance ,law.invention ,Effective mass (solid-state physics) ,law ,Materials Chemistry ,Ion cyclotron resonance - Abstract
We have observed breakdown of cyclotron resonance in large magnetic fields oriented perpendicular to the growth direction in semiconductor superlattices. At small magnetic fields conventional cyclotron resonance is observed with the mass related to the miniband mass. At large magnetic fields, when the cyclotron diameter approaches the superlattice period, the resonance frequency appears to saturate and is determined by orbits impaled on the barrier. A model calculation gives good account of the magnetic field dependence of the resonance position and line width.
- Published
- 1988
- Full Text
- View/download PDF
20. Adiabatic cooling in spin glasses
- Author
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C N Guy and T Duffield
- Subjects
Spin glass ,Physics and Astronomy (miscellaneous) ,Condensed matter physics ,Equilibrium thermodynamics ,Chemistry ,Metals and Alloys ,General Engineering ,Magnetic refrigeration ,Thermodynamics ,Adiabatic process - Abstract
Measurements of the magnetocaloric effect in two different spin glasses, CuMn and LaGdAl2 are presented and compared with the predictions of equilibrium thermodynamics. It is shown that LaGdAl2 is an extremely reversible system that exhibits a relatively large amount of adiabatic cooling below TG and very little irreversibility. CuMn, on the other hand, is much more irreversible and a definite observation of adiabatic cooling has not been made. It is proposed on the basis of these results that the spin-glass phenomenon is fundamentally an equilibrium one that is often obscured by secondary irreversible properties.
- Published
- 1985
- Full Text
- View/download PDF
21. Calorimetric studies of magnetic hysteresis in CuMn alloys
- Author
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T Duffield, C N Guy, and P.W. Gilberd
- Subjects
Spin glass ,Physics and Astronomy (miscellaneous) ,Magnetic energy ,Condensed matter physics ,business.industry ,Chemistry ,Metals and Alloys ,General Engineering ,Thermodynamics ,Magnetic hysteresis ,Magnetic field ,Condensed Matter::Materials Science ,Magnetization ,Hysteresis ,Remanence ,sense organs ,skin and connective tissue diseases ,business ,Thermal energy - Abstract
Calorimetric measurements on the hysteresis loop of the spin glass CuMn show that the energy changes take place on those legs of the loop which correspond to reversals of the remanent magnetisation and that it is always heating which occurs, irrespective of the direction of the applied magnetic field. Cycling through successive hysteresis loops causes large initial changes in sample heating and loop area, with both of these quantities tending to a temperature-independent limit. Although the limit cycle is displaced from the origin, the thermal energy changes on both irreversible legs are approximately equal, indicating a change of internal magnetic energy on reversal of the remanence. It is argued that the energy released in the initial magnetisation reversals is attributable to irreversible rearrangements of the relative spin directions and that it is only in the limit cycle that energy changes represent exclusively the intrinsic irreversible processes of magnetisation reversal.
- Published
- 1988
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22. A Comparison of Modulation Techniques for Quantized Voice Communications
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T. Duffield
- Subjects
business.industry ,Pulse (signal processing) ,Computer science ,Bandwidth (signal processing) ,Transmitter ,Electrical engineering ,Communications system ,Amplitude modulation ,Modulation ,Electronic engineering ,Radio frequency ,Electrical and Electronic Engineering ,business ,Frequency modulation ,Pulse-width modulation ,Intermodulation - Abstract
Using the requirements of a quantized multiple access voice communications system as a base, an investigation of several methods of modulation was conducted. Two frequency modulation (FM) techniques and one amplitude modulation (AM) technique were investigated in detail. The AM technique is the quantized pulse position modulation-AM (QPPM-AM) method used in the U. S. Army random access-discrete address (RADA) communications system. The quantized FM techniques were investigated as possible alternates to the RADA technique. Comparisons between the techniques are made in the areas of required transmitter power, RF bandwidth, circuit complexity, and several other areas relevant to communications systems of this type. The results indicate superior performance of one FM technique in several areas.
- Published
- 1970
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23. Photovoltaic detection of infrared light in a GaAs/AlGaAs superlattice
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A. Kastalsky, J. P. Harbison, S. J. Allen, and T. Duffield
- Subjects
Condensed Matter::Quantum Gases ,Physics and Astronomy (miscellaneous) ,Condensed matter physics ,Condensed Matter::Other ,Infrared ,Chemistry ,business.industry ,Superlattice ,Optical polarization ,Photovoltaic effect ,Photodetection ,Electroluminescence ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect ,Photoexcitation ,Condensed Matter::Materials Science ,Optoelectronics ,business ,Astrophysics::Galaxy Astrophysics ,Quantum well - Abstract
We report the observation of photovoltaic infrared photodetection in an n‐type GaAs/AlGaAs superlattice within the optical range 3.6–6.2 μm. A built‐in graded AlGaAs barrier (∼0.2 eV) provides charge polarization in the sample by allowing the optically excited electrons in the second miniband of the superlattice to diffuse over this barrier. The optical polarization of the infrared signal is consistent with the selection rules applicable to the superlattice. The infrared photoresponse results from first‐to‐second miniband as well as shallow donor‐to‐second miniband photoexcitations within the superlattice. Donor‐to‐second miniband photoexcitation is dominant at low temperatures (
- Published
- 1988
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24. Electron mass tunneling along the growth direction of (Al,Ga)As/GaAs semiconductor superlattices
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T. Duffield, F. DeRosa, D. M. Hwang, Rajaram Bhat, S. J. Allen, M. Koza, and P. Grabbe
- Subjects
Tunnel effect ,Materials science ,Condensed matter physics ,Solid-state physics ,Superlattice ,Cyclotron resonance ,General Physics and Astronomy ,Electron ,Semiconductor device ,Quantum tunnelling ,Magnetic field - Published
- 1986
25. Tunneling Cyclotron Resonance in Semiconductor Superlattices
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Maria C. Tamargo, J. P. Harbison, Rajaram Bhat, K. M. Rush, S. J. AllenJr., F. DeRosa, M.A. Koza, D. M. Hwang, T. Duffield, and P. Grabbe
- Subjects
Materials science ,Semiconductor ,Field (physics) ,business.industry ,Doping ,Cyclotron resonance ,Landau quantization ,Electron ,business ,Layer (electronics) ,Engineering physics ,Quantum tunnelling - Abstract
One of the more remarkable achievements in the field of materials science has been the growth of semiconductor single crystals atomic layer by atomic layer. By varying the composition along the growth direction a very great degree of control can be exercised over semiconductor doping and bandgaps. Although the scientific understanding and technological development of these materials has been unusually rapid, the early vision[1] that focused on the engineering of bulk, 3-dimensional, bandstructures has been largely forsaken in favor of properties that emerge due to confinement of the electron states to the two dimensions of a single layer.
- Published
- 1987
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26. Output feedback decoupling and pole placement in linear time-invariant systems
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T. Duffield and M.M. Bayoumi
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Multivariable calculus ,MathematicsofComputing_NUMERICALANALYSIS ,Nonlinear control ,Closed-loop pole ,Minor loop feedback ,Computer Science Applications ,LTI system theory ,Matrix (mathematics) ,Control and Systems Engineering ,Control theory ,ComputingMethodologies_SYMBOLICANDALGEBRAICMANIPULATION ,Full state feedback ,Electrical and Electronic Engineering ,Decoupling (electronics) ,Mathematics - Abstract
The question of closed-loop pole placement for linear multivariable systems decoupled by output feedback is considered. The class of decoupling feedback matrices is extended to include those which are proper functions of s . This result insures that all uncancelled poles of the resulting closed-loop system can be reassigned to any desired location by suitable choice of the feedback matrix.
- Published
- 1977
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27. A Review of Mining Operations in the State of South Australia during the Half-Year Ended December 31, 19l0. No. 13. T. Duffield
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T. Duffield
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History ,State (polity) ,media_common.quotation_subject ,Economic history ,Geology ,media_common - Published
- 1911
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28. Identification of genetic markers associated with hyperketonemia patterns in early lactation Holstein cows.
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Muniz MMM, Serrenho RC, Duffield T, de Oliveira Junior GA, McArt JAA, Baes CF, Schenkel FS, and Squires EJ
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- Animals, Cattle genetics, Female, Genetic Markers genetics, Polymorphism, Single Nucleotide, Milk metabolism, Lactation genetics, Ketosis veterinary, Ketosis genetics, Cattle Diseases genetics, Cattle Diseases blood, 3-Hydroxybutyric Acid blood
- Abstract
Ketosis, evidenced by hyperketonemia with elevated blood β-hydroxybutyrate (BHB) levels, is a significant metabolic disorder of dairy cattle, typically diagnosed within the first 6 weeks post-calving when high energy levels are essential to milk production. Our study aimed to identify genetic markers linked to hyperketonemia (HYK) patterns in Holstein cows during early lactation and compare these to HYK-negative cows. We screened 964 cows for HYK using a threshold of BHB ≥1.2 mmol/L during the first 2 weeks postpartum (screening period, SP). Cows that tested negative initially were retested the following week. Cows were deemed HYK-negative (CON group) if BHB levels were below 1.2 mmol/L in both tests, while those with BHB levels exceeding this threshold at any test were treated and classified as HYK-positive (HYK+). Post-treatment, HYK+ cows were monitored for two-week follow-up period (FP) and classified based on their recovery: cured (CUR; consistently low BHB), recurrent (REC; fluctuating BHB levels), severe (SEV; high initial BHB that decreased), or chronic (CHR; persistently high BHB). Using 489 cows that were genotyped, a GWAS was conducted using GCTA software, revealing significant associations of several SNPs across different HYK patterns when compared to the CON group. These SNPs were primarily linked to genes affecting milk traits and were enriched in biological pathways relevant to protein glycosylation, inflammatory response, glucose homeostasis, and fatty acid synthesis. Our findings highlight genomic regions, potential candidate genes, and biological pathways related to ketosis, underscoring potential targets for improving health management in dairy cattle. These insights could lead to better strategies for managing ketosis through genetic selection, ultimately enhancing dairy cattle welfare and productivity. Further research with a larger number of cows is recommended to validate these findings and help confirm the implicated SNPs and genes., (© 2024 The Author(s). Journal of Animal Breeding and Genetics published by John Wiley & Sons Ltd.)
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- 2024
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29. Corrigendum to "Characterizing ruminal acidosis risk: A multiherd, multicountry study" (J. Dairy Sci. 106:3155-3175).
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Golder HM, LeBlanc SJ, Duffield T, Rossow HA, Bogdanich R, Hernandez L, Block E, Rehberger J, Smith AH, Thomson J, and Lean IJ
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- 2024
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30. A focus group study exploring dairy farmers' perspectives of cull cow management in Ontario, Canada.
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Marshall J, Haley DB, Kelton D, Miltenburg C, Roche S, and Duffield T
- Abstract
Introduction: Maintaining the welfare of cull dairy cows from the farm to slaughter is an ongoing challenge for the dairy industry. Recent research suggests that some cull dairy cows within the marketing system are in physical states that are below regulatory standards, and further research is required to determine why these unfit cows are found throughout the journey to abattoirs. Since dairy farms are the origin of these cows, decision making by dairy farmers has been identified as key to preventing cull cows that are considered unfit for transport from entering the marketing system. The objectives of this study were to understand dairy farmers' perspectives on their cull dairy cow management practices, recommendations and requirements of regulations, management tools, and welfare issues., Methods: Four focus groups with a total of 21 participants were each conducted virtually, video recorded, and transcribed verbatim, with dairy farmers from Ontario, Canada. A thematic analysis of focus group discussions was conducted utilizing deductive reasoning., Results: There were three themes identified including deciding to cull or not, management of cows being culled, and knowledge and perceptions of cull cow regulations. When making culling decisions, farmers utilize multiple sources of information including personal experiences and values and external referents like veterinarians, family members and other farmers. The welfare of their cows was a high priority but one that was often weighed against the financial outcomes of culling decisions. Finally, most participants considered recent regulatory changes for the management of cows before shipment to be of little importance on their farms., Discussion: In conclusion, the farmers from this study showed the diversity of considerations they make in culling decisions and the large contribution of animal productivity and economic factors. There was a general lack of knowledge of recent regulatory changes for the shipment of cull cows, and there is room for improving the uptake of new recommendations for culling only cows fit for transportation., Competing Interests: SR is employed by ACER Consulting Limited. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Marshall, Haley, Kelton, Miltenburg, Roche and Duffield.)
- Published
- 2023
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31. Characterizing ruminal acidosis risk: A multiherd, multicountry study.
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Golder HM, LeBlanc SJ, Duffield T, Rossow HA, Bogdanich R, Hernandez L, Block E, Rehberger J, Smith AH, Thomson J, and Lean IJ
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- Female, Animals, Cattle, Ammonia metabolism, Rumen metabolism, Milk chemistry, Lactation, Fatty Acids, Volatile metabolism, Diet veterinary, Lactic Acid metabolism, Carbohydrates analysis, Fermentation, Hydrogen-Ion Concentration, Animal Feed analysis, Acidosis veterinary, Acidosis metabolism, Cattle Diseases epidemiology, Cattle Diseases metabolism
- Abstract
A multicenter observational study was conducted on early lactation Holstein cows (n = 261) from 32 herds from 3 regions (Australia, AU; California, CA; and Canada, CAN) to characterize their risk of acidosis into 3 groups (high, medium, or low) using a discriminant analysis model previously developed. Diets ranged from pasture supplemented with concentrates to total mixed ration (nonfiber carbohydrates = 17 to 47 and neutral detergent fiber = 27 to 58% of dry matter). Rumen fluid samples were collected <3 h after feeding and analyzed for pH, and ammonia, d- and l-lactate, and volatile fatty acid (VFA) concentrations. Eigenvectors were produced using cluster and discriminant analysis from a combination of rumen pH, and ammonia, d-lactate, and individual VFA concentrations and were used to calculate the probability of the risk of ruminal acidosis based on proximity to the centroid of 3 clusters. Bacterial 16S ribosomal DNA sequence data were analyzed to characterize bacteria. Individual cow milk volume, fat, protein, and somatic cell count values were obtained from the closest herd test to the rumen sampling date (median = 1 d before rumen sampling). Mixed model analyses were performed on the markers of rumen fermentation, production characteristics, and the probability of acidosis. A total of 26.1% of the cows were classified as high risk for acidosis, 26.8% as medium risk, and 47.1% as low risk. Acidosis risk differed among regions with AU (37.2%) and CA (39.2%) having similar prevalence of high-risk cows and CAN only 5.2%. The high-risk group had rumen phyla, fermentation, and production characteristics consistent with a model of acidosis that reflected a rapid rate of carbohydrate fermentation. Namely, acetate to propionate ratio (1.98 ± 0.11), concentrations of valerate (2.93 ± 0.14 mM), milk fat to protein ratio (1.11 ± 0.047), and a positive association with abundance of phylum Firmicutes. The medium-risk group contains cows that may be inappetant or that had not eaten recently or were in recovery from acidosis. The low-risk group may represent cattle that are well fed with a stable rumen and a slower rumen fermentation of carbohydrates. The high risk for acidosis group had lower diversity of bacteria than the other groups, whereas CAN had a greater diversity than AU and CA. Rumen fermentation profile, abundance of ruminal bacterial phyla, and production characteristics of early lactation dairy cattle from 3 regions were successfully categorized in 3 different acidosis risk states, with characteristics differing between acidosis risk groups. The prevalence of acidosis risk also differed between regions., (The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)
- Published
- 2023
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32. Associations of parity with health disorders and blood metabolite concentrations in Holstein cows in different production systems.
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Lean IJ, LeBlanc SJ, Sheedy DB, Duffield T, Santos JEP, and Golder HM
- Subjects
- Pregnancy, Female, Cattle, Animals, Parity, Fatty Acids, Nonesterified, Lameness, Animal metabolism, Lactation, 3-Hydroxybutyric Acid, Glucose metabolism, Postpartum Period metabolism, Milk metabolism, Cattle Diseases epidemiology, Cattle Diseases metabolism, Ketosis epidemiology, Ketosis veterinary, Ketosis metabolism, Mastitis metabolism, Mastitis veterinary
- Abstract
Data were obtained from studies in Australia, Canada, and the United States using individual cow data from 28,230 Holstein cows to evaluate associations between parity and disease. Our goal was to develop understanding of disease risks for cows of differing parity. We hypothesized that there would be increased risks of disease and changes in metabolite concentrations with increased parity. Parity ≥5 represented 2,533 cows or 9.0%, parity 4 was 9.8% (2,778), parity 3 as 19.0% (5,355), parity 2 as 28.1% (7,925), and parity 1 was 34.1% (9,639) of the sample. Of these cows, 15.5% were in Australia, 14.7% in Canada, and 69.8% in the United States. Lactational incidence (LI) risk of clinical hypocalcemia increased with parity from 0.1% for parity 1 to 13% for parity ≥5 cows. The marked increase suggests profound differences in metabolism with increased parity. The LI of clinical mastitis was 17.4%. The odds of mastitis increased with parity to 2.5 times greater in parity ≥5 than in parity 1. The LI of lameness increased with parity; specifically, the odds of lameness was 5.6 times greater for parity ≥5 than parity 1. Dystocia incidence was 8.7% and greatest for parity 1 cows. The LI of retained placenta was 7.4% and increased with parity, with the odds for parity ≥5 2.3 times greater than for parity 1. The LI of metritis was 10% and of endometritis 14%, with the greatest odds in parity 1. The LI of clinical ketosis was 3.3% with a marked increase in odds with parity. The prevalence of subclinical ketosis was 26.8% with only cows in parity 1 having lower odds than other parities. Parity ≥5 cows had greater odds (odds ratio = 1.7) of respiratory disease than parity 1 cows, which were lesser than other parities. Metabolite concentrations were evaluated in 5,154 Holstein cows in the precalving, calving, and immediate postcalving data sets. Metabolic measures near peak lactation provided 1,906 observations. Concentrations of β-hydroxybutyrate (BHB) and nonesterified fatty acids increased with parity on d 1 to 3 of lactation and at peak lactation. On d 1 to 3 after calving differences in glucose, nonesterified fatty acids, and BHB indicated a greater reliance on mobilized lipid to export energy to peripheral tissues as BHB for greater parity cows. Differences in concentrations among parity groups were marked at times, for example >0.20 mM in Ca for parity 1 and 2 to parity ≥5 and >0.33 mM for all older parities compared with parity 1 for P on the day of calving. The marked increase suggests profound differences in metabolism with increased parity are probably influenced, in part, by increased production. We found marked differences in concentrations of metabolites with parity that are consistent with reduced reproduction, health, and body condition for higher parity cows. These unfavorable differences in metabolism in Ca, P, glucose, and cholesterol concentrations for higher parity cows also complement the often-substantial differences in disease risk with parity and suggest a need to carefully consider the parity structure in study design. Managers and advisors will need to consider methods to reduce risk of health disorders tailored to cows of different ages., (The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)
- Published
- 2023
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33. Increased parity is negatively associated with survival and reproduction in different production systems.
- Author
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Lean IJ, Golder HM, LeBlanc SJ, Duffield T, and Santos JEP
- Subjects
- Pregnancy, Female, Cattle, Animals, Parity, Retrospective Studies, Milk Proteins analysis, Reproduction, Lactation physiology
- Abstract
We conducted a retrospective meta-analysis based on individual cow data to assess the associations of parity, level of production, and pasture-based or intensively fed systems with fertility. Our goal was to provide understandings of the role of parity in risks for removal and reproductive failure. Multilevel models were used to evaluate the fixed effects of parity, milk, milk solids, milk fat and protein percentage and yield, and production system [intensively fed (n = 28,675) or predominantly pasture fed (n = 4,108)] on reproductive outcomes. The outcomes were the hazard of not being bred (HNBRED), hazard of pregnancy (HPREG), pregnancy to first breeding (PREG1), and odds of becoming pregnant in a lactation (OPAL). The 32,783 cows were in 13 studies conducted in Australia (14.6% of cows), Canada (2.4% of cows), and the United States (83.0% of cows). There were 38.5% of cows in the sample in parity 1, 27.3% in parity 2, 16.7% in parity 3, 9.0% in parity 4, and 8.6% in parity ≥5. Compared with cows of parity 1, parity ≥5 cows had a greater HNBRED [hazard ratio (HR) = 2.45], lesser HPREG (HR = 0.73), and reduced OPAL (odds ratio = 0.36). However, the parity ≥5 cows had similar PREG1 to other parities except for parity 1. This suggests the possibility of a higher proportion of subfertile parity ≥5 cows than for other parities. Associations between parity and reproductive measures were influenced by the different milk production measures, indicating that milk yield and milk component percentages and yields modified the odds or hazards of successful reproduction. All milk production measures had quadratic associations with OPAL, indicating that either low or high production or concentration of solids within a cohort reduced OPAL. This reduced OPAL reflected a greater HNBRED for lower milk yield and milk protein and fat yielding cows. Both milk yield and milk protein percentage had quadratic associations with HPREG. When centered milk yield was categorized into quartiles, small differences in HPREG existed. A more marked association of milk protein percentage occurred with HPREG, with optimal HPREG at approximately 0.5% above group mean milk protein percentage. Milk fat percentage (HR = 0.901), fat yield (kg/d; HR = 0.78), protein yield (kg/d; HR = 0.71), and milk solids yield (kg/d; HR = 0.84) were all linearly associated with reduced HPREG. Difference in production systems did not have substantive effects on PREG1 but did for HNBRED, HPREG, and OPAL. Estimates of associations of parity with reproductive outcomes HNBRED, HPREG, and OPAL were influenced by milk and milk solids yield; older cows had markedly lower reproductive outcomes. Interestingly, for PREG1, there were few differences among parities and differences were less influenced by milk yield and constituent measures. The marked associations of parity with removal for all reasons, deaths and culling, and reductions in HNBRED, HPREG, and OPAL indicate a need to focus on the physiological changes with parity to produce better strategies to support optimal longevity of cows., (The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)
- Published
- 2023
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34. Veterinarians' use of shared decision making during on-farm interactions with dairy and beef producers.
- Author
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DeGroot A, Coe JB, and Duffield T
- Subjects
- Cattle, Animals, Humans, Farms, Decision Making, Shared, Cross-Sectional Studies, Ontario, Decision Making, Veterinarians
- Abstract
Background: The objectives of this study were to explore the level of shared decision making (SDM) between veterinarians and dairy and beef producers during on-farm interactions and to identify factors associated with veterinarians' use of SDM behaviours., Methods: A cross-sectional sample of food-animal veterinarians and their clients were recruited in Ontario, Canada. Their on-farm interactions were audio-video recorded. The recordings were analysed using the 'Observing Patient Involvement in Decision Making' (observer OPTION
5 ) instrument to determine the level of SDM utilised during preference-sensitive decisions. A logistic regression model was developed to assess factors associated with a preference-sensitive decision occurring. Meanwhile, a linear regression model was developed to identify factors associated with the level of SDM used., Results: Forty-one veterinarians participated, and 186 unique veterinarian-producer interactions were audio-video recorded and OPTION5 score was calculated. SDM scores were low and comparable to other studies using the OPTION5 instrument. The only factor associated with whether a preference-sensitive decision occurred was the length of the veterinarian and producer's relationship (in years). As the length of their relationship increased, a preference-sensitive decision was less likely to occur. The use of SDM behaviours was found to decrease as veterinarian burnout score increased. These findings demonstrate that SDM behaviours are being used by food-animal veterinarians, yet an opportunity exists to further implement more producer-centred SDM skills into on-farm interactions., Limitations: Small portions of veterinarian-producer conversation occurred outside of audio-video-recorded interactions and were not included in the analysis., Conclusion: The results of this study aid in further understanding on-farm interactions between veterinarians and producers and can help to further improve veterinary communication curricula., (© 2022 British Veterinary Association.)- Published
- 2023
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35. Holstein dairy cows lose body condition score and gain body weight with increasing parity in both pasture-based and total mixed ration herds.
- Author
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Lean IJ, Sheedy DB, LeBlanc SJ, Duffield T, Santos JEP, and Golder HM
- Abstract
Body condition scoring (BCS) and body weight (BW) are observations associated with labile tissue reserves, health, and reproduction efficiency of dairy cows. The effect of parity (1 through to ≥5) and feeding system (pasture-based and TMR) on BCS and BW were evaluated utilizing raw data sets from 16 retrospective studies that totaled 24,807 Holstein cows across 3 nations (Australia, Canada, and the United States). Linear regression models were used to investigate the 5 outcome variables of precalving BCS, peak milk BCS, change in BCS from precalving to peak milk, and peak milk BW and their respective associations with parity and feeding system. To help control for the influence of calendar time, study treatment protocols when applicable, and genetic change, all outcome variables were center-transformed around each study group mean. Including feeding system as a covariate improved model fit for most outcome variables; however, the relative effect size of parity was generally much greater than feeding system effect size. Parity 2 cows had the lowest precalving BCS of -0.087 [95% confidence interval (CI): -0.107, -0.065] less than the mean, whereas parity 1 cows had the greatest, 0.068 (95% CI: 0.043, 0.092) above mean, regardless of feeding system. Peak milk BCS overall decreased with increasing parity (parity 1 to parity ≥5: -0.13, 95% CI: -0.19, -0.08) and BCS change during the transition period monotonically decreased with increasing parity (parity 1 to parity ≥5: -0.22, 95% CI: -0.26, -0.17). Peak milk BW monotonically increased with increased parity (parity 1 to parity ≥5: 114 kg, 95% CI: 104, 125). A waffle plot was used to present the proportions of cows, by parity, that were partitioned into "low BCS and low BW," "low BCS and high BW," "high BCS and low BW," or "high BCS and high BW" groups. Cows were assigned either a high or low status by being above or below their specific centered study group means, respectively. Considering a null hypothesis of 25% per BCS-BW category, there was a striking change in category from parity 1 cows that were predominantly in the "high BCS and low BW" category (61.2%) to parity ≥5 cows that were predominantly in the "low BCS and high BW" category (55.5%). The study supports studies showing increased weight and change in BCS with increased parity. We highlight the associations among production system, BCS, BW, and parity., (© 2022.)
- Published
- 2022
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36. A systematic review of the cost of ketosis in dairy cattle.
- Author
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Cainzos JM, Andreu-Vazquez C, Guadagnini M, Rijpert-Duvivier A, and Duffield T
- Subjects
- Animals, Cattle, Dairying, Farms, Female, Lactation, Milk, Prevalence, Cattle Diseases epidemiology, Ketosis epidemiology, Ketosis veterinary
- Abstract
A systematic review was conducted to assess the cost of ketosis in dairy cattle, and to elucidate how ketosis cost is estimated in each of the studies. Scientific papers addressing the economic impact of ketosis in dairy cows were identified through a search in 4 databases (Medline, ISI Web of Science, CAB Abstracts, and Agricola). The literature search was conducted with no restrictions on the date of study publication, publication type, or language. The methodological quality of the studies was assessed regarding study design, data collection, and analysis and interpretation of the study results. Of 531 identified records, 10 were selected, of which 9 were published from 2015 onward. Of the 10 studies reviewed, 9 report cost of a case of ketosis, and the estimates vary widely, with values ranging from €19 to €812. Two studies report ketosis cost at a farm level (€3.6-€29/cow per year). Among the studies, we observed great variation not only in the estimation models and inputs used (costs and losses associated with the disease) but also in the definition of ketosis and its prevalence or incidence figures. Moreover, the cost of ketosis was estimated for dairy farms in the United States, Canada, the Netherlands, Denmark, France, Germany, Spain, Sweden, Norway, and India. Consequently, there was great heterogeneity regarding herd characteristics, milk production, milk prices, culled cows' value, feed prices, and costs of veterinary services. Ketosis cost estimates vary as a consequence of all these aspects. Therefore, although most of the studies were well-designed and used high-quality data, the systematic approach review does not allow combination of the cost estimates of into a single figure. In conclusion, our review highlights an overall considerable economic impact of ketosis in dairy cattle. Economic prevention and mitigation strategies should be taken according to herd- and country-specific conditions. Ketosis cost figures reported in economic studies should always be considered carefully and interpreted with appropriate consideration of the inputs of the estimation, country context, and herd parameters., (The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)
- Published
- 2022
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37. Concussion Management Guidelines Neglect Auditory Symptoms.
- Author
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Theodoroff SM, Papesh M, Duffield T, Novak M, Gallun F, King L, Chesnutt J, Rockwood R, Palandri M, and Hullar T
- Subjects
- Humans, Athletic Injuries diagnosis, Athletic Injuries therapy, Brain Concussion complications, Brain Concussion diagnosis, Brain Concussion therapy
- Abstract
Competing Interests: The authors report no conflicts of interest.
- Published
- 2022
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38. Genome-wide association study and functional analyses for clinical and subclinical ketosis in Holstein cattle.
- Author
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Soares RAN, Vargas G, Duffield T, Schenkel F, and Squires EJ
- Subjects
- 3-Hydroxybutyric Acid analysis, Animals, Cattle genetics, Female, Genome-Wide Association Study veterinary, Lactation genetics, Male, Milk chemistry, Cattle Diseases genetics, Ketosis genetics, Ketosis veterinary
- Abstract
Ketosis is one of the most frequent metabolic diseases in high-yielding dairy cows and is characterized by high concentrations of ketone bodies in blood, urine, and milk, causing high economic losses. The search for polymorphic genes, whose alleles have different effects on resistance to developing the disease, is of extreme importance to help select less susceptible animals. The aims of this study were to identify genomic regions associated with clinical and subclinical ketosis (β-hydroxybutyrate concentration) in North American Holstein dairy cattle and to investigate these regions to identify candidate genes and metabolic pathways associated with these traits. To achieve this, a GWAS was performed for 4 traits: clinical ketosis lactation 1, clinical ketosis lactation 2 to 5, subclinical ketosis lactation 1, and subclinical ketosis lactation 2 to 5. The estimated breeding values from 77,277 cows and 7,704 bulls were deregressed and used as pseudophenotypes in the GWAS. The top-20 genomic regions explaining the largest proportion of the genetic variance were investigated for putative genes associated with the traits through functional analyses. Regions of interest were identified on chromosomes 2, 5, and 6 for clinical ketosis lactation 1; 3, 6, and 7 for clinical ketosis lactation 2 to 5; 1, 2, and 12 for subclinical ketosis lactation 1; and 20, 11, and 25 for subclinical ketosis lactation 2 to 5. The highlighted genes potentially related to clinical and subclinical ketosis included ACAT2 and IGF1. Enrichment analysis of the list of candidate genes for clinical and subclinical ketosis showed molecular functions and biological processes involved in fatty acid metabolism, lipid metabolism, and inflammatory response in dairy cattle. Several genomic regions and SNPs related to susceptibility to ketosis in dairy cattle that were previously described in other studies were confirmed. The novel genomic regions identified in this study aid to characterize the most important genes and pathways that explain the susceptibility to clinical and subclinical ketosis in dairy cattle., (The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).)
- Published
- 2021
- Full Text
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39. Comparison of food-animal veterinarians' and producers' perceptions of producer-centered communication following on-farm interactions.
- Author
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DeGroot A, Coe JB, Kelton D, Miltenburg C, Wichtel J, and Duffield T
- Subjects
- Animals, Communication, Cross-Sectional Studies, Farms, Female, Humans, Ontario, Surveys and Questionnaires, Veterinarians
- Abstract
Background: Human medicine has demonstrated that a patient-centered physician-patient relationship is more effective than the traditional physician-centered model. Objectives were to explore food-animal veterinarians' and producers' perceptions of producer-centered communication (VPPC and PPPC), during on-farm interactions and examine associated factors., Methods: A cross-sectional sample of food-animal veterinarians and their clients were recruited in Ontario, Canada. Immediately following on-farm veterinarian-producer interactions, the producer and veterinarian independently completed a questionnaire assessing PPC. Symmetry of paired responses between veterinarians and producers was examined. Employing listwise deletion, independent mixed linear regression models were developed to determine factors associated with PPPC and VPPC, respectively., Results: Two hundred and three paired veterinarian and producer survey responses were analysed. Significant asymmetry (p-value < 0.05) was observed, with veterinarians assessing PPC lower than producers. Based on data from 32 veterinarians and 159 producers, the only factor associated with PPPC was veterinarian burnout (PPPC decreased with burnout). Based on data from 32 veterinarians and 155 producers, factors positively associated with VPPC included veterinarian compassion satisfaction (VPPC increased with compassion satisfaction), length of interaction (VPPC increased with length of interaction) and producers identifying as female (VPPC higher with female producers)., Conclusion: Producer's positive PPPC is encouraging, yet veterinarians should be aware that mental health parameters may impact producers' and their own perceptions of PPC. Further examining veterinarians' delivery of PPC is important for food-animal practice., (© 2021 British Veterinary Association.)
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- 2021
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40. Spectrophotometric evaluation of hemolysis in plasma by quantification of free oxyhemoglobin, methemoglobin, and methemalbumin in presence of bilirubin.
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Heckl C, Lang A, Rühm A, Sroka R, Duffield T, Vogeser M, and Paal M
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- Bilirubin, Hemoglobins analysis, Hemolysis, Humans, Methemalbumin, Spectrophotometry, Methemoglobin analysis, Oxyhemoglobins analysis
- Abstract
Severe intravascular hemolysis leads to the simultaneous presence of free heme pigments (oxyhemoglobin, methemoglobin, and methemalbumin) and bilirubin in human plasma. Standard spectrophotometric methods used to assess in vivo hemolysis inadequately address this complex analytical situation. Thus, we propose a novel quantification algorithm to ensure the highest analytical specificity. A corresponding second-derivative fitting algorithm was validated according to the guideline of bioanalytical method validation from the European Medicines Agency using plasma specimens (n = 1759) spiked with different concentrations of oxyhemoglobin and methemoglobin. The results were compared to standard spectrophotometric quantification methods described by Harboe, Noe, and Fairbanks. Based on the second-derivative method, simultaneous quantification of oxyhemoglobin and methemoglobin/methemalbumin in samples with total bilirubin concentrations ≤4.9 mg/dL (83.8 μmol/L) provided robust results (inaccuracy ≤20%, imprecision ≤16%). Analyzing UV/VIS spectra of plasma from patients with confirmed severe intravascular hemolysis evidenced an underestimation of up to 33% for the combined free heme pigment content. The employed second-derivative algorithm allows for automated and highly specific quantification of the free heme pigment content in diluted human plasma, which cannot be realized with standard spectrophotometric evaluation methods. An Excel-based tool readily applicable to clinical datasets accompanies this manuscript., (© 2021 The Authors. Journal of Biophotonics published by Wiley-VCH GmbH.)
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- 2021
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41. Factors associated with food-animal producer visit-specific satisfaction following on-farm interaction with a veterinarian.
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DeGroot A, Coe J, Kelton D, Miltenburg C, Wichtel J, and Duffield T
- Subjects
- Age Factors, Animals, Cross-Sectional Studies, Farmers statistics & numerical data, Farms, Female, Humans, Male, Ontario, Reproducibility of Results, Sex Factors, Surveys and Questionnaires, Farmers psychology, Food Industry, Interprofessional Relations, Patient Satisfaction statistics & numerical data, Veterinarians psychology
- Abstract
Background: Effective communication has been found to have positive associations with client satisfaction, client adherence and veterinarian satisfaction in companion animal medicine. Better understanding the role of communication on these outcomes, specifically producer satisfaction, is likely to benefit food-animal medicine. Objectives were to identify factors associated with producer visit-specific satisfaction following on-farm veterinarian-producer interactions and evaluate the validity of the Client Satisfaction Questionnaire for use in food-animal medicine., Methods: A cross-sectional sample of practicing food-animal veterinarians and their producer clients were recruited in Ontario, Canada. Immediately following the veterinarian-producer interaction, producers completed a questionnaire that assessed their visit-specific satisfaction and their perception of the producer-centeredness of the interaction. Veterinarians completed a questionnaire that assessed their perception of the interaction's producer-centeredness. A linear regression model was developed to identify factors associated with producer visit-specific satisfaction., Results: Forty-one veterinarians and 207 producers participated. Factors associated with producer visit-specific satisfaction included producer age (satisfaction decreased with age), producer gender (males less satisfied) and producer perception of producer-centeredness score (satisfaction increased with producer perception of producer-centeredness score)., Conclusion: Findings raise awareness of the importance of a producer's perception of producer-centeredness in food-animal practice and encourage its use by food-animal veterinarians in working towards positive outcomes., (© 2021 British Veterinary Association.)
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- 2021
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42. Paradigm Shift Toward Digital Neuropsychology and High-Dimensional Neuropsychological Assessments: Review.
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Parsons T and Duffield T
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- Big Data, Humans, Machine Learning standards, Neuropsychology methods
- Abstract
Neuropsychologists in the digital age have increasing access to emerging technologies. The National Institutes of Health (NIH) initiatives for behavioral and social sciences have emphasized these developing scientific and technological potentials (eg, novel sensors) for augmented characterization of neurocognitive, behavioral, affective, and social processes. Perhaps these innovative technologies will lead to a paradigm shift from disintegrated and data-poor behavioral science to cohesive and data-rich science that permits improved translation from bench to bedside. The 4 main advances influencing the scientific priorities of a recent NIH Office of Behavioral and Social Sciences Research strategic plan include the following: integration of neuroscience into behavioral and social sciences, transformational advances in measurement science, digital intervention platforms, and large-scale population cohorts and data integration. This paper reviews these opportunities for novel brain-behavior characterizations. Emphasis is placed on the increasing concern of neuropsychology with these topics and the need for development in these areas to maintain relevance as a scientific discipline and advance scientific developments. Furthermore, the effects of such advancements necessitate discussion and modification of training as well as ethical and legal mandates for neuropsychological research and praxes., (©Thomas Parsons, Tyler Duffield. Originally published in the Journal of Medical Internet Research (http://www.jmir.org), 16.12.2020.)
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- 2020
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43. Case-Based e-Learning Experiences of Second-Year Veterinary Students in a Clinical Medicine Course at the Ontario Veterinary College.
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Sawras M, Khosa D, Lissemore K, Duffield T, and Defarges A
- Subjects
- Animals, Humans, Ontario, Students, Clinical Medicine, Computer-Assisted Instruction, Education, Veterinary
- Abstract
Exposure to real-life clinical cases has been regarded as the optimal method of achieving deep learning in medical education. Case-based e-learning (CBEL) has been considered a promising alterative to address challenges in the availability of teaching cases and standardizing case exposure. While the use of CBEL has been positive in veterinary medical education, insight into students' learning experience with a CBEL tool have not been considered. This article investigates students' views around the utility and usability of a CBEL tool, as well as perceived effectiveness, clinical confidence, and impact of veterinary students' learning preferences on CBEL use. Through focus groups as well as pre- and post-use questionnaires, students expressed that the design and utility of the online cases, including their authenticity, played an instrumental role in perspectives and acceptance of the CBEL tool. Students perceived the CBEL tool as highly effective in both achieving CBEL outcomes and teaching a methodical approach to a clinical case. CBEL elements were also perceived to potentially contribute to increased clinical confidence after CBEL use. Additionally, exploration of students' preferred approach to learning revealed that hands-on learners and those who prefer to learn by practicing and applying knowledge were more likely to show positive perceptions of a CBEL tool. This article's findings can help guide educators in the future design and implementation of online cases in various capacities and provide a platform for further exploration of the effectiveness and use of CBEL in veterinary medical education.
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- 2020
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44. Editorial: Animal Transport and Related Management.
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Herskin MS and Duffield T
- Abstract
Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
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- 2020
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45. Fitness for transport of cull dairy cows at livestock markets.
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Stojkov J, von Keyserlingk MAG, Duffield T, and Fraser D
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- Animals, British Columbia, Commerce, Dairying, Farms, Female, Seasons, Transportation, Animal Welfare, Cattle physiology, Milk metabolism, Physical Fitness
- Abstract
Cows are regularly removed from dairy herds and sold at livestock markets. Many cows are removed because of health problems, and their fitness for transport may vary because of seasonal variation, delayed or poor on-farm culling decisions, injuries during transport, and other factors. However, many dairy producers lack feedback about the condition of their cows during the marketing process and how cow condition influences sale price. This study evaluated the condition of cull dairy cows sold at livestock markets, tested how changing demand for milk influenced fitness for transport, and quantified how cow condition affected the price paid. For 12 mo, 2 livestock markets in British Columbia, Canada, were visited during 137 auction events when cull dairy cows were sold; 3 trained assessors observed 6,263 cull dairy cows while they were marketed in a sale ring. Observers recorded the cows' body condition score (BCS), locomotion score (LS), udder condition, quality defects (e.g., injuries, illness), and price. Logistic regression was used to test how month-to-month changes in demand for milk affected cows' fitness for transport, and a linear mixed model assessed how the animals' condition influenced the price. About 10% of the cows were thin (BCS ≤2), 7% were severely lame (locomotion score ≥4), 13% had engorged or inflamed udders, and 6% had other quality defects including abscesses, injuries, and signs of sickness (e.g., pneumonia). Cows culled during months with increased milk demand had much higher odds of poor fitness for transport (odds ratio 8.6, 95% confidence interval: 4.02-18.22). The price was most reduced if cows were thin (BCS ≤2) or visibly sick (-$0.63 ± 0.01/kg and -$0.56 ± 0.02/kg, respectively). Prices were reduced to a lesser degree by locomotion score ≥4 (-$0.35 ± 0.02/kg) and by udder condition (udder inflammation; -$0.30 ± 0.02/kg). Overall fitness for transport reduced the price by $0.51 ± 0.01/kg. In summary, about 30% of the cows sold at livestock markets had poor fitness for transport, which was partially influenced by increased milk demand and resulted in reduced market prices., (Copyright © 2020 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)
- Published
- 2020
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46. Management of cull dairy cows: Culling decisions, duration of transport, and effect on cow condition.
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Stojkov J, von Keyserlingk MAG, Duffield T, and Fraser D
- Subjects
- Abattoirs, Animals, British Columbia, Cattle, Dairying, Farmers, Farms, Female, Lactation, Lameness, Animal, Mammary Glands, Animal physiology, Transportation, Animal Culling, Animal Welfare, Cattle Diseases prevention & control, Decision Making, Milk metabolism
- Abstract
Many cows culled from dairy farms arrive at livestock markets or abattoirs in compromised condition, but it is unknown whether cows are compromised at the time of culling or deteriorate during the marketing process. This study followed cull cows from farm to abattoir, monitored any deterioration, and tested the effect of providing such information on subsequent culling. For 11 mo, data were collected from 20 dairy farms, livestock markets, and abattoirs. Cows' body condition, lameness, and udder condition (as binary outcomes) were assessed at 4 points: when placed on the culling list, before leaving the farm, at auction, and at the abattoir. Based on the first 5 mo of data (baseline period), information materials were provided to 10 randomly selected farms (Informed treatment), and the other 10 served as a Control. Logistic mixed models were used to test differences in cows' condition at the 4 points of assessment, using the assessment before leaving the farm as a reference value and cow-within-farm as a random effect. The effects of providing information on outcome measures (proportion thin, severely lame, with udder edema, poor fitness for transport, euthanized, and died) were tested with a general linear model. As demand for milk increased during the baseline period, additional linear mixed models were fitted to test whether the same outcome measures were affected by time (baseline or treatment period) and treatment (Informed or Control) using farm as a random effect. While cows were on the culling list (before shipping) the odds of being thin or having poor fitness for transport increased. After leaving the farms, cows spent (mean ± standard deviation) 82 ± 46 h in the marketing system before being slaughtered. Shipping from farm to abattoir increased the odds of being thin, having udder edema, or showing poor fitness for transport [odds ratio (OR) 5.8, 95% confidence interval 4.2 to 8.1; OR 14.7, 10.7 to 20.2; and OR 7.3, 5.7 to 9.5, respectively]. Providing this information to farmers (Informed treatment) did not affect the outcome measures. Compared with the baseline, during the treatment period fewer cows were shipped when thin (4.9 versus 9.0%) and with poor fitness for transport (15.7 versus 25.8%), and fewer cows died (5.4 versus 11.9%) or were euthanized (13.3 versus 20.5%). Increased demand for milk appeared to lead to delayed culling, such that more compromised cows were sent to slaughter. The results of this study show a need for clear and specific guidelines to assess fitness for transport of cull dairy cows., (Copyright © 2020 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)
- Published
- 2020
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47. Post-traumatic Headache After Pediatric Traumatic Brain Injury: Prevalence, Risk Factors, and Association With Neurocognitive Outcomes.
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McConnell B, Duffield T, Hall T, Piantino J, Seitz D, Soden D, and Williams C
- Subjects
- Adolescent, Child, Child, Preschool, Female, Humans, Male, Neuropsychological Tests, Post-Traumatic Headache etiology, Prevalence, Retrospective Studies, Risk Factors, Young Adult, Brain Injuries, Traumatic complications, Cognition physiology, Post-Traumatic Headache epidemiology
- Abstract
Post-traumatic headache is common after pediatric traumatic brain injury and affects thousands of children every year, but little is known about how headache affects recovery after traumatic brain injury in other symptom domains. We aimed to determine the association between headache and other common symptoms after pediatric traumatic brain injury and explore whether subjective complaints of headache are associated with objective deficits on specialized neurocognitive testing. We conducted a retrospective cohort study of children ages 3-19 years following traumatic brain injury with a completed Sports Concussion Assessment Tool (SCAT) questionnaire. Post-traumatic headache was defined by a score more than 2 on the SCAT question for headache and define headache groups for comparison. In our cohort, we analyzed data from the Delis-Kaplan Executive Function System and the Wechsler Abbreviated Scale of Intelligence, Second Edition (WASI-II). Headache was reported in 40 (33%) patients presenting for post-traumatic brain injury care among 121 pediatric traumatic brain injury patients and did not differ by injury severity. Median total SCAT symptom score in the headache group was 5-fold higher compared to patients without headache (median 45.5 vs 9; P < .001). Significantly lower-scaled scores in color naming, matrix reasoning, letter sequencing, and letter switching were also found in the headache group (all P ≤ .03). Our study shows that headache, as reported by patients on the SCAT, is associated with higher symptom scores in all other symptom domains, including sleep, mood, sensory, and cognitive. Headache was also associated with worse objective neurocognitive measures and may identify patients who could benefit from specialized follow-up care and management.
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- 2020
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48. A Comparison of Virtual Reality Classroom Continuous Performance Tests to Traditional Continuous Performance Tests in Delineating ADHD: a Meta-Analysis.
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Parsons TD, Duffield T, and Asbee J
- Subjects
- Attention Deficit Disorder with Hyperactivity psychology, Humans, Reaction Time, Attention Deficit Disorder with Hyperactivity diagnosis, Neuropsychological Tests, Virtual Reality
- Abstract
Computerized continuous performance tests (CPTs) are commonly used to characterize attention in attention deficit-hyperactivity disorder (ADHD). Virtual classroom CPTs, designed to enhance ecological validity, are increasingly being utilized. Lacking is a quantitative meta-analysis of clinical comparisons of attention performance in children with ADHD using virtual classroom CPTs. The objective of the present systematic PRISMA review was to address this empirical void and compare three-dimensional (3D) virtual classroom CPTs to traditional two-dimensional (2D) CPTs. The peer-reviewed literature on comparisons of virtual classroom performance between children with ADHD and typically developing children was explored in six databases (e.g., Medline). Published studies using a virtual classroom to compare attentional performance between children with ADHD and typically developing children were included. Given the high heterogeneity with modality comparisons (i.e., computerized CPTs vs. virtual classroom CPTs for ADHD), both main comparisons included only population comparisons (i.e., control vs. ADHD) using each CPT modality. Meta-analytic findings were generally consistent with previous meta-analyses of computerized CPTs regarding the commonly used omission, commission, and hit reaction time variables. Results suggest that the virtual classroom CPTs reliably differentiate attention performance in persons with ADHD. Ecological validity implications are discussed pertaining to subtle meta-analytic outcome differences compared to computerized 2D CPTs. Further, due to an inability to conduct moderator analyses, it remains unclear if modality differences are due to other factors. Suggestions for future research using the virtual classroom CPTs are provided.
- Published
- 2019
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49. National Institutes of Health initiatives for advancing scientific developments in clinical neuropsychology.
- Author
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Parsons TD and Duffield T
- Subjects
- Humans, Mental Disorders diagnosis, Mental Disorders epidemiology, Neuropsychology education, Smartphone trends, Therapy, Computer-Assisted methods, Therapy, Computer-Assisted trends, United States epidemiology, Mental Disorders psychology, National Institutes of Health (U.S.) trends, Neuropsychological Tests, Neuropsychology trends
- Abstract
Objective: The current review briefly addresses the history of neuropsychology as a context for discussion of developmental milestones that have advanced the profession, as well as areas where the progression has lagged. More recently in the digital/information age, utilization and incorporation of emerging technologies has been minimal, which has stagnated ongoing evolution of the practice of neuropsychology despite technology changing many aspects of daily living. These authors advocate for embracing National Institutes of Health (NIH) initiatives, or interchangeably referred to as transformative opportunities, for the behavioral and social sciences. These initiatives address the need for neuropsychologists to transition from fragmented and data-poor approaches to integrated and data-rich scientific approaches that ultimately improve translational applications. Specific to neuropsychology is the need for the adoption of novel means of brain-behavior characterizations., Method: Narrative review Conclusions: Clinical neuropsychology has reached a developmental plateau where it is ready to embrace the measurement science and technological advances which have been readily adopted by the human neurosciences. While there are ways in which neuropsychology is making inroads into these areas, a great deal of growth is needed to maintain relevance as a scientific discipline (see Figures 1, 2, and 3) consistent with NIH initiatives to advance scientific developments. Moreover, implications of such progress require discussion and modification of training, ethical, and legal mandates of the practice of neuropsychology.
- Published
- 2019
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50. Hot topic: Management of cull dairy cows-Consensus of an expert consultation in Canada.
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Stojkov J, Bowers G, Draper M, Duffield T, Duivenvoorden P, Groleau M, Haupstein D, Peters R, Pritchard J, Radom C, Sillett N, Skippon W, Trépanier H, and Fraser D
- Subjects
- Animals, Canada, Consensus, Dairying, Farmers, Farms, Female, Policy, Referral and Consultation, Animal Welfare, Cattle physiology, Transportation
- Abstract
Many cull dairy cows enter the marketing system and travel to widely dispersed and specialized slaughter plants, and they may experience multiple handling events (e.g., loading, unloading, mixing), change of ownership among dealers, and feed and water deprivation during transport and at livestock markets. The objectives of this study were to describe the diverse management of cull dairy cows in Canada and establish consensus on ways to achieve improvements. A 2-day expert consultation meeting was convened, involving farmers, veterinarians, regulators, and experts in animal transport, livestock auction, and slaughter. The 15 participants, recruited from across Canada, discussed regional management practices for cull cattle, related risk factors, animal welfare problems, and recommendations. An audio recording of the meeting was used to extract descriptive data on cull cattle management and identify points of agreement. Eight consensus points were reached: (1) to assemble information on travel times and delays from farm to slaughter; (2) to increase awareness among producers and herd veterinarians of potential travel distances and delays; (3) to promote pro-active culling; (4) to improve the ability of personnel to assess animal condition before loading; (5) to identify local options for slaughter of cull dairy cows; (6) to investigate different management options such as emergency slaughter and mobile slaughter; (7) to ensure that all farms and auctions have, or can access, personnel trained and equipped for euthanasia; and (8) to promote cooperation among enforcement agencies and wider adoption of beneficial regulatory options., (The Authors. Published by FASS Inc. and Elsevier Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).)
- Published
- 2018
- Full Text
- View/download PDF
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