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1.
Int J Drug Policy ; 132: 104558, 2024 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-39226770

RESUMEN

BACKGROUND: Our goal in this report was to quantify the degree to which opioid prescription rates and socioeconomic correlates of income inequality predicted overdose deaths in the 1055 U.S. Midwest counties. The study follows up a state-level analysis which reported that opioid prescription rates, social capital and unemployment explained much of the variance in opioid overdose death rates (Heyman, McVicar, & Brownell, 2019). METHODS: We created a data set that included drug overdose death rates, opioid prescription rates, and correlates of income inequality. Given that the variables of interest varied at the state and county level, multilevel regression was our statistical approach. RESULTS: From 2006 to 2021, Midwest overdose drug deaths increased according to an exponential equation that closely approximated the equation that describes the increases in overdose deaths for the entire U.S. from 1978 to 2016 (e.g., Jalal et al., 2018). Retail opioid prescription sales increased from 2006 to 2012, but then declined so that by 2017 they were lower than in 2006. The regression analyses revealed that intergenerational income mobility was the strongest predictor of overdose deaths. The other consistently statistically significant predictors were opioid prescription rates, social capital, and unemployment rates. Together these predictors, plus pupil teacher ratios, single parent families, and attending college accounted for approximately 47 % of the variance in overdose death rates each year. In keeping with the decline in opioid prescription rates, the explanatory power of opioid prescription rates weakened over the course of the study. CONCLUSIONS: Overdose deaths increased at a constant exponential rate for the years that it was possible to apply our regression model. This occurred even though access to legal opioids decreased. What remained invariant was the predictive strength of intergenerational income mobility; each year it was the predictor that explained the most variance in overdose deaths.


Asunto(s)
Analgésicos Opioides , Sobredosis de Droga , Renta , Factores Socioeconómicos , Humanos , Sobredosis de Droga/mortalidad , Sobredosis de Droga/epidemiología , Analgésicos Opioides/envenenamiento , Renta/estadística & datos numéricos , Medio Oeste de Estados Unidos/epidemiología , Masculino , Femenino , Adulto , Desempleo/estadística & datos numéricos , Prescripciones de Medicamentos/estadística & datos numéricos
2.
Appl Ergon ; 121: 104363, 2024 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-39096745

RESUMEN

Prior research has demonstrated experience with a forecasting algorithm decreases reliance behaviors (i.e., the action of relying on the algorithm). However, the influence of model experience on reliance intentions (i.e., an intention or willingness to rely on the algorithm) has not been explored. Additionally, other factors such as self-confidence and domain knowledge are posited to influence algorithm reliance. The objective of this research was to examine how experience with a statistical model, task domain (used car sales, college grade point average (GPA), GitHub pull requests), and self-confidence influence reliance intentions, reliance behaviors, and perceived accuracy of one's own estimates and the model's estimates. Participants (N = 347) were recruited online and completed a forecasting task. Results indicate that there was a statistically significant effect of self-confidence and task domain on reliance intentions, reliance behaviors, and perceived accuracy. However, unlike previous findings, model experience did not significantly influence reliance behavior, nor did it lead to significant changes in reliance intentions or perceived accuracy of oneself or the model. Our data suggest that factors such as task domain and self-confidence influence algorithm use more so than model experience. Individual differences and situational factors should be considered important aspects that influence forecasters' decisions to rely on predictions from a model or to instead use their own estimates, which can lead to sub-optimal performance.


Asunto(s)
Algoritmos , Intención , Autoimagen , Humanos , Masculino , Femenino , Adulto , Adulto Joven , Análisis y Desempeño de Tareas , Predicción , Persona de Mediana Edad , Adolescente , Modelos Estadísticos
3.
Mil Psychol ; : 1-14, 2024 Jul 08.
Artículo en Inglés | MEDLINE | ID: mdl-38975902

RESUMEN

The purpose of the current paper is to explore the influence of the perceived trustworthiness factors of ability, benevolence and integrity on general and specific trust across supervisors, subordinates and peers with the same focal referent. This study used a 360-degree approach to examine how positional power asymmetries influence the relationship between trustworthiness and trust for a general and situation-specific referent. Data were obtained from military supervisors (N = 200), peers (N = 123), and subordinates (N = 85). Measures of trustworthiness and trust of a common military officer were obtained. Supervisors and subordinates differed in their relative weighting of trustworthiness factors (i.e. ability, benevolence, and integrity) when evaluating general and specific trust. Peers evidenced no difference in the relative weighting of trustworthiness factors. The relationship between benevolence and specific trust was stronger for subordinates than for supervisors. One implication of our findings is that trust can develop differently in bottom-up versus top-down organizational relationships. This study provides evidence that supervisors and subordinates emphasize different aspects of trustworthiness when evaluating their trust of a focal officer, and this process was different for general versus specific trust referents. The study also extends previous research by replicating previous findings across raters.

4.
Avian Dis ; 67(4): 310-316, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-38300652

RESUMEN

A retrospective analysis encompassing 18 yr (1999-2016) of broiler chicken health surveys from broiler production complexes throughout the United States was conducted to identify trends and areas of opportunity. The analysis used necropsy data from 19,577 broiler chickens considered to be "healthy" or "clinically normal" by visual assessment. The very low incidence of dehydrated (0.01%) or undersized (0.02%) broilers is evidence that the objective of examining "healthy" birds was achieved. The results of the correlation analysis were what was expected for "healthy" broilers, with these birds having positive correlations with skin color and size of the bursa of Fabricius. The average age of broilers included in this analysis ranged from 26.2 days in 2008 to 33.7 days in 2013. The percentage of "normal" broilers (those without visible lesions or abnormalities) varied from 5.63% in 2012 to 28.33% in 1999. The results of this study identified four areas of opportunity for improving poultry health: 1) coccidiosis, 2) oral lesions and gizzard erosions, 3) retained yolks, and 4) pododermatitis.


Encuesta retrospectiva sobre la salud de los pollos de engorde: alcance, parámetros y tendencias generales. Se realizó un análisis retrospectivo que abarcó 18 años (1999-2016) de encuestas de salud de pollo de engorde de complejos de producción en los Estados Unidos para identificar tendencias y áreas de oportunidad. El análisis utilizó datos de necropsia de 19,577 pollos de engorde considerados "saludables" o "clínicamente normales" mediante evaluación visual. La incidencia muy baja de pollos de engorde deshidratados (0.01%) o de tamaño pequeño (0.02%) es evidencia de que se logró el objetivo de examinar aves "sanas". Los resultados del análisis de correlación fueron los esperados para pollos de engorde "sanos", ya que estas aves tuvieron correlaciones positivas con el color de la piel y el tamaño de la bolsa de Fabricio. La edad promedio de los pollos de engorde incluidos en este análisis osciló entre 26.2 días en 2008 y 33.7 días en 2013. El porcentaje de pollos de engorde "normales" (aquellos sin lesiones o anomalías visibles) varió del 5.63% en 2012 al 28.33% en 1999. Los resultados de este estudio identificaron cuatro áreas de oportunidad para mejorar la salud de las aves: 1) coccidiosis, 2) lesiones orales y erosiones de la molleja, 3) retención de saco vitelino y 4) pododermatitis.


Asunto(s)
Coccidiosis , Enfermedades de las Aves de Corral , Animales , Pollos , Estudios Retrospectivos , Enfermedades de las Aves de Corral/epidemiología , Autopsia/veterinaria , Coccidiosis/veterinaria
5.
Anim Nutr ; 15: 71-87, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-37799133

RESUMEN

Current methods for feed formulation are based on minimizing costs, not maximizing profits. Complex models of bird growth and reproduction as functions of genetic, feed and other environmental variables are being developed, but their adaptation has been slow. The development of profit maximizing models will evolve to center on the production functions of broilers and layers. The production functions are the relationship between the value of products (mainly meat and eggs) and the cost of feed. The production function is the tool used to maximize profits subject to all the various inputs, not just feed or nutrition. The production function is subject to the law of diminishing returns. The most profitable output levels are those where the marginal value (price) of the meat or eggs is just equal to the marginal cost of the inputs including feed, housing, processing and all other costs. Anything that affects the production function, bird genetics, feed quality, housing and environment, will be considered to maximize profits for the poultry firm. The profit maximizing models of poultry firms will improve as various technical improvements are made: metabolizable energy to describe ingredients will evolve to net energy systems that consider that the heat production (and therefore energetic efficiency) of broilers is different depending on the ingredients used to formulate the feed and the environmental temperatures under which they are reared. Amino acid needs will include a method to find the birds' needs for the non-essential amino acids. "Digestible" amino acid assays will differentiate between digestion and absorption to best balance various sources. The carbohydrate fractions of feed ingredients will be determined to optimize the use of exogenous enzymes. The value of meat and egg co-products will reduce overall costs (e.g., organic fertilizer for crop enhancement). Future profit maximizing production models will be ever evolving processes where field conditions and results are continually being utilized to re-calibrate the technical models so that the management team can use them with cost and return projections to decide on the best choices of inputs and outputs.

6.
Psychol Sport Exerc ; 67: 102432, 2023 07.
Artículo en Inglés | MEDLINE | ID: mdl-37665885

RESUMEN

Scholars have argued that mental toughness is a term that represents hypermasculine ideals. This hypermasculinity ideal could be considered relevant in the sport of Australian rules football, which has been played, at the professional level, by male athletes for the majority of its existence. Given the rising popularity of the Australian Football League Women's (AFLW), the present research sought to explore how the term mental toughness was understood at an AFLW club through a cultural sport psychology lens. Interviews were conducted with players (n = 4) and coaches (n = 6) from an AFLW club over the course of a competitive season. Data were transcribed verbatim and thematically analysed, with themes constructed to correspond with different levels of contextual influence. From this analysis, the club values and underlying assumptions, the social truths, and the role models/archetypes that provided a collective understanding of the term were identified. Mental toughness was defined by high-performance values of the men's game, which had implications for female athletes in this environment who are not afforded the same opportunities to fully embody these values. Mental toughness is positioned, in this environment, as an ideal with different meanings for female athletes due to structural factors associated with elite-level competition (e.g., full-time versus part-time professionalism).


Asunto(s)
Atletas , Hombres , Humanos , Femenino , Masculino , Australia , Deportes de Equipo
7.
Psychol Sport Exerc ; 69: 102510, 2023 11.
Artículo en Inglés | MEDLINE | ID: mdl-37665944

RESUMEN

OBJECTIVE: This study aimed to develop, and pilot esports-adapted coping effectiveness training (E-CET) and measure its influence on coping effectiveness (global and specific), subjective performance, mental health (psychological distress and wellbeing), and resilience. DESIGN: Five elite male League of Legends players competing in the League of Legends Circuit Oceania participated in a mixed methods research design. The effects of E-CET were measured using a within-subjects quasi-experimental design (i.e., pre-to-post, no control group). To measure the effects of E-CET on specific stressors, a longitudinal diary design was used. METHOD: Players participated in a 2-h session of E-CET and a 45-min follow-up workshop. The 2-h workshop delivered content on two conceptual areas: (1) developing awareness of the stress and coping process; and (2) how to cope with stress. Players completed pre-intervention, post-intervention, and follow-up measures and twice-weekly stress journals. RESULTS: E-CET led to increases in players' perceived coping effectiveness and subjective performance, but there were no changes in psychological distress, psychological wellbeing, and resilience. However, the results indicate some positive signs for future coping interventions with League of Legends players and iterations of E-CET. CONCLUSION: The E-CET program appears to provide an opportunity to improve performance and mental health for esports players.


Asunto(s)
Adaptación Psicológica , Salud Mental , Masculino , Humanos , Proyectos Piloto , Grupos Control , Ácido Hialurónico
8.
Hum Factors ; : 187208231189000, 2023 Jul 17.
Artículo en Inglés | MEDLINE | ID: mdl-37458319

RESUMEN

OBJECTIVE: We created and validated a scale to measure perceptions of system trustworthiness. BACKGROUND: Several scales exist in the literature that attempt to assess trustworthiness of system referents. However, existing measures suffer from limitations in their development and validation. The current study sought to develop a scale based on theory and methodological rigor. METHOD: We conducted exploratory and confirmatory factor analyses on data from two online studies to develop the System Trustworthiness Scale (STS). Additional analyses explored the manipulation of the factors and assessed convergent and divergent validity. RESULTS: The exploratory factor analyses resulted in a three-factor solution that represented the theoretical constructs of trustworthiness: performance, purpose, and process. Confirmatory factor analyses confirmed the three-factor solution. In addition, correlation and regression analyses demonstrated the scale's divergent and predictive validity. CONCLUSION: The STS is a psychometrically valid and predictive scale for assessing trustworthiness perceptions of system referents. APPLICATIONS: The STS assesses trustworthiness perceptions of systems. Importantly, the scale differentiates performance, purpose, and process constructs and is adaptable to a variety of system referents.

9.
J Med Chem ; 66(11): 7534-7552, 2023 06 08.
Artículo en Inglés | MEDLINE | ID: mdl-37235865

RESUMEN

Glycogen synthase kinase-3 (GSK-3) is a serine/threonine kinase that serves as an important regulator of a broad range of cellular functions. It has been linked to Alzheimer's disease as well as various other diseases, including mood disorders, type 2 diabetes, and cancer. There is considerable evidence indicating that GSK-3ß in the central nervous system plays a role in the production of abnormal, hyperphosphorylated, microtubule-associated tau protein found in neurofibrillary tangles associated with Alzheimer's disease. A series of analogues containing a pyrimidine-based hinge-binding heterocycle was synthesized and evaluated, leading to the identification of highly potent GSK-3 inhibitors with excellent kinase selectivity. Further evaluation of 34 and 40 in vivo demonstrated that these compounds are orally bioavailable, brain-penetrant GSK-3 inhibitors that lowered levels of phosphorylated tau in a triple-transgenic mouse Alzheimer's disease model.


Asunto(s)
Enfermedad de Alzheimer , Diabetes Mellitus Tipo 2 , Ratones , Animales , Enfermedad de Alzheimer/tratamiento farmacológico , Enfermedad de Alzheimer/metabolismo , Proteínas tau/metabolismo , Glucógeno Sintasa Quinasa 3/metabolismo , Glucógeno Sintasa Quinasa 3 beta/metabolismo , Ratones Transgénicos , Pirimidinas/farmacología , Pirimidinas/uso terapéutico , Fosforilación
10.
Anim Nutr ; 13: 19-30, 2023 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-36968095

RESUMEN

It has been demonstrated that the fiber content of oilseed meals and total amino acids (AA) in distillers' grains products affects standardized ileal digestibility (SID) values from swine assays and that total protein concentration affects the AA digestibility in assays using chickens. This analysis was conducted to test the hypothesis that the total AA content of test samples affects the SID assay results. Databases containing total AA profiles and SID values of 20 feedstuffs commonly fed to pigs from 2 sources, AMINODat 5.0 (Evonik Industries, 2015) and the Nutrient Requirements of Swine, 12th edition (NRC, 2012) were used to compare AA concentration effects on standardized ileal digestibility coefficients. Databases were compared with AA and SID available in both data sets. The total AA values were similar for the 2 databases with an R 2 of 0.979 (P < 0.001). The linear relationship between digestibility coefficients from the 2 databases was highly significant, an R 2 of 0.810 (P < 0.001). Both databases had increased SID values with increasing AA contents within and across feed ingredients. The SID = f(AA concentration) relationship was confirmed with an individual paper. Since SID, as typically measured, is a function of both digestion and absorption, both processes following Michaelis-Menten kinetics, SID = f(AA concentration) may simply be a natural phenomenon. Other reasons for the relationship were explored. Methods of estimating endogenous AA losses and misapplication statistical procedures may contribute to variation in results and at least partially explain why SID = f(AA concentration).

11.
Front Psychol ; 14: 1003756, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36949921

RESUMEN

Item response tree (IRTree) models are theorized to extract response styles from self-report data by utilizing multidimensional item response theory (IRT) models based on theoretical decision processes. Despite the growing popularity of the IRTree framework, there has been little research that has systematically examined the ability of its most popular models to recover item parameters across sample size and test length. This Monte Carlo simulation study explored the ability of IRTree models to recover item parameters based on data created from the midpoint primary process model. Results indicate the IRTree model can adequately recover item parameters early in the decision process model, specifically the midpoint node. However, as the model progresses through the decision hierarchy, item parameters have increased associated error variance. The authors ultimately recommend caution when employing the IRTree framework.

12.
J Med Chem ; 66(6): 4231-4252, 2023 03 23.
Artículo en Inglés | MEDLINE | ID: mdl-36950863

RESUMEN

Glycogen synthase kinase-3 (GSK-3) is a serine/threonine kinase that regulates numerous cellular processes, including metabolism, proliferation, and cell survival. Due to its multifaceted role, GSK-3 has been implicated in a variety of diseases, including Alzheimer's disease, type 2 diabetes, cancer, and mood disorders. GSK-3ß has been linked to the formation of the neurofibrillary tangles associated with Alzheimer's disease that arise from the hyperphosphorylation of tau protein. The design and synthesis of a series of imidazo[1,2-b]pyridazine derivatives that were evaluated as GSK-3ß inhibitors are described herein. Structure-activity relationship studies led to the identification of potent GSK-3ß inhibitors. In vivo studies with 47 in a triple-transgenic mouse Alzheimer's disease model showed that this compound is a brain-penetrant, orally bioavailable GSK-3ß inhibitor that significantly lowered levels of phosphorylated tau.


Asunto(s)
Enfermedad de Alzheimer , Diabetes Mellitus Tipo 2 , Ratones , Animales , Enfermedad de Alzheimer/metabolismo , Glucógeno Sintasa Quinasa 3 beta/metabolismo , Glucógeno Sintasa Quinasa 3/metabolismo , Proteínas tau/metabolismo , Ratones Transgénicos , Encéfalo/metabolismo , Relación Estructura-Actividad , Fosforilación
13.
Bioorg Med Chem Lett ; 81: 129143, 2023 02 01.
Artículo en Inglés | MEDLINE | ID: mdl-36669575

RESUMEN

In our continuing efforts to explore structure-activity relationships around the novel class of potent, isonicotinamide-based GSK3 inhibitors described in our previous report, we extensively explored structural variations around both 4/5-pyridine substitutions and the amide group. Some analogs were found to have greatly improved pTau lowering potency while retaining high kinase selectivity. In contrast to previous active compounds 1a-c, a close analog 3h did not show in vivo efficacy in a triple-transgenic mouse Alzheimer's disease model. In general, these 2­pyridinyl amide derivatives were prone to amidase mediated hydrolysis in mouse plasma.


Asunto(s)
Enfermedad de Alzheimer , Glucógeno Sintasa Quinasa 3 , Ratones , Animales , Relación Estructura-Actividad , Ratones Transgénicos , Amidas/farmacología , Glucógeno Sintasa Quinasa 3 beta , Inhibidores de Proteínas Quinasas/farmacología , Inhibidores de Proteínas Quinasas/química
14.
J Exp Anal Behav ; 119(1): 91-103, 2023 01.
Artículo en Inglés | MEDLINE | ID: mdl-36518022

RESUMEN

Howard Rachlin's widely influential behavioral economic approach to self-control and related issues provides the model for this submission. The topic is overconsumption. Current human consumption levels are unsustainable. Explanations typically focus on societal factors, such as the seductive power of advertising and/or misguided tax policies. However, the effectiveness of these factors depends on the degree to which individuals are susceptible to the message: "consume more." Humans are not blank slates. This paper argues that how individuals frame their choices establishes the susceptibility to overconsume. According to economic theory, consumers frame their options as bundles, composed of different combinations of the available items and activities. This leads to maximizing. In experiments, participants tend to frame their options as "either-or" choices. This leads to the matching law. Mathematical models of concurrent schedule choice procedures show that (1) the matching law implies overconsumption of the most preferred option and (2) that individuals will persist in preferring their favorite option even when doing so reduces overall reward rates. Given that the matching law better describes how individuals choose than does maximizing, the mathematical models of widely used choice procedures help explain why efforts to increase consumption have been more influential than efforts to control consumption.


Asunto(s)
Conducta de Elección , Recompensa , Humanos
15.
Appl Ergon ; 106: 103858, 2023 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-35994948

RESUMEN

The research on human-robot interactions indicates possible differences toward robot trust that do not exist in human-human interactions. Research on these differences has traditionally focused on performance degradations. The current study sought to explore differences in human-robot and human-human trust interactions with performance, consideration, and morality trustworthiness manipulations, which are based on ability/performance, benevolence/purpose, and integrity/process manipulations, respectively, from previous research. We used a mixed factorial hierarchical linear model design to explore the effects of trustworthiness manipulations on trustworthiness perceptions, trust intentions, and trust behaviors in a trust game. We found partner (human versus robot) differences across all three trustworthiness perceptions, indicating biases towards robots may be more expansive than previously thought. Additionally, there were marginal effects of partner differences on trust intentions. Interestingly, there were no differences between partners on trust behaviors. Results indicate human biases toward robots may be more complex than considered in the literature.


Asunto(s)
Robótica , Humanos , Confianza , Sesgo , Beneficencia
16.
Hum Factors ; : 187208221145261, 2022 Dec 13.
Artículo en Inglés | MEDLINE | ID: mdl-36511147

RESUMEN

OBJECTIVE: The effects of asset degradation on trust in human-swarm interaction were investigated through the lens of system-wide trust theory. BACKGROUND: Researchers have begun investigating contextual features that shape human interactions with robotic swarms-systems comprising assets that coordinate behavior based on their nearest neighbors. Recent work has begun investigating how human trust toward swarms is affected by asset degradation through the lens of system-wide trust theory, but these studies have been marked by several limitations. METHOD: In an online study, the current work manipulated asset degradation and measured trust-relevant criteria in a within-subjects design and addressed the limitations of past work. RESULTS: Controlling for swarm performance (i.e., target acquisition), asset degradation and trust (i.e., reliance intentions) in swarms were negatively related. In addition, as degradation increased, perceptions of swarm cohesion, obstacle avoidance, target acquisition, and terrain exploration efficiency decreased, the latter two of which (coupled with the reliance intentions criterion) support the tenets of system-wide trust theory as well as replicate and extend past work on the effects of asset degradation on trust in swarms. CONCLUSION: Human-swarm interaction is a context in which system-wide trust is relevant, and future work ought to investigate how to calibrate human trust toward swarm systems. APPLICATIONS: Based on these findings, design professionals should prioritize ways to depict swarm performance and system health such that humans do not abandon trust in systems that are still functional yet not over-trust those systems which are indeed performing poorly.

17.
J Dance Med Sci ; 26(4): 232-243, 2022 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-36096652

RESUMEN

This study aimed to investigate the perceptions of training load practices of dance artistic and health professionals. Artistic staff and health professionals with experience in dance were invited to participate in a cross-sectional survey study relating to training load practices in pre-professional and professional, ballet and contemporary dance. The survey was developed from previous investigations in soccer and consisted of multiple-choice, Likert scale, and free-text responses. Responses to closed questions were reported by percentage and 95% confidence intervals (95% CI). Thematic analysis was performed by two independent assessors of free-text responses. There were six artistic staff and 18 health professional participants. Artistic staff were perceived to be "mostly/completely responsible" for planning training (artistic staff: 100%, 95% CI: 61%, 100%; health professionals: 94%, 95% CI: 76%, 100%), with health professionals "mostly/completely responsible" at times of injury (artistic staff: 83%, 95% CI: 41%, 99%; health professionals: 95% CI: 61%, 96%). Both groups reported using individual modification to manage training loads and recognized the benefits of rest. Artistic staff recognized the need to modify training when injured, in line with experience levels, workload, age, and general health. Both groups "agree/strongly agree" that monitoring would be or is useful (artistic staff: 83%, 95% CI: 41%, 99%; health professionals: 95% CI: 61%, 96%). This investigation provides insight into the perceptions of artistic staff and health professionals with experience in dance toward training practices. Artistic staff and health professionals need to work together and adapt monitoring practices to their context to support artistic staff in planning training. The findings guide the implementation of these interventions by understanding potential barriers to their effectiveness that may potentially reduce injury.


Asunto(s)
Baile , Humanos , Estudios Transversales , Encuestas y Cuestionarios
18.
Anim Nutr ; 10: 294-304, 2022 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-35785247

RESUMEN

In this paper, we discuss the theory behind calibration curve experiments and their application to a zinc (Zn) bioavailability study with broiler chickens. Seven replicates of 16 male commercial broiler chicks were fed starter diets for 14 days. Six diets had different levels of a potential Zn source and one was a positive control with standard industry levels of Zn for comparison. Four commonly used methods of calculating bioavailability means and confidence intervals (CI) from a calibration curve (standard curve) experiment to estimate the bioavailability of a new zinc source in broiler chickens were compared. The methods compared were the following: 1) the Counter-Intuitive Method uses a multiple-range test to compare unknown test and standard samples; 2) the Intuitive Method uses standard linear regression and inverts the equation to predict Zn bioavailability for each replicate of test samples; 3) the Abductive Method uses Graybill's Equation, based on theory and observation, to estimate CI's; and 4) the Sophistic Method uses reverse regression, and calculates Zn bioavailability values directly from the equation. The Counter-Intuitive Method only gives information about which standards the test samples are, or are not, significantly different from respectively (average available Zn not predicted). The Intuitive Method ignores error about the standard curve and theoretically cannot estimate the CI directly ( X ¯ ± SEM  = 107.5 ± 15.8 mg Zn/kg). The Sophistic Method underestimates and overestimates the test sample mean values above and below the mean of the standards, respectively ( X ¯  = 96.6 mg Zn/kg). The Abductive Method has an advantage over the other methods: The mean prediction estimation is consistent with theory (107.5 ± 6.1 mg Zn/kg; X ¯ ± SEM ). When test or "unknown" samples are near the mean of the standard samples, the CI is smaller than when near the extremes of the calibration curve. When calibration curve error is small (R 2 > approximately 0.95), there is little advantage to using the Abductive Method, but when calibration curve error is larger, as in many bioassays with growing animals, the Abductive Method improves the accuracy of the CI calculations. The Abductive Method was used to demonstrate the influence of the number of replicate samples on experimental power and cost.

20.
Poult Sci ; 101(9): 102004, 2022 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-35882093

RESUMEN

As the cost of research increases, mathematical models become valuable tools to answer research questions. A major application of mathematical modeling is accurate estimation of production performance, growth, and feed consumption for poultry research and production. There are many ways that a given data set can be analyzed, and different models have been proposed to fit those curves. To explore the models available, data were investigated from a study on the effects of a series of balanced dietary protein levels on egg production and egg quality parameters in lying hens from 18 to 74 wk of age. Forty eight pullets were assigned to each of 3 different protein levels. The results clearly demonstrated that balanced dietary protein level was the limiting factor for body weight (BW), average daily feed intake (ADFI), egg weight, and egg production. To test differences of fitted curves, the sum of squared reduction test is used. Using a unique data set with data from individual hens, 6 commonly used models were fitted to hen performance technical data. The resulting statistical inferences from using individual and pooled data were compared. There are only differences in using individual or grouped data in fitting nonlinear models to laying hen response data. For the most important response variables, hen-day egg production, and feed intake, predicted responses are within 0.12 and 0.65%, respectively, throughout the production cycle.


Asunto(s)
Fenómenos Fisiológicos Nutricionales de los Animales , Pollos , Alimentación Animal/análisis , Animales , Pollos/fisiología , Dieta/veterinaria , Proteínas en la Dieta , Femenino , Dinámicas no Lineales
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