Videofluoroscopy of the aerodigestive tract in Phoca vitulina: reshaping perspectives on translational medicine.

Thousands of rescued harbor seals (Phoca vitulina) require rehabilitation worldwide. Many require resource intensive gavage feeding due to abandonment soon after birth. Little is known about seal swallowing, therefore, our primary objective was to determine the feasibility of conducting videofluoroscopic swallowing studies (VFS) on seal pups prior to their release. Secondarily, we propose swallowing phase descriptions. We adapted a VFS approach used in humans and our feasibility parameters included: bolus detection and consumption, and number of analyzable swallowing events. Unrestrained seals were imaged in a dry environment using a Siemens mobile c-arm fluoroscopy unit. Oral boluses were thawed herring injected with liquid barium suspension (105% w/v). Two independent raters described swallows using a standardized approach with results summarized descriptively. We successfully completed freely-behaving VFS with two infant seals (1 male: 8 wks, 3 d; 1 female: 5 wks, 3 d). Both consumed five boluses with six fully analyzable swallowing events. We describe four swallow phases: preparatory, prehension, oropharyngeal and esophageal. Airway protection likely occurs in two ways: (1) during the preparatory phase through modified corniculate cartilage contact with the glottis and (2) with soft palate contact to the base of tongue prior to swallow initiation. We have conducted a unique VFS approach on rehabilitated seals, prior to their release. We have described airway protection and suggest that swallowing is initiated earlier in the feeding process than described previously. This protocol success will afford: (1) collection of normative swallowing data, and (2) future knowledge translation from humans to seals.

Labor trafficking of migrant registered nurses.

BACKGROUND: Labor trafficking of registered nurses (RNs) in the USA impedes justice by denying inalienable human rights and equal economic opportunities. Nursing shortages in developed countries, poverty, social upheaval, and government actions influence migration, as do other factors related to determinants of health. Migrant RNs are visa workers, displaced, refugees, immigrants, or asylum seekers. Labor traffickers target vulnerable migrant RNs seeking employment outside their home country. Unlike ethical recruiters, traffickers lure migrant RNs into indentured contracts in work environments that result in health-threatening conditions, long shifts, and exorbitant fines that threaten families with financial retribution. PURPOSE: The purpose of the paper is to raise awareness. METHODS: Authors explain the background of influences and nuances in migrant RN labor trafficking. DISCUSSION: Identifying labor traffickers' deceitful, coercive, fraudulent, and illegal methods, assist organizational approaches for establishing Total Worker Health, trauma-informed care, coordinated community response, and No Door Closed actions when wanting to mitigate or eradicate labor trafficking of migrant RNs.

Postvasectomy Semen Analysis Compliance With Utilization of a Mail-In Semen Analysis Kit.

PURPOSE: The AUA recommends postvasectomy semen analysis (PVSA) to verify successful vasectomy. However there remains poor patient compliance. We sought to assess whether mail-in PVSA improves patient compliance across a wide range of practice types. MATERIALS AND METHODS: Prospective data were collected on all men who received a Fellow PVSA kit between April 2021 and August 2023 in a nationwide cohort. Date of kit activation, practice type, clinic zip code, and date of kit accession/processing at the lab was collected. Compliance rates for each practice area were reported. χ2 tests of independence, logistic regression models, and multivariable logistic analysis were performed to assess the impact of relevant variables. RESULTS: Overall compliance across all practice areas was 69% following an 18-week period of observation (n = 16,105) and 82% (n = 6687) following a 40-week period. Compliance rates were highest and similar for small urology practices (<5 providers), including Veterans Affairs practices, ranging from 76% to 82% at 18 weeks to 85% to 87% at 40 weeks. Large urology practices had slightly lower compliance rates with 66% at 18 weeks to 80% at 40 weeks. The univariable logistic regression model demonstrated that patients in small urology practices have a 63% greater odds of 26-week compliance, on average, compared to those who receive care in large urology practices (odds ratio 1.63, 95% CI 1.48-1.79). CONCLUSIONS: Fellow's mail-in PVSA offers improved PVSA compliance over previously published data. Improved compliance is seen across all practice types. Despite these successes, there is significant room for improvement to achieve 100% compliance.

Association between racial residential segregation and screening uptake for colorectal and cervical cancer among Black and White patients in five US health care systems.

BACKGROUND: Despite increased recognition that structural racism contributes to poorer health outcomes for racial and ethnic minorities, there are knowledge gaps about how current patterns of racial residential segregation are associated with cancer screening uptake. The authors examined associations between Black residential segregation and screening for colorectal cancer (CRC) and cervical cancer among non-Hispanic Black and non-Hispanic White adults. METHODS: This was a retrospective study of CRC and cervical cancer screening-eligible adults from five health care systems within the Population-Based Research to Optimize the Screening Process (PROSPR II) Consortium (cohort entry, 2010-2012). Residential segregation was measured using site-specific quartiles of the Black local isolation score (LIS). The outcome was receipt of CRC or cervical cancer screening within 3 years of cohort entry (2010-2015). Logistic regression was used to calculate associations between the LIS and screening completion, adjusting for patient-level covariates. RESULTS: Among CRC (n = 642,661) and cervical cancer (n = 163,340) screening-eligible patients, 456,526 (71.0%) and 106,124 (65.0%), respectively, received screening. Across PROSPR sites, living in neighborhoods with higher LIS tended to be associated with lower odds of CRC screening (Kaiser Permanente Northern California: adjusted odds ratio [aOR] LIS trend in Black patients, 0.95 [p < .001]; aOR LIS trend in White patients, 0.98 [p < .001]; Kaiser Permanente Southern California: aOR LIS trend in Black patients, 0.98 [p = .026]; aOR LIS trend in White patients, 1.01 [p = .023]; Kaiser Permanente Washington: aOR LIS trend in White patients, 0.97 [p = .002]. However, for cervical cancer screening, associations with the LIS varied by site and race (Kaiser Permanente Washington: aOR LIS trend in White patients, 0.95 [p < .001]; Mass General Brigham: aOR LIS trend in Black patients, 1.12 [p < .001]; aOR LIS trend in White patients, 1.03 [p < .001]). CONCLUSIONS: Across five diverse health care systems, the direction of the association between Black residential segregation and screening varied by PROSPR site, race, and screening type. Additional research, including studies that examine multiple dimensions of segregation and structural racism using intersectional approaches, are needed to further disentangle these relationships.

Differences and similarities in patient-reported outcomes among men and women with haemophilia.

INTRODUCTION: Both men and women can be diagnosed with haemophilia and the experience with haemophilia may be different between men and women. AIM: This study aimed to compare patient-reported outcomes in men versus women with haemophilia. METHODS: This cross-sectional study is a post-hoc analysis of data collected as part of the Haemophilia-related Distress Questionnaire validation study. Adults aged ≥18 years with haemophilia A or B were recruited from one of two haemophilia treatment centres between July 2017 and December 2019. Outcomes included quality of life, measures of mental and physical health, and overall health. Unadjusted and multivariable linear regression models were used to examine potential mediators of sex-based differences in outcomes. RESULTS: Of the 139 study participants included (21 women, 118 men), the mean age was 36.9 years and most (89.2%) had haemophilia A. Approximately 85.7% and 26.3% of women and men had mild haemophilia, respectively.  PHQ-9 depression and PROMIS-29 Profile anxiety and fatigue scores were significantly higher in women than men in unadjusted and adjusted analyses. There were no statistically significant differences in other outcomes. CONCLUSIONS: Women with haemophilia are more likely to experience depression, anxiety, and fatigue than men with haemophilia. This study highlights the need for mental health services to be integrated into the care of women with haemophilia. Future research is needed to understand whether women with haemophilia are more or less likely to experience depression, anxiety, and fatigue than women without haemophilia as well as determine the impact of reduced mental health on clinical outcomes.

Stem cell therapeutics and gene therapy for neurologic disorders.

Rapid advances in biological knowledge and technological innovation have greatly advanced the fields of stem cell and gene therapies to combat a broad spectrum of neurologic disorders. Researchers are currently exploring a variety of stem cell types (e.g., embryonic, progenitor, induced pluripotent) and various transplantation strategies, each with its own advantages and drawbacks. Similarly, various gene modification techniques (zinc finger, TALENs, CRISPR-Cas9) are employed with various delivery vectors to modify underlying genetic contributors to neurologic disorders. While these two individual fields continue to blaze new trails, it is the combination of these technologies which enables genetically engineered stem cells and vastly increases investigational and therapeutic opportunities. The capability to culture and expand stem cells outside the body, along with their potential to correct genetic abnormalities in patient-derived cells or enhance cells with extra gene products, unleashes the full biological potential for innovative, multifaceted approaches to treat complex neurological disorders. In this review, we provide an overview of stem cell and gene therapies in the context of neurologic disorders, highlighting recent advances and current shortcomings, and discuss prospects for future therapies in clinical settings.

NCCN Guidelines® Insights: Rectal Cancer, Version 3.2024.

The determination of an optimal treatment plan for an individual patient with rectal cancer is a complex process. In addition to decisions relating to the intent of rectal cancer surgery (ie, curative or palliative), consideration must also be given to the likely functional results of treatment, including the probability of maintaining or restoring normal bowel function/anal continence and preserving genitourinary functions. Particularly for patients with distal rectal cancer, finding a balance between curative-intent therapy while having minimal impact on quality of life can be challenging. Furthermore, the risk of pelvic recurrence is higher in patients with rectal cancer compared with those with colon cancer, and locally recurrent rectal cancer is associated with a poor prognosis. Careful patient selection and the use of sequenced multimodality therapy following a multidisciplinary approach is recommended. These NCCN Guidelines Insights detail recent updates to the NCCN Guidelines for Rectal Cancer, including the addition of endoscopic submucosal dissection as an option for early-stage rectal cancer, updates to the total neoadjuvant therapy approach based on the results of recent clinical trials, and the addition of a "watch-and-wait" nonoperative management approach for clinical complete responders to neoadjuvant therapy.

Milkweed in agricultural field margins - A neonicotinoid exposure route for pollinators at multiple life stages.

Neonicotinoid insecticides move from targeted crops to wildflowers located in adjacent field margins, acting as a potential exposure source for wild pollinators and insect species of conservation concern, including monarch butterflies. Monarchs rely on milkweed over multiple life stages, including as a host plant for eggs and a food source for both larvae (leaves) and adults (flowers). Milkweeds, which are closely associated with field margins, can contain neonicotinoid residues, but previous assessments are constrained to a single plant tissue type. In 2017 and 2018, we sampled milkweeds from 95 field margins adjacent to crop fields (corn, soybean, hay, wheat, and barley) in agricultural landscapes of eastern Ontario, Canada. Milkweeds were sampled during the flower blooming period and leaves and flower tissues were analysed. The neonicotinoids acetamiprid, clothianidin, thiamethoxam, and thiacloprid were detected. Maximum concentrations in leaf samples included 10.30 ng/g of clothianidin in 2017, and 24.4 ng/g of thiamethoxam in 2018. Clothianidin and thiamethoxam percent detections in flowers (72 % and 61 %, respectively) were significantly higher than detections in leaves (24 % and 31 %, respectively). Thiamethoxam concentrations were significantly higher in paired flower samples than leaf samples (median 0.33 ng/g vs <0.07 ng/g) while clothianidin concentrations also trended higher in flowers (median 0.18-0.55 ng/g vs <0.18 ng/g). Only thiamethoxam showed significant differences between years, and we found no effect of crop type, with hay, soybean and corn fields all yielding 50-56 % detections in leaves. We found significantly higher concentrations in older milkweed flowers than young flowers or leaves (medians 0.87 ng/g vs <0.18 ng/g and 0.45 ng/g vs <0.07 ng/g for clothianidin and thiamethoxam, respectively). Our results highlight the importance of considering variation in milkweed tissue type and age of flowers in neonicotinoid exposure risk assessments. Efforts to increase milkweed availability in agricultural landscapes should consider how exposure to neonicotinoids can be mitigated.

Targeting NGF but not VEGFR1 or BDNF signaling reduces endometriosis-associated pain in mice.

INTRODUCTION: Endometriosis is a chronic inflammatory disease that affects âˆ¼10 % of women. A significant fraction of patients experience limited or no efficacy with current therapies. Tissue adjacent to endometriosis lesions often exhibits increased neurite and vascular density, suggesting that disease pathology involves neurotrophic activity and angiogenesis. OBJECTIVES: We aim to evaluate the potential for key tyrosine-kinase-receptor-coupled neurotrophic molecules to contribute to endometriosis-associated pain in mice. METHODS: Peritoneal fluid was collected from endometriosis patients undergoing surgery and the levels of NGF and VEGFR1 regulators (VEGFA, VEGFB, PLGF, and sVEGFR1) were quantified by ELISA. VEGFR1 regulator concentrations were used to calculate VEGFR1 occupancy. We used genetic depletion, neutralizing antibodies, and pharmacological approaches to specifically block neurotrophic ligands (NGF or BDNF) or receptors (VEGFR1, TRKs) in a murine model of endometriosis-associated pain. Endometriosis-associated pain was measured using von Frey filaments, quantification of spontaneous abdominal pain-related behavior, and thermal discomfort. Disease parameters were evaluated by lesion size and prevalence. To evaluate potential toxicity, we measured the effect of entrectinib dose and schedule on body weight, liver and kidney function, and bone structure (via micro-CT). RESULTS: We found that entrectinib (pan-Trk inhibitor) or anti-NGF treatments reduced evoked pain, spontaneous pain, and thermal discomfort. In contrast, even though calculated receptor occupancy revealed that VEGFR1 agonist levels are sufficient to support signaling, blocking VEGFR1 via antibody or tamoxifen-induced knockout did not reduce pain or lesion size in mice. Targeting BDNF-TrkB with an anti-BDNF antibody also proved ineffective. Notably, changing dosing schedule to once weekly eliminated entrectinib-induced bone-loss without decreasing efficacy against pain. CONCLUSIONS: This suggests NGF-TrkA signaling, but not BDNF-TrkB or VEGF-VEGFR1, mediates endometriosis-associated pain. Moreover, entrectinib blocks endometriosis-associated pain and reduces lesion sizes. Our results also indicated that entrectinib-like molecules are promising candidates for endometriosis treatment.

Passive infusion of an S2-Stem broadly neutralizing antibody protects against SARS-CoV-2 infection and lower airway inflammation in rhesus macaques.

The continued evolution of SARS-CoV-2 variants capable of subverting vaccine and infection-induced immunity suggests the advantage of a broadly protective vaccine against betacoronaviruses (ß-CoVs). Recent studies have isolated monoclonal antibodies (mAbs) from SARS-CoV-2 recovered-vaccinated donors capable of neutralizing many variants of SARS-CoV-2 and other ß-CoVs. Many of these mAbs target the conserved S2 stem region of the SARS-CoV-2 spike protein, rather the receptor binding domain contained within S1 primarily targeted by current SARS-CoV-2 vaccines. One of these S2-directed mAbs, CC40.8, has demonstrated protective efficacy in small animal models against SARS-CoV-2 challenge. As the next step in the pre-clinical testing of S2-directed antibodies as a strategy to protect from SARS-CoV-2 infection, we evaluated the in vivo efficacy of CC40.8 in a clinically relevant non-human primate model by conducting passive antibody transfer to rhesus macaques (RM) followed by SARS-CoV-2 challenge. CC40.8 mAb was intravenously infused at 10mg/kg, 1mg/kg, or 0.1 mg/kg into groups (n=6) of RM, alongside one group that received a control antibody (PGT121). Viral loads in the lower airway were significantly reduced in animals receiving higher doses of CC40.8. We observed a significant reduction in inflammatory cytokines and macrophages within the lower airway of animals infused with 10mg/kg and 1mg/kg doses of CC40.8. Viral genome sequencing demonstrated a lack of escape mutations in the CC40.8 epitope. Collectively, these data demonstrate the protective efficiency of broadly neutralizing S2-targeting antibodies against SARS-CoV-2 infection within the lower airway while providing critical preclinical work necessary for the development of pan-ß-CoV vaccines.

Symptom flares in women with chronic pelvic pain: Questionnaire study within a cohort study (translational research in pelvic pain (TRiPP)).

OBJECTIVE: To quantify the variation, triggers and impact on quality of life of symptom flares in women with chronic pelvic pain (CPP). DESIGN: Cross-sectional questionnaire within the Translational Research in Pelvic Pain clinical cohort study. SETTING: Women with CPP, with subgroups of women with endometriosis (EAP), interstitial cystitis/bladder pain syndrome (BPS), comorbid endometriosis and interstitial cystitis/bladder pain syndrome (EABP), and those with pelvic pain without endometriosis or interstitial cystitis/bladder pain syndrome (PP). POPULATION OR SAMPLE: A total of 100 participants. METHODS: Descriptive and comparative analysis from flares questionnaire. MAIN OUTCOME MEASURES: The prevalence, characteristics and triggers of short, medium and long symptom flares in CPP. RESULTS: We received 100 responses of 104 questionnaires sent. Seventy-six per cent of women with CPP have ever experienced symptom flares of at least one length (short, medium and/or long). Flares are associated with painful and non-painful symptoms. There is large variation for the frequency, duration, symptoms and triggers for flares. Over 60% of participants reported flares as stopping them from doing things they would usually do, >80% reported thinking about symptoms of flares and >80% reported flares being bothersome. CONCLUSIONS: Flares are prevalent and clinically very important in CPP. More research is needed to elucidate the mechanisms and characteristics underlying flares. Clinical practice should include an enquiry into flares with the aim of finding strategies to lessen their burden.

Improving Recruitment and Retention of Transgender Women in HIV Prevention Trials: Strategies to Make Trial Participation More Congruent with the Needs of Transgender Women.

Transgender women are disproportionately burdened by HIV. Though there is a substantial body of research exploring barriers and facilitators of HIV prevention among transgender women, many barriers remain unaddressed. This study identifies strategies to make HIV prevention trials more congruent with transgender women's preferences and needs to boost trial participation and ultimately enhance initiation and uptake of pre-exposure prophylaxis (PrEP). We conducted in-depth interviews with 15 sexually active, HIV-negative transgender women in New York City to understand: (1) preferences concerning long-acting injectable cabotegravir for PrEP and (2) ideas on how to make HIV prevention trial environments more comfortable. We identified five themes related to increasing transgender women's appeal to trials: (1) creating a more inclusive/welcoming environment, (2) providing compensation that is responsive to transgender women and community needs, (3) centering transgender women in recruitment and informational materials, (4) training study staff on gender-affirming practices, and (5) hiring transgender people as study staff. Participants wanted to see more gender diversity, representation, correct pronouns, gender-affirming practices, and compensation or reimbursements. Together, these practices may improve recruitment and retention of transgender women in HIV prevention trials.

Colon Cancer, Version 3.2024, NCCN Clinical Practice Guidelines in Oncology.

Colorectal cancer (CRC) is the fourth most frequently diagnosed cancer and the second leading cause of cancer death in the United States. Management of disseminated metastatic CRC involves various active drugs, either in combination or as single agents. The choice of therapy is based on consideration of the goals of therapy, the type and timing of prior therapy, the mutational profile of the tumor, and the differing toxicity profiles of the constituent drugs. This manuscript summarizes the data supporting the systemic therapy options recommended for metastatic CRC in the NCCN Guidelines for Colon Cancer.

Use of Circulating Tumor DNA to Guide Decision-making in Adjuvant Colon Cancer.

PURPOSE OF REVIEW: The use of circulating tumor DNA (ctDNA) assays to guide clinical decision-making in early-stage colon cancer is an area of rapidly advancing active research. With assays clinically available, clinicians must be informed how to best use this novel tool to treat patients. RECENT FINDINGS: Recent observational and prospective studies have suggested that ctDNA has potential to guide clinical decision-making in early-stage colon cancer by detecting minimal residual disease (MRD) and predicting recurrence risks. MRD-negative patients may be able to de-escalate or forgo adjuvant chemotherapy (ACT) without compromising disease-free survival or overall survival, while MRD-positive patients may benefit significantly from ACT. Recent and ongoing studies have given reason for optimism about the future of ctDNA as a useful biomarker for clinicians treating early-stage colon cancer. Data thus far are mostly limited to observational studies; inconsistent results highlight the need for caution. As more evidence emerges, ctDNA may become standard of care for colon cancer patients.

Effectiveness of telehealth versus in-person care during the COVID-19 pandemic: a systematic review.

In this systematic review, we compared the effectiveness of telehealth with in-person care during the pandemic using PubMed, CINAHL, PsycINFO, and the Cochrane Central Register of Controlled Trials from March 2020 to April 2023. We included English-language, U.S.-healthcare relevant studies comparing telehealth with in-person care conducted after the onset of the pandemic. Two reviewers independently screened search results, serially extracted data, and independently assessed the risk of bias and strength of evidence. We identified 77 studies, the majority of which (47, 61%) were judged to have a serious or high risk of bias. Differences, if any, in healthcare utilization and clinical outcomes between in-person and telehealth care were generally small and/or not clinically meaningful and varied across the type of outcome and clinical area. For process outcomes, there was a mostly lower rate of missed visits and changes in therapy/medication and higher rates of therapy/medication adherence among patients receiving an initial telehealth visit compared with those receiving in-person care. However, the rates of up-to-date labs/paraclinical assessment were also lower among patients receiving an initial telehealth visit compared with those receiving in-person care. Most studies lacked a standardized approach to assessing outcomes. While we refrain from making an overall conclusion about the performance of telehealth versus in-person visits the use of telehealth is comparable to in-person care across a variety of outcomes and clinical areas. As we transition through the COVID-19 era, models for integrating telehealth with traditional care become increasingly important, and ongoing evaluations of telehealth will be particularly valuable.

Association between COVID-19 vaccination and menstruation: a state of the science review.

INTRODUCTION: Menstrual health is a key patient-reported outcome beyond its importance as a general indicator of health and fertility. However, menstrual function was not measured in the clinical trials of COVID-19 vaccines. The purpose of this review was to synthesise the existing literature on the relationship between COVID-19 vaccination and menstrual health outcomes. METHODS: A PubMed search to 31 October 2023 identified a total of 53 publications: 11 prospective cohort studies, 11 retrospective cohort studies or registry-based cohort studies, and 31 cross-sectional or retrospective case-control studies. RESULTS: Identified studies were generally at moderate-to-high risk of bias due to retrospective design, interviewer bias, and failure to include a non-vaccinated control group. Nonetheless, the bulk of the literature demonstrates that COVID-19 vaccine is associated with temporary changes in menstrual characteristics (cycle length and flow) and menstrual pain. Follicular phase (at the time of vaccination) is associated with greater increases in cycle length. Evidence suggests temporary post-vaccine menstrual changes in adolescents, abnormal vaginal bleeding in postmenopausal individuals, and a potential protective effect of using hormonal contraception. CONCLUSIONS: In this review we found evidence supporting an association between the COVID-19 vaccine and menstrual health outcomes. Given the importance of menstrual function to overall health, we recommend that all future vaccine trials include menstruation as a study outcome. Future vaccine studies should include rigorous assessment of the menstrual cycle as an outcome variable to limit sources of bias, identify biological mechanisms, and elucidate the impact of stress.

Utilizing gas flux from automated head chamber systems to estimate dietary energy values for beef cattle fed a finishing diet.

Dietary net energy for maintenance (NEm) and gain (NEg) can be estimated using calculations based on live performance or adjusted-final body weight, which is calculated based on carcass characteristics. These values are commonly referred to as performance-adjusted (pa) NEm (paNEm) and NEg (paNEg). The NEm and NEg of a diet can also be estimated by adding recovered energy (RE) with heat production (HP) derived from an automated head chamber system (AHCS), which we will term gas-adjusted (ga) NEm (gaNEm) and NEg (gaNEg). Furthermore, HP from the Brouwer equation requires an estimate of urinary nitrogen (UN) excretion, which can be calculated based on N intake, blood urea N, UN concentration, and urine creatinine, or it could be zeroed. Alternatively, HP can be calculated using an alternative equation based on the respiratory quotient. Demonstrating agreement between pa and ga derived dietary energy values provides an opportunity to validate using the AHCS for energetic experiments and this comparison has not been conducted previously. Accordingly, the objective of this experiment was to assess the agreement between live and carcass paNEm and paNEg with gaNEm and gaNEg, where HP was calculated using 4 different approaches. Estimates of HP were not different (P = 0.99) between the 4 approaches employed, indicating that all options investigated are appropriate. Live paNEm and paNEg had a higher agreement (Lin's concordance correlation coefficient [CCC] = 0.91) with gaNEm and gaNEg than carcass values (CCC ≤ 0.84). These results suggest that researchers can implement the AHCS to provide good estimates of dietary energy values in finishing beef cattle that are unrestrained.

Automated head chamber systems (AHCS) implemented into beef cattle research allow estimation of gas flux, heat production (HP), and calculated gas-adjusted dietary net energy for maintenance (gaNEm) and gain (gaNEg) values when paired with recovered energy. However, a comparison between AHCS-derived values and performance-adjusted NEm (paNEm) and NEg (paNEg) from either live performance (live paNEm and paNEg) or carcass data (carcass paNEm and paNEg) has not been conducted. Accordingly, the objectives of this experiment were to evaluate the agreement between gaNEm and gaNEg, estimated using different approaches for calculating HP, with live paNEm and paNEg or carcass paNEm and paNEg. Accounting for urinary nitrogen or methane when calculating HP does not appreciably influence HP estimates or subsequent calculations to estimate dietary NEm and NEg. There was excellent agreement between live paNEm and gaNEm, and between paNEg and gaNEg. Measures of precision, accuracy, and agreement were lower for carcass than for live-derived values when compared to gaNEm and gaNEg but were still acceptable. These results suggest that researchers can implement the AHCS to provide estimates of HP, gas flux, and estimates of dietary energy values in unrestrained finishing beef cattle-fed diets ranging in crude protein content (10.8% to 12.5%). Additional research is warranted on the use of the AHCS to conduct energetic studies across varying diets and production systems, particularly grazing systems.

Recommendations on visit duration and sample number requirements for an automated head chamber system.

Automated head chamber systems (AHCS; GreenFeed, C-Lock Inc., Rapid City, SD) increasingly are being used for measuring the gas flux of unrestrained cattle. There are a wide range of recommendations for what constitutes a "good" visit (i.e., duration) to an AHCS and how many visits are required for the AHCS to quantify gas fluxes accurately and precisely. Accordingly, the purpose of this experiment was to investigate the effects of visit duration thresholds and the subsequent effects of these thresholds on the number of visits needed to provide adequate estimates of carbon dioxide (CO2) and methane (CH4) emissions, and oxygen (O2) consumption by beef cattle. This analysis utilized data from three previously published experiments with grazing beef steers and one experiment with finishing beef steers, with 103 steers total. When comparing all available visits, there was excellent agreement [Lin's concordance correlation coefficient (CCC) ≥ 0.96] between visits ≥ 3 min in duration and those ≥ 2 min for the three gases in all four experiments. When data from all four experiments were pooled, there was excellent agreement between visits ≥ 3 min and those ≥ 2 min and ≥ 1 min for all gases (CCC ≥ 0.96). These results suggest that estimates from visits ≥ 2 min are like those from visits ≥ 3 min. Next, we investigated if including visits ≥ 2 min or ≥ 1 min would increase the minimal number of visits required to provide excellent agreement with the "gold-standard" (mean of all visits ≥ 3 min). For this, we used only one of the experiments and randomly selected visits per animal ranging from n = 5 to 60, in increments of 5. The sole experiment was used because all animals had more than 60 visits. We then assessed the agreement between the "gold-standard" (mean of all visits ≥ 3 min [144 ±â€…55.01 visits per steer]) estimates of CO2, O2, and CH4. The minimum number of visits required to achieve excellent agreement (CCC ≥ 0.90) to the "gold-standard" estimate for all gases was 30 visits ≥ 3 min in duration, or 40 visits ≥ 2 min in duration. Visits ≥ 1 min in duration did not achieve excellent agreement, even when 60 were used. Based on these results, we recommend excluding visits < 3 min in duration with 30 minimum visit records per animal. However, if researchers choose to implement a 2-min visit duration threshold then 40 visit records are needed per animal.

GreenFeed systems (C-Lock Inc., Rapid City, SD) are being increasingly used for measuring carbon dioxide (CO2) and methane (CH4) emissions and oxygen consumption (O2) of free-roaming cattle. These systems utilize averages of multiple visits to provide estimates of daily gas flux. There currently exists a range of recommendations for what constitutes a "good" visit to GreenFeed. Additionally, the number of recommended visits required to achieve adequate estimates of these gas fluxes appears to be dependent on the minimum visit duration that is used. To date, there has been only one experiment that has investigated visit duration and the recommended number of visits for CO2 and CH4 emissions and to our knowledge this has not been assessed for O2 consumption. Based on the results of this experiment, we recommend using a 3-min minimum visit duration threshold with 30 visit records per animal. If researchers choose to use a 2-min visit duration threshold, then 40 visit records per animal are recommended.