Assessing vulnerability to embolism and hydraulic safety margins in reed-like Restionaceae.

The African Restionaceae (Poales), the dominant graminoid layer in the megadiverse Cape Floristic Region of South Africa, are distributed across a wide range of moisture availability, yet currently there is very little known about the underlying hydraulics of this group. We tested two methods for measuring culm vulnerability to embolism, the optical and pneumatic methods, in three species of Cannomois ranging in habitat from semi-riparian (Cannomois virgata) to dryland (Cannomois parviflora and C. congesta). Estimates of culm xylem vulnerability were coupled with measures of turgor loss point (ΨTLP) and minimum field water potential (ΨMD) to assess hydraulic safety margins. The optical and pneumatic methods produced similar estimates of P50, but differed for P12 and P88. All three species were quite vulnerable to embolism, with P50 of -1.9 MPa (C. virgata), -2.3 MPa (C. congesta), and -2.4 MPa (C. parviflora). Estimates of P50, ΨTLP and ΨMD aligned with habitat moisture stress, with highest values found in the semi-riparian C. virgata. Consistent differences in P50, ΨMD and ΨTLP between species resulted in consistent hydraulic safety margins across species of 0.96 ± 0.1 MPa between ΨMD and P50, with onset of embolism occurring 0.43 ± 0.04 MPa after ΨTLP for all three species. Our study demonstrates that restio occupancy of dry environments involves more than the evolution of highly resistant xylem, suggesting that other aspects of water relations are key to understanding trait-environment relationships in this group.

Consensus-Derived Recommended Skills for Transition to Residency Courses.

PURPOSE: Transition to residency (TTR) courses facilitate the medical student-residency transition and are an integral part of senior medical student training. The authors established a common set of skills for TTR courses, and an expected level of entrustment students should demonstrate in each skill on TTR course completion. METHOD: A modified Delphi approach was used with 3 survey iterations between 2020 and 2022 to establish skills to be included in a TTR course. Nine TTR experts suggested general candidate skills and conducted a literature search to ensure no vital skills were missed. A stakeholder panel was solicited from email lists of TTR educators, residency program directors, and residents at the panelists' institutions. Consensus was defined as more than 75% of participants selecting a positive inclusion response. An entrustment questionnaire asked panelists to assign a level of expected entrustment to each skill, with 1 indicating observation only and 6 indicating perform independently. RESULTS: The stakeholder panel initially consisted of 118 respondents with representation across educational contexts and clinical specialties. Response rates were 54% in iteration 2, 42% in iteration 3, and 33% on the entrustment questionnaire. After 3 iterations, 54 skills met consensus and were consolidated into 37 final skills categorized into 18 clinical skills (e.g., assessment and management of inpatient concerns), 14 communication skills (e.g., delivering serious news or having difficult conversations), 4 personal and professional skills (e.g., prioritization of clinical tasks), and 1 procedural skill (mask ventilation). Median entrustment levels were reported for all skills, with 19 skills having a level of expected entrustment of 4 (perform independently and have all findings double-checked). CONCLUSIONS: These consensus skills can serve as the foundation of a standardized national TTR curriculum framework. Entrustment guidance may help educational leaders optimize training and allocation of resources for TTR curriculum development and implementation.

The long-term incidence of chronic post-surgical pain after coronary artery bypass surgery - A prospective observational study.

BACKGROUND: Chronic post-surgical pain (CPSP) represents a significant issue for many patients following surgery; however, the long-term incidence and impact have not been well described following cardiac surgery. Our aim was to characterize CPSP at least 5 years following coronary artery bypass grafting (CABG) surgery. METHODS: This prospective observational study investigated a cohort of patients from a larger trial investigating cognitive outcomes following CABG surgery, with 89 of 148 eligible patients (60.1%) assessed for CPSP at a mean (standard deviation [SD]) of 6.8 [1.2] years. Questionnaires interrogated pain presence, intensity, location, neuropathic characteristics, Geriatric Depression Scale scores (GDS) and instrumental activities of daily living (IADL). RESULTS: CPSP was described in 21/89 (23.6%), with 10 rating it as moderate to severe. Six of the CPSP patients (29%) met criteria for neuropathic pain (6.7% overall). The highest rate of CPSP was associated with the leg surgical site (chest 12/89 [13.5%], arm 8/68 [11.8%] and leg (saphenous vein graft-SVG) 11/37 [29.7%]; χ2 = 6.523, p = 0.038). IADL scores were significantly lower for patients with CPSP (mean [SD]: 36.7 [1.6] vs. no CPSP 40.6 [0.6]; p = 0.006). Patients had GDS scores consistent with moderate depression (GDS >8) in 3/21 (14.3%) with CPSP, versus 3/68 (4.4%) non-CPSP patients (χ2 = 3.20, p = 0.073). CONCLUSIONS: This study identified a CPSP incidence of 23.6% at a mean of 6.8 years after CABG surgery, with the highest pain proportion at SVG harvest sites. CPSP was associated with neuropathic pain symptoms and had a significant impact on IADLs. This emphasizes the need for long-term follow-up of CABG patients. SIGNIFICANCE: This study highlights the impact of CPSP 7 years following cardiac surgery and highlights the effect of surgical site, neuropathic pain and the importance of including pain assessment and management in the long-term follow-up of cardiac surgical patients. Strategies to address and prevent chronic pain following cardiac surgery should be further explored.

External validation of Cardiac disease, Hypertension, and Logarithmic Left anterior descending coronary artery radiation dose (CHyLL) for predicting major adverse cardiac events after lung cancer radiotherapy.

Background and purpose: Major adverse cardiac events(MACE) are prevalent in patients with locally advanced-non-small cell lung cancer(LA-NSCLC) following radiotherapy(RT). The CHyLL model, incorporating coronary heart disease(CHD),Hypertension(HTN),Logarithmic LADV15 was developed and internally-validated to predict MACE among LA-NSCLC patients. We sought to externally validate CHyLL to predict MACE in an independent LA-NSCLC cohort. Patients and methods: Patients with LA-NSCLC treated with RT were included. CHyLL score was calculated:5.51CHD + 1.28HTN + 1.48ln(LADV15 + 1)-1.36CHD*ln(LADV15 + 1). CHyLL performance in predicting MACE was assessed and compared to mean heart dose(MHD) using Cox-proportional hazard(PH) analyses and Harrel's concordance(C)-indices. MACE and overall survival(OS) among low-vs high-risk groups(CHyLL < 5 vs ≥ 5) were compared. Results: In the external validation cohort(N = 102), the median age was 71 years and 55% were females. Most(n = 74,73%), had clinical Stage III disease and 35(34%) underwent surgery. CHyLL demonstrated good MACE prediction with C-index of 0.73(95% Confidence Interval(CI):0.58-0.89), while MHD did not (C-index = 0.46 (95% CI:0.30-0.62)). Per CHyLL, 32(31%) and 70(69%) patients were considered low-and high-risk for MACE, respectively. CHyLL consistently identified lower MACE rates in the low-vs high-risk group(log-rank p = 0.108):0 vs 8%(12 months),5 vs 16%(24 months),5 vs 16%(36 months),and 5 vs 19%(48 months) post-RT. In the pooled internal and external validation cohort(N = 303), MACE rates in low-vs high-risk groups were statistically significantly different(log-rank p = 0.01):1 vs 6%(12 months),3 vs 12%(24 months),6 vs 19%(36 months),and 6 vs 21%(48 months). Conclusions: CHyLL was externally validated and superior to MHD in predicting MACE. CHyLL has the potential to identify high-risk patients who may benefit from cardio-oncology optimization and to estimate personalized LADV15 constraints based on cardiac risk factors and acceptable MACE thresholds.

Enhancing Clinical Teaching in Critical Thinking, High-Value Care, and Health Care Equity.

INTRODUCTION: Faculty development in the clinical setting is challenging to implement and assess. This study evaluated an intervention (IG) to enhance bedside teaching in three content areas: critical thinking (CT), high-value care (HVC), and health care equity (HCE). METHODS: The Communities of Practice model and Theoretical Domains Framework informed IG development. Three multidepartmental working groups (WGs) (CT, HVC, HCE) developed three 2-hour sessions delivered over three months. Evaluation addressed faculty satisfaction, knowledge acquisition, and behavior change. Data collection included surveys and observations of teaching during patient care. Primary analyses compared counts of post-IG teaching behaviors per hour across intervention group (IG), comparison group (CG), and WG groups. Statistical analyses of counts were modeled with generalized linear models using the Poisson distribution. RESULTS: Eighty-seven faculty members participated (IG n = 30, CG n = 28, WG n = 29). Sixty-eight (IG n = 28, CG n = 23, WG n = 17) were observed, with a median of 3 observation sessions and 5.2 hours each. Postintervention comparison of teaching (average counts/hour) showed statistically significant differences across groups: CT CG = 4.1, IG = 4.8, WG = 8.2; HVC CG = 0.6, IG = 0.9, WG = 1.6; and HCE CG = 0.2, IG = 0.4, WG = 1.4 ( P < .001). DISCUSSION: A faculty development intervention focused on teaching in the context of providing clinical care resulted in more frequent teaching of CT, HVC, and HCE in the intervention group compared with controls. WG faculty demonstrated highest teaching counts and provide benchmarks to assess future interventions. With the creation of durable teaching materials and a cadre of trained faculty, this project sets a foundation for infusing substantive content into clinical teaching.

Acute peri-operative neurocognitive disorders: a narrative review.

Peri-operative neurocognitive disorders are the most common complication experienced by older individuals undergoing anaesthesia and surgery. Peri-operative neurocognitive disorders, particularly postoperative delirium, result in long-term poor outcomes including: death; dementia; loss of independence; and poor cognitive and functional outcomes. Recent changes to the nomenclature of these disorders aims to align peri-operative neurocognitive disorders with cognitive disorders in the community, with consistent definitions and clinical diagnosis. Possible mechanisms include: undiagnosed neurodegenerative disease; inflammation and resulting neuroinflammation; neuronal damage; and comorbid systemic disease. Pre-operative frailty represents a significant risk for poor postoperative outcomes; it is associated with an increase in the incidence of cognitive decline at 3 and 12 months postoperatively. In addition to cognitive decline, frailty is associated with poor functional outcomes following elective non-cardiac surgery. It was recently shown that 29% of frail patients died or experienced institutionalisation or new disability within 90 days of major elective surgery. Identification of vulnerable patients before undergoing surgery and anaesthesia is the key to preventing peri-operative neurocognitive disorders. Current approaches include: pre-operative delirium and cognitive screening; blood biomarker analysis; intra-operative management that may reduce the incidence of postoperative delirium such as lighter anaesthesia using processed electroencephalography devices; and introduction of guidelines which may reduce or prevent delirium and postoperative neurocognitive disorders. This review will address these issues and advocate for an approach to care for older peri-operative patients which starts in the community and continues throughout the pre-operative, intra-operative, postoperative and post-discharge phases of care management, involving multidisciplinary medical teams, as well as family and caregivers wherever possible.

Self-Directed Learning in Medical Education: Training for a Lifetime of Discovery.

Issue: Life-long learning is a skill that is central to competent health professionals, and medical educators have sought to understand how adult professionals learn, adapt to new information, and independently seek to learn more. Accrediting bodies now mandate that training programs teach in ways that promote self-directed learning (SDL) but do not provide adequate guidance on how to address this requirement. Evidence: The model for the SDL mandate in physician training is based mostly on early childhood and secondary education evidence and literature, and may not capture the unique environment of medical training and clinical education. Furthermore, there is uncertainty about how medical schools and postgraduate training programs should implement and evaluate SDL educational interventions. The Shapiro Institute for Education and Research, in conjunction with the Association of American Medical Colleges, convened teams from eight medical schools from North America to address the challenge of defining, implementing, and evaluating SDL and the structures needed to nurture and support its development in health professional training. Implications: In this commentary, the authors describe SDL in Medical Education, (SDL-ME), which is a construct of learning and pedagogy specific to medical students and physicians in training. SDL-ME builds on the foundations of SDL and self-regulated learning theory, but is specifically contextualized for the unique responsibilities of physicians to patients, inter-professional teams, and society. Through consensus, the authors offer suggestions for training programs to teach and evaluate SDL-ME. To teach self-directed learning requires placing the construct in the context of patient care and of an obligation to society at large. The SDL-ME construct builds upon SDL and SRL frameworks and suggests SDL as foundational to health professional identity formation.KEYWORDSself-directed learning; graduate medical education; undergraduate medical education; theoretical frameworksSupplemental data for this article is available online at https://doi.org/10.1080/10401334.2021.1938074 .

The Harvard Medical School Pathways Curriculum: Reimagining Developmentally Appropriate Medical Education for Contemporary Learners.

As the U.S. health care system changes and technology alters how doctors work and learn, medical schools and their faculty are compelled to modify their curricula and teaching methods. In this article, educational leaders and key faculty describe how the Pathways curriculum was conceived, designed, and implemented at Harvard Medical School. Faculty were committed to the principle that educators should focus on how students learn and their ability to apply what they learn in the evaluation and care of patients. Using the best evidence from the cognitive sciences about adult learning, they made major changes in the pedagogical approach employed in the classroom and clinic. The curriculum was built upon 4 foundational principles: to enhance critical thinking and provide developmentally appropriate content; to ensure both horizontal integration between courses and vertical integration between phases of the curriculum; to engage learners, foster curiosity, and reinforce the importance of student ownership and responsibility for their learning; and to support students' transformation to a professional dedicated to the care of their patients and to their obligations for lifelong, self-directed learning.The practice of medicine is rapidly evolving and will undoubtedly change in multiple ways over the career of a physician. By emphasizing personal responsibility, professionalism, and thinking skills over content transfer, the authors believe this curriculum will prepare students not only for the first day of practice but also for an uncertain future in the biological sciences, health and disease, and the nation's health care system, which they will encounter in the decades to come.

Data-driven models to predict the elimination of sleeping sickness in former Equateur province of DRC.

Approaching disease elimination, it is crucial to be able to assess progress towards key objectives using quantitative tools. For Gambian human African trypanosomiasis (HAT), the ultimate goal is to stop transmission by 2030, while intermediary targets include elimination as a public health problem - defined as <1 new case per 10,000 inhabitants in 90% of foci, and <2000 reported cases by 2020. Using two independent mathematical models, this study assessed the achievability of these goals in the former Equateur province of the Democratic Republic of Congo, which historically had endemic levels of disease. The two deterministic models used different assumptions on disease progression, risk of infection and non-participation in screening, reflecting biological uncertainty. To validate the models a censor-fit-uncensor procedure was used to fit to health-zone level data from 2000 to 2012; initially the last six years were censored, then three and the final step utilised all data. The different model projections were used to evaluate the expected transmission and reporting for each health zone within each province under six intervention strategies using currently available tools. In 2012 there were 197 reported HAT cases in former Equateur reduced from 6828 in 2000, however this reflects lower active testing for HAT (1.3% of the population compared to 7.2%). Modelling results indicate that there are likely to be <300 reported cases in former Equateur in 2020 if screening continues at the mean level for 2000-2012 (6.2%), and <120 cases if vector control is introduced. Some health zones may fail to achieve <1 new case per 10,000 by 2020 without vector control, although most appear on track for this target using medical interventions alone. The full elimination goal will be harder to reach; between 39 and 54% of health zones analysed may have to improve their current medical-only strategy to stop transmission completely by 2030.

Abnormalities in the Visual Processing of Viewing Complex Visual Stimuli Amongst Individuals With Body Image Concern.

Individuals with body dysmorphic disorder (BDD) and clinically concerning body-image concern (BIC) appear to possess abnormalities in the way they perceive visual information in the form of a bias towards local visual processing. As inversion interrupts normal global processing, forcing individuals to process locally, an upright-inverted stimulus discrimination task was used to investigate this phenomenon. We examined whether individuals with nonclinical, yet high levels of BIC would show signs of this bias, in the form of reduced inversion effects (i.e., increased local processing). Furthermore, we assessed whether this bias appeared for general visual stimuli or specifically for appearance-related stimuli, such as faces and bodies. Participants with high-BIC (n = 25) and low-BIC (n = 30) performed a stimulus discrimination task with upright and inverted faces, scenes, objects, and bodies. Unexpectedly, the high-BIC group showed an increased inversion effect compared to the low-BIC group, indicating perceptual abnormalities may not be present as local processing biases, as originally thought. There was no significant difference in performance across stimulus types, signifying that any visual processing abnormalities may be general rather than appearance-based. This has important implications for whether visual processing abnormalities are predisposing factors for BDD or develop throughout the disorder.

PACS-2 mediates the ATM and NF-κB-dependent induction of anti-apoptotic Bcl-xL in response to DNA damage.

Nuclear factor kappa B (NF-κB) promotes cell survival in response to genotoxic stress by inducing the expression of anti-apoptotic proteins including Bcl-xL, which protects mitochondria from stress-induced mitochondrial outer membrane permeabilization (MOMP). Here we show that the multifunctional sorting protein Pacs-2 (phosphofurin acidic cluster sorting protein-2) is required for Bcl-xL induction following DNA damage in primary mouse thymocytes. Consequently, in response to DNA damage, Pacs-2(-/-) thymocytes exhibit a blunted induction of Bcl-xL, increased MOMP and accelerated apoptosis. Biochemical studies show that cytoplasmic PACS-2 promotes this DNA damage-induced anti-apoptotic pathway by interacting with ataxia telangiectasia mutated (ATM) to drive NF-κB activation and induction of Bcl-xL. However, Pacs-2 was not required for tumor necrosis factor-α-induced NF-κB activation, suggesting a role for PACS-2 selectively in NF-κB activation in response to DNA damage. These findings identify PACS-2 as an in vivo mediator of the ATM and NF-κB-dependent induction of Bcl-xL that promotes cell survival in response to DNA damage.

A novel resident-as-teacher training program to improve and evaluate obstetrics and gynecology resident teaching skills.

BACKGROUND: Residents play a significant role in teaching, but formal training, feedback, and evaluation are needed. AIMS: Our aims were to assess resident teaching skills in the resident-as-teacher program, quantify correlations of faculty evaluations with resident self-evaluations, compare resident-as-teacher evaluations with clinical evaluations, and evaluate the resident-as-teacher program. METHOD: The resident-as-teacher training program is a simulated, videotaped teaching encounter with a trained medical student and standardized teaching evaluation tool. Evaluations from the resident-as-teacher training program were compared to evaluations of resident teaching done by faculty, residents, and medical students from the clinical setting. RESULTS: Faculty evaluation of resident teaching skills in the resident-as-teacher program showed a mean total score of 4.5 ± 0.5 with statistically significant correlations between faculty assessment and resident self-evaluations (r = 0.47; p < 0.001). However, resident self-evaluation of teaching skill was lower than faculty evaluation (mean difference: 0.4; 95% CI 0.3-0.6). When compared to the clinical setting, resident-as-teacher evaluations were significantly correlated with faculty and resident evaluations, but not medical student evaluations. Evaluations from both the resident-as-teacher program and the clinical setting improved with duration of residency. CONCLUSIONS: The resident-as-teacher program provides a method to train, give feedback, and evaluate resident teaching.

Developing expert-derived rating standards for the peer assessment of lectures.

PURPOSE: For peer review of teaching to be credible and reliable, peer raters must be trained to identify and measure teaching behaviors accurately. Peer rater training, therefore, must be based on expert-derived rating standards of teaching performance. The authors sought to establish precise lecture rating standards for use in peer rater training at their school. METHOD: From 2008 to 2010, a panel of experts, who had previously helped to develop an instrument for the peer assessment of lecturing, met to observe, discuss, and rate 40 lectures, using a consensus-building model to determine key behaviors and levels of proficiency for each of the instrument's 11 criteria. During this process, the panelists supplemented the original instrument with precise behavioral descriptors of lecturing. The reliability of the derived rating standards was assessed by having the panelists score six sample lectures independently. RESULTS: Intraclass correlation coefficients of the panelists' ratings of the lectures ranged from 0.75 to 0.96. There was moderate to high positive association between 10 of the 11 instrument's criteria and the overall performance score (r = 0.752-0.886). There were no statistically significant differences among raters in terms of leniency or stringency of scores. CONCLUSIONS: Two relational themes, content and style, were identified within the instrument's variables. Recommendations for developing expert-derived ratings standards include using an interdisciplinary group for observation, discussion, and verbal identification of behaviors; asking members to consider views that contrast with their own; and noting key teaching behaviors for use in future peer rater training.

Local adaptation and the evolution of species' ranges under climate change.

The potential impact of climate change on biodiversity is well documented. A well developed range of statistical methods currently exists that projects the possible future habitat of a species directly from the current climate and a species distribution. However, studies incorporating ecological and evolutionary processes remain limited. Here, we focus on the potential role that local adaptation to climate may play in driving the range dynamics of sessile organisms. Incorporating environmental adaptation into a stochastic simulation yields several new insights. Counter-intuitively, our simulation results suggest that species with broader ranges are not necessarily more robust to climate change. Instead, species with broader ranges can be more susceptible to extinction as locally adapted genotypes are often blocked from range shifting by the presence of cooler adapted genotypes that persist even when their optimum climate has left them behind. Interestingly, our results also suggest that it will not always be the cold-adapted phenotypes that drive polewards range expansion. Instead, range shifts may be driven by phenotypes conferring adaptation to conditions prevalent towards the centre of a species' equilibrium distribution. This may have important consequences for the conservation method termed predictive provenancing. These initial results highlight the potential importance of local adaptation in determining how species will respond to climate change and we argue that this is an area requiring urgent theoretical and empirical attention.

Lamb survival in Australian Merino sheep: a genetic analysis.

Direct and maternal components of variance for lamb survival to birth, 7 d, and weaning (110 d) were estimated by REML procedures in a flock of Australian Merino sheep. A total of 14,142 lambs, the progeny of 421 sires and 3,666 dams, born between 1975 and 1983 were available for analysis. The study has produced some of the most precise estimates of genetic parameters for lamb survival in the Australian Merino. Very low heritabilities for lamb viability (0.03) and the performance of the dam or ewe rearing ability (0.07) suggest that genetic solutions to lamb survival are unlikely to be significant. But, despite the low heritabilities, there is still potential for improvement through selective breeding. The estimated repeatability of at least 0.10 shows that multiple records on the rearing ability of a ewe over its lifetime can increase selection accuracy. More importantly, such repeatabilities indicate that current generation improvement can be achieved by culling ewes from the breeding flock with poor rearing ability. Despite maternal bond score and lamb birth weight being highly repeatable and moderately heritable traits, correlations with lamb survival were essentially zero. These traits therefore have no value as indirect selection criteria for Merino lamb survival.

Phenotypic aspects of lamb survival in Australian Merino sheep.

Lamb survival in Australian Merino sheep was investigated using survival records from 14,142 lambs born between 1975 and 1983. This data set included roll calls of live lambs at birth, 7 d, marking (30 d), and weaning (110 d), which allowed 4 binomial traits (alive or dead) to be recorded for each lamb at each time interval. The average survival to weaning was 72.4% with 23% of singles, 32% of twins, and 45% of multiple-born lambs not surviving to weaning. The timing of lamb loss was consistent across birth types; 6% died within 24 h of birth, a further 14% by 7 d, 3% between 7 and 30 d, and 8% between 30 and 110 d. Partitioning of phenotypic variation revealed that after the first postpartum week, mothering ability of Australian Merino ewes is not an important factor in lamb survival. Some ewes repeatedly lose lambs at birth and in the early postnatal period, but the intraclass correlation decreased by a factor of 10 for survival after 7 d of age (0.096 at birth and 0.100 at 7 d, falling to 0.009 at marking and 0.018 at weaning). This study examined the relationships of lamb survival with lamb birth weight and found varying relationships at each time period. Whereas birth weight had a highly significant curvilinear relationship with survival to weaning, the relationship was flatter for survival to 24 h with only small differences between average birth weights and the birth weight at which survival was optimized (-0.04, 0.28, and 0.54 kg for single-, twin-, and multiple-born lambs, respectively). This suggests that any management interventions to increase birth weight may increase the risk of death to both lamb and ewe during the lambing process due to dystocia. Among twin-born lambs there was a carryover effect of losses at birth on subsequent loss in the first week of life. Survival to 7 d of age was highly dependent on the survival of the littermate, favoring those whose littermate survived, but after the first week, this trend was reversed. Lamb birthcoat score had a small positive impact on survival only at birth.

Genetic parameters for carcass and meat quality traits and their relationships to liveweight and wool production in hogget Merino rams.

Genetic parameters for carcass and meat quality traits of about 18-month-old Merino rams (n = 5870), the progeny of 543 sires from three research resource flocks, were estimated. The estimates of heritability for hot carcass weight (HCW) and the various fat and muscle dimension measurements were moderate and ranged from 0.20 to 0.37. The brightness of meat (colour L*, 0.18 +/- 0.03 standard error) and meat pH (0.22 +/- 0.03) also had moderate estimates of heritability, although meat relative redness (colour a*, 0.10 +/- 0.03) and relative yellowness (colour b*, 0.10 +/- 0.03) were lower. Heritability estimates for live weights were moderate and ranged from 0.29 to 0.41 with significant permanent maternal environmental effects (0.13 to 0.10). The heritability estimates for the hogget wool traits were moderate to high and ranged from 0.27 to 0.60. The ultrasound measurements of fat depth (FATUS) and eye muscle depth (EMDUS) on live animals were highly genetically correlated with the corresponding carcass measurements (0.69 +/- 0.09 FATC and 0.77 +/- 0.07 EMD). Carcass tissue depth (FATGR) had moderate to low genetic correlations with carcass muscle measurements [0.18 +/- 0.10 EMD and 0.05 +/- 0.10 eye muscle area (EMA)], while those with FATC were negative. The genetic correlation between EMD and eye muscle width (EMW) was 0.41 +/- 0.08, while EMA was highly correlated with EMD (0.89 +/- 0.0) and EMW (0.78 +/- 0.04). The genetic correlations for muscle colour with muscle measurements were moderately negative, while those with fat measurements were close to zero. Meat pH was positively correlated with muscle measurements (0.14 to 0.17) and negatively correlated with fat measurements (-0.06 to -0.18). EMDUS also showed a similar pattern of correlations to EMD with meat quality indicator traits, although FATUS had positive correlations with these traits which were generally smaller than their standard error. The genetic correlations among the meat colour traits were high and positive while those with meat pH were high and negative, which were all in the favourable direction. Generally, phenotypic correlations were similar or slightly lower than the corresponding genetic correlations. There were generally small to moderate negative genetic correlations between clean fleece weight (CFW) and carcass fat traits while those with muscle traits were close to zero. As the Merino is already a relatively lean breed, this implies that particular attention should be given to this relationship in Merino breeding programmes to prevent the reduction of fat reserves as a correlated response to selection for increased fleece weight. The ultrasound scan traits generally showed a similar pattern to the corresponding carcass fat and muscle traits. There was a small unfavourable genetic correlation between CFW and meat pH (0.19 +/- 0.07).

Genetic correlations between ewe reproduction and carcass and meat quality traits in Merino sheep.

Genetic correlations between reproduction traits in ewes and carcass and meat quality traits in Merino rams were obtained using restricted maximum likelihood procedures. The carcass data were from 5870 Merino rams slaughtered at approximately 18 months of age that were the progeny of 543 sires from three research resource flocks over 7 years. The carcass traits included ultrasound scan fat and eye muscle depth (EMDUS) measured on live animals, dressing percentage and carcass tissue depth (at the GR site FATGR and C site FATC), eye muscle depth, width and area and the meat quality indicator traits of muscle final pH and colour (L*, a*, b*). The reproduction data consisted of 13 464 ewe joining records for number of lambs born and weaned and 9015 records for LS. The genetic correlations between reproduction and fat measurements were negative (range -0.06 +/- 0.12 to -0.37 +/- 0.12), with smaller correlations for live measurement than carcass traits. There were small favourable genetic correlations between reproduction traits and muscle depth in live rams (EMDUS, 0.10 +/- 0.12 to 0.20 +/- 0.12), although those with carcass muscle traits were close to zero. The reproduction traits were independent of meat colour L* (relative brightness), but tended to be favourably correlated with meat colour a* (relative redness, 0.12 +/- 0.17 to 0.19 +/- 0.16). There was a tendency for meat final pH to have small negative favourable genetic correlations with reproduction traits (0.05 +/- 0.11 to -0.17 +/- 0.12). This study indicates that there is no antagonism between reproduction traits and carcass and meat quality indicator traits, with scope for joint improvement of reproduction, carcass and meat quality traits in Merino sheep.

Genetic correlations among and between wool, growth and reproduction traits in Merino sheep.

Data from seven research resource flocks across Australia were combined to provide accurate estimates of genetic correlations among production traits in Merino sheep. The flocks represented contemporary Australian Merino fine, medium and broad wool strains over the past 30 years. Over 110,000 records were available for analysis for each of the major wool traits, and 50,000 records for reproduction and growth traits with over 2700 sires and 25,000 dams. Individual models developed from the single trait analyses were extended to the various combinations of two-trait models to obtain genetic correlations among six wool traits [clean fleece weight (CFW), greasy fleece weight, fibre diameter (FD), yield, coefficient of variation of fibre diameter and standard deviation of fibre diameter], four growth traits [birth weight, weaning weight, yearling weight (YWT), and hogget weight] and four reproduction traits [fertility, litter size, lambs born per ewe joined, lambs weaned per ewe joined (LW/EJ)]. This study has provided for the first time a comprehensive matrix of genetic correlations among these 14 wool, growth and reproduction traits. The large size of the data set has also provided estimates with very low standard errors. A moderate positive genetic correlation was observed between CFW and FD (0.29 +/- 0.02). YWT was positively correlated with CFW (0.23 +/- 0.04), FD (0.17 +/- 0.04) and LWEJ (0.58 +/- 0.06), while LW/EJ was negatively correlated with CFW (-0.26 +/- 0.05) and positively correlated with FD (0.06 +/- 0.04) and LS (0.68 +/- 0.04). These genetic correlations, together with the estimates of heritability and other parameters provide the basis for more accurate prediction of outcomes in complex sheep-breeding programmes designed to improve several traits.