We use cookies to distinguish you from other users and to provide you with a better experience on our websites. Close this message to accept cookies or find out how to manage your cookie settings.
To save content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about saving content to .
To save content items to your Kindle, first ensure coreplatform@cambridge.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
People with psychotic disorders receive mental healthcare services mainly for their psychiatric care needs. However, patients often experience multiple physical or social wellbeing-related care needs as well. This study aims to identify care needs, investigate their changes over time and examine their association with mental healthcare consumption and evidence-based pharmacotherapy.
Methods
This study combined annually obtained routine outcome monitoring (ROM) data with care consumption data of people with a long-term psychotic illness receiving treatment in four Dutch mental healthcare institutes between 2012 and 2016. Existing treatment algorithms were used to determine psychiatric, physical and social wellbeing-related care needs based on self-report questionnaires, semi-structured interviews and physical parameters. Care consumption was measured in hours of outpatient mental healthcare consumption per year. Generalised estimating equation models were used to calculate odds ratios of care needs and their associations with time, mental healthcare consumption and medication use.
Results
Participants (n = 2054) had on average 7.4 care needs per measurement and received 25.4 h of care per year. Physical care needs are most prevalent and persistent and people with more care needs receive more mental healthcare. Care needs for psychotic symptoms and most social wellbeing-related care needs decreased, whereas the chance of being overweight significantly increased with subsequent years of care. Several positive associations were found between care needs and mental healthcare consumption as well as positive relations between care needs and evidence-based pharmacotherapy.
Conclusions
This longitudinal study present a novel approach in identifying care needs and their association with mental healthcare consumption and pharmacotherapy. Identification of care needs in this way based on ROM can assist daily clinical practice. A recovery-oriented view and a well-coordinated collaboration between clinicians and general practitioners together with shared decisions about which care needs to treat, can improve treatment delivery. Special attention is required for improving physical health in psychosis care which, despite appropriate pharmacotherapy and increasing care consumption, remains troublesome.
Higher milk intake has been associated with a lower stroke risk, but not with risk of CHD. Residual confounding or reverse causation cannot be excluded. Therefore, we estimated the causal association of milk consumption with stroke and CHD risk through instrumental variable (IV) and gene-outcome analyses. IV analysis included 29 328 participants (4611 stroke; 9828 CHD) of the European Prospective Investigation into Cancer and Nutrition (EPIC)-CVD (eight European countries) and European Prospective Investigation into Cancer and Nutrition-Netherlands (EPIC-NL) case-cohort studies. rs4988235, a lactase persistence (LP) SNP which enables digestion of lactose in adulthood was used as genetic instrument. Intake of milk was first regressed on rs4988235 in a linear regression model. Next, associations of genetically predicted milk consumption with stroke and CHD were estimated using Prentice-weighted Cox regression. Gene-outcome analysis included 777 024 participants (50 804 cases) from MEGASTROKE (including EPIC-CVD), UK Biobank and EPIC-NL for stroke, and 483 966 participants (61 612 cases) from CARDIoGRAM, UK Biobank, EPIC-CVD and EPIC-NL for CHD. In IV analyses, each additional LP allele was associated with a higher intake of milk in EPIC-CVD (β = 13·7 g/d; 95 % CI 8·4, 19·1) and EPIC-NL (36·8 g/d; 95 % CI 20·0, 53·5). Genetically predicted milk intake was not associated with stroke (HR per 25 g/d 1·05; 95 % CI 0·94, 1·16) or CHD (1·02; 95 % CI 0·96, 1·08). In gene-outcome analyses, there was no association of rs4988235 with risk of stroke (OR 1·02; 95 % CI 0·99, 1·05) or CHD (OR 0·99; 95 % CI 0·95, 1·03). Current Mendelian randomisation analysis does not provide evidence for a causal inverse relationship between milk consumption and stroke or CHD risk.
There is an increasing interest in integrative (mental) health care and a growth in centers offering such services, but a paucity of research on patient characteristics, diagnosis, treatments offered, the effects of those treatments and patient satisfaction.
Objectives
To examine the course of mental health outcomes in the context of the nature and quality of care of outpatients at a center for integrative psychiatry in the Netherlands, as well as relevant sociodemographic, clinical, and treatment-related moderators of this course.
Methods
Baseline patient demographics, clinical and treatment characteristics of 537 patients with a completed care episode between 2012 and 2019 were assessed. Satisfaction and mental health treatment outcomes were examined using routine outcome monitoring and analyzed with multilevel intention-to-treat models.
Results
Two thirds of patients were woman (median age 41 years), predominantly with a primary diagnosis of mood or anxiety disorder. Mean number of treatment sessions was 49 (SD=94) and total clinical time was 54 hours (SD=109). Mean treatment duration was 460 days (SD=407). Ninety percent of the sample filled out one or more assessment(s). Of the individuals with a baseline assessment, 50% completed a follow-up. Significant improvements in symptomatology, social functioning, interpersonal functioning, wellbeing, resilience and quality of life were found. Clinical and scientific interpretation, moderator analyses and patient satisfaction will be presented at the conference.
Conclusions
Although no definite conclusions can be drawn due to the naturalistic design and missing data, especially at follow-up, patients seem to improve on all measured domains, including psychopathology, functioning and wellbeing.
Recovery in schizophrenia is a complex process, involving clinical, societal and personal recovery. Until now, studies analysed these domains separately, without examining their mutual relations and changes over time.
Aims
This study aimed to examine different states of recovery and transition rates between states.
Method
The Pharmacotherapy Monitoring and Outcome Survey (2006–2017) yearly assesses patients with schizophrenia in the Northern Netherlands. Data from 2327 patients with one up to 11 yearly measurements on clinical, societal and personal recovery were jointly analysed with a mixture latent Markov model (MLMM).
Results
The selected MLMM had four states that differed in degree and pattern of recovery outcomes. Patients in state 1 were least recovered on any domain (16% of measurements), and partly recovered in states 2 (25%; featured by negative symptoms) and 3 (21%; featured by positive symptoms). Patients in state 4 (38%) were most recovered, except for work, study and housekeeping. At the subsequent measurement, the probability of remaining in the same state was 77–89%, transitioning to a better state was 4–12% and transitioning to a worse state was 4–6%; no transitions occurred between states 1 and 4. Female gender, shorter illness duration and less schizophrenia were more prevalent in better states.
Conclusions
Quite a high recovery rate was present among a substantial part of the measurements (38%, state 4), with a high probability (89%) of remaining in this state. Transition rates in the other states might increase to a more favourable state by focusing on adequate treatment of negative and positive symptoms and societal problems.
Purine metabolism encompasses the metabolic pathways involved in the synthesis, interconversion, salvage, and degradation of purine-based nucleosides and nucleotides. These metabolic pathways are involved in many essential cellular processes, including energy transfer, oxidative phosphorylation, synthesis of DNA and RNA, and signal transduction. A nucleoside is a nitrogenous base linked to a 5-carbon sugar (either ribose or deoxyribose). For purines, this nitrogenous base is either adenine, guanine, or hypoxanthine. When nucleosides are covalently linked to one or more phosphate groups, they are referred to as nucleotides.
Suicide remains the leading cause of premature death in patients with psychotic disorders. The lifetime suicide risk for schizophrenia is approximately 10%.
Objectives
This study aims to compare the suicide risk over the past decade following recent onset psychosis to findings from the eighties and nineties in the same catchment area and to identify predictors of suicide in the context of the Psychosis Recent Onset Groningen – Survey (PROGR-S).
Methods
A medical file search was carried out to determine the current status of all patients admitted between 2000 and 2009. The suicide rate was compared with a study executed in 1973-1988 in the same catchment area. Predictors of suicide were investigated using Cox regression.
Results
The status of 424 of the 614 patients was known in July 2014. Suicide occurred in 2.4% of the patients with psychotic disorders (n=10; mean follow-up 5.6 years); 6 out of 10 suicides took place within two years. Within two decades, the suicide rate dropped from 11% (follow-up 15 years, 8.5% after 5 years) to 2.4%. The Standardized Mortality Rate (SMR) of suicides compared with the general population was 41.6. A higher age was the only significant predictor for suicide. Neuroticism, living situation, disorganized and negative symptoms, and passive coping style showed a trend for significance. A significant reduction in the suicide rate was found for people with psychosis over the past decades.
Conclusions
A considerable drop in suicide rate was found. Given the high SMR, suicide research should have the highest priority.
In the Netherlands, there is an increased incidence of non-affective psychotic disorders (NAPD) among first- and second-generation migrants from Turkey, Morocco, Surinam and the Netherlands Antilles.
Objectives/aims:
The purpose of this population-based study was to compare the risk of suicide in Dutch natives and immigrants with or without NAPD. We examined the influence of NAPD, ethnicity and history of migration (first or second generation).
Methods:
Cases of NAPD (n = 12,580) from three Dutch psychiatric registers were linked to the cause of death register of Statistics Netherlands and compared to matched controls (n = 124,547) from the population register, who had no such diagnosis. Hazard ratios (HRs) of suicide were estimated and adjusted for age and gender by Cox regression analysis.
Results:
The presence of NAPD was strongly associated with suicide risk in each ethnic group.
However, for most ethnic minority groups the HRs were somewhat lower than among Dutch natives, for whom the HR was 30.4 (95%; 22.8–40.7). A closer examination revealed that suicide risk was influenced by history of migration. While the risk for immigrants of the first generation, diagnosed with NAPD, was significantly lower than that for native Dutch patients (HR = 0.44; 95% CI: 0.27–0.72), the risk for those of the second generation was similar to that for the Dutch (HR = 0.81; 95% CI: 0.48–1.38). The same pattern was found among first- and second-generation immigrants not diagnosed with NAPD.
Conclusion:
Immigrants of the first generation appear to be protected against suicide, whereas this protection is waning among those of the second generation.
Studies in the general population show cannabis use has a beneficial effect on metabolic disorders. Given the increased cardiometabolic risk in patients with psychotic disorders, as well as their prevalent use of cannabis, we aim to investigate whether such effects are also evident in these patients.
Method
3176 patients with chronic psychotic disorders from mental health institutions in the Netherlands were included in the study. With multivariate regression analyses we examined the effects of cannabis use on metabolic risk factors; BMI, waist circumference, blood pressure (BP), cholesterol, HDL-C, LDL-C, triglycerides, glucose and HbA1c. Age, sex, smoking, alcohol use and antipsychotic drugs were included as confounders. Next, we examined change in metabolic risk factors after one-year follow up for cannabis users, non-users, discontinuers and starters.
Results
We found a significant negative association between cannabis use and BMI (p=0.003), waist circumference (p>0.001), diastolic BP (p=0.015) and HbA1c (0.004). One year later, patients who had discontinued their cannabis use had a greater increase of BMI (p=0.002) and waist circumference (p=0.011) than other patients. They also had a greater increase of diastolic BP than non-users (p=0.036) or starters (p=0.004).
Conclusion
Discontinuation of cannabis use increased metabolic risk. To stop cannabis use is often an important treatment goal, because it reduces psychotic symptoms. However, physicians should be aware of the increased metabolic risk in patients who discontinue the use of cannabis. Extra attention should be paid to monitoring and treatment of metabolic parameters in these patients to prevent cardiovascular diseases and premature cardiovascular mortality.
There is a large mortality gap between patients with a non-affective psychotic disorder (NAPD) and the general population.
Objectives
To assess whether mortality risks vary for different death causes according to duration since diagnosis and age in a large sample of NAPD patients.
Aims
To get insight into the risk of specific death causes along the treatment trajectory, important for interventions that are tailored to the patients' risk profile.
Methods
Data of NAPD patients (n=12,580) from three Dutch psychiatric registers were linked to the registers of Statistics Netherlands and compared to personally matched controls (n=124,143). Death rates were analysed by duration since the date of diagnosis of the (matched) patient and age using Poisson regression.
Results
Among patients, the rates of all-cause death decreased with longer duration. This was explained by lower suicide rates. E.g., among those aged 40-60 years, the rate ratios (RRs) of suicide during 2-5 and >5 years compared to the early years after diagnosis were 0.52 and 0.46 (P=0.002). Compared with controls, patients experienced higher rates of natural death causes during all stages and in all age categories: RRs 2.35-5.04, P < 0.05. No increase in these RRs for patients compared to controls with increasing duration or increasing age was found.
Conclusions
The high risk of natural death causes among NAPD patients is not (only) an effect of accumulating risks induced by the chronic nature of the disorder and/or antipsychotic treatment, but is already present during the early stages of the treatment and at young age.
In adolescence, help-seeking is affected by different actors. The influence of each actor on help-seeking is often studied in isolation, or, if multiple informants are included, using only few assessments of adolescents’ mental health.
Objectives
The aim of this study is to determine the extent to which self-, parent- and teacher-reported problem behavior predict secondary care in adolescence and to what extent the informants’ relative importance changes over time.
Methods
Data from the Dutch community-based cohort study tracking adolescents’ individual lives survey (TRAILS) were linked to administrative records of secondary care from 2000 (age 9) to 2011 (age 21). Internalizing and externalizing problems were assessed using the youth self-report, child behavior checklist and teacher checklist of psychopathology at ages 11, 13 and 16, and the adult self-report at age 19.
Results
The annual incidence of secondary care fluctuated between 1.3% and 2.4%. In Cox regression analyses that adjusted for sociodemographic covariates and problem behavior, internalizing problems but not externalizing problems predicted secondary care. Secondary care between the ages 11 to 13 years was predicted best by teachers, between the ages 13 to 16 by parents, and between the ages 16 to 21 by adolescents.
Conclusions
The relative importance of informants for predicting secondary care shifts over time, which suggests that each informant is the driving force behind secondary care at a different phase of adolescence. The treatment gap may be reduced by improving problem recognition of teachers in secondary education and by educating young adults about mental health problems.
Disclosure of interest
The authors have not supplied their declaration of competing interest.
Multidisciplinary guidelines in adolescent mental health care are based on RCTs, while treatment efficacy can be different from effectiveness seen in ‘the real world’. Studies in the real world conducted so far suggest that treatment has a negligible effect on follow-up symptomatology. However, these studies did not incorporate the pre-treatment trajectory of symptoms nor investigated a dose-response relationship.
Objectives
To test whether future treatment users and non-users differed in emotional and behavioural problem scores, whether specialist mental health treatment (SMHT) was effective in reducing problem levels while controlling for pre-treatment trajectory, and to seek evidence of a dose-response relationship.
Methods
Six-year follow up data were used from the Tracking Adolescents’ Individual Lives Survey (TRAILS). We identified adolescents with a clinical level of problem behaviour on the Child Behaviour Checklist or Youth Self Report and first SMHT between the ages 13 and 16. Adolescents with a clinical level of problem behaviour but without SMHT use served as control group. A psychiatric case register provided data on number of treatment contacts. Using regression analysis, we predicted the effect of treatment on post-treatment problem scores.
Results
Treated adolescents more often had a (severe) diagnosis than untreated adolescents. Pre-treatment trajectories barely differed between treated and untreated adolescents. Treatment predicted an increase in follow-up problem scores, regardless of the number of sessions.
Conclusion
The quasi-experimental design calls for modest conclusions. We might however need to take a closer look at real-world service delivery, and invest in developing treatments that can achieve sustainable benefits.
Disclosure of interest
The authors have not supplied their declaration of competing interest.
To gain insight in Dutch food bank recipients’ perception on the content of the food parcels, their dietary intake and how the parcels contribute to their overall dietary intake.
Design:
Eleven semi-structured focus group discussions were conducted. Focus group topics were based on Andersons food insecurity definition: the lack of availability of nutritionally adequate foods and the assured ability to acquire foods in socially acceptable ways. Data were coded and analysed with Atlas.ti 7.0 software, using the framework approach.
Setting:
Seven food banks throughout the Netherlands.
Participants:
A total of 44 Dutch food bank recipients.
Results:
Food bank recipients were not always satisfied with the amount, quality, variation and type of foods in the food parcel. For the participants who could afford to, supplementing the food parcel was reported as main reason for buying foods, and price was the most important aspect in selecting these foods. Participants were not satisfied with their dietary intake; they mainly reported not having enough to eat. The content of the food parcel importantly influenced participants’ overall dietary intake. Finally, participants reported struggling with their feelings of dissatisfaction, while also being grateful for the foods they receive.
Conclusions:
This study suggests that, despite their best efforts, food banks are not meeting food bank recipients’ needs. Our results provide valuable directions for improving the content of the food parcels by increasing the quantity, quality and variation in the foods supplied. Whether this also improves the dietary intake of recipients needs to be determined.
Review findings on the role of dietary patterns in preventing depression are inconsistent, possibly due to variation in assessment of dietary exposure and depression. We studied the association between dietary patterns and depressive symptoms in six population-based cohorts and meta-analysed the findings using a standardised approach that defined dietary exposure, depression assessment and covariates.
Methods
Included were cross-sectional data from 23 026 participants in six cohorts: InCHIANTI (Italy), LASA, NESDA, HELIUS (the Netherlands), ALSWH (Australia) and Whitehall II (UK). Analysis of incidence was based on three cohorts with repeated measures of depressive symptoms at 5–6 years of follow-up in 10 721 participants: Whitehall II, InCHIANTI, ALSWH. Three a priori dietary patterns, Mediterranean diet score (MDS), Alternative Healthy Eating Index (AHEI-2010), and the Dietary Approaches to Stop Hypertension (DASH) diet were investigated in relation to depressive symptoms. Analyses at the cohort-level adjusted for a fixed set of confounders, meta-analysis used a random-effects model.
Results
Cross-sectional and prospective analyses showed statistically significant inverse associations of the three dietary patterns with depressive symptoms (continuous and dichotomous). In cross-sectional analysis, the association of diet with depressive symptoms using a cut-off yielded an adjusted OR of 0.87 (95% confidence interval 0.84–0.91) for MDS, 0.93 (0.88–0.98) for AHEI-2010, and 0.94 (0.87–1.01) for DASH. Similar associations were observed prospectively: 0.88 (0.80–0.96) for MDS; 0.95 (0.84–1.06) for AHEI-2010; 0.90 (0.84–0.97) for DASH.
Conclusion
Population-scale observational evidence indicates that adults following a healthy dietary pattern have fewer depressive symptoms and lower risk of developing depressive symptoms.
Emotion regulation dysfunction is characteristic of psychotic disorders, but little is known about how the use of specific types of emotion regulation strategies differs across phases of psychotic illness. This information is vital for understanding factors contributing to psychosis vulnerability states and developing targeted treatments. Three studies were conducted to examine emotion regulation across phases of psychosis, which included (a) adolescent community members with psychotic-like experiences (PLEs; n = 262) and adolescents without PLEs (n = 1,226); (b) adolescents who met clinical high-risk criteria for a prodromal syndrome (n = 29) and healthy controls (n = 29); and (c) outpatients diagnosed with schizophrenia or schizoaffective disorder (SZ; n = 61) and healthy controls (n = 67). In each study, participants completed the Emotion Regulation Questionnaire and measures of psychiatric symptoms and functional outcome. The three psychosis groups did not differ from each other in reported use of suppression; however, there was evidence for a vulnerability-related, dose-dependent decrease in reappraisal. Across each sample, a lower use of reappraisal was associated with poorer clinical outcomes. Findings indicate that emotion regulation abnormalities occur across a continuum of psychosis vulnerability and represent important targets for intervention.
This study investigated bidirectional associations between intake of food groups and depressive symptoms in 1058 Italian participants (aged 20–102 years) of the Invecchiare in Chianti study. Dietary intake, assessed with a validated FFQ, and depressive symptoms, measured with the Center for Epidemiologic Studies Depression scale (CES-D), were assessed at baseline and after 3, 6 and 9 years. Associations of repeated measurements of intakes of thirteen food groups with 3-year changes in depressive symptoms, and vice versa, were analysed using linear mixed models and logistic generalised estimating equations. Fish intake was inversely (quartile (Q)4 v. Q1, B=–0·97, 95 % CI –1·74, –0·21) and sweet food intake positively (Q4 v. Q1, B=1·03, 95 % CI 0·25, 1·81) associated with subsequent CES-D score. In the other direction, higher CES-D scores were associated with decreases in intakes of vegetables (ratio: 0·995, 95 % CI 0·990, 0·999) and red and processed meat (B=–0·006, 95 % CI –0·010, –0·001), an increase in dairy product intake (ratio: 1·008, 95 % CI 1·004, 1·013), and increasing odds of eating savoury snacks (OR: 1·012, 95 % CI 1·000, 1·024). Fruit, nuts and legumes, potatoes, wholegrain bread, olive oil, sugar-sweetened beverages, and coffee and tea were not significantly associated in either direction. Our study confirmed bidirectional associations between food group intakes and depressive symptoms. Fish and sweet food intakes were associated with 3-year improvement and deterioration in depressive symptoms, respectively. Depressive symptoms were associated with 3-year changes in vegetable, meat, dairy product and savoury snack intakes. Trials are necessary to examine the causal associations between food groups and depression.
Individuals with autism spectrum disorder (ASD) appear to be at increased risk of non-affective psychotic disorder (NAPD) and bipolar disorder (BD). However, most previous studies examined the co-occurrence of ASD and NAPD or BD, ignoring possible diagnostic bias and selection bias. We used longitudinal data from Dutch psychiatric case registers to assess the risk of NAPD or BD among individuals with ASD, and compared the results to those obtained for the Dutch population in earlier studies.
Methods
Individuals with ASD (n = 17 234) were followed up between 16 and 35 years of age. Kaplan–Meier estimates were used to calculate the risk of NAPD or BD. We conducted separate analyses to reduce possible bias, including an analysis among individuals diagnosed with ASD before age 16 years (n = 8337).
Results
Of the individuals with ASD, 23.50% (95% confidence interval 21.87–25.22) were diagnosed with NAPD and 3.79% (3.06–4.69) with BD before age 35 years. The corresponding figures for the general population were 0.91% (0.63–1.28) and 0.13% (0.08–0.20). Risk estimates were substantially lower, but still higher than general population estimates, when we restricted our analyses to individuals diagnosed with ASD before age 16, with 1.87% (1.33–2.61) being diagnosed with NAPD and 0.57% (0.21–1.53) with BD before age 25 years. The corresponding figures for the general population were 0.63% (0.44–0.86) and 0.08% (0.05–0.12).
Conclusions
Individuals with ASD are at increased risk of NAPD or BD. This is likely not the result of diagnostic or selection bias.
To investigate socio-economic differences in changes in fruit and vegetable intake between 2004 and 2011 and explore the mediating role of financial barriers in this change.
Design
Respondents completed a self-reported questionnaire in 2004 and 2011, including questions on fruit and vegetable intake (frequency per week), indicators of socio-economic position (education, income) and perceived financial barriers (fruits/vegetables are expensive, financial distress). Associations were analysed using ordinal logistic regression. The mediating role of financial barriers in the association between socio-economic position and change in fruit and vegetable intake was studied with the Baron and Kenny approach.
Setting
Longitudinal GLOBE study.
Subjects
A total of 2978 Dutch adults aged 25–75 years.
Results
Respondents with the lowest income in 2004 were more likely to report a decrease in intake of cooked vegetables (P-trend<0·001) and raw vegetables (P-trend<0·001) between 2004 and 2011, compared with those with the highest income level. Respondents with the lowest education level in 2004 were more likely to report a decrease in intake of fruits (P-trend=0·021), cooked vegetables (P-trend=0·033), raw vegetables (P-trend<0·001) and fruit juice (P-trend=0·027) between 2004 and 2011, compared with those with the highest education level. Financial barriers partially mediated the association between income and education and the decrease in fruit and cooked vegetable intake between 2004 and 2011.
Conclusions
These results show a widening of relative income and educational differences in fruit and vegetable intake between 2004 and 2011. Financial barriers explained a small part of this widening.
The major histocompatibility complex region has been implicated in explaining some of the variation observed in adaptability and tick susceptibility of cattle. The bovine leukocyte antigen region of 192 cattle representing indigenous, composite and exotic breeds used in commercial beef production in Namibia and South Africa was investigated using four microsatellite markers. Ticks counted under the tail were taken as an indicator of tick susceptibility. Tick scores of all but one population was low (11 to 20 ticks), with only the South African Bonsmara population having an average score of 31 to 40 ticks per animal. The observed variation based on four microsatellite markers ranged from 5.5 alleles in Namibian Afrikaner to 7.7 alleles in South African Nguni and Bonsmara cattle. Unbiased heterozygosity values ranged from 0.66 (Namibian Afrikaner) to 0.76 (South African Bonsmara). Structure analyses grouped the five populations into three indistinct clusters with limited genetic variation between the populations.
The most popular beef breed in South Africa is the Bonsmara, a locally developed composite breed adapted to sub-tropical conditions. The establishment of a genomic reference population is currently ongoing for the application of genomic selection. To date, 583 Bonsmara cattle (388 bulls and 195 cows) have been genotyped with the GeneSeek® Genomic Profiler Bovine HD™ Chip (GGP-HD) 80 K chip, and the population structure of the reference population was studied. The average minor allele frequency for the Bonsmara was 0.280 across 56 248 autosomal single-nucleotide polymorphisms (SNPs), whereas the observed and expected heterozygosity values were 0.361 and 0.365, respectively. After pruning the data set for SNPs in linkage disequilibrium, 19 119 SNPs were retained, averaging 659 SNPs per autosomal chromosome. This generated an average SNP density of 1 SNP per 90 kb. Structure analysis revealed a non-homogenous population with a high level of genetic admixture, which may negatively influence genomic breeding value prediction accuracy. Genotyping of a further 990 Bonsmara cattle are pending, using the GeneSeek® GGP-HD 150 K chip. As more animals will be added to the reference population, the profile of the reference population are expected to change in such a way to ensure improved genomic estimated breeding value accuracies.