Sarah Berry

Estimation of genetic and crossbreeding parameters of fatty acid concentrations in milk fat predicted by mid-infrared spectroscopy in New Zealand dairy cattle.

The objective of this study was to estimate heritability and crossbreeding parameters (breed and heterosis effects) of various fatty acid (FA) concentrations in milk fat of New Zealand dairy cattle. For this purpose, calibration equations to predict concentration of each of the most common FAs were derived with partial least squares (PLS) using mid-infrared (MIR) spectral data from milk samples (n=850) collected in the 2003-04 season from 348 second-parity crossbred cows during peak, mid and late lactation. The milk samples produced both, MIR spectral data and concentration of the most common FAs determined using gas chromatography (GC). The concordance correlation coefficients (CCC) between the concentration of a FA determined by GC and the PLS equation ranged from 0.63 to 0.94, suggesting that some prediction equations can be considered to have substantial predictive ability. The PLS calibration equations were then used to predict the concentration of each of the fatty acids in 26,769 milk samples from 7385 cows that were herd-tested during the 2007-08 season. Data were analysed using a single-trait repeatability animal model. Shorter chain FA (16:0 and below) were significantly higher (P<0.05) in Jersey cows, while longer chain, including unsaturated longer chain FA were higher in Holstein-Friesian cows. The estimates of heritabilities ranged from 0.17 to 0.41 suggesting that selective breeding could be used to ensure milk fat composition stays aligned to consumer, market and manufacturing needs.

Phenotypic population screen identifies a new mutation in bovine DGAT1 responsible for unsaturated milk fat

Selective breeding has strongly reduced the genetic diversity in livestock species, and contemporary breeding practices exclude potentially beneficial rare genetic variation from the future gene pool. Here we test whether important traits arising by new mutations can be identified and rescued in highly selected populations. We screened milks from 2.5 million cows to identify an exceptional individual which produced milk with reduced saturated fat content, and improved unsaturated and omega-3 fatty acid concentrations. The milk traits were transmitted dominantly to her offspring, and genetic mapping and genome sequencing revealed a new mutation in a previously unknown splice enhancer of the DGAT1 gene. Homozygous carriers show features of human diarrheal disorders, and may be useful for the development of therapeutic strategies. Our study demonstrates that high-throughput phenotypic screening can uncover rich genetic diversity even in inbred populations, and introduces a novel strategy to develop novel milks with improved nutritional properties.

Widespread prevalence of a CREBRF variant amongst Māori and Pacific children is associated with weight and height in early childhood

Objective:Investigating a large and ethnically diverse cohort from the Pacific region, we aimed to replicate and extend the recently reported findings that a CREBRF genetic variant is strongly associated with body mass index in Samoans.Methods:A birth cohort of more than six thousand children was utilised. In this study, genotyping of two markers (rs12513649 and rs373863828) was undertaken in Māori, Pacific, European and Asian individuals in the cohort.Results:We report that these CREBRF genetic variants are not confined to Samoans but are prevalent in all other Pacific populations sampled, including Māori. We found that the rs373863828 variant was significantly associated with growth at 4 years of age. On average, we observed allele-specific increases in weight (P=0·004, +455u2009g, s.e. 0.158), height (P=0·007, +0·70u2009cm, s.e. 0.26) and waist circumference (P=0·004, +0·70u2009cm, s.e. 0.24) at 4 years of age. The rs373863828 variant was not associated with birth weight (P=0·129).Conclusions:We replicated the finding that a CREBRF variant is associated with increased body mass. We then built on the original findings by demonstrating the prevalence of the rs12513649 and rs373863828 variants in multiple Pacific population groups and by demonstrating that the rs373863828 variant is associated with growth in early childhood. Pacific population groups experience a disproportionately high burden of obesity, starting in early childhood. This new knowledge offers potential for evidence-based interventions aimed at establishing healthy growth trajectories from the earliest possible age.

Antibiotic consumption by New Zealand children: exposure is near universal by the age of 5 years

BackgroundnIncreasing concerns about antibiotic resistance and microbiome disruption have stimulated interest in describing antibiotic consumption in young children. Young children are an age group for whom antibiotics are frequently prescribed.nnnObjectivesnTo describe community antibiotic dispensing during the first 5u2009years of life in a large, socioeconomically and ethnically diverse cohort of children, and to determine how antibiotic dispensing varied between population subgroups.nnnMethodsnThis study was performed within the Growing Up in New Zealand longitudinal cohort study ( www.growingup.co.nz ) with linkage to national administrative antibiotic dispensing data. Descriptive statistics and univariate and multivariable associations were determined.nnnResultsnThe 5581 cohort children received 53u2009052 antibiotic courses, of which 54% were amoxicillin. By age 5u2009years, 97% of children had received one or more antibiotic courses, and each child had received a median of eight antibiotic courses (IQR 4-13). The mean incidence of antibiotic dispensing was 1.9u2009courses/child/year. Multivariable negative binomial regression showed that Māori and Pacific children received more antibiotic courses than European children, as did children in the most-deprived compared with the least-deprived areas. A distinct seasonal pattern was noted.nnnConclusionsnThis study provided a detailed description of antibiotic dispensing within a large and diverse child cohort. Antibiotic exposure was near universal by age 5u2009years. The predominance of amoxicillin use and the seasonal pattern suggest much antibiotic use may have been for self-limiting respiratory infections. There is a need for safe and effective interventions to improve antibiotic prescribing practices for New Zealand children.

Internal living environment and respiratory disease in children: Findings from the Growing Up in New Zealand longitudinal child cohort study

BackgroundThe incidence of early childhood acute respiratory infections (ARIs) has been associated with aspects of the indoor environment. In recent years, public awareness about some of these environmental issues has increased, including new laws and subsequent changes in occupant behaviours. This New Zealand study investigated current exposures to specific risk factors in the home during the first five years of life and provided updated evidence on the links between the home environment and childhood ARI hospitalisation.MethodsPregnant women (nu2009=u20096822) were recruited in 2009 and 2010, and their 6853 children created a child cohort that was representative of New Zealand births from 2007-10. Longitudinal data were collected through face-to-face interviews and linkage to routinely collected national datasets. Incidence rates with Poisson distribution confidence intervals were computed and Cox regression modelling for repeated events was performed.ResultsLiving in a rented dwelling (48%), household crowding (22%) or dampness (20%); and, in the child’s room, heavy condensation (20%) or mould or mildew on walls or ceilings (13%) were prevalent. In 14% of the households, the mother smoked cigarettes and in 30%, other household members smoked. Electric heaters were commonly used, followed by wood, flued gas and unflued portable gas heaters. The incidence of ARI hospitalisation before age five years was 33/1000 person-years. The risk of ARI hospitalisation was higher for children living in households where there was a gas heater in the child’s bedroom: hazard ratio for flued gas heater 1.69 (95% CI: 1.21-2.36); and for unflued gas heater 1.68 (95% CI: 1.12-2.53); and where a gas heater was the sole type of household heating (hazard ratio: 1.64 (95% CI: 1.29-2.09)). The risk was reduced in households that used electric heaters (Hazard ratio: 0.74 (95% CI: 0.61-0.89)) or wood burners (hazard ratio: 0.79 (95% CI: 0.66-0.93)) as a form of household heating. The associations with other risk factors were not significant.ConclusionsThe risk of early childhood ARI hospitalisation is increased by gas heater usage, specifically in the child’s bedroom. Use of non-gas forms of heating may reduce the risk of early childhood ARI hospitalisation.

Staphylococcus aureus colonisation and its relationship with skin and soft tissue infection in New Zealand children

New Zealand children suffer from high rates of skin and soft tissue infection (SSTI). Staphylococcus aureus colonisation is known to increase the risk of nosocomial infection. We aimed to determine whether S. aureus colonisation also increased the risk of community-onset SSTI. This study, performed within the Growing Up in New Zealand cohort, used interview and administrative data, and bacterial culture results from the nose, throat, and skin swabs collected at 4½xa0years of age. Multivariable log-binomial regression was used to derive adjusted risk ratios. S. aureus was isolated from 2225/5126 (43.4%) children. SSTI affected 1509/5126 (29.4%) children before age five. S. aureus colonisation at any site was associated with SSTI (aRRu2009=u20091.09, 95%CI 1.01–1.19), particularly in the year prior to swab collection (aRRu2009=u20091.18, 95%CI 1.02–1.37). The strongest association was between skin colonisation and SSTI within the year prior to swab collection (aRRu2009=u20091.47, 95%CI 1.14–1.84). Socioeconomic and ethnic variables remained independent determinants of SSTI. S. aureus colonisation was associated with an increased risk of community-onset SSTI. Socioeconomic and ethnic factors and eczema had independent effects on SSTI risk. Interventions which reduce the prevalence of S. aureus colonisation may be expected to reduce the incidence of community-onset SSTI.

Quantitation of 25-hydroxyvitamin D in dried blood spots by 2D LC-MS/MS without derivatization and correlation with serum in adult and pediatric studies

BACKGROUNDnDemand for measurement of 25-hydroxyvitamin D (25OHD) is growing and dried blood spot (DBS) sampling is attractive as samples are easier to collect, transport and store.nnnMETHODSnA 2D LC-MS/MS assay without derivatization was developed. DBS punches (3.2u202fmm) were ultrasonicated with d6-25OHD3 in 70% methanol followed by hexane extraction, dry-down and reconstitution. The assay was validated and applied to two studies comparing whole blood adult DBS with serum samples (nu202f=u202f40) and neonatal whole blood DBS with cord serum samples (nu202f=u202f80).nnnRESULTSnThe assay was validated in whole blood DBS over the range 13-106u202fnmol/L 25OHD3 and 11-91u202fnmol/L 25OHD2 with a limit of detection of 3u202fnmol/L. Intra- and inter-day imprecision was <13% CV and bias <12%. The assay had high recovery and minimal matrix effects. Triplicate DBS study samples had a mean CV of ≤13% for 25OHD3. No 25OHD2 was detected. DBS calculated serum 25OHD3 concentrations correlated strongly with serum concentrations in the adult DBS/serum study (ru202f=u202f0.94) and moderately in the neonatal DBS/cord serum study (ru202f=u202f0.69).nnnCONCLUSIONSnDirect quantitation of 25OHD in DBS by 2D LC-MS/MS without derivatization was found to be an alternative to serum quantitation applicable to clinical research studies on adult DBS samples.

Emergency department visits of young children and long-term exposure to neighbourhood smoke from household heating ??? The Growing Up in New Zealand child cohort study

In developed countries, exposure to wood or coal smoke occurs predominantly from neighbourhood emissions arising from household heating. The effect of this exposure on child health is not well characterized. Within a birth cohort study in New Zealand we assessed healthcare events associated with exposure to neighbourhood smoke from household heating. Our outcome measure was non-accidental presentations to hospital emergency departments (ED) before age three years. We matched small area-level census information with the geocoded home locations to measure the density of household heating with wood or coal in the neighbourhood and applied a time-weighted average exposure method to account for residential mobility. We then used hierarchical multiple logistic regression to assess the independence of associations of this exposure with ED presentations adjusted for gender, ethnicity, birth weight, breastfeeding, immunizations, number of co-habiting smokers, wood or coal heating at home, bedroom mold, household- and area-level deprivation and rurality. The adjusted odds ratio of having a non-accidental ED visit was 1.07 [95%CI: 1.03-1.12] per wood or coal heating household per hectare. We found a linear dose-response relationship (p-value for trendxa0=xa00.024) between the quartiles of exposure (1st as reference) and the same outcome (odds ratio in 2nd to 4th quartiles: 1.14 [0.95-1.37], 1.28 [1.06-1.54], 1.32 [1.09-1.60]). Exposure to neighbourhoods with higher density of wood or coal smoke-producing households is associated with an increased odds of ED visits during early childhood. Policies that reduce smoke pollution from domestic heating by as little as one household per hectare using solid fuel burners could improve child health.

Housing tenure as a focus for reducing inequalities in the home safety environment: evidence from Growing Up in New Zealand

Objectives: To determine whether specific demographic characteristics are associated with the presence or absence of household safety strategies.