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Worldwide milk production is predominantly founded on indoor, high‐concentrate feeding systems, whereas pasture‐based feeding systems are most common in New Zealand and Ireland but have received greater attention recently in countries utilizing conventional systems. Consumer interest in 'pasture‐fed' dairy products has also increased, arising from environmental, ethical, and nutritional concerns. A substantial body of research exists describing the effect of different feeding strategies on the composition of milk, with several recent studies focusing on the comparison of pasture‐ and concentrate‐based feeding regimes. Significant variation is typically observed in the gross composition of milk produced from different supplemental feeds, but various changes in the discrete composition of macromolecular components in milk have also been associated with dietary influence, particularly in relation to the fatty acid profile. Changes in milk composition have also been shown to have implications for milk and dairy product processability, functionality and sensory properties. Methods to determine the traceability of dairy products or verify marketing claims such as 'pasture‐fed' have also been established, based on compositional variation due to diet. This review explores the effects of feed types on milk composition and quality, along with the ultimate effect of diet‐induced changes on milk and dairy product functionality, with particular emphasis placed on pasture‐ and concentrate‐based feeding systems. [ABSTRACT FROM AUTHOR]

The effect of preheat temperature (63 or 77 °C for 30 s; final heat 120 °C for 30 s) and casein to whey protein ratio on the physical characteristics of 3.3%, w/w, dairy protein beverages was investigated. Dispersions preheated at 77 °C had lower viscosity than dispersions preheated at 63 °C. Casein‐containing dispersions had significantly lower levels of α‐lactalbumin denaturation than whey protein‐only dispersions. A higher proportion of casein improved the thermal stability of protein dispersions. Overall, alteration of preheat temperature and casein to whey protein ratio can influence dairy beverage quality, with increasing levels of casein reducing physical changes due to heat treatment. [ABSTRACT FROM AUTHOR]

Milk and dairy products are comprised of a complex matrix of components that can interfere with analysis and, as a result, are often not suitable for direct introduction into analytical instruments. Energy‐dispersive X‐ray fluorescence spectrometry (EDXRF) can bypass time‐consuming preparation steps, with potential for rapid, onsite analysis of minerals. In this study, five major milk minerals, sodium, magnesium, potassium, phosphorus and calcium, were quantified in dairy powders, using EDXRF, and the systemic bias of the method was evaluated by Bland–Altman analysis. No significant systemic bias was observed for the quantification of sodium, magnesium, potassium and phosphorus, meaning that EDXRF has potential to be used as a rapid offline analytical technology suitable for the analysis of these minerals in skim milk powders. [ABSTRACT FROM AUTHOR]

The genetic structure of bacterial populations can be related to geographical locations of isolation. In some species, there is a strong correlation between geographical distance and genetic distance, which can be caused by different evolutionary mechanisms. Patterns of ancient admixture in Helicobacter pylori can be reconstructed in concordance with past human migration, whereas in Mycobacterium tuberculosis it is the lack of recombination that causes allopatric clusters. In Campylobacter, analyses of genomic data and molecular typing have been successful in determining the reservoir host species, but not geographical origin. We investigated biogeographical variation in highly recombining genes to determine the extent of clustering between genomes from geographically distinct Campylobacter populations. Whole-genome sequences from 294 Campylobacter isolates from North America and the UK were analysed. Isolates from within the same country shared more recently recombined DNA than isolates from different countries. Using 15 UK/American closely matched pairs of isolates that shared ancestors, we identify regions that have frequently and recently recombined to test their correlation with geographical origin. The seven genes that demonstrated the greatest clustering by geography were used in an attribution model to infer geographical origin which was tested using a further 383 UK clinical isolates to detect signatures of recent foreign travel. Patient records indicated that in 46 cases, travel abroad had occurred <2 weeks prior to sampling, and genomic analysis identified that 34 (74%) of these isolates were of a non- UK origin. Identification of biogeographical markers in Campylobacter genomes will contribute to improved source attribution of clinical Campylobacter infection and inform intervention strategies to reduce campylobacteriosis. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the effects of calcium chelating agents on the dissolution and functionality of 10% (w/w) milk protein concentrate ( MPC) powder. MPC powder dissolution rate and solubility significantly ( P > 0.05) increased with addition of sodium phosphate, trisodium citrate ( TSC) and sodium hexametaphosphate ( SHMP), compared to MPC dispersions alone. Trisodium citrate and SHMP addition increased viscosity as a result of micelle swelling. However, dispersions containing SHMP showed a decrease in viscosity after prolonged time due to micelle dissociation. Overall, MPC powder dissolution was aided by the addition of calcium chelating agents. [ABSTRACT FROM AUTHOR]

Campylobacter jejuni is a major cause of bacterial gastroenteritis worldwide, primarily associated with the consumption of contaminated poultry. C. jejuni lineages vary in host range and prevalence in human infection, suggesting differences in survival throughout the poultry processing chain. From 7343 MLST-characterised isolates, we sequenced 600 C. jejuni and C. coli isolates from various stages of poultry processing and clinical cases. A genome-wide association study (GWAS) in C. jejuni ST-21 and ST-45 complexes identified genetic elements over-represented in clinical isolates that increased in frequency throughout the poultry processing chain. Disease-associated SNPs were distinct in these complexes, sometimes organised in haplotype blocks. The function of genes containing associated elements was investigated, demonstrating roles for cj1377c in formate metabolism, nuoK in aerobic survival and oxidative respiration, and cj1368-70 in nucleotide salvage. This work demonstrates the utility of GWAS for investigating transmission in natural zoonotic pathogen populations and provides evidence that major C. jejuni lineages have distinct genotypes associated with survival, within the host specific niche, from farm to fork. [ABSTRACT FROM AUTHOR]

The contribution of wild birds as a source of human campylobacteriosis was investigated in Oxfordshire, United Kingdom ( UK) over a 10 year period. The probable origin of human C ampylobacter jejuni genotypes, as described by multilocus sequence typing, was estimated by comparison with reference populations of isolates from farm animals and five wild bird families, using the STRUCTURE algorithm. Wild bird-attributed isolates accounted for between 476 (2.1%) and 543 (3.5%) cases annually. This proportion did not vary significantly by study year ( P = 0.934) but varied seasonally, with wild bird-attributed genotypes comprising a greater proportion of isolates during warmer compared with cooler months ( P = 0.003). The highest proportion of wild bird-attributed illness occurred in August ( P < 0.001), with a significantly lower proportion in November ( P = 0.018). Among genotypes attributed to specific groups of wild birds, seasonality was most apparent for T urdidae-attributed isolates, which were absent during cooler, winter months. This study is consistent with some wild bird species representing a persistent source of campylobacteriosis, and contributing a distinctive seasonal pattern to disease burden. If Oxfordshire is representative of the UK as a whole in this respect, these data suggest that the national burden of wild bird-attributed isolates could be in the order of 10 000 annually. [ABSTRACT FROM AUTHOR]

This study examined the effects of total solids ( TS), preheat treatment temperature, and first- and second-stage homogenisation pressures on the stability of model infant formula emulsions, using factorial statistical design. Oil droplet size decreased with increasing first- and second-stage homogenisation pressures. The viscosity of emulsions after homogenisation was mainly affected by TS. Spray drying altered the protein profile of the interfacial layer around oil droplets compared to that posthomogenisation, but did not alter oil droplet size. This work made it possible to select optimum conditions to produce a stable infant formula emulsion, with the use of lower homogenisation pressures. [ABSTRACT FROM AUTHOR]

A free-range broiler breeder flock was studied in order to determine the natural patterns of C ampylobacter colonization over a period of 63 weeks. C ampylobacter sequence types ( STs) were not mutually exclusive and on average colonized only 17.7% of the birds tested at any time. C ampylobacter STs typically reached a peak in prevalence upon initial detection in the flock before tailing off, although the ST and antigenic flaA short variable region in combination were stable over a number of months. There was evidence that, with a couple of exceptions, the ecology of C . jejuni and C . coli differed, with the latter forming a more stable population. Despite being free range, no newly colonizing STs were detected over a 6-week period in autumn and a 10-week period in winter, towards the end of the study. There was limited evidence that those STs identified among broiler chicken flocks on the same farm site were likely to colonize the breeder flock earlier ( R2 0.16, P 0.01). These results suggest that there is natural control of C ampylobacter dynamics within a flock which could potentially be exploited in designing new intervention strategies, and that the two different species should perhaps be considered separately. [ABSTRACT FROM AUTHOR]

Zoonotic pathogens often infect several animal species, and gene flow among populations infecting different host species may affect the biological traits of the pathogen including host specificity, transmissibility and virulence. The bacterium Campylobacter jejuni is a widespread zoonotic multihost pathogen, which frequently causes gastroenteritis in humans. Poultry products are important transmission vehicles to humans, but the bacterium is common in other domestic and wild animals, particularly birds, which are a potential infection source. Population genetic studies of C. jejuni have mainly investigated isolates from humans and domestic animals, so to assess C. jejuni population structure more broadly and investigate host adaptation, 928 wild bird isolates from Europe and Australia were genotyped by multilocus sequencing and compared to the genotypes recovered from 1366 domestic animal and human isolates. Campylobacter jejuni populations from different wild bird species were distinct from each other and from those from domestic animals and humans, and the host species of wild bird was the major determinant of C. jejuni genotype, while geographic origin was of little importance. By comparison, C. jejuni differentiation was restricted between more phylogenetically diverse farm animals, indicating that domesticated animals may represent a novel niche for C. jejuni and thereby driving the evolution of those bacteria as they exploit this niche. Human disease is dominated by isolates from this novel domesticated animal niche. [ABSTRACT FROM AUTHOR]

Hybridization between distantly related organisms can facilitate rapid adaptation to novel environments, but is potentially constrained by epistatic fitness interactions among cell components. The zoonotic pathogens Campylobacter coli and C. jejuni differ from each other by around 15% at the nucleotide level, corresponding to an average of nearly 40 amino acids per protein-coding gene. Using whole genome sequencing, we show that a single C. coli lineage, which has successfully colonized an agricultural niche, has been progressively accumulating C. jejuni DNA. Members of this lineage belong to two groups, the ST-828 and ST-1150 clonal complexes. The ST-1150 complex is less frequently isolated and has undergone a substantially greater amount of introgression leading to replacement of up to 23% of the C. coli core genome as well as import of novel DNA. By contrast, the more commonly isolated ST-828 complex bacteria have 10-11% introgressed DNA, and C. jejuni and nonagricultural C. coli lineages each have <2%. Thus, the C. coli that colonize agriculture, and consequently cause most human disease, have hybrid origin, but this cross-species exchange has so far not had a substantial impact on the gene pools of either C. jejuni or nonagricultural C. coli. These findings also indicate remarkable interchangeability of basic cellular machinery after a prolonged period of independent evolution. [ABSTRACT FROM AUTHOR]

Summary Identifying the Campylobacter genotypes that colonize farmed and wild ducks will help to assess the proportion of human disease that is potentially attributable to the consumption of duck meat and environmental exposure to duck faeces. Comparison of temporally and geographically matched farmed and wild ducks showed that they had different Campylobacter populations in terms of: (i) prevalence, (ii) Campylobacter species and (iii) diversity of genotypes. Furthermore, 92.4% of Campylobacter isolates from farmed ducks were sequence types (STs) commonly associated with human disease, in contrast to just one isolate from the wild ducks. Only one ST, ST-45, was shared between the two sources, accounting for 0.9% of wild duck isolates and 5% of farmed duck isolates. These results indicate that domestic 'niche' as well as host type may affect the distribution of Campylobacter, and that husbandry practises associated with intensive agriculture may be involved in generating a reservoir of human disease associated lineages. [ABSTRACT FROM AUTHOR]

Bacterial populations can display high levels of genetic structuring but the forces that influence this are incompletely understood. Here, by combining modelling approaches with multilocus sequence data for the zoonotic pathogen Campylobacter, we investigated how ecological factors such as niche (host) separation relate to population structure. We analysed seven housekeeping genes from published C. jejuni and C. coli isolate collections from a range of food and wild animal sources as well as abiotic environments. By reconstructing genetic structure and the patterns of ancestry, we quantified C. jejuni host association, inferred ancestral populations, investigated genetic admixture in different hosts and determined the host origin of recombinant C. jejuni alleles found in hybrid C. coli lineages. Phylogenetically distinct C. jejuni lineages were associated with phylogenetically distinct wild birds. However, in the farm environment, phylogenetically distant host animals shared several C. jejuni lineages that could not be segregated according to host origin using these analyses. Furthermore, of the introgressed C. jejuni alleles found in C. coli lineages, 73% were attributed to genotypes associated with food animals. Our results are consistent with an evolutionary scenario where distinct Campylobacter lineages are associated with different host species but the ecological factors that maintain this are different in domestic animals such that phylogenetically distant animals can harbour closely related strains. [ABSTRACT FROM AUTHOR]

Campylobacter jejuni is the most common cause of bacterial gastroenteritis worldwide, with contaminated chicken meat considered to represent a major source of human infection. Biosecurity measures can reduce C. jejuni shedding rates of housed chickens, but the increasing popularity of free-range and organic meat raises the question of whether the welfare benefits of extensive production are compatible with food safety. The widespread assumption that the free-range environment contaminates extensively reared chickens has not been rigorously tested. A year-long survey of 64 free-range broiler flocks reared on two sites in Oxfordshire, UK, combining high-resolution genotyping with behavioural and environmental observations revealed: (i) no evidence of colonization of succeeding flocks by the C. jejuni genotypes shed by preceding flocks, (ii) a high degree of similarity between C. jejuni genotypes from both farm sites, (iii) no association of ranging behaviour with likelihood of Campylobacter shedding, and (iv) higher genetic differentiation between C. jejuni populations from chickens and wild birds on the same farm than between the chicken samples, human disease isolates from the same region and national samples of C. jejuni from chicken meat. [ABSTRACT FROM AUTHOR]

This study investigated the effect of modifying the mineral composition through adjustment of pH prior to ultrafiltration on the functionality of acid whey protein concentrate (WPC; pH 4.6). Increasing pH to 6.5 prior to ultrafiltration produced a concentrate with a significantly higher calcium and phosphorous content, compared to ultrafiltration at pH 4.6. WPC produced at pH 6.5 also had significantly more calcium‐phosphate precipitation following pasteurisation and evaporation and had a higher viscosity at 30% solids (300 s−1, 50°C). In addition, both reconstituted powders (5%, w/w, protein) had strong gelation properties following heat treatment at 90°C; however, the WPC produced at pH 6.5 had a significantly firmer gel strength, but such gels appeared to be more sensitive to breakage at increased frequency and oscillation strain. Overall, the pH prior to UF had a significant impact on the processing of acid whey and final product functionality. [ABSTRACT FROM AUTHOR]

The aim of this study was to utilise mid‐infrared spectroscopy with fatty acid (FA) predictions to characterise the seasonality‐associated changes to the FA profile of milk from Irish spring‐calving pasture‐based dairy cow production systems. A total of 546 454 individual milk records were collected from the Years 2015 to 2020, from 264 003 cows in 2400 commercial dairy farms. Significant changes occur to the predicted FA profile of milk across the year, such as increases in unsaturated FAs including C18:1 n‐9 until April. This can be associated with the increasing proportion of fresh pasture in the cows' diet, and a decrease between September and October as the cows begin to transition indoors for the winter period. The opposite trend was noted for saturated FAs and in particular C16:0, where proportions decreased until April and increased between September and November. Milk produced between April and September also coincided with the lowest spreadability index, indicating a more beneficial milk FA profile for more spreadable butter texture during this period. This work provides a valuable reference resource at a national level of the FA profile of milk from pasture‐based spring‐calving dairy systems. [ABSTRACT FROM AUTHOR]