Showing papers by "Rowett Research Institute published in 2015"

Mechanistic Models of Forage Cell Wall Degradation

Abstract: This chapter is concerned primarily with the molecular events that occur when forage plant cell walls are degraded by gut microorganisms. As such it is narrowly focused and is concerned with the individual cell wall or part of the cell wall rather than forages per se. It is important to place these molecu­ lar or "mural" events into an appropriate botanical and ecological context and to recognize that many factors other than cell wall composition and ar­ chitecture influence the nutritive value of a forage and its cell wall fraction when consumed by an animal. All forages are composed of a heterogeneous population of cell types, each of which has a cell wall with unique properties. Forages differ in the potential nutritive value of their cell wall (fiber) fraction because of differ­ ences in both the amount of cell walls derived from the various cell types consumed by the animal and their individual degradabilities. Currently, no routine methods exist for estimating the weight of the various cell types con­ sumed and few measurements have been made of the degradability of cell walls from individual cell types. Certainly no comparative studies between forage species or cultivars based on such methods have been attempted. At best, estimates of leaf, leaf sheath, and stem ratios have been made which reflect, at a morphological level, variations in amounts of different cell types present (e.g., Wilman & Altimimi, 1982; Nordkvist et aI., 1987). Although a relatively crude indicator, morphological measurements have the value of demonstrating the importance of changes in the proportion of cell types present in determining the digestion characteristics of the forage. A com­ parison of barley straw (Hordeum vulgare L.) cultivars with degradability values ranging from 40 to 60070 indicated that approximately one-half of the differences in overall cell wall degradability could be attributed to the varia­ tion in plant morphology, the more degradable cultivars having the highest leaf blade and lowest stem content (Goto et aI., 1991).

Weight outcomes audit in 1.3 million adults during their first 3 months' attendance in a commercial weight management programme.

Abstract: Over sixty percent of adults in the UK are now overweight/obese. Weight management on a national scale requires behavioural and lifestyle solutions that are accessible to large numbers of people. Evidence suggests commercial weight management programmes help people manage their weight but there is little research examining those that pay to attend such programmes rather than being referred by primary care. The objective of this analysis was to evaluate the effectiveness of a UK commercial weight management programme in self-referred, fee-paying participants. Electronic weekly weight records were collated for self-referred, fee-paying participants of Slimming World groups joining between January 2010 and April 2012. This analysis reports weight outcomes in 1,356,105 adult, non-pregnant participants during their first 3 months’ attendance. Data were analysed by regression, ANOVA and for binomial outcomes, chi-squared tests using the R statistical program. Mean (SD) age was 42.3 (13.6) years, height 1.65 m (0.08) and start weight was 88.4 kg (18.8). Mean start BMI was 32.6 kg/m2 (6.3 kg/m2) and 5 % of participants were men. Mean weight change of all participants was −3.9 kg (3.6), percent weight change −4.4 (3.8), and BMI change was −1.4 kg/m2 (1.3). Mean attendance was 7.8 (4.3) sessions in their first 3 months. For participants attending at least 75 % of possible weekly sessions (n = 478,772), mean BMI change was −2.5 kg/m2 (1.3), weight change −6.8 kg (3.7) and percent weight change −7.5 % (3.5). Weight loss was greater in men than women absolutely (−6.5 (5.3) kg vs −3.8 (3.4) kg) and as a percentage (5.7 % (4.4) vs 4.3 % (3.7)), respectively. All comparisons were significant (p < 0.001). Level of attendance and percent weight loss in the first week of attendance together accounted for 55 % of the variability in weight lost during the study period. A large-scale commercial lifestyle-based weight management programme had a significant impact on weight loss outcomes over 3 months. Higher levels of attendance led to levels of weight loss known to be associated with significant clinical benefits, which on this scale may have an impact on public health.

Size and Persistence of Nitrous Oxide Hot-Spots in Grazed and Ungrazed Grassland

Abstract: Nitrous oxide (N 2 O) emissions from agriculture contributed an estimated 60% of the global total in 2005. In the UK, grassland soils account for 30% of total emissions, 22% of which are estimated to come from urine and dung patches. These patches are possible sources of ‘hot-spots’ (area ca. 1 m 2 ) of N 2 O fluxes. Spatial and temporal heterogeneity of N 2 O hot-spot fluxes were investigated in three grassland fields (grazed with dairy cows (DG), grazed with young stock (YG) or cut for silage (SC)) using gas sampling chambers surrounding historic hot-spots to establish their size. Fluxes from old dung and urine patches were measured, as well as freshly applied dung and urine to simulate the creation of hot-spots. Potential chemical and physical drivers were also measured. Large spatial variability of N 2 O fluxes was seen in all three grassland fields. Mean N 2 O fluxes for the historic hot-spots in the grazed fields (DG and YG) were significantly greater than (SC). The mean N 2 O fluxes in DG and YG (117.9 and 243.5 ng N m -2 s -1 ) were 15 to 30% greater than for SC. Soil temperature (15 - 20 °C) was the most significant driver of N 2 O production with a 1°C rise in soil temperature increasing emissions under DG and YG. N 2 O fluxes were enhanced by the fresh dung but not by urine. However, in the urine treatment, the nutrient input increased the microbial respiration response for the CO 2 flux. Hot-spot N 2 O emissions from old urine and dung patches were persistent several months after application.

Assessing compliance with healthy eating recommendations for food groups: comparison of a food frequency questionnaire and diet diary

Abstract: The Eatwell plate was developed to give a food-based visual representation of the balance of five food groups for a recommended healthy diet. The five groups being: bread, rice, potatoes, pasta and other starchy foods (starchy), fruit and vegetables (F&V), milk and dairy foods (dairy), meat, fish, eggs, beans and other non-dairy sources of protein (protein) and foods and drinks high in fat or sugar (HFHS). Manufactured dishes comprise ingredients from several food groups and consumers must consider how these fit with the proportions of the Eatwell plate. This will present a difficulty for many consumers, and is a further level of complexity in estimating how well a diet compares to the recommendations. A simple to use tool that is not reliant on the consumers’ nutritional knowledge could be beneficial in providing them with information on their Eatwell plate proportions, and could be used in research to monitor the progress of the population’s diet towards health eating goals. The aim of the study was to assess the relative validity of the Scottish Collaborative Group Food Frequency Questionnaire (FFQ), compared to food intake diaries, in estimating the Eatwell plate proportions of the diets of Scottish adults. Dietary data were taken from two existing studies when subjects were consuming their normal diets. Subjects (110 F and 94 M) completed an FFQ followed by a weighed food intake record (WR) for 4, 6 or 7 days. Proportions of the five Eatwell food groups were estimated for each of the foods and beverages recorded by subjects in their WR, and for all items (n = 155) of the FFQ. Composite foods were disaggregated where necessary. Weights of milk and fruit juices were halved to avoid their high water content having a large effect on the Eatwell plate proportions. Eatwell plate proportions for each subject’s overall diet were calculated for the FFQ and WR. Subjects were grouped into thirds of intake for each Eatwell food group and dietary method, and the percentages of subjects in the same third and opposite third by the two methods calculated. The weighted kappa statistic was calculated for each of the Eatwell food groups to assess the agreement between the FFQ and WR.