262,831 research outputs found
Evaluation of a model to investigate the host-parasite interactions between first season grazing calves and O. ostertagi
No full textImplications We show that a simulation model predicting impacts of gastrointestinal parasitism on calves produces output results that agree well with independently produced experimental data, and we identify the most influential parameters. Introduction We have developed a model that predicts parasitological outputs (worm burdens and total egg outputs) and performance traits (food intakes and performance) for different infection modes and levels of infection in grazing calves (Berk et al., 2015). But before confidence can be placed in model predictions an evaluation must be conducted. The objectives of this study were to conduct a sensitivity analysis, and to compare model predictions with observations from relevant parasitological data, to validate the model concepts and parameters (Michel, 1970; Syzska and Kyriazakis, 2013). Material and methods A sensitivity analysis was conducted on model predictions for a subset of parameters using a Latin hypercube design. Parameter combinations covered a wide scope of possibilities, whilst having relatively few simulations (250). The mean parameter values were taken as the best estimate and all parameters were assumed to be normally distributed with CVs of 20%. To analyse the impact of variation in parameter on model predictions, an ANOVA was conducted for each parameter to test for significance (P <0.05). Independent sets of published experimental data were then used to independently validate model performance using both graphical comparisons and statistical tests of goodness-of-fit. Bias and root-mean-square error were calculated from differences in model predictions and reported data; these were tested for significance (P <0.05). Literature studies were selected as follows (1) Infections were O. ostertagi alone with no other parasite species involved; (2) all calves were infected during the growing phase; (3) calves were allowed access to adlibitum, high quality feed; (4) calves had no prior experience of parasitism at the start of the experiment. Comparisons reported here are for worm burdens (Michel, 1970) and faecal egg outputs (FECs) (Syzska and Kyriazakis, 2013). Results The sensitivity analysis revealed that model prediction of parasitological traits were most sensitive to the rate of immune development for host-controlled larval establishment and worm mortality; this implies the immune development rate has a large impact on worm burdens and subsequent parasitological outputs. Michel (1970) investigated worm burdens following trickle infections. The simulated and observed values followed the same pattern of increasing worm burdens up to a peak followed by a decrease: the correlation between predicted and observed values was r=0.78 (Figure 1). Although there was no systematic bias in the predicted results, not all predicted values fell within the one standard deviation (SD) of true values as indicated by the RMSE. Szyszka and Kyriazakis (2013) investigated the FEC for weekly larval challenge and found that FECs started low, increased to a peak approximately 35 d post infection and decreased thereafter. There was a positive correlation (0.75) with our model predictions (Figure 2). The predicted values were mostly within the one SD as indicated by the RMSE well within the 95% confidence interval; hence there was also no significant bias. Conclusion In general the developed model satisfactorily predicted parasitological traits, although after several comparisons with published literature (results not shown) the model was more effective at predicting the effects of subclinical rather than clinical challenges. Differences amongst independent published studies were large; this has been attributed to variability in calf genotypes and small samples sizes. The key question is whether development of a stochastic model incorporating variability between animals will account for the full range of experimentally observed outcomes. Acknowledgments The authors acknowledge funding from BBSRC and Merial References Berk, Z.L, Bishop, S, Forbes, A., Kyriazakis, I. 2015. Advances in Animal Biosciences 6 (2) 179 Michel, J.F. 1970. Parasitology 61, 435–447 Szyszka, O., Kyriazakis, I. 2013. Applied Animal Behaviour Science 147, 1–1
Circular Feed Production and Consumption in the Context of Smart Animal Nutrition
No full textSmart nutrition represents an innovation in farm animal nutrition and is one of the most promising ways to promote safe, high-quality animal products such as meat and milk, high animal welfare, and minimal impact on the environment. Smart livestock nutrition implies also the design of high nutritious diets for feeding animals in line with their needs and requirements. This goal can be achieved not only by selecting ingredients characterized by high nutrient density and digestibility, but also by looking for sustainable ingredients, including “circular” ingredients from waste and from nature. Using such alternative feed ingredients in the diet of farm animals is interesting for several reasons. Food leftovers are one way of converting losses from the food industry into ingredients for the animal feed industry, thereby keeping nutrients in the food chain. These materials can be extremely rich in carbohydrates, free sugars, and, depending on their origin, also in fats. Food leftovers, such as former food products (FFPs) and bakery by-products (BBPs) are subject to considerable processing including technological (milling, etc.) and heat treatments (cooking, extrusion, etc.). These impact not only the availability of nutrients and the kinetics of digestion but also on GIT/rumen health/functions and the animal response. FFPs and BBPs are safe from a microbiological point of view since; their microbiological loads are always below established tolerance levels. Using leftovers as feed also responds to the requirements of the circular economy. Understanding that food that is not suitable for human consumption is actually a resource rather than a waste product, our food industry can limit the amount of waste sent to landfill, thus saving costs and reducing the environmental impact of the food production chain. This approach can be considered a virtuous example of smart livestock nutrition and feeding that can and will become an option in sustainable animal production optimization
Basics and Applications of an Exponential Nitrogen Utilization Model ('Goettingen Approach') for Assessing Amino Acid Requirements in Growing Pigs and Meat Type Chickens Based on Dietary Amino Aci Efficiency
No full textBasics and Applications of an Exponential Nitrogen Utilization Model ('Goettingen Approach') for Assessing Amino Acid Requirements in Growing Pigs and Meat Type Chickens Based on Dietary Amino Aci Efficiency
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
The use of genetic variation in short-term feeding behaviour in broiler breeding programmes
Full text linkGenetic variation between individuals is of great importance for the development of breeding
programmes, to select for animals with the most favourable traits. Many production companies
routinely measure the feed intake of their animals, in order to calculate efficiency traits such as
feed conversion ratio. The development of electronic feeders which automatically record
individual intake on a visit-by-visit basis now allows the short-term feeding behaviour of
animals to be monitored and analysed as another source of variation between individuals. Due
to differences in the resolutions of these feeders as a measurement tool, a standard unit of
feeding event needs to be estimated to allow for comparisons between studies. Different
models for estimation of the defining value of a meal, the meal criterion, have been used, with
the most recent incorporating the change in satiety with time since last feeding as part of the
model.
In this study I developed a new methodology, based on these models, for use when a within meal
population of intervals cannot be easily modelled. I then used this model for application
to data from four lines of broiler chickens to estimate meal criteria and compare feeding
behaviour within and between the lines. Significant differences were found between fast and
slow growing birds, with the faster growing birds having fewer but larger meals than the
slower growing birds. However, the lines showed similar structure and bouting of their feeding
behaviour, indicating that the fundamental controls of feeding behaviour, such as hunger and
satiety, in these lines had been unaltered despite intensive selection for growth. The models
were also applied across poultry species, kept in different experimental conditions. A similar structure to the feeding behaviour was found across all these species, with all showing clear
separation of feeding events into bouts.
In order to estimate the potential use of these behavioural observations in a breeding
programme, the heritabilities and genetic correlations with existing performance traits were
calculated for the four broiler lines. Heritabilities of all feeding behaviour traits were found to
be moderate to high, and very similar across the lines. Correlations with performance traits,
however, were low, meaning that there were no clear links of the traits with the current
production goals investigated. This indicates that past selection for production has had limited
impact on feeding behaviour and also that potential selection for feeding behaviour will have
little effect on production gains.
To identify the areas of the genome controlling feeding behaviour, traits were associated with a
SNP panel. Many regions were found to have highly significant association with feeding
behaviour traits, with the most highly correlated traits showing associations with the same
regions, suggesting pleiotropic effects of genes in these regions. Future work in this area
should include identification of individual genes controlling feeding behaviour to allow
prediction of the effects of selection for favourable feeding behaviour on other traits, and
comparison of the genotypes of different lines of broilers, to further understand the control of
feeding behaviour
Protecting Animals 36: Author Witi Ihimaera
No full textIn this very special episode of Knowing Animals I am joined by beloved New Zealand author Witi Ihimaera. Witi has written many books featuring nonhuman animals. He offers us a non-colonial lens through which to think about the human/nonhuman relationship
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
Interactive effects of protein nutrition, genetic growth potential and heligmosomoides bakeri infection pressure on resilience and resistance in mice
Full text linkThe ability of animals to cope with an increasing parasite load, in terms of resilience and resistance, may be affected by both nutrient supply and demand. Here, we hypothesized that host nutrition and growth potential interact and influence the ability of mice to cope with different parasite doses. Mice selected for high (ROH) or low (ROL) body weight were fed a low (40 g/kg; LP) or high (230 g/kg; HP) protein diet and infected with 0, 50, 100, 150, 200 or 250 L3 infective Heligmosomoides bakeri larvae. ROH-LP mice grew less at doses of 150 L3 and above, whilst growth of ROH-HP and of ROL mice was not affected by infection pressure. Total worm burdens reached a plateau at doses of 150L3, whilst ROH mice excreted fewer worm eggs than ROL mice. Serum antibodies increased with infection dose and ROH mice were found to have higher parasite-specific IgG1 titres than ROL mice. In contrast, ROL had higher total IgE titres than ROH mice, only on HP diets. The interaction between host nutrition and growth potential appears to differentially affect resilience and resistance in mice. However, the results support the view that parasitism penalises performance in animals selected for higher growth
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