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Strategies towards Improved Feed Efficiency in Pigs Comprise Molecular Shifts in Hepatic Lipid and Carbohydrate Metabolism
Get PDFPublication history: Accepted - 28 July 2017; Published online - 1 August 2017Due to the central role of liver tissue in partitioning and metabolizing of nutrients, molecular liver-specific alterations are of considerable interest to characterize an efficient conversion and usage of feed in livestock. To deduce tissue-specific and systemic effects on nutrient metabolism and feed efficiency (FE) twenty-four animals with extreme phenotypes regarding residual feed intake (RFI) were analyzed. Transcriptome and fatty acid profiles of liver tissue were complemented with measurements on blood parameters and thyroid hormone levels. Based on 803 differentially-abundant probe sets between low- and high-FE animals, canonical pathways like integrin signaling and lipid and carbohydrate metabolism, were shown to be affected. Molecular alterations of lipid metabolism show a pattern of a reduced hepatic usage of fatty acids in high-FE animals. Complementary analyses at the systemic level exclusively pointed to increased circulating triglycerides which were, however, accompanied by considerably lower concentrations of saturated and polyunsaturated fatty acids in the liver of high-FE pigs. These results are in accordance with altered muscle-to-fat ratios usually ascribed to FE animals. It is concluded that strategies to improve FE might favor a metabolic shift from energy storage towards energy utilization and mobilization.This work was funded by
the European Union Seventh Framework Programme (FP7/2007–2013) as part of the ECO-FCE project under
grant agreement No. 311794. The Leibniz Institute for Farm Animal Biology provided its own matched fundin
Intestinal microbiota profiles associated with low and high residual feed intake in chickens across two geographical locations
Get PDFPublication history: Accepted - 25 October 2017; Published online - 15 November 2017Intestinal microbe-host interactions can affect the feed efficiency (FE) of chickens. As inconsistent findings for FE-associated bacterial taxa were reported across studies, the present objective was to identify whether bacterial profiles and predicted metabolic functions that were associated with residual feed intake (RFI) and performance traits in female and male chickens were consistent across two different geographical locations. At six weeks of life, the microbiota in ileal, cecal and fecal samples of low (n = 34) and high (n = 35) RFI chickens were investigated by sequencing the V3-5 region of the 16S rRNA gene. Location-associated differences in α-diversity and relative abundances of several phyla and genera were detected. RFI-associated bacterial abundances were found at the phylum and genus level, but differed among the three intestinal sites and between males and females. Correlation analysis confirmed that, of the taxonomically classifiable bacteria, Lactobacillus (5% relative abundance) and two Lactobacillus crispatus-OTUs in feces were indicative for high RFI in females (P < 0.05). In males, Ruminococcus in cecal digesta (3.1% relative abundance) and Dorea in feces (<0.1% relative abundance) were best indicative for low RFI, whereas Acinetobacter in feces (<1.5% relative abundance) related to high RFI (P < 0.05). Predicted metabolic functions in feces of males confirmed compositional relationships as functions related to amino acid, fatty acid and vitamin metabolism correlated with low RFI, whereas an increasing abundance of bacterial signaling and interaction (i.e. cellular antigens) genes correlated with high RFI (P < 0.05). In conclusion, RFI-associated bacterial profiles could be identified across different geographical locations. Results indicated that consortia of low-abundance taxa in the ileum, ceca and feces may play a role for FE in chickens, whereby only bacterial FE-associations found in ileal and cecal digesta may serve as useful targets for dietary strategies.This project (ECO-FCE) has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration (grant no. 311794) to Barbara U Metzler-Zebeli
Relative abundance of Mycobacterium bovis molecular types in cattle: a simulation study of potential epidemiological drivers
Get PDFPublication history: Accepted - 11 August 2017; Published online - 22 August 2017.Background: The patterns of relative species abundance are commonly studied in ecology and epidemiology to
provide insights into underlying dynamical processes. Molecular types (MVLA-types) of Mycobacterium bovis, the
causal agent of bovine tuberculosis, are now routinely recorded in culture-confirmed bovine tuberculosis cases in
Northern Ireland. In this study, we use ecological approaches and simulation modelling to investigate the
distribution of relative abundances of MVLA-types and its potential drivers. We explore four biologically plausible
hypotheses regarding the processes driving molecular type relative abundances: sampling and speciation;
structuring of the pathogen population; historical changes in population size; and transmission heterogeneity
(superspreading).
Results: Northern Irish herd-level MVLA-type surveillance shows a right-skewed distribution of MVLA-types, with a
small number of types present at very high frequencies and the majority of types very rare. We demonstrate that
this skew is too extreme to be accounted for by simple neutral ecological processes. Simulation results indicate that
the process of MVLA-type speciation and the manner in which the MVLA-typing loci were chosen in Northern
Ireland cannot account for the observed skew. Similarly, we find that pathogen population structure, assuming for
example a reservoir of infection in a separate host, would drive the relative abundance distribution in the opposite
direction to that observed, generating more even abundances of molecular types. However, we find that historical
increases in bovine tuberculosis prevalence and/or transmission heterogeneity (superspreading) are both capable of
generating the skewed MVLA-type distribution, consistent with findings of previous work examining the distribution
of molecular types in human tuberculosis.
Conclusion: Although the distribution of MVLA-type abundances does not fit classical neutral predictions, our
simulations show that increases in pathogen population size and/or superspreading are consistent with the pattern
observed, even in the absence of selective pressures acting on the system.HT was funded by a BBSRC DTG studentship and Novartis Animal Health
Case studentship. Molecular typing surveillance of confirmed bTB cases in NI
was supported initially by DARD R&D Project DARD0407 and subsequently
under the Assigned Work Programm
“Hot spots” of N and C impact nitric oxide, nitrous oxide and nitrogen gas emissions from a UK grassland soil
Get PDFPublication history: Accepted - 6 June 2017; Published online - 3 July 2017.Agricultural soils are a major source of nitric- (NO) and nitrous oxide (N2O), which are produced and consumed
by biotic and abiotic soil processes. The dominant sources of NO and N2O are microbial nitrification and denitrification,
and emissions of NO and N2O generally increase after fertiliser application.
The present study investigated the impact of N-source distribution on emissions of NO and N2O from soil and
the significance of denitrification, rather than nitrification, as a source of NO emissions. To eliminate spatial
variability and changing environmental factors which impact processes and results, the experiment was conducted
under highly controlled conditions. A laboratory incubation system (DENIS) was used, allowing simultaneous
measurement of three N-gases (NO, N2O, N2) emitted from a repacked soil core, which was combined
with 15N-enrichment isotopic techniques to determine the source of N emissions.
It was found that the areal distribution of N and C significantly affected the quantity and timing of gaseous
emissions and 15N-analysis showed that N2O emissions resulted almost exclusively from the added amendments.
Localised higher concentrations, so-called hot spots, resulted in a delay in N2O and N2 emissions causing a longer
residence time of the applied N-source in the soil, therefore minimising NO emissions while at the same time
being potentially advantageous for plant-uptake of nutrients. If such effects are also observed for a wider range
of soils and conditions, then this will have major implications for fertiliser application protocols to minimise
gaseous N emissions while maintaining fertilisation efficiency.Rothamsted Research receives strategic funding by the
Biotechnology and Biological Sciences Research Council (BBSRC). This
study was funded by BBSRC project BB/K001051/1.
D. Abalos thanks the Spanish Ministry of Science and Innovation for economic support through the Project AGL2009-08412-AGR
Meta-analyses of the sensitivity and specificity of ante-mortem andpost-mortem diagnostic tests for bovine tuberculosis in the UK andIreland
No full textPublication history: Accepted - 26 February 2017; Published online - 6th March 2017.Bovine Tuberculosis (bTB) in cattle is a global health problem and eradication of the disease requires accu-rate estimates of diagnostic test performance to optimize their efficiency. The objective of this study was,through statistical meta-analyses, to obtain estimates of sensitivity (Se) and specificity (Sp), for 14 differ-ent ante-mortem and post-mortem diagnostic tests for bTB in cattle. Using data from a systematic reviewof the scientific literature (published 1934–2009) diagnostic Se and Sp were estimated using Bayesianlogistic regression models adjusting for confounding factors. Random effect terms were used to accountfor unexplained heterogeneity. Parameters in the models were implemented using Markov Chain MonteCarlo (MCMC), and posterior distributions for the diagnostic parameters with adjustment for covariates(confounding factors) were obtained using the inverse logit function. Estimates for Se and/or Sp of thetuberculin skin tests and the IFN- blood test were compared with estimates published 2010–2015.Median Se for the single intradermal comparative cervical tuberculin skin (SICCT) test (standard inter-pretation) was 0.50 and Bayesian credible intervals (CrI) were wide (95% CrI 0.26, 0.78). Median Sp forthe SICCT test was 1.00 (95% CrI 0.99, 1.00). Estimates for the IFN- blood test Bovine Purified ProteinDerivative (PPD)-Avian PPD and Early Secreted Antigen target 6 and Culture Filtrate Protein 10 (ESAT-6/CFP10) ESAT6/CFP10 were 0.67 (95% CrI 0.49, 0.82) and 0.78 (95% CrI 0.60, 0.90) respectively for Se,and 0.98 (95% CrI 0.96, 0.99) and 0.99 (95% CrI 0.99, 1.00) for Sp. The study provides an overview of theaccuracy of a range of contemporary diagnostic tests for bTB in cattle. Better understanding of diagnostictest performance is essential for the design of effective control strategies and their evaluation.The SE3238 project “Meta-analysis of diagnostic tests and modelling to identify appropriate testing strategies to reduce M. bovis infection in GB herds” was funded by the UK Department for Envi-ronment, Food and Rural Affairs (Defra)
Seasonal hogget grazing as a potential alternative grazing system for the Qinghai-Tibetan plateau: weight gain and animal behaviour under continuous or rotational grazing at high or low stocking rates
Get PDFPublication history: Accepted - 25 August 2017; Published online - 20 September 2017.The traditional transhumance grazing system on the Qinghai-Tibetan Plateau (QTP) is being replaced by a
system in which pastoralists are allocated fixed areas for grazing. In this context, we conducted experiments to evaluate a
possible change to seasonal grazing of young animals for weight gain, and the effects of grazing management (continuous
grazing (CG) vs rotational grazing (RG)) and stocking rate (SR) on the performance and behaviour of Oura-type Tibetan
sheep. In Experiment 1 (June–December 2014), 72 Tibetan sheep (initial bodyweight (BW) 32.2 3.37 kg) were allocated
to one of three treatments: (1) CG24 – eight sheep grazed continuously in a single 2-ha plot for the entire duration of the
experiment; (2) RG24 – eight sheep grazed in a 1-ha plot from June to September (growing season), and then moved to a new
plot for September–December grazing (early cold season); (3) RG48 – eight sheep grazed in a 0.5-ha plot, but otherwise as
for RG24. All treatments had three replicates. In Experiment 2 (September–December 2014), 48 Tibetan sheep (initial
BW46.3 1.62 kg) were used to repeat theRG24andRG48treatments imposed in the early cold season of the Experiment 1.
In both experiments, increasing SR significantly reduced bodyweight gain (BWG) per head and increased BWG per ha in
the RG treatments. In Experiment 1, RG, compared with CG, did not significantly affect BWG per head, BWG per ha, or
feed utilisation efficiency. In both experiments weight gain was small or negative in the early cold season. These results
indicate that removal of sheep at the onset of the cold season will be important for retention of the weight gain achieved in the
growing season but choice between aCGandRGgrazing system is unimportant for the production efficiency in the proposed
grazing system of Tibetan sheep.This research was supported by the National Key Project of Scientific and
Technical Supporting Programs (2014CB138706), the National Natural
Science Foundation of China (No. 31672472) and Program for Changjiang
Scholars and Innovative Research Team in University (IRT17R50)
Invited review: Large-scale indirect measurements for enteric methane emissions in dairy cattle: A review of proxies and their potential for use in management and breeding decisions
Get PDFPublication history: Accepted - 7 December 2016; Published online - 1 February 2017.Efforts to reduce the carbon footprint of milk production through selection and management of low-emitting
cows require accurate and large-scale measurements of
methane (CH4) emissions from individual cows. Several
techniques have been developed to measure CH4 in a research setting but most are not suitable for large-scale
recording on farm. Several groups have explored proxies (i.e., indicators or indirect traits) for CH4; ideally
these should be accurate, inexpensive, and amenable
to being recorded individually on a large scale. This
review (1) systematically describes the biological basis
of current potential CH4 proxies for dairy cattle; (2)
assesses the accuracy and predictive power of single
proxies and determines the added value of combining
proxies; (3) provides a critical evaluation of the relative
merit of the main proxies in terms of their simplicity,
cost, accuracy, invasiveness, and throughput; and (4)
discusses their suitability as selection traits. The proxies range from simple and low-cost measurements such
as body weight and high-throughput milk mid-infrared
spectroscopy (MIR) to more challenging measures such
as rumen morphology, rumen metabolites, or microbiome profiling. Proxies based on rumen samples are generally poor to moderately accurate predictors of CH4,
and are costly and difficult to measure routinely onfarm. Proxies related to body weight or milk yield and
composition, on the other hand, are relatively simple,
inexpensive, and high throughput, and are easier to
implement in practice. In particular, milk MIR, along
with covariates such as lactation stage, are a promising
option for prediction of CH4 emission in dairy cows.
No single proxy was found to accurately predict CH4,
and combinations of 2 or more proxies are likely to be
a better solution. Combining proxies can increase the
accuracy of predictions by 15 to 35%, mainly because
different proxies describe independent sources of variation in CH4 and one proxy can correct for shortcomings
in the other(s). The most important applications of
CH4 proxies are in dairy cattle management and breeding for lower environmental impact. When breeding for
traits of lower environmental impact, single or multiple
proxies can be used as indirect criteria for the breeding
objective, but care should be taken to avoid unfavorable correlated responses. Finally, although combinations of proxies appear to provide the most accurate
estimates of CH4, the greatest limitation today is the
lack of robustness in their general applicability. Future
efforts should therefore be directed toward developing
combinations of proxies that are robust and applicable
across diverse production systems and environments.Technical and financial support from the COST Action FA1302 of the European Union
A Review of the Strain Diversity and Pathogenesis of Chicken Astrovirus
Get PDFPublication history: Accepted - 25 January 2017; Published online - 10 February 2017.Although a relatively recently emerged virus, identified only in 2004 as a separate species of avian astrovirus, chicken astrovirus (CAstV) has been associated with poor growth of broiler flocks, enteritis and diarrhea and is a candidate pathogen in cases of runting stunting syndrome. More recently CAstV has been implicated in cases of two other diseases of broilers as the sole etiological agent, namely severe kidney disease of young broilers with visceral gout and the “White Chicks” hatchery disease. Examination of the strains of CAstV associated with the two latter diseases reveals they are closely related genetically. This review will discuss the pathogenesis of CAstV in relation to strain diversity and the effects of vertical versus horizontal transmission, virus load, co-infections and age of bird at infection, all factors that may impact upon disease severity.The author would like to thank the Department of Agriculture, Environment and Rural Affairs (DAERA) in Northern Ireland for supporting this review
Control of Nematodirus spp. infection by sheep flock owners in Northern Ireland
Get PDFPublication history: Accepted - 10 October 2017; Published online - 19 October 2017.Background
To address a lack of information on the control of ovine helminth parasites in Northern Ireland (NI), a number of research projects have been undertaken, dealing with gastrointestinal nematodes, tapeworms and liver fluke. This investigation concerns Nematodirus and concentrates on three aspects of disease: farm management strategies for its control, derived from the results of a Questionnaire; the efficacy of treatment used by farmers, as determined by a coprological survey; and the hatching requirements of Nematodirus eggs, that is, whether prolonged chilling is a pre-requisite for hatching.
Results
A Questionnaire was sent to 252 sheep farmers in NI in March 2012 (covering the years 2009–2012) and replies were received from 228 farmers. Under-dosing, inaccurate calibration of equipment and inappropriate product choice were poor practices identified. Following this survey, the efficacy of treatment of Nematodirus spp. in sheep flocks was evaluated in April and May 2012. Sampling kits were sent to 51 flock owners, all of whom returned pre- and post-anthelmintic dosing faecal samples to the laboratory for analysis. At the time of treatment, 41 flocks were positive for Nematodirus (as diagnosed by the presence of eggs). Reduced benzimidazole efficacy was detected in 35.7% of flocks tested (n = 28). Although only involving a small number of flocks, reduced efficacy of levamisole treatment was detected in 50%, of avermectins in 33% and of moxidectin in 75% of flocks tested (n = 2, 6 and 4, respectively). In the egg hatch experiment, carried out under “chilled” and “non-chilled” conditions, 43% of the eggs in the “non-chilled” group were able to hatch, compared to 100% in the “chilled” group.
Conclusions
The identification of inefficient control strategies argues for continued education of stockholders, in order to improve their management programmes. This is particularly important where the practices might impact on the development of anthelmintic resistance, which has been shown to exist on NI farms. The appropriate choice of anthelmintic is a vital part of this plan. The ability of eggs to hatch under non-chilled conditions demonstrates a flexibility in hatching behaviour. This may represent an adaptation to climate change and account for the recent emergence of a second, autumnal peak of infection
Detection of Tetrodotoxin Shellfish Poisoning (TSP) Toxins and Causative Factors in Bivalve Molluscs from the UK
Get PDFPublication history: Accepted - 28 August 2017; Published online - 30 August 2017.Tetrodotoxins (TTXs) are traditionally associated with the occurrence of tropical Pufferfish Poisoning. In recent years, however, TTXs have been identified in European bivalve mollusc shellfish, resulting in the need to assess prevalence and risk to shellfish consumers. Following the previous identification of TTXs in shellfish from southern England, this study was designed to assess the wider prevalence of TTXs in shellfish from around the coast of the UK. Samples were collected between 2014 and 2016 and subjected to analysis using HILIC-MS/MS. Results showed the continued presence of toxins in shellfish harvested along the coast of southern England, with the maximum concentration of total TTXs reaching 253 µg/kg. TTX accumulation was detected in Pacific oysters (Crassostrea gigas), native oysters (Ostrea edulis) common mussels (Mytilus edulis) and hard clams (Mercenaria mercenaria), but not found in cockles (Cerastoderma edule), razors (Ensis species) or scallops (Pecten maximus). Whilst the highest concentrations were quantified in samples harvested during the warmer summer months, TTXs were still evident during the winter. An assessment of the potential causative factors did not reveal any links with the phytoplankton species Prorocentrum cordatum, instead highlighting a greater level of risk in areas of shallow, estuarine waters with temperatures above 15 °CFunding from Cefas internal funding sources (Seedcorn, DP345B and DP402); and FS