Knowledge Center for Agriculture

Århus, Denmark

Knowledge Center for Agriculture

Århus, Denmark

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Kristensen E.,Knowledge Center for Agriculture | Kristensen E.,StrateKo Aps | Jakobsen E.B.,StrateKo Aps
Preventive Veterinary Medicine | Year: 2011

To implement biosecurity measures at farm-level is a motivational challenge to dairy farmers as emerging diseases and their consequences largely are unpredictable. One of the reasons for this challenge is that outcomes are more likely to benefit society than the individual farmer. From the individual farmer's point of view the impacts of zoonotic risk, international trade and welfare concerns appear less obvious than the direct costs at farm-level. Consequently, a social dilemma may arise where collective interests are at odds with private interests. To improve biosecurity at farm-level farmers must be motivated to change behavior in the 'right' direction which could provide selfish farmers with unintended possibilities to exploit the level of biosecurity provided by other dairy farmers' collective actions. Farmers' perception of risk of disease introduction into a dairy herd was explored by means of Q-methodology. Participating farmers owned very large dairy herds and were selected for this study because Danish legislation since 2008 has required that larger farms develop and implement a farm specific biosecurity plan. However, a year from introduction of this requirement, none of the participating farmers had developed a biosecurity plan. Farmers' perception of biosecurity could meaningfully be described by four families of perspectives, labeled: cooperatives; confused; defectors, and introvert. Interestingly, all families of perspectives agreed that sourcing of animals from established dealers represented the highest risk to biosecurity at farm-level. Farmers and policy-makers are faced with important questions about biosecurity at farm-level related to the sanctioning system within the contextual framework of social dilemmas. To solve these challenges we propose the development of a market-mediated system to (1) reduce the risk of free-riders, and (2) provide farmers with incentives to improve biosecurity at farm-level. © 2011 Elsevier B.V.


Zadoks R.N.,Moredun Research Institute | Zadoks R.N.,University of Edinburgh | Zadoks R.N.,Cornell University | Middleton J.R.,University of Missouri | And 3 more authors.
Journal of Mammary Gland Biology and Neoplasia | Year: 2011

Mastitis, inflammation of the mammary gland, can be caused by a wide range of organisms, including gram-negative and gram-positive bacteria, mycoplasmas and algae. Many microbial species that are common causes of bovine mastitis, such as Escherichia coli, Klebsiella pneumoniae, Streptococcus agalactiae and Staphylococcus aureus also occur as commensals or pathogens of humans whereas other causative species, such as Streptococcus uberis, Streptococcus dysgalactiae subsp. dysgalactiae or Staphylococcus chromogenes, are almost exclusively found in animals. A wide range of molecular typing methods have been used in the past two decades to investigate the epidemiology of bovine mastitis at the subspecies level. These include comparative typing methods that are based on electrophoretic banding patterns, library typing methods that are based on the sequence of selected genes, virulence gene arrays and whole genome sequencing projects. The strain distribution of mastitis pathogens has been investigated within individual animals and across animals, herds, countries and host species, with consideration of the mammary gland, other animal or human body sites, and environmental sources. Molecular epidemiological studies have contributed considerably to our understanding of sources, transmission routes, and prognosis for many bovine mastitis pathogens and to our understanding of mechanisms of host-adaptation and disease causation. In this review, we summarize knowledge gleaned from two decades of molecular epidemiological studies of mastitis pathogens in dairy cattle and discuss aspects of comparative relevance to human medicine. © The Author(s) 2011.


Sahana G.,University of Aarhus | Nielsen U.S.,Knowledge Center for Agriculture | Aamand G.P.,Nordic Cattle Genetic Evaluation | Lund M.S.,University of Aarhus | Guldbrandtsen B.,University of Aarhus
PLoS ONE | Year: 2013

Using genomic data, lethal recessives may be discovered from haplotypes that are common in the population but never occur in the homozygote state in live animals. This approach only requires genotype data from phenotypically normal (i.e. live) individuals and not from the affected embryos that die. A total of 7,937 Nordic Holstein animals were genotyped with BovineSNP50 BeadChip and haplotypes including 25 consecutive markers were constructed and tested for absence of homozygotes states. We have identified 17 homozygote deficient haplotypes which could be loosely clustered into eight genomic regions harboring possible recessive lethal alleles. Effects of the identified haplotypes were estimated on two fertility traits: non-return rates and calving interval. Out of the eight identified genomic regions, six regions were confirmed as having an effect on fertility. The information can be used to avoid carrier-by-carrier mattings in practical animal breeding. Further, identification of causative genes/polymorphisms responsible for lethal effects will lead to accurate testing of the individuals carrying a lethal allele. © 2013 Sahana et al.


Stentoft C.,University of Aarhus | Vestergaard M.,University of Aarhus | Lovendahl P.,University of Aarhus | Kristensen N.B.,Knowledge Center for Agriculture | And 2 more authors.
Journal of Chromatography A | Year: 2014

Improved nitrogen utilization in cattle is important in order to secure a sustainable cattle production. As purines and pyrimidines (PP) constitute an appreciable part of rumen nitrogen, an improved understanding of the absorption and intermediary metabolism of PP is essential. The present work describes the development and validation of a sensitive and specific method for simultaneous determination of 20 purines (adenine, guanine, guanosine, inosine, 2'-deoxyguanosine, 2'-deoxyinosine, xanthine, hypoxanthine), pyrimidines (cytosine, thymine, uracil, cytidine, uridine, thymidine, 2'-deoxyuridine), and their degradation products (uric acid, allantoin, β-alanine, β-ureidopropionic acid, β-aminoisobutyric acid) in blood plasma of dairy cows. The high performance liquid chromatography-based technique coupled to electrospray ionization tandem mass spectrometry (LC-MS/MS) was combined with individual matrix-matched calibration standards and stable isotopically labelled reference compounds. The quantitative analysis was preceded by a novel pre-treatment procedure consisting of ethanol precipitation, filtration, evaporation and reconstitution. Parameters for separation and detection during the LC-MS/MS analysis were investigated. It was confirmed that using a log-calibration model rather than a linear calibration model resulted in lower CV% and a lack of fit test demonstrated a satisfying linear regression. The method covers concentration ranges for each metabolite according to that in actual samples, e.g. guanine: 0.10-5.0. μmol/L, and allantoin: 120-500. μmol/L. The CV% for the chosen quantification ranges were below 25%. The method has good repeatability (CV%. ≤. 25%) and intermediate precision (CV%. ≤. 25%) and excellent recoveries (91-107%). All metabolites demonstrated good long-term stability and good stability within-runs (CV%. ≤. 10%). Different degrees of absolute matrix effects were observed in plasma, urine and milk. The determination of relative matrix effects revealed that the method was suitable for almost all examined PP metabolites in plasma drawn from an artery and the portal hepatic, hepatic and gastrosplenic veins and, with a few exceptions, also for other species such as chicken, pig, mink, human and rat. © 2014 Elsevier B.V.


Katholm J.,Knowledge Center for Agriculture | Bennedsgaard T.W.,University of Aarhus | Koskinen M.T.,Thermo Fisher Scientific | Rattenborg E.,Knowledge Center for Agriculture
Journal of Dairy Science | Year: 2012

Results of a commercial real-time PCR analysis for 11 mastitis pathogens from bulk tank milk (BTM) samples from all 4,258 Danish dairy herds in November 2009 to January 2010 were compared with somatic cell count (SCC) and total bacteria count (TBC) estimates in BTM. For Streptococcus agalactiae, Streptococcus dysgalactiae, and Streptococcus uberis, a low real-time PCR cycle threshold (Ct) value (corresponding to high bacterial DNA quantity) was correlated with higher SCC and higher TBC. For Staphylococcus aureus, low Ct values were correlated only with higher SCC. For the environmental mastitis pathogens Klebsiella spp., Enterococcus spp., and Escherichia coli, low Ct values had a correlation with higher TBC. Staphylococcus spp. were found in the BTM from all herds, Strep. uberis in 95%, Staph. aureus in 91%, and Strep. dysgalactiae in 86%, whereas E. coli, Klebsiella, and Strep. agalactiae were found in 61, 13, and 7% of the herds. It is concluded that the real-time PCR used provides results that are related to the milk quality in the herds. Real-time PCR can be used in the same way as culture for monitoring BTM samples, and is especially useful for bacteria with low prevalence (e.g., Strep. agalactiae). © 2012 American Dairy Science Association.


Clausen M.R.,University of Aarhus | Pedersen B.H.,University of Aarhus | Pedersen B.H.,Knowledge Center for Agriculture | Bertram H.C.,University of Aarhus | Kidmose U.,University of Aarhus
Journal of Agricultural and Food Chemistry | Year: 2011

Juice was manufactured from seven different sour cherry clones/cultivars and evaluated by quantitative descriptive sensory analysis and 1H NMR spectroscopy. The sensory evaluation showed a large variation in several sensory attributes between the sour cherry clones/cultivars, which could be divided into two groups on the basis of both the sensory data and the NMR spectroscopic data. These groups were closely related to the genetic background of the clones. Kelleris clones were distinctly different from Stevnsberry and Fanal clones. Hence, 1H NMR spectroscopic data seem to correlate with sensory quality of different sour cherry clones. In addition, malic acid was the most important metabolite for modeling the two highly correlated sensory attributes sweetness and sourness, whereas the glucose content had a slight effect and the fructose content had no impact on sweetness/sourness. Other metabolites (ethyl acetate, asparagine, ethanol) could be correlated with sensory attributes; however, a direct causal connection could not be established. © 2011 American Chemical Society.


Kargo M.,University of Aarhus | Kargo M.,Knowledge Center for Agriculture | Madsen P.,University of Aarhus | Norberg E.,University of Aarhus
Journal of Dairy Science | Year: 2012

The economic benefit of crossbreeding has been well known for many years within dairy production. However, in most countries with an intensive dairy production, an extended use of systematic crossbreeding has not occurred. This may be due to the myth that heterosis is expressed mainly in low-producing herds. The aim of the study was to investigate the effect of heterosis with different management levels in Danish Jersey herds. More than 300,000 records of 305-d milk, fat, and protein yield from first-lactation Danish Jersey cows with different contributions from original Danish and US Jersey were analyzed using an animal model. The herds were distributed in 5 management groups based on production level. First, the results showed a large increase in additive genetic variance from the herds with lowest production level to the high-producing ones, and second, heterosis for all 3 production traits were lowest within the low-intensity management group and tended to be highest in the intermediate management groups. The results, therefore, support that crossbreeding is a breeding system that should be considered valuable for all management levels. © 2012 American Dairy Science Association.


Rubaek G.H.,University of Aarhus | Kristensen K.,University of Aarhus | Olesen S.E.,University of Aarhus | Ostergaard H.S.,Knowledge Center for Agriculture | Heckrath G.,University of Aarhus
Geoderma | Year: 2013

Over the past century phosphorus (P) has accumulated in Danish agricultural soils. We examined the soil P content and the degree of P saturation in acid oxalate (DPS) in 337 agricultural soil profiles and 32 soil profiles from deciduous forests sampled at 0-0.25, 0.25-0.50, 0.50-0.75 and 0.75-1.00m in the nationwide 7km Grid System in Denmark. Changes in soil P content between 1987 and 1998 at 0-0.25 and 0.25-0.50m were also examined in 337 and 335 agricultural soil profiles, respectively. Compared to forest soils, the agricultural soils contained more total P down to 0.75m depth (264mgPkg-1, or 88% more at 0-0.25m depth, 191mgPkg-1 or 82% more at 0.25-0.50m depth and 120mgPkg-1 or 63% more at 0.50-0.75m depth). The mean degrees of phosphorus saturation (DPS) of the agricultural soils were 32, 23 and 15% in the three upper soil layers, which were approximately twice as high as at the corresponding depths of deciduous forest soils. Between 1987 and 1998 total soil P content in the agricultural soils increased at both 0-0.25 and 0.25-0.50m depth. On average, the increase corresponded to an annual accumulation of c. 25kgPha-1, with the increase fairly equally divided between the two soil layers. The accumulation corresponds with the national P surplus of c. 20kgPha-1 calculated from national statistics. This investigation shows that long-term surplus P fertilisation of agricultural soils has resulted in P accumulation to at least 0.75m depth. The paper discusses the potential importance of leaching, deep tillage, erosion and bioturbation for the observed accumulation of P in the subsoil. © 2013 Elsevier B.V.


Mweu M.M.,Copenhagen University | Toft N.,Copenhagen University | Katholm J.,Knowledge Center for Agriculture | Nielsen S.S.,Copenhagen University
Veterinary Microbiology | Year: 2012

Streptococcus agalactiae mastitis persists as a significant economic problem for the dairy industry in many countries. In Denmark, the annual surveillance programme for this mastitis pathogen initially based only on bacteriological culture of bulk tank milk (BTM) samples, has recently incorporated the use of the real-time PathoProof Mastitis PCR assay with the goal of improving detection of infected herds. The objective of our study was to estimate the herd sensitivity (Se) and specificity (Sp) of both tests of BTM samples using latent class models in a Bayesian analysis while evaluating the effect of herd-level covariates on the Se and Sp of the tests. BTM samples were collected from all 4258 Danish dairy herds in 2009 and screened for the presence of S. agalactiae using both tests.The highest Se of PCR was realized at a cycle threshold (Ct) cut-off value of 40. At this cut-off, the Se of the PCR was significantly higher (95.2; 95% posterior credibility interval [PCI] [88.2; 99.8]) than that of bacteriological culture (68.0; 95% PCI [55.1; 90.0]). However, culture had higher Sp (99.7; 95% PCI [99.3; 100.0]) compared to PCR (98.8; 95% PCI [97.2; 99.9]). The accuracy of the tests was unaffected by the herd-level covariates. We propose that screenings of BTM samples for S. agalactiae be based on the PCR assay with Ct readings of <40 considered as positive. However, for higher Ct values, confirmation of PCR test positive herds by bacteriological culture is advisable especially when the between-herd prevalence of S. agalactiae is low. © 2012 Elsevier B.V.


Pedersen M.F.,Knowledge Center for Agriculture | Olsen J.V.,Knowledge Center for Agriculture
Agricultural Finance Review | Year: 2013

Purpose – The purpose of this paper is to introduce a novel measure of access to credit suited to estimate the relative change in credit reserves. Design/methodology/approach – A debt possibility frontier is estimated using data envelopment analysis and the Malmquist index is calculated. The Malmquist index is redubbed the Debt Development index and decomposed into “change in debt capacity” and “change in debt capacity utilization”. Bootstrapping is applied for statistical inference. The method is applied to an unbalanced panel of 92,000 Danish farm accounts from 1996 to 2009. Findings – The paper finds that credit capacity roughly doubled for Danish farmers over the period, and that utilization of credit capacity generally was proportional to capacity change, utilization being higher for dairy and pig farms, than for crop farms. Research limitations/implications – Changes in credit reserves may have important implications for risk management practice, investment and technology adoption and related policy issues. The method is limited by the possibility of strategic behavior of lenders during credit cycle busts. In credit cycle booms, the method gives a good basis for the estimates of change in credit reserves. Practical implications – In a period of increasing credit reserves, risk management institutions are unlikely to develop. Like agricultural policy, access to credit may crowd out market-based risk management. Originality/value – The study represents a novel application and interpretation of a well-known method. © Emerald Group Publishing Limited.

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