Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Controlling Superstructure-Property Relationships via Critical Casimir Assembly of Quantum Dots
Marino, Emanuele ; Balazs, Daniel M. ; Crisp, Ryan W. ; Hermida-Merino, Daniel ; Loi, Maria A. ; Kodger, Thomas E. ; Schall, Peter - \ 2019
The Journal of Physical Chemistry Part C: Nanomaterials and Interfaces 123 (2019)22. - ISSN 1932-7447 - p. 13451 - 13457.

The assembly of colloidal quantum dots (QDs) into dense superstructures holds great promise for the development of novel optoelectronic devices. Several assembly techniques have been explored; however, achieving direct and precise control over the interparticle potential that controls the assembly has proven to be challenging. Here, we exploit the application of critical Casimir forces to drive the growth of QDs into superstructures. We show that the exquisite temperature-dependence of the critical Casimir potential offers new opportunities to control the assembly process and morphology of the resulting QD superstructures. The direct assembly control allows us to elucidate the relation between structural, optical, and conductive properties of the critical Casimir-grown QD superstructures. We find that the choice of the temperature setting the interparticle potential plays a central role in maximizing charge percolation across QD thin-films. These results open up new directions for controlling the assembly of nanostructures and their optoelectronic properties.

Improving scientific advice for the conservation and management of oceanic sharks and rays : Final report - Study
Coelho, R. ; Apostolaki, P. ; Bach, P. ; Brunel, T.P.A. ; Davies, T. ; Diez, G. ; Ellis, J. ; Escalle, L. ; Lopez, J. ; Merino, Gorka ; Mitchell, R. ; Macias, D. ; Murua, H. ; Overzee, H.M.J. van; Poos, J.J. ; Richardson, H. ; Rosa, D. ; Sanchez, S. ; Santos, C. ; Seret, B. ; Urbina, J.O. ; Walker, N. - \ 2019
Brussels : European Commission - ISBN 9789292024550 - 658 p.
The purpose of this specific study is to provide the Directorate-General for Maritime Affairs and Fisheries (DG MARE) with: Updated information regarding the association or occurrence of pelagic sharks and rays in different fisheries; Updated information regarding data collection and methodological approaches for the assessment of conservation status of sharks; A critical review of existing Conservation and Management Measures (CMMs) for sharks and of the current conservation status of the species concerned; and Proposals to improve and/or provide alternative options for conservation and management of sharks taking into account any recent methodological advances and new data or information. The species of interest are the main pelagic sharks caught by pelagic fisheries, including under Sustainable Fisheries Partnership Agreements (longline and purse seine fisheries). The study also considers some pelagic elasmobranchs included in Article 13 (species prohibitions) of the Council Regulation 2016/72 fixing for 2016 the fishing opportunities for certain fish stocks. The main regions focused are the oceanic regions covered by tuna-RFMOs where those species of elasmobranch are represented in the catches, specifically the Atlantic (ICCAT region), the Indian Ocean (IOTC region) and the Pacific (WCPFC and IATTC regions)
Archetypes of Climate Vulnerability: a Mixed-method Approach Applied in the Peruvian Andes
Vidal Merino, Mariana ; Sietz, Diana ; Jost, Francois ; Berger, Uta - \ 2019
Climate and Development 11 (2019)5. - ISSN 1756-5529 - p. 418 - 434.
adaptive capacity - agro-ecological zones - Andean agriculture - pattern analysis - sustainable livelihoods
Farm household systems (FHSs) in the Andes handle climate-related hazards such as frost and droughts with risk-coping and risk-management strategies based on the adaptive capital available to them. Nevertheless, a higher frequency of climatic stressors observed during the last few decades is challenging their capacity to adapt at a pace fast enough to keep up with the changes in external conditions. This increases the demand on the scientific community from policy and decision makers to investigate climate impacts and propose viable adaptation pathways at the local and regional scales. Better understanding heterogeneity in climate vulnerability is an important step towards addressing this demand. We present here a mixed-method approach to assessing archetypes or patterns of climate vulnerability that combines qualitative tools from participatory rural assessment approaches and quantitative techniques including cluster analysis. We illustrate this by looking at a case study of the Central Andes of Peru. The operationalization of the methods revealed differential factors for climate vulnerability, allowing us to categorize FHS archetypes according to the differences in those underlying factors. The archetypes differed mainly according to farm area, agro-ecological zones, irrigation, off-farm employment and climate-related damages. The results suggest that the approach is useful for explaining vulnerability as a function of recurrent internal and external determinants of vulnerability and developing related adaptive strategies.
Sensitivity of the breeding values for growth rate and worm egg count to environmental worm burden in Australian Merino sheep
Hollema, Baukje L. ; Bijma, Piter ; Werf, Julius H.J. van der - \ 2018
Journal of Animal Breeding and Genetics 135 (2018)5. - ISSN 0931-2668 - p. 357 - 365.
Environmental mean - Faecal egg count - Gastrointestinal nematode infection - Tolerance

The objective of this study was to explore the sensitivity of breeding values for growth rate and worm egg count (WEC, cube root transformed) to environmental worm burden, measured as the average WEC for each contemporary group (CGWEC). Growth rate and WEC were measured on 7,818 naturally infected Merino lambs in eight flocks across Australia, linked through common use of AI sires. Through bivariate analysis, genetic correlations of 0.55 ± 0.23 and 0.30 ± 0.16 were found for growth rate and WEC between low and high CGWEC, respectively. In a second analysis, breeding values for growth rate and WEC were regressed on CGWEC with a random regression model. The heritability for growth rate varied from 0.23 to 0.16 from low to high CGWEC, and the heritability for WEC varied from 0.25 to 0.36. Results suggest that breeding values for both growth rate and WEC are sensitive to environmental worm burden. Animals expressed less genetic variation for growth rate and more genetic variation for WEC in high CGWEC than in low CGWEC. This form of genotype-by-environment interaction should therefore be considered in genetic evaluation of both growth rate and WEC, to increase the efficiency of selection for animals that are more parasite resistant and more resilient to environmental worm challenge.

Networks of micronized fat crystals grown under static conditions
Nikolaeva, T. ; Adel, R. den; Velichko, E. ; Bouwman, W.G. ; Hermida-Merino, D. ; As, H. Van; Voda, A. ; Duynhoven, J. Van - \ 2018
Food & Function 9 (2018)4. - ISSN 2042-6496 - p. 2102 - 2111.
Dispersing micronized fat crystals (MFCs) in oil is a novel route to largely decouple fat crystallisation and network formation and thus to simplify the manufacture of fat-continuous food products. MFCs dispersed in oil form a weak-interaction network organized by crystal aggregates in a continuous net of crystalline nanoplatelets. The rough surface of MFC nanoplatelets hampers stacking into one-dimensional aggregates, which explains the high mass fractal dimensions of the networks formed in MFC dispersions. Applying shear does not have a significant effect on the fractal dimensions of MFC networks, and MFC aggregates in the range of 5–10 μm remain intact. However, shear leads to a significant loss of storage modulus and yield stress over a time frame of an hour. This can be attributed to irreversible disruption of the continuous net of nanoplatelets. Rheo-SAXS revealed that shear releases nanoplatelets from the continuous net, which subsequently align in the shear field and undergo rapid recrystallisation. The release of thin and metastable nanoplatelets from the weak-link network bears relevance for simplified and more effective manufacturing of emulsified food products by effectively decoupling crystallisation, network formation and emulsification.
Sephadex filtration as successful alternative to density-gradient centrifugation procedures for ram sperm selection with improved kinetics
Galarza, D.A. ; López-Sebastián, A. ; Woelders, H. ; Blesbois, E. ; Santiago-Moreno, J. - \ 2018
Animal Reproduction Science 192 (2018). - ISSN 0378-4320 - p. 261 - 270.
Centrifugation - Filtration - Gradients - Selection - Sperm
Density-gradients centrifugation (DGC) and filtration columns (FC) are used to separate deformed or dead sperm, debris, and other cells that may negatively affect the fertilizing capacity of sperm in fresh, chilled and frozen/thawed semen. The present study was conducted to evaluate the suitability of DGC (BoviPure®, Percoll® and Accudenz®) and FC (Sephadex G-15®) sperm selection procedures for fresh-extended and cold-stored ram semen by assessment of post-treatment sperm quality variables. Twenty normospermic ejaculates from ten adult Merino rams were used. Sperm concentration of recovered cells was greater (P < 0.001) after BoviPure treatment than other procedures in both fresh and cold semen. With the Sephadex method, there were more desirable values than with use of DGC procedures in several sperm motility variables measured by using the CASA system. In non-refrigerated semen samples, the percentage of progressive sperm motility (%PSM) after Sephadex filtration was greater (P < 0.05) than after BoviPure treatment; the straightline velocity (VSL) value after Sephadex filtration was greater (P < 0.01) than after Accudenz treatment; the amplitude of lateral head displacement (ALH) after Sephadex and Accudenz treatment was less than non-filtered semen (P < 0.001) and after Percoll (P < 0.01) and BoviPure (P < 0.05) treatments. In cold-stored semen samples, the %PSM after Sephadex filtration was greater than non-filtered (P < 0.05) semen and after BoviPure (P < 0.05), Percoll (P < 0.05) and Accudenz (P < 0.001) treatments. It is concluded that Sephadex column filtration can be used to select ram sperm in non-refrigerated and cooled semen, because percentage progressively motile sperm and some other sperm motility characteristics are greater with use of this techniques as compared with use of DGC methods.
Developing an ethically acceptable virtual fencing system for sheep
Marini, Danila ; Meuleman, M.D. ; Belson, Sue ; Rodenburg, T.B. ; Llewellyn, Rick ; Lee, Caroline - \ 2018
Animals 8 (2018)3. - ISSN 2076-2615
Associative learning - Sheep management - Technology - Virtual fencing - Welfare
To ensure animal welfare isn’t compromised when using virtual fencing, animals must be able to associate a benign conditioned stimulus with an aversive stimulus. This study used an associative learning test to train 30, four-year-old, Merino x Suffolk ewes, to associate an audio cue with an electric stimulus. Collars manually controlled by a GPS hand-held unit were used to deliver the audio and electric stimuli cues. For the associative learning, when sheep approached an attractant at a distance of three m from the trough, an audio cue was applied for one s. If the sheep stopped or changed direction, the audio cue ceased immediately and no electrical stimulus was applied. If the sheep did not respond to the audio cue it was followed by a low-level electrical stimulus. Approaches to the attractant significantly decreased from day one to day two. It took a mean of three pairings of the audio cue and electrical stimulus for a change in behaviour to occur, after which sheep that approached the attractant had a 52% probability of avoiding the electrical stimulus and responding to the audio cue alone. Further research is required to determine whether sheep can be trained to associate an audio cue with a negative stimulus for use in group grazing situations.
Strategies for greenhouse gas emissions mitigation in Mediterranean agriculture: A review
Sanz-Cobena, A. ; Lassaletta, L. ; Aguilera, E. ; Prado, A. Del; Garnier, J. ; Billen, G. ; Iglesias, A. ; Sánchez, B. ; Guardia, G. ; Abalos Rodriguez, Diego ; Plaza-Bonilla, D. ; Puigdueta-bartolomé, I. ; Moral, R. ; Galán, E. ; Arriaga, H. ; Merino, P. ; Infante-Amate, J. ; Meijide, A. ; Pardo, G. ; Álvaro-Fuentes, J. ; Gilsanz, C. ; Báez, D. ; Doltra, J. ; González-Ubierna, S. ; Cayuela, M.L. ; Menéndez, S. ; Díaz-Pinés, E. ; Le-Noë, J. ; Quemada, M. ; Estellés, F. ; Calvet, S. ; Grinsven, H.J.M. Van; Westhoek, H. ; Sanz, M.J. ; Gimeno, B.S. ; Vallejo, A. ; Smith, P. - \ 2017
Agriculture, Ecosystems and Environment 238 (2017). - ISSN 0167-8809 - p. 5 - 24.
An integrated assessment of the potential of different management practices for mitigating specific components of the total GHG budget (N2O and CH4 emissions and C sequestration) of Mediterranean agrosystems was performed in this study. Their suitability regarding both yield and environmental (e.g. nitrate leaching and ammonia volatilization) sustainability, and regional barriers and opportunities for their implementation were also considered. Based on its results best strategies to abate GHG emissions in Mediterranean agro-systems were proposed. Adjusting N fertilization to crop needs in both irrigated and rain-fed systems could reduce N2O emissions up to 50% compared with a non-adjusted practice. Substitution of N synthetic fertilizers by solid manure can be also implemented in those systems, and may abate N2O emissions by about 20% under Mediterranean conditions, with additional indirect benefits associated to energy savings and positive effects in crop yields. The use of urease and nitrification inhibitors enhances N use efficiency of the cropping systems and may mitigate N2O emissions up to 80% and 50%, respectively. The type of irrigation may also have a great mitigation potential in the Mediterranean region. Drip-irrigated systems have on average 80% lower N2O emissions than sprinkler systems and drip-irrigation combined with optimized fertilization showed a reduction in direct N2O emissions up to 50%. Methane fluxes have a relatively small contribution to the total GHG budget of Mediterranean crops, which can mostly be controlled by careful management of the water table and organic inputs in paddies. Reduced soil tillage, improved management of crop residues and agro-industry by-products, and cover cropping in orchards, are the most suitable interventions to enhance organic C stocks in Mediterranean agricultural soils. The adoption of the proposed agricultural practices will require farmers training. The global analysis of life cycle emissions associated to irrigation type (drip, sprinkle and furrow) and N fertilization rate (100 and 300 kg N ha−1 yr−1) revealed that these factors may outweigh the reduction in GHG emissions beyond the plot scale. The analysis of the impact of some structural changes on top-down mitigation of GHG emissions revealed that 3–15% of N2O emissions could be suppressed by avoiding food waste at the end-consumer level. A 40% reduction in meat and dairy consumption could reduce GHG emissions by 20–30%. Reintroducing the Mediterranean diet (i.e. ∼35% intake of animal protein) would therefore result in a significant decrease of GHG emissions from agricultural production systems under Mediterranean conditions.
Actinomyces succiniciruminis sp. nov. and Actinomyces glycerinitolerans sp. nov., two novel organic acid-producing bacteria isolated from rumen
Palakawong Na Ayudthaya, Susakul ; Pristaš, Peter ; Hrehová, Ludmila ; Javorský, Peter ; Stams, A.J.M. ; Plugge, Caroline M. - \ 2016
Systematic and Applied Microbiology 39 (2016)7. - ISSN 0723-2020 - p. 445 - 452.
Actinomyces - Glycerol tolerance - Organic acid production - Rumen bacteria - Succinate production

Two bacterial strains, Am4 and G10 were isolated from rumen fluid of different ruminants: cow (Holstein-Friesian) and sheep (Slovenskè merino), respectively. They were isolated from different hosts and regions, but showed 99.2% similarity of the 16S rRNA genes. Both strains are versatile and ferment various sugars to mainly succinate and lactate and small amounts of acetate and formate. The 16S rRNA sequences of Am4 and G10 revealed that they belonged to the genus Actinomyces, and are related to Actinomyces ruminicola JCM 13352T with 97.0% and 97.4% similarity, respectively. DDH showed strain Am4 and G10 had only 55.8 and 43.3% similarity with the Actinomyces ruminicola JCM 13352T, and had 69.9% similarity among each other. Comparing strain Am4 and G10, gANI value and dDDH were 92.9% and 68.6%, respectively. Additionally, AAI between the strains was 95.8%. MLSA of housekeeping genes showed difference of metG and pheS. The G + C% contents of strain Am4 and G10 were 69.8% and 68.5%, respectively. MK-10(H4) was the principal quinone for strain Am4 (82%) and G10 (91%) with small amounts of MK-10(H8) and MK-10(H6) for both strains. Only MK-9(H4) was detected in strain Am4. MALDI-TOF analysis of protein profiles also revealed that Am4 and G10 are different from each other and from Actinomyces ruminicola JCM 13352T. Based on phylogenetic and physiological characteristics, together with genome comparison and MLSA we propose two novel species in the genus Actinomyces: Actinomyces succiniciruminis sp. nov. (type strain Am4T = TISTR 2317T = DSM 10376T) and Actinomyces glycerinitolerans sp. nov. (type strain G10T = TISTR 2318T = DSM 10377T).

Costs and benefits to European shipping of ballast-water and hull-fouling treatment : Impacts of native and non-indigenous species
Fernandes, Jose A. ; Santos, Lionel ; Vance, Thomas ; Fileman, Tim ; Smith, David ; Bishop, John D.D. ; Viard, Frédérique ; Queirós, Ana M. ; Merino, Gorka ; Buisman, Erik ; Austen, Melanie C. - \ 2016
Marine Policy 64 (2016). - ISSN 0308-597X - p. 148 - 155.
Ballast water - Biofouling - Economic impact - Maritime - Mitigation measures - Native - Non-indigenous species - Shipping

Maritime transport and shipping are impacted negatively by biofouling, which can result in increased fuel consumption. Thus, costs for fouling reduction can be considered an investment to reduce fuel consumption. Anti-fouling measures also reduce the rate of introduction of non-indigenous species (NIS). Further mitigation measures to reduce the transport of NIS within ballast water and sediments impose additional costs. The estimated operational cost of NIS mitigation measures may represent between 1.6% and 4% of the annual operational cost for a ship operating on European seas, with the higher proportional costs in small ships. However, fouling by NIS may affect fuel consumption more than fouling by native species due to differences in species' life-history traits and their resistance to antifouling coatings and pollution. Therefore, it is possible that the cost of NIS mitigation measures could be smaller than the cost from higher fuel consumption arising from fouling by NIS.

Invasieve soorten Waddenzee: : Ecosysteem resistentie en de Filipijnse tapijtschelp
Sneekes, A.C. ; Mendez Merino, Natalia ; Weide, B.E. van der; Glorius, S.T. ; Tamis, J.E. - \ 2015
Den Helder : IMARES (Rapport / IMARES C175/15) - 67 p.
invasieve soorten - schaaldieren - veevervoer - weerstand - aquatische ecosystemen - milieueffect - waddenzee - nederland - invasive species - shellfish - transport of animals - resistance - aquatic ecosystems - environmental impact - wadden sea - netherlands
Breeding objectives for sheep should be customised depending on variation in pasture growth across years
Rose, I.J. ; Mulder, H.A. ; Thompson, A.N. ; Werf, J.H.J. van der; Arendonk, J.A.M. van - \ 2015
Animal 9 (2015)8. - ISSN 1751-7311 - p. 1268 - 1277.
Breeding programmes for livestock require economic weights for traits that reflect the most profitable animal in a given production system, which affect the response in each trait after selection. The profitability of sheep production systems is affected by changes in pasture growth as well as grain, meat and wool prices between seasons and across years. Annual pasture growth varies between regions within Australia’s Mediterranean climate zone from low growth with long periods of drought to high growth with shorter periods of drought. Therefore, the objective of this study was to assess whether breeding objectives need to be adapted for regions, depending on how reliable the pasture growth is across years. We modelled farms with Merino sheep bred for wool and meat in 10 regions in Western Australia. Across these 10 regions, mean annual pasture growth decreased, and the CV of annual pasture growth increased as pasture growth for regions became less reliable. We calculated economic values for nine traits, optimising management across 11 years, including variation for pasture growth and wool, meat and grain prices between and within years from 2002 to 2012. These economic values were used to calculate responses to selection for each trait for the 10 regions. We identified two potential breeding objectives, one for regions with low or high reliability and the other for regions with medium reliability of pasture growth. Breeding objectives for high or low pasture growth reliability had more emphasis on live weight traits and number of lambs weaned. Breeding objectives for medium reliability of pasture growth had more emphasis on decreasing fibre diameter. Relative economic weights for fleece weight did not change across the regions. Regions with low or high pasture reliability had similar breeding objectives and response to selection, because the relationship between the economic values and CV of pasture growth were not linear for live weight traits and the number of lambs weaned. This non-linearity was caused by differences in distribution of pasture growth between regions, particularly during summer and autumn, when ewes were pregnant, with increases in energy requirements affecting the value of lambs weaned. In addition, increasing live weight increased the intake capacity of sheep, which meant that more poor quality pasture could be consumed during summer and autumn, which had more value in regions with low and high pasture reliability. We concluded that breeding values for sheep production systems should be customised depending on the reliability of pasture growth between years.
Varying pasture growth and commodity prices change the value of traits in sheep breeding objectives
Rose, I.J. ; Mulder, H.A. ; Thompson, P.N. ; Werf, J.H.J. van der; Arendonk, J.A.M. van - \ 2014
Agricultural Systems 131 (2014). - ISSN 0308-521X - p. 94 - 104.
multiple rearing ability - economic values - mediterranean environment - bioeconomic approach - functional traits - wool production - fleece weight - merino ewes - model - reproduction
Breeding programs for livestock require economic weights for traits that reflect the most profitable animal in a given production system. Economic weights are commonly based on average conditions. In pasture based livestock production systems the cost of feed is an important profit driver, but availability of feed from pasture can vary greatly within and between years. Additionally, the price of supplementary feed during periods of feed shortage and the prices for meat and wool vary between years. Varying prices and pasture growth can change the optimal management of the flock affecting profitability. This paper investigates how variation in commodity prices and pasture growth affect the economic values of traits in the breeding objective. We modelled a sheep farm with a self-replacing Merino flock bred for wool and meat in a Mediterranean environment. We optimised management decisions across 5 years using dynamic recursive analysis to maximise profit when commodity prices and pasture growth varied annually. Actual pasture growth and wool, meat, and grain prices from 2005 to 2009 were used. Management could adapt to varying pasture growth and commodity prices by changing sheep numbers, age structure of the flock and amount of grain fed to sheep. The economic value of seven traits in the breeding objective were compared for a scenario with average pasture growth and commodity prices over years and a scenario with varying pasture growth and commodity prices over years. Variation in pasture growth and commodity prices decreased average profit and increased the economic value of all breeding goal traits compared to the average scenario. The order of importance of traits stayed the same between varying and average scenarios but the relative importance of traits changed. The economic values that increased the most were for traits that had increased profit with the smallest impact on energy requirements such as yearling live weight, longevity and fibre diameter. Our results showed that it is important to account for variation in feed availability and commodity prices when determining the expected profit and economic values for traits. The results also suggest that whereas variation in pasture growth and commodity prices between years makes the farming operations less profitable, these changing conditions increase the genetic variation in profitability of sheep. Therefore, genetic improvement has more value relative to scenarios where pasture feed supply and prices are constant.
Breeding strategies to make sheep farms resilient to uncertainty
Rose, I.J. - \ 2014
Wageningen University. Promotor(en): Johan van Arendonk, co-promotor(en): Herman Mulder; J. Werf. - Wageningen : Wageningen University - ISBN 9789462570900 - 188
schapen - schapenhouderij - dierveredeling - veredelingsprogramma's - economische haalbaarheid - rentabiliteit - veerkracht - weiden - schapenvoeding - western australia - sheep - sheep farming - animal breeding - breeding programmes - economic viability - profitability - elasticity - pastures - sheep feeding - western australia

The sheep industry in Western Australian has had many challenges over the last 20 years which have caused sheep numbers to decline. This decline is because sheep farms are not resilient to uncertain pasture growth and commodity prices. One way to improve resilience and profitability of farming systems is through breeding of sheep. Therefore, this thesis had two aims; 1. Quantify the potential to select and breed sheep that are more resilient and 2. Quantify how sheep breeding can make farming systems more resilient. To determine if sheep can be bred to be resilient to varying pasture growth I investigated if live weight change is a heritable trait. I investigated live weight change in adult Merino ewes managed in a Mediterranean climate in Katanning in Western Australia. Live weight change traits were during mating and lactation. The heritability of live weight change was low to moderate. Therefore that live weight change could be a potential indicator trait for resilience to uncertain pasture growth. To include live weight change in a breeding goal, correlations with other traits are needed. I calculated the genetic correlations between live weight change during mating, pregnancy and lactation, and reproduction traits. Most genetic correlations were not significant, but genetically gaining live weight during mating in two-year old ewes and during pregnancy for three-year-old ewes improved reproduction. Therefore, optimised selection strategies can select for live weight change and reproduction simultaneously. To investigate optimal breeding programs to make sheep farms resilient to uncertain pasture growth and prices, I modelled a sheep farm in a Mediterranean environment. The economic value of seven traits in the breeding objective were estimated. Including variation in pasture growth and commodity prices decreased average profit and increased the economic value of all breeding goal traits compared to the average scenario. Economic values increased most for traits that had increases in profit with the smallest impact on energy requirements. I also compared optimal breeding programs for across 11 years for 10 regions in Western Australia with different levels of reliability of pasture growth. I identified two potential breeding goals, one for regions with low or high pasture growth reliability and one for regions with medium reliability of pasture growth. Regions with low or high reliability of pasture growth had similar breeding goals because the relationship between economic values and reliability of pasture growth were not linear for some traits. Therefore, farmers can customise breeding goals depending on the reliability of pasture growth on their farm.

Genetic correlations between bodyweight change and reproduction traits in Merino ewes depend on age
Rose, I.J. ; Mulder, H.A. ; Werf, J.H.J. van der; Thompson, A.N. ; Arendonk, J.A.M. van - \ 2014
Journal of Animal Science 92 (2014)8. - ISSN 0021-8812 - p. 3249 - 3257.
wool production - liveweight - nutrition - sheep - parameters - pregnancy - survival - components - lactation - variance
Merino sheep in Australia experience periods of variable feed supply. Merino sheep can be bred to be more resilient to this variation by losing less bodyweight when grazing poor quality pasture and gaining more bodyweight when grazing good quality pasture. Therefore, selection on bodyweight change might be economically attractive but correlations with other traits in the breeding objective need to be known. The genetic correlations (rg) between bodyweight, bodyweight change, and reproduction were estimated using records from ~7350 fully pedigreed Merino ewes managed at Katanning in Western Australia. Number of lambs and total weight of lambs born and weaned were measured on ~5300 2-year-old ewes, ~4900 3-year-old ewes and ~3600 4-year-old ewes. On a proportion of these ewes bodyweight change was measured: ~1950 two-year-old ewes, ~1500 three old ewes and ~1100 four-year-old ewes. The bodyweight measurements were for three periods. The first period was during mating period over 42 days on poor pasture. The second period was during pregnancy over 90 days for ewes that got pregnant on poor and medium quality pasture. The third period was during lactation over 130 days for ewes that weaned a lamb on good quality pasture. Genetic correlations between weight change and reproduction were estimated within age classes. Genetic correlations were tested to be significantly greater magnitude than zero using likelihood ratio tests. Nearly all bodyweights had significant positive genetic correlations with all reproduction traits. In two-year old ewes, bodyweight change during the mating period had a positive genetic correlation with number of lambs weaned (rg = 0.58); bodyweight change during pregnancy had a positive genetic correlation with total weight of lambs born (rg = 0.33) and a negative genetic correlation with number of lambs weaned (rg = - 0.49). All other genetic correlations were not significantly greater magnitude than zero but estimates of genetic correlations for three-year-old ewes were generally consistent with these findings. The direction of the genetic correlations mostly coincided with the energy requirements of the ewes, and the stage of maturity of the ewes. In conclusion, optimized selection strategies on bodyweight changes to increase resilience will depend on the genetic correlations with reproduction, and are dependent on age.
Quantitative trait loci associated with pre-weaning growth in South African Angora goats
Visser, C. ; Marle-Koster, E. van; Snyman, M.A. ; Bovenhuis, H. ; Crooijmans, R.P.M.A. - \ 2013
Small Ruminant Research 112 (2013)1-3. - ISSN 0921-4488 - p. 15 - 20.
genome-wide association - microsatellite markers - genetic-parameters - parentage verification - conformation traits - carcass composition - wool production - fleece traits - merino sheep - beef-cattle
This study aimed to identify chromosomal regions associated with genetic variation in pre-weaning growth traits in Angora goats. A genome-wide scan was performed by genotyping 1042 offspring from 12 half-sib families using 88 microsatellite caprine markers covering 1368cM. Phenotypes were recorded at birth (BW) and weaning (WW) and analysed using GridQTL software. A total of six putative QTL were detected on six different chromosomes, all at chromosome-wide significance level. Four QTL were identified for BW on CHI 4, 8, 17 and 27 and two QTL for WW on CHI 16 and 19. QTL effects ranged from -0.32 to 0.25 in units of residual standard deviation in different families. Some of these QTL correspond to chromosomes where QTL associated with growth have been identified in other species. These chromosomal segments hold potential to influence weight gain in young goats.
Simulated selection responses for breeding programs including resistance and resilience to parasites in Creole goats
Gunia, M. ; Phocas, F. ; Gourdine, J.L. ; Bijma, P. ; Mandonnet, N. - \ 2013
Journal of Animal Science 91 (2013)2. - ISSN 0021-8812 - p. 572 - 581.
meat quality traits - nematode infections - genetic-parameters - production systems - gastrointestinal helminths - small ruminants - dairy sheep - merino ewes - schemes - contamination
The Creole goat is a local breed used for meat production in Guadeloupe (French West Indies). As in other tropical countries, improvement of parasite resistance is needed. In this study, we compared predicted selection responses for alternative breeding programs with or without parasites resistance and resilience traits. The overall breeding goal included traits for production, reproduction and parasite resilience and resistance to ensure a balanced selection outcome. The production traits were body weight (BW) and dressing percentage (DP). The reproduction trait was fertility (FER), which was the number of doe kiddings per mating. The resistance trait was worm fecal egg count (FEC), which is a measurement of the number of gastro-intestinal parasite eggs found in the feces. The resilience trait was the packed cell volume (PCV), which is a measurement of the volume of red blood cells in the blood. DP, BW and FEC were measured at 11 mo of age, which is the mating or selling age. FER and PCV were measured on females at each kidding period. The breeding program accounting for the overall breeding goal and a selection index including all traits gave annual selection responses of 800 g for BW, 3.75% for FER, 0.08% for DP, -0.005 ln(eggs/g) for FEC, and 0.28% for PCV. The expected selection responses for BW and DP in this breeding program were reduced by 2% and 6%, respectively, compared to a breeding program not accounting for FEC and PCV. The overall breeding program, proposed for the Creole breed, offers the best breeding strategy in terms of expected selection responses, making it possible to improve all traits together. It offers a good balance between production and adaptation traits and may present some interest for the selection of other goat breeds in the tropics.
Effects of sheep breed and soybean meal supplementation on rumen environment and degradation kinetics
Lourenco, A. ; Cone, J.W. ; Fontes, P. ; Dias-Da-Silva, A. - \ 2013
NJAS Wageningen Journal of Life Sciences 64-65 (2013). - ISSN 1573-5214 - p. 77 - 85.
voluntary food-intake - low-quality roughage - bos-indicus cattle - dry-matter - nitrogen supplementation - apparent digestibility - merino sheep - digestion - herbage - protein
The aim of this study was to evaluate if the in vivo digestibility and intake differences, observed in previous studies, between Ile-de-France (IF) and Churra-da-Terra-Quente (CTQ) sheep breeds, were due to rumen environment and degradability differences. The intake, digestibility, rumen environment and degradability and urinary allantoin-nitrogen excretion were evaluated in 8 adult cannulated ewes (4 CTQ and 4 IF ewes). The animals were fed ad libitum hay – with and without a soybean meal supplementation (150 g/kg ingested hay, dry matter basis). The organic matter intake per kg of body weight was higher (P <0.05) and the NDF and hay organic matter digestibility was lower in CTQ ewes (P <0.05), irrespective of supplementation. The rumen pH remained above 6.35 in all treatments, and the difference between the breeds was not biologically relevant. The ammonia nitrogen rumen content and the urinary allantoin-nitrogen excretion were similar (P > 0.05), whether the breeds where fed hay or hay supplemented with soybean meal. The volatile fatty acid concentrations in the rumen were similar (P > 0.05) for both genotypes. There was no breed effect (P > 0.05) on the rumen protozoa population, although supplementation increased its number (P <0.001). As a result of the absence of differences in rumen content characteristics, there were no differences between the breeds (P > 0.05) on rumen in sacco degradation results. Thus, the effective rumen degradation was lower in the CTQ breed, when its inherit lower outflow rate was used to calculate it. This study suggests that the native CTQ breed and the IF breed exhibit similar rumen conditions for the microbial degradation of fibrous feeds. Thus the higher intake and lower digestibility of the CTQ breed can only result from its inherit faster flow through the gastrointestinal tract
Merino ewes can be bred for body weight change to be more tolerant to uncertain feed supply
Rose, I.J. ; Kause, A. ; Mulder, H.A. ; Werf, J.H.J. van der; Thompson, A.N. ; Ferguson, M.B. ; Arendonk, J.A.M. van - \ 2013
Journal of Animal Science 91 (2013)6. - ISSN 0021-8812 - p. 2555 - 2565.
random regression-models - parameter-estimation - heat-stress - environment - covariance - liveweight - survival - climate - cattle
Sheep in Australia experience periods with different feed supply causing them to gain and lose BW during the year. It is more efficient if ewes lose less BW during periods of poor nutrition and gain more BW during periods of good nutrition. We investigated whether BW loss during periods of poor nutrition and BW gain during periods of good nutrition are genetically different traits. We used BW measurements from 2,336 adult Merino ewes managed over 5 yr in a Mediterranean climate in Katanning, Australia. Body weight loss is the difference between 2 BW measured 42 d apart during mating, a period of poor nutrition. Body weight gain is the difference between 2 BW measured 131 d apart during a period of good nutrition between prelambing and weaning. We estimated variance compnents of BW change using 3 methods: 1) as a trait calculated by subtracting the first BW from the second, 2) multivariate analysis of BW traits, and 3) random regression analysis of BW. The h(2) and genetic correlations (rg) estimated using the multivariate analysis of BW and the BW change trait were very similar whereas the random regression analysis estimated lower heritabilities and more extreme negative genetic correlations between BW loss and gain. The multivariate model fitted the data better than random regression based on Akaike and Bayesian information criterion so we considered the results of the multivariate model to be more reliable. The heritability of BW loss (h(2) = 0.05-0.16) was smaller than that of BW gain (h(2) = 0.14-0.37). Body weight loss and gain can be bred for independently at 2 and 4 yr of age (rg = 0.03 and -0.04) whereas at 3 yr of age ewes that genetically lost more BW gained more BW (rg = -0.41). Body weight loss is genetically not the same trait at different ages (rg range 0.13-0.39). Body weight gain at age 3 yr is genetically the same trait at age 4 yr (rg = 0.99) but is different between age 2 yr and the older ages (rg = 0.53 and 0.51). These results suggest that as the ewes reach their mature BW, BW gain at different ages becomes the same trait. This does not apply to BW loss. We conclude that BW change could be included in breeding programs to breed adult Merino ewes that are more tolerant to variation in feed supply.
Towards the implementation of an integrated ecosystem fleet-based management of European fisheries
Gascuel, D. ; Merino, G. ; Döring, R.D. ; Druon, D.N. ; Goti, L. ; Guénette, S. ; Macher, C. ; Soma, K. ; Travers-Trolet, M. ; Mackinson, S. - \ 2012
Marine Policy 36 (2012)5. - ISSN 0308-597X - p. 1022 - 1032.
marine food webs - fish stocks - trophic-level - celtic sea - indicators - strategies - evaluate - policies - model
Using the Celtic Sea and the North Sea as case studies, the fleet-based approach is shown to be the pathway to implement an effective ecosystem approach to fisheries management (EAFM) in European seas. First, a diagnostic on the health of each ecosystem is proposed based on the reconstruction of long time-series of catch, the analysis of mean indicators or stocks trajectories derived from ICES stock assessment results, and the analysis of ecosystem indicators. Then, a fleet-based synthesis is presented using indicators of both the ecological impact and the economic performances of the major fleets operating within each ecosystem. In particular, assessment diagrams show whether each fleet segment, on average, sustainably exploits the stocks. Although results are preliminary due to the poor quality of available data, the analysis shows that simple indicators can be estimated and clearly highlight contrasts between fleet segments. Such an approach contributes to the evolution from a stock-based to a fleet-based management, which reflects the ecological, economical and social pillars of the sustainable development of fisheries.
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