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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Big data analysis for smart farming : Results of TO2 project in theme food security
Kempenaar, C. ; Lokhorst, C. ; Bleumer, E.J.B. ; Veerkamp, R.F. ; Been, Th. ; Evert, F.K. van; Boogaardt, M.J. ; Ge, L. ; Wolfert, J. ; Verdouw, C.N. ; Bekkum, Michael van; Feldbrugge, L. ; Verhoosel, Jack P.C. ; Waaij, B.D. ; Persie, M. van; Noorbergen, H. - \ 2016
Wageningen : Wageningen University & Research (Wageningen Plant Research report ) - 82 p.
animal production - milk production - farming - data analysis - data collection - information technology - models - dierlijke productie - melkproductie - landbouw bedrijven - gegevensanalyse - gegevens verzamelen - informatietechnologie - modellen
In this report we describe results of a one-year TO2 institutes project on the development of big data technologies within the milk production chain. The goal of this project is to ‘create’ an integration platform for big data analysis for smart farming and to develop a show case. This includes both technical (hard/software) and organizational integration (developing business ecosystem) and combining and linking of data and models. DLO, NLR and TNO worked together in 2015 towards the realization of an IT data infrastructure that makes it possible to solve to connect data from different sources and models in an effective and safe way, ontology problems, specific analysis tools develop, opportunities and risks to identify and assess the acquired knowledge and experience and present it in a smart farming show case, from 'grass to glass‘.
Village poultry production system : Perception of farmers and simulation of impacts of interventions
Wondmeneh, E. ; Waaij, E.H. van der; Udo, H.M.J. ; Tadelle, D. ; Arendonk, J.A.M. van - \ 2016
African Journal of Agricultural Research 11 (2016)24. - ISSN 1991-637X - p. 2075 - 2081.
This study identified perception of poultry farmers’ on impact of interventions in village poultry production and quantified the impacts of interventions on flock and economic performance using modelling. A structured questionnaire was used to collect data on perceptions of poultry keeping and performances from 240 randomly selected households in two districts of Ethiopia. Crop was the major source of income, and poultry generated supplementary income. Farmers perceived that demand and price of poultry products increased. Majority of the farmers believed that additional inputs would not lead to higher income. A dynamic simulation showed that the base situation made a positive financial
contribution. Vaccinations had the largest positive impact on flock performances and using improved indigenous chicken had the smallest. Application of interventions had the largest effect on flock performances in the base situation but did not lead to profitability. The sensitivity analysis showed that feed cost had the largest impact on the profitability followed by housing, vaccination and breed. Farmers’ perceptions affected their decisions regarding implementation of interventions. Simulated interventions increased productivity but only in a few cases the increased incomes outweighed the additional costs. Interventions need to be tailored towards the local situation to ensure improved productivity and improved income
Comparison of different poultry breeds under station and on-farm conditions in Ethiopia
Wondmeneh, E. ; Waaij, E.H. Van der; Udo, H.M.J. ; Tadelle, D. ; Arendonk, J.A.M. Van - \ 2016
Livestock Science 183 (2016). - ISSN 1871-1413 - p. 72 - 77.
Improved chicken - Laying traits - Performance traits - Selective breeding program

A selective breeding program was implemented to improve the performance of indigenous chickens. Improved chicken from the 7th generation was compared with commercial layer, crossbred and unselected indigenous chickens both on-station and on-farm. A total of 870 chickens were used. More than 600 chickens (n=150 and n=120 from each breed during growing and laying period respectively) arranged in completely randomized design were followed on-station, and 270 (90 from commercial, crossbred and improved during laying period) were evaluated on-farm in Ada (n=6 farms) and Horro (n=9 farms) districts in a split-plot design. Body weight, cumulative feed intake, and survival were recorded while feed conversion ratio was calculated at week 8, 12, 16 and 20 during the growing period on-station. Age at first egg and total egg number during lifetime were recorded once. Survival and hen housed egg production were recorded at month 3, 6, 9 and 12 of age both on-station and on-farm. Egg weight, and feed per egg were recorded and used to calculate feed conversion ratio during the laying period on-station. Significant effect of breed (P

Genetic Variation and Signatures of Selection in the Genomes of Kenyan Indigenous Chicken and Commercial Layers
Ngeno, K. ; Herrero-Medrano, J. ; Waaij, E.H. van der; Kahi, A.K. ; Megens, H.J.W.C. ; Arendonk, J.A.M. van; Crooijmans, R.P.M.A. - \ 2015
In: Improving Indigenous Chicken Productivity for Health and Wealth. - - p. 40 - 40.
Breeding of indigenous chicken in developing countries is mainly done by the resource-poor rural households that raise birds in a scavenging system characterized by low inputs, adverse climatic conditions and high disease pressure. As a result, indigenous chicken may have developed specific genetic adaptations for such challenging environments. In this study, genomic variation of indigenous chicken kept under low input production systems was assessed using autosomal microsatellite markers and whole genome re-sequence data. Indigenous chickens were further compared to high input commercial layers to identify selection signatures and candidate mutations that may explain the phenotypic divergence between these populations. Commercial layers had much lower nucleotide diversity (0.31 - 0.36) than indigenous chicken (0.58 - 0.62). We also identified up to 59 genomic regions with high Fst values (0.44 - 0.85) between indigenous and commercial chickens, overlapping 16 genes. Five genes (SLC26A8, BRPF3, MAPK13, PDIA4 and MRPL32) out of the 16 are associated with the missense variants that could explain partially the phenotypic divergence between these populations. Differently to commercial chickens, indigenous chickens preserved a high genomic variability that may be important, for addressing present and future challenges associated with adaptability to the environment and to cope with farmers breeding goals.
Genetic diversity of different indigenous chicken ecotypes using highly polymorphic MHC-linked and non-MHC microsatellite markers
Ngeno, K. ; Waaij, E.H. van der; Megens, H.J.W.C. ; Kahi, A.K. ; Arendonk, J.A.M. van; Crooijmans, R.P.M.A. - \ 2015
In: Improving Indigenous Chicken Productivity for Health and Wealth. - - p. 33 - 33.
The study investigated the genetic make-up of different ecotypes of indigenous chickens (ICs) in Kenya based on major histocompatibility complex (MHC)-linked and non-MHC microsatellite markers. Blood samples were collected from eight regions (48 birds per region) of Kenya: Kakamega (KK), Siaya (BN), West Pokot (WP), Turkana (TK), Bomet (BM), Narok (NR), Lamu (LM) and Taita-Taveta (TT) and genotyped using two MHC-linked and ten non-MHC markers. All MHC-linked and non-MHC markers were polymorphic with a total of 140 alleles, of which 56 were identified in MHC-linked markers. Mean number of alleles (Na and Ne), private alleles, heterozygosity and genetic distances were higher for MHC-linked markers compared with non-MHC markers. The ad hoc statistic ¿K detected the true numbers of clusters to be three for MHC-linked markers and two in non-MHC markers. In conclusion, Kenyan ICs belong into two to three genetically distinct groups. Different markers systems have different clustering system. MHC-linked markers divided ICs into three mixed clusters, composing of individuals from the different ecotypes whereas non-MHC markers grouped ICs into two groups. These IC ecotypes host many and highly diverse MHC-linked alleles. Higher allelic diversity indicated a huge amount of genetic variation in the MHC region of ICs and supported their reputation of being hardy and resistant to diseases.
Genetic diversity of different indigenous chicken ecotypes using highly polymorphic MHC-linked and non-MHC microsatellite markers
Ngeno, K. ; Waaij, E.H. van der; Megens, H.J.W.C. ; Kahi, A.K. ; Arendonk, J.A.M. van; Crooijmans, R.P.M.A. - \ 2015
Animal Genetic Resources 56 (2015). - ISSN 2078-6336 - p. 1 - 7.
The study investigated the genetic make-up of different ecotypes of indigenous chickens (ICs) in Kenya based on major histocompatibility complex (MHC)-linked and non-MHC microsatellite markers. Blood samples were collected from eight regions (48 birds per region) of Kenya: Kakamega (KK), Siaya (BN), West Pokot (WP), Turkana (TK), Bomet (BM), Narok (NR), Lamu (LM) and Taita-Taveta (TT) and genotyped using two MHC-linked and ten non-MHC markers. All MHC-linked and non-MHC markers were polymorphic with a total of 140 alleles, of which 56 were identified in MHC-linked markers. Mean number of alleles (Na and Ne), private alleles, heterozygosity and genetic distances were higher for MHC-linked markers compared with non-MHC markers. The ad hoc statistic ¿K detected the true numbers of clusters to be three for MHC-linked markers and two in non-MHC markers. In conclusion, Kenyan ICs belong into two to three genetically distinct groups. Different markers systems have different clustering system. MHC-linked markers divided ICs into three mixed clusters, composing of individuals from the different ecotypes whereas non-MHC markers grouped ICs into two groups. These IC ecotypes host many and highly diverse MHC-linked alleles. Higher allelic diversity indicated a huge amount of genetic variation in the MHC region of ICs and supported their reputation of being hardy and resistant to diseases.
Genetic improvement in indigenous chicken of Ethiopia
Woldegiorgiss, W.E. - \ 2015
University. Promotor(en): Johan van Arendonk, co-promotor(en): Liesbeth van der Waaij; T. Dessie. - Wageningen : Wageningen University - ISBN 9789462573161 - 130
kippen - pluimvee - inheems vee - genetische verbetering - houding van boeren - perceptie - kippenrassen - prestatieniveau - dierveredeling - ethiopië - fowls - poultry - native livestock - genetic improvement - farmers' attitudes - perception - fowl breeds - performance - animal breeding - ethiopia

Abstract

Wondmeneh Esatu Woldegiorgiss (2015). Genetic improvement in indigenous chicken of Ethiopia. PhD thesis, Wageningen University, the Netherlands

This thesis considered various approaches to study the potential for improvement of village poultry production system using improved indigenous chicken. The approaches were structured survey questionnaire, village poultry simulation model (VIPOSIM), Heckman two-step model (econometric model), and experiments involving laboratory and field. First factors that determine the probability and intensity of adoption of exotic chickens were assessed. The probability of adopting exotic chickens was found to be positively affected by access to an off-farm income and negatively by livestock income. The intensity of adoption was negatively affected by being male household head, having a larger farm size, and having livestock income. Then, perceptions of farmers towards village poultry and impacts of interventions on flock and economic performance were assessed. Farmers’ perceptions affected their decisions about implementation of interventions, and interventions increased productivity but only in a few cases the increased revenues outweighed the additional costs. Subsequently, the evaluation of the breeds was conducted by comparing the natural antibody and productivity of improved indigenous chicken with crossbred, commercial and unimproved indigenous chickens. The results revealed that not only the NAb levels but also the effect of NAbs on survival differ between indigenous and improved breeds. NAb levels are associated with survival in commercial layer breed, but reduced survival in indigenous chickens placed in confinement. Improved indigenous chickens showed higher performance than unimproved one for all traits measured on-station, but remains lighter and developed more into a laying type than meat through the short-term selective breeding program. Overall, the present studies indicate that interventions need to be tailored towards the local situation to ensure that they lead not only to improved productivity but also to improved income.

Breeding program for indigenous chicken in Kenya
Ngeno, K. - \ 2015
University. Promotor(en): Johan van Arendonk, co-promotor(en): Liesbeth van der Waaij; A.K. Kahi. - Wageningen : Wageningen University - ISBN 9789462572775 - 154
kippen - pluimvee - inheems vee - dierveredeling - veredelingsprogramma's - genetische diversiteit - ecotypen - genomen - genetische verbetering - kenya - fowls - poultry - native livestock - animal breeding - breeding programmes - genetic diversity - ecotypes - genomes - genetic improvement

Abstract

Ngeno, K. (2015). Breeding program for indigenous chicken in Kenya. Analysis of diversity in indigenous chicken populations. PhD thesis, Wageningen University, the Netherlands

The objective of this research was to generate knowledge required for the development of an indigenous chicken (IC) breeding program for enhanced productivity and improved human livelihood in Kenya. The initial step was to review five questions; what, why and how should we conserve IC in an effective and sustainable way, who are the stakeholders and what are their roles in the IC breeding program. The next step of the research focused on detecting distinctive IC ecotypes through morphological and genomic characterization. Indigenous chicken ecotypes were found to be populations with huge variability in the morphological features. Molecular characterization was carried out using microsatellite markers and whole genome re-sequenced data. The studied IC ecotypes are genetically distinct groups. The MHC-linked microsatellite markers divided the eight IC ecotypes studied into three mixed clusters, composing of individuals from the different ecotypes whereas non-MHC markers grouped ICs into two groups. Analysis revealed high genetic variation within the ecotype with highly diverse MHC-linked alleles which are known to be involved in disease resistance. Whole genome re-sequencing revealed genomic variability, regions affected by selection, candidate genes and mutations that can explain partially the phenotypic divergence between IC and commercial layers. Unlike commercial chickens, IC preserved a high genomic variability that may be important in addressing present and future challenges associated with environmental adaptation and farmers’ breeding goals. Lastly, this study showed that there is an opportunity to improve IC through selection within the population. Genetic improvement utilizing within IC selection requires setting up a breeding program. The study described the systematic and logical steps in designing a breeding program by focusing on farmers’ need, how to improve IC to fit the farming conditions, and management regimes.

High natural antibody titers of indigenous chickens are related with increased hazard in confinement
Wondmeneh, E. ; Arendonk, J.A.M. van; Waaij, E.H. van der; Ducro, B.J. ; Parmentier, H.K. - \ 2015
Poultry Science 94 (2015)7. - ISSN 0032-5791 - p. 1493 - 1498.
laying hens - responses - survival - immunity - corticosterone - population - strains - stress - innate - plasma
Natural antibody (NAb) levels and survival rates were evaluated in 4 breeds of laying hens in Ethiopia: indigenous, improved indigenous, exotic layer, and crossbred. Titers of NAb isotypes IgG and IgM binding keyhole limpet hemocyanin (KLH) in serum were measured at 20, 26, 35, and 45 wk age. Repeated-measure ANOVA showed that IgG and IgM levels vary with time within each breed (P <0.05). Indigenous chickens had significantly (P <0.05) higher NAb levels at all ages. The Cox proportional hazard analysis showed increased hazard with increased levels of NAbs in the exotic layers (P <0.05). However, the reduced hazards with increased levels of NAbs were not significant in the improved indigenous and crossbred chickens. Indigenous chickens showed increased hazard with increasing levels of NAb (P > 0.05). We concluded that not only the NAb levels but also the effect of Nabs on survival vary between indigenous and improved breeds. The results indicate that NAb levels are associated with survival in elite (improved) breeds, but are associated with increased hazard in indigenous chickens.
Textbook animal breeding : animal breeding andgenetics for BSc students
Oldenbroek, Kor ; Waaij, Liesbeth van der - \ 2014
Wageningen : Centre for Genetic Resources and Animal Breeding and Genomics Group, Wageningen University and Research Centre - 311
dierveredeling - selectief fokken - huisdieren - agrarisch onderwijs - diergenetica - lesmaterialen - hoger onderwijs - animal breeding - selective breeding - domestic animals - agricultural education - animal genetics - teaching materials - higher education
This textbook contains teaching material on animal breeding and genetics for BSc students. The text book started as an initiative of the Dutch Universities for Applied (Agricultural) Sciences. The textbook is made available by the Animal Breeding and Genomics Centre (ABGC) of Wageningen UR (University and Research Centre).
Morphological features of indigenous chicken ecotype populations of Kenya
Ngeno, K. ; Waaij, E.H. van der; Kahi, A.K. ; Arendonk, J.A.M. van - \ 2014
Animal Genetic Resources 55 (2014). - ISSN 2078-6336 - p. 115 - 124.
This study characterized indigenous chicken (IC) ecotypes morphologically. Five IC ecotypes studied were Kakamega (KK), Siaya (BN), West Pokot (WP), Narok (NR) and Bomet (BM). Data on morphological features were collected from 1 580 chickens and 151 for zoometric measurements. Descriptive statistics, non-parametric and F tests were used in analysis. A non-parametric Kruskal–Wallis, Binomial test and Mann–Whitney U test was used to evaluate whether the ecotype have effects on the qualitative morphological variables. Zoometric measurements was analysed with the PROC GLM of SAS. Results revealed that, black, black-white striped, brown and red body plumage colours were significantly different (P <0.05) between the ecotypes. Feather morphology (%) were not significantly different (P > 0.05). Distribution of body feathers (%), comb types (%) and zoometric measurements were significantly different (P <0.05). Eye colours varied significantly (P <0.001) within the ecotypes unlike between the populations. In conclusion, IC ecotypes studied are heterogeneous population with huge variability in morphological features.
Adoption of exotic chicken breeds by rural poultry keepers in Ethiopia
Wondmeneh, E. ; Waaij, E.H. van der; Tadelle, D. ; Udo, H.M.J. ; Arendonk, J.A.M. van - \ 2014
Acta Agriculturae Scandinavica Section A-Animal Science 64 (2014)4. - ISSN 0906-4702 - p. 210 - 216.
technology
This study examines factors that determine the probability and intensity of adoption of exotic chickens among rural poultry producers in Ethiopia. A total of 240 respondents were interviewed from households that were selected by systematic random sampling. The differences between adopters and non-adopters were identified using descriptive statistics. Factors that affect the probability and intensity of adoption were identified using the Heckman selection two-step model. Adopters of exotic chickens had more social contact and less livestock income than non-adopters. Additionally, adopters had access to an off-farm income and credit and considered exotic chickens easier to manage than non-adopters (p <0.001). In the econometric analysis, the probability of adopting exotic chickens was found to be positively affected by access to an an off-farm income (p <0.01) and negatively by livestock income (p <0.05). The intensity of adoption was negatively affected by being male household head (p <0.001), having a larger farm size (p <0.01), and having livestock income (p <0.05).
How to teach Animal Breeding and Genetics to undergraduate students: presentation of a thinking process.
Waaij, E.H. van der; Lont, D.E. ; Mulder, H.A. - \ 2014
Lecture notes Animal and Genetics (ABG-20306)
Waaij, E.H. van der; Oldenbroek, J.K. ; Lont, D.E. ; Mulder, H.A. - \ 2014
Wageningen : WUR - 261 p.
Indigenous chicken genetic resources in Kenya: their unique attributes and conservation options for improved use
Ngeno, K. ; Waaij, E.H. van der; Kahi, A.K. - \ 2014
Worlds Poultry Science Journal 70 (2014)1. - ISSN 0043-9339 - p. 173 - 184.
native fowl - temperature - association - disease
The indigenous chicken (Gallus gallus domesticus) genetic resources (IC) comprise more than 80% of the overall poultry population in rural villages despite their low productivity. However, a holistic approach that increases productivity without increasing production costs or leading to loss of biodiversity is presently limited. Conversely, in most developing countries, there is almost no organizational structure for breeding programmes for improving and conserving IC. These locally adapted IC can only be conserved in the most rational and sustainable way by ensuring that they are functional part of different production systems. Their conservation should be through utilisation if they are to be of any benefit to the poor rural households. This discussion focuses on five very relevant questions that need to be answered if the conservation of IC is to be effective and sustainable: What, why and how should we conserve, who are the stakeholders and what are their roles in conservation efforts?
Effect of heat stress during intrauterine development on subsequent litter size in sows
Sevillano Del Aguila, C.A. ; Bloemhof, S. ; Waaij, E.H. van der; Knol, Egbert F. - \ 2013
In: Book of Abstracts of the 64th Annual Meeting of the European Federation of Animal Science Wageningen : Wageningen Academic Publishers - ISBN 9789086862283 - p. 288 - 288.
Effect of daily environmental temperature on farrowing rate and total born in dam line sows
Bloemhof, S. ; Mathur, P.K. ; Knol, E.F. ; Waaij, E.H. van der - \ 2013
Journal of Animal Science 91 (2013)6. - ISSN 0021-8812 - p. 2667 - 2679.
heat-stress - genetic-parameters - primiparous sows - pigs - reproduction - traits - gilts - progesterone - lactation - tolerance
Heat stress is known to adversely affect reproductive performance of sows. However, it is important to know on which days or periods during the reproduction cycle heat stress has the greatest effects for designing appropriate genetic or management strategies. Therefore, this study was conducted to identify days and periods that have greatest effects on farrowing rate and total born of sows using 5 different measures of heat stress. The data consisted of 22,750 records on 5024 Dutch Yorkshire dam line sows from 16 farms in Spain and Portugal. Heat stress on a given day was measured in terms of maximum temperature, diurnal temperature range and heat load. The heat load was estimated using 3 definitions considering different upper critical temperatures. Identification of days during the reproduction cycle that had maximum effect was based on the Pearson correlation between the heat stress variable and the reproduction trait, estimated for each day during the reproduction cycle. Polynomial functions were fitted to describe the trends of these correlations and the days with greatest negative correlation were considered as days with maximum effect. Correlations were greatest for maximum temperature, followed by those for heat load and diurnal temperature range. Correlations for both farrowing rate and total born were stronger in gilts than in sows. This implies that heat stress has a stronger effect on reproductive performance of gilts than of sows. Heat stress during the third week (21 to 14 d) before first insemination had largest effect on farrowing rate. Heat stress during the period between 7 d before successful insemination until 12 d after that had largest effect on total born. Correlations between temperatures on consecutive days during these periods were extremely high ( > 0.9). Therefore, for farrowing rate the maximum temperature on 21 d before first insemination and for total born the maximum temperature at day of successful insemination can be used as predictive measures of heat stress in commercial sow farms. Additionally, differences between daughter groups of sires were identified in response to high temperatures. This might indicate possibilities for genetic selection on heat tolerance.
Effect of gestating sow body condition, feed refusals, and group housing on growth and feed intake in grower-finishing pigs
Sell-Kubiak, E.B. ; Waaij, E.H. van der; Bijma, P. - \ 2013
Journal of Animal Science 91 (2013)8. - ISSN 0021-8812 - p. 3538 - 3548.
muscle-fiber number - group-housed sows - genetic-parameters - postnatal-growth - birth-weight - meat quality - maternal nutrition - hormonal profiles - performance-test - embryo survival
The main focus of this study was to identify sow gestation features that affect growth rate (GR) and feed intake (FI) of their offspring during grower–finishing stage. Because the sow provides a specific environment to her offspring during gestation, certain features (e.g., BW of the sow), feed refusals or gestation group, may affect her ability to deliver and feed a healthy litter. Data on 17,743 grower–finishing pigs, coming from 604 sires and 681 crossbred sows, were obtained from the Institute for Pigs Genetics. Sow gestation features were collected during multiple gestations and divided into 3 clusters describing i) sow body condition (i.e., BW, backfat, and gestation length), ii) sow feed refusals (FR), the difference between offered and eaten feed during 3 periods of gestation: 1 to 28, 25 to 50, 45 to 80 d, and iii) sow group features (i.e., number of sows, and average parity). Sow gestation features were added to the base model 1 at a time to study their effect on GR and FI. Significant gestation features (P <0.1) were fitted simultaneously in animal model to investigate whether they could explain common litter and permanent sow effects. Gestation length had effect on GR [1.4 (g/d)/d; P = 0.04] and FI [6.8 (g/d)/d; P = 0.007]. Body weights of the sow at insemination [0.07 (g/d)/kg; P = 0.08], at farrowing [0.14 (g/d)/kg; P <0.0001], and after lactation [0.1 (g/d)/kg; P = 0.003] had effect on GR. Sow parturition–lactation loss in backfat thickness and weight were not significant for GR and FI. Days with FR during 25 to 50 and 45 to 80 d of gestation and average FR during 45 to 80 d of gestation had negative effect on GR and when substantially increased had also a positive effect on FI. Sow FR from 1 to 28 d of gestation were not significant. Number of sows in gestation group had effect on FI [–9 (g/d)/group member; P = 0.04] and day sow entered group had an effect on GR [–0.9 (g/d)/day; P = 0.04]. Sow gestation features explained 1 to 3% of the total variance in grower–finishing pigs. Gestation features did explain phenotypic variance due to permanent sow and part of phenotypic variance due to common litter effects for FI but not for GR.
Snow shoes and sandals? : genetic aspects of heat stress sensitivity and sow reproduction
Bloemhof, S. - \ 2013
University. Promotor(en): Johan van Arendonk; I. Misztal, co-promotor(en): E.F. Knol; Liesbeth van der Waaij. - S.l. : s.n. - ISBN 9789461735881 - 173
zeugen - warmtestress - diergenetica - gevoeligheid - geslachtelijke voortplanting - voortplantingsvermogen - kritische temperatuur - hittetolerantie - selectief fokken - genetische correlatie - veredelingsprogramma's - varkensfokkerij - sows - heat stress - animal genetics - sensitivity - sexual reproduction - reproductive performance - critical temperature - heat tolerance - selective breeding - genetic correlation - breeding programmes - pig breeding

Globally the average size of pig herds are increasing and amount of labour spent per sow / finisher pig is decreasing. These changes require sows which need less management interventions. In addition to easier manageable sows modern genotypes will also need to be more adaptable considering that global temperatures are expected to increase and pork production is partially moving to warmer climates. The end result is that commercial pigs nowadays will potentially face more heat stress challenges during their productive lives.

In this thesis, a model was developed which was used to estimate upper critical temperatures for sows’ reproductive performance. Additionally the possibility to breed for reduced heat tolerance of sows was investigated. Therefore heritability for the random regression slope of farrowing rate against increasing temperature at day of insemination (= heat tolerance) and the genetic correlation between farrowing rate and heat tolerance was estimated.Commercial production pigs are crossbreds farmed all over the world. In contrast, selection is practiced mainly in temperate climates, in nucleus herds using purebred pigs. The success of genetic selection depends on how much genetic progress is realized in crossbred pigs. Within this thesis these genetic correlations for farrowing rate between purebreds and crossbreds were estimated.

Sow productivity depends on a number of related traits, such as ovulation rate, the number of litters per sow per year, the number of weaned piglets per sow per year, and the length of productive live. Traditionally pig breeding programs have improved sow productivity by increasing number weaned piglets per sow per year. To improve herd-level litters per sow per year a new trait was proposed called problem free sow production by parity, which incorporates the traits interval weaning first insemination, non-return rate, farrowing rate, and selection for next parity. Heritability of problem free sow production and genetic correlations with other sow production traits were estimated.

The main conclusion of this thesis was that it is possible to select for improved heat resistance in addition to improved commercial production levels in commercial pigs. However, genetic correlation between production in temperate and hot climates is high. This high correlation implies that, within-line, pigs with the best performance in a hot climate will be the best in temperate climate too. Most important for the success of a pig breeding program is to define appropriate breeding goals which are based on the environment(s) that market pigs are expected to perform in. The overall data collection for the genetic evaluation needs to be done in those specific environments and this will favour pigs which are able to produce over more than one specific environment.

Effect of match or mismatch of maternal-offspring nutritional environment on the development of offspring in broiler chickens
Waaij, E.H. van der; Brand, H. van den; Arendonk, J.A.M. van; Kemp, B. - \ 2011
Animal 5 (2011)5. - ISSN 1751-7311 - p. 741 - 748.
catch-up growth - long-term consequences - nutrient restriction - insulin-resistance - skeletal-muscle - obesity - leads - age - hatchability - trajectories
In mammals, maternal food restriction around conception and during pregnancy results in low birth weight and an adjusted growth trajectory of offspring. If, subsequently, the offspring are born into a food-abundant environment, they are at increased risk of developing obesity, type 2 diabetes, hypertension and renal dysfunction. Here, we show similar effects of maternal undernutrition on hatch weight, growth and fat deposition in offspring of birds (domestic chicken). Both mothers and offspring were fed either ad libitum or restricted in a two-by-two factorial design, resulting in two matched and two mismatched maternal–offspring nutritional environments. Offspring of ad libitum mothers grew heavier than those of restricted mothers, possibly due to the larger muscle mass. Ad libitum-fed offspring, especially females, of restricted mothers were lighter at hatch, and were heavier and had more abdominal fat at 6 weeks of age than daughters of ad libitum-fed mothers. These results suggest a common mechanism in mammals and birds in response to a mismatch in the maternal–offspring nutritional environment. They also indicate that the common practice of restrictive feeding of the broiler breeders and subsequent ad libitum feeding of the broilers may result in reduced growth and increased abdominal fat as compared to broilers of less restricted broiler breeders.
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