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Esther D. Ellen
Animal Breeding and Genomics, Wageningen University and Research, Droevendaalsesteeg 1 (Building 107), 6708 PB Wageningen, The Netherlands

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Feed

Review
Published: 03 August 2021 in Animals
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Livestock feed encompasses both human edible and human inedible components. Human edible feed components may become less available for livestock. Especially for proteins, this calls for action. This review focuses on using alternative protein sources in feed and protein efficiency, the expected problems, and how these problems could be solved. Breeding for higher protein efficiency leading to less use of the protein sources may be one strategy. Replacing (part of) the human edible feed components with human inedible components may be another strategy, which could be combined with breeding for livestock that can efficiently digest novel protein feed sources. The potential use of novel protein sources is discussed. We discuss the present knowledge on novel protein sources, including the consequences for animal performance and production costs, and make recommendations for the use and optimization of novel protein sources (1) to improve our knowledge on the inclusion of human inedible protein into the diet of livestock, (2) because cooperation between animal breeders and nutritionists is needed to share knowledge and combine expertise, and (3) to investigate the effect of animal-specific digestibility of protein sources for selective breeding for each protein source and for precision feeding. Nutrigenetics and nutrigenomics will be important tools.

ACS Style

Marinus Te Pas; Teun Veldkamp; Yvette de Haas; André Bannink; Esther Ellen. Adaptation of Livestock to New Diets Using Feed Components without Competition with Human Edible Protein Sources—A Review of the Possibilities and Recommendations. Animals 2021, 11, 2293 .

AMA Style

Marinus Te Pas, Teun Veldkamp, Yvette de Haas, André Bannink, Esther Ellen. Adaptation of Livestock to New Diets Using Feed Components without Competition with Human Edible Protein Sources—A Review of the Possibilities and Recommendations. Animals. 2021; 11 (8):2293.

Chicago/Turabian Style

Marinus Te Pas; Teun Veldkamp; Yvette de Haas; André Bannink; Esther Ellen. 2021. "Adaptation of Livestock to New Diets Using Feed Components without Competition with Human Edible Protein Sources—A Review of the Possibilities and Recommendations." Animals 11, no. 8: 2293.

Journal article
Published: 27 June 2020 in Sensors
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Individual data are valuable for assessing the health, welfare and performance of broilers. In particular, data on the first few days of life are needed to study the predictive value of traits recorded early in life for later life performance. However, broilers are generally kept in groups, which hampers individual identification and monitoring of animals. Sensor technologies may aid in identifying and monitoring individual animals. In this study, a passive radio frequency identification (RFID) system was implemented to record broiler activity, in combination with traditional video recordings. The two main objectives were 1) to validate the output of the RFID system by comparing it to the recorded locations on video, and 2) to assess whether the number of antennas visited per unit time could serve as a measure of activity, by comparing it to the distance recorded on video and to the distance moved as recorded using a validated ultra-wideband (UWB) tracking system. The locations recorded by the RFID system exactly matched the video in 62.5% of the cases, and in 99.2% of the cases when allowing for a deviation of one antenna grid cell. There were moderately strong Spearman rank correlations between the distance recorded with the RFID system and the distance recorded from video (rs = 0.82) and between UWB and RFID (rs = 0.70) in approximately one-hour recordings, indicating that the RFID system can adequately track relative individual broiler activity, i.e., the activity level of a broiler in comparison to its group members. As the RFID tags are small and lightweight, the RFID system is well suited for monitoring the individual activity of group-housed broilers throughout life.

ACS Style

Malou Van Der Sluis; Yvette De Haas; Britt De Klerk; T. Bas Rodenburg; Esther D. Ellen. Assessing the Activity of Individual Group-Housed Broilers Throughout Life using a Passive Radio Frequency Identification System—A Validation Study. Sensors 2020, 20, 3612 .

AMA Style

Malou Van Der Sluis, Yvette De Haas, Britt De Klerk, T. Bas Rodenburg, Esther D. Ellen. Assessing the Activity of Individual Group-Housed Broilers Throughout Life using a Passive Radio Frequency Identification System—A Validation Study. Sensors. 2020; 20 (13):3612.

Chicago/Turabian Style

Malou Van Der Sluis; Yvette De Haas; Britt De Klerk; T. Bas Rodenburg; Esther D. Ellen. 2020. "Assessing the Activity of Individual Group-Housed Broilers Throughout Life using a Passive Radio Frequency Identification System—A Validation Study." Sensors 20, no. 13: 3612.

Journal article
Published: 01 September 2019 in Poultry Science
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Mortality due to feather pecking (FP) has large economic and welfare consequences in the commercial poultry industry, and reduces survival of birds. With FP, the survival time of a hen depends both on her own genetic ability to avoid becoming the victim of FP (direct genetic effect; DGE), and on the genetic tendency of her group mates to perform FP (indirect genetic effect; IGE). Thus, to improve survival time of laying hens, it is important to use a breeding strategy that captures both the DGE and the IGE of selection candidates. Here, we investigate the prospects for solving mortality due to FP in laying hens by genetic selection. First, we review genetic parameters for survival time. Second, we use deterministic simulation to predict response to selection for 2 multi-trait crossbred breeding programs, a traditional recurrent testing scheme (RT) and a genomic selection scheme (GS). Finally, we investigate the prospects for sustained improvement of survival time when mortality becomes low. Results show that survival time has considerable heritable variation; most estimates of the total additive genetic standard deviation are larger than 1 mo. As expected, predicted single generation response to selection in survival time with GS is substantial larger than with RT. Particularly when the correlation between survival time and other breeding goal traits is zero, the GS scheme yields substantial improvement in survival time. For example, when mortality is 35%, the genetic correlation between survival time and other traits is 0, allowing for a 10% reduction of response in other traits, and when selection takes place in both the sire line and dam line, survival time can be improved with ∼23 D in one generation, using GS. Results, however, also show a strong decrease in heritability when mortality decreases, indicating that continued improvement becomes increasingly difficult. In summary, our results show that breeders can considerably reduce mortality due to FP with limited reduction of improvement in other breeding goal traits.

ACS Style

Esther D. Ellen; Piter Bijma. Can breeders solve mortality due to feather pecking in laying hens? Poultry Science 2019, 98, 3431 -3442.

AMA Style

Esther D. Ellen, Piter Bijma. Can breeders solve mortality due to feather pecking in laying hens? Poultry Science. 2019; 98 (9):3431-3442.

Chicago/Turabian Style

Esther D. Ellen; Piter Bijma. 2019. "Can breeders solve mortality due to feather pecking in laying hens?" Poultry Science 98, no. 9: 3431-3442.

Journal article
Published: 20 August 2019 in Animals
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Individual data on activity of broilers is valuable, as activity may serve as a proxy for multiple health, welfare and performance indicators. However, broilers are often kept in large groups, which makes it difficult to identify and monitor them individually. Sensor technologies might offer solutions. Here, an ultra-wideband (UWB) tracking system was implemented with the goal of validating this system for individual tracking of activity of group-housed broilers. The implemented approaches were (1) a comparison of distances moved as recorded by the UWB system and on video and (2) a study recording individual levels of activity of broilers and assessing group-level trends in activity over time; that could be compared to activity trends from literature. There was a moderately strong positive correlation between the UWB system and video tracking. Using the UWB system, we detected reductions in activity over time and we found that lightweight birds were on average more active than heavier birds. Both findings match with reports in literature. Overall, the UWB system appears well-suited for activity monitoring in broilers, when the settings are kept the same for all individuals. The longitudinal information on differences in activity can potentially be used as proxy for health, welfare and performance; but further research into individual patterns in activity is required.

ACS Style

Malou Van Der Sluis; Britt De Klerk; Esther D. Ellen; Yvette De Haas; Thijme Hijink; T. Bas Rodenburg. Validation of an Ultra-Wideband Tracking System for Recording Individual Levels of Activity in Broilers. Animals 2019, 9, 580 .

AMA Style

Malou Van Der Sluis, Britt De Klerk, Esther D. Ellen, Yvette De Haas, Thijme Hijink, T. Bas Rodenburg. Validation of an Ultra-Wideband Tracking System for Recording Individual Levels of Activity in Broilers. Animals. 2019; 9 (8):580.

Chicago/Turabian Style

Malou Van Der Sluis; Britt De Klerk; Esther D. Ellen; Yvette De Haas; Thijme Hijink; T. Bas Rodenburg. 2019. "Validation of an Ultra-Wideband Tracking System for Recording Individual Levels of Activity in Broilers." Animals 9, no. 8: 580.

Review
Published: 22 March 2019 in Animals
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Damaging behaviors, like feather pecking (FP), have large economic and welfare consequences in the commercial laying hen industry. Selective breeding can be used to obtain animals that are less likely to perform damaging behavior on their pen-mates. However, with the growing tendency to keep birds in large groups, identifying specific birds that are performing or receiving FP is difficult. With current developments in sensor technologies, it may now be possible to identify laying hens in large groups that show less FP behavior and select them for breeding. We propose using a combination of sensor technology and genomic methods to identify feather peckers and victims in groups. In this review, we will describe the use of "-omics" approaches to understand FP and give an overview of sensor technologies that can be used for animal monitoring, such as ultra-wideband, radio frequency identification, and computer vision. We will then discuss the identification of indicator traits from both sensor technologies and genomics approaches that can be used to select animals for breeding against damaging behavior.

ACS Style

Esther D. Ellen; Malou Van Der Sluis; Janice Siegford; Oleksiy Guzhva; Michael J. Toscano; Jörn Bennewitz; Lisette E. Van Der Zande; Jerine A. J. Van Der Eijk; Elske N. De Haas; Tomas Norton; Deborah Piette; Jens Tetens; Britt De Klerk; Bram Visser; T. Bas Rodenburg. Review of Sensor Technologies in Animal Breeding: Phenotyping Behaviors of Laying Hens to Select Against Feather Pecking. Animals 2019, 9, 108 .

AMA Style

Esther D. Ellen, Malou Van Der Sluis, Janice Siegford, Oleksiy Guzhva, Michael J. Toscano, Jörn Bennewitz, Lisette E. Van Der Zande, Jerine A. J. Van Der Eijk, Elske N. De Haas, Tomas Norton, Deborah Piette, Jens Tetens, Britt De Klerk, Bram Visser, T. Bas Rodenburg. Review of Sensor Technologies in Animal Breeding: Phenotyping Behaviors of Laying Hens to Select Against Feather Pecking. Animals. 2019; 9 (3):108.

Chicago/Turabian Style

Esther D. Ellen; Malou Van Der Sluis; Janice Siegford; Oleksiy Guzhva; Michael J. Toscano; Jörn Bennewitz; Lisette E. Van Der Zande; Jerine A. J. Van Der Eijk; Elske N. De Haas; Tomas Norton; Deborah Piette; Jens Tetens; Britt De Klerk; Bram Visser; T. Bas Rodenburg. 2019. "Review of Sensor Technologies in Animal Breeding: Phenotyping Behaviors of Laying Hens to Select Against Feather Pecking." Animals 9, no. 3: 108.

Journal article
Published: 23 July 2018 in Genetics Selection Evolution
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Cannibalism is an important welfare problem in the layer industry. Cannibalism is a social behavior where individual survival is affected by direct genetic effects (DGE) and indirect genetic effects (IGE). Previous studies analysed repeated binomial survival, instead of survival time, which improved accuracies of breeding value predictions. Our study aimed at identifying SNPs associated with DGE and IGE for survival time, and comparing results from models that analyse survival time and repeated binomial survival. Survival data of three layer crosses (W1 * WA, W1 * WB, and W1 * WC) were used. Each individual had one survival time record and 13 monthly survival (0/1) records. Approximately 30,000 single nucleotide polymorphisms (SNPs) were included in the genome-wide association study (GWAS), using a linear mixed model for survival time, a linear mixed model and a generalized linear mixed model for repeated binomial survival (0/1). Backwards elimination was used to determine phenotypic and genetic variance explained by SNPs. The same quantitative trait loci were identified with all models. A SNP associated with DGE was found in cross W1 * WA, with an allele substitution effect of 22 days. This SNP explained 3% of the phenotypic variance, and 36% of the total genetic variance. Four SNPs associated with DGE were found in cross W1 * WB, with effects ranging from 16 to 35 days. These SNPs explained 1 to 6% of the phenotypic variance and 9 to 44% of the total genetic variance. Our results suggest a link of DGE and IGE for survival time in layers with the gamma-aminobutyric acid (GABA) system, since a SNP located near a gene for a GABA receptor was associated with DGE and with IGE (not significant). This is one of the first large studies investigating the genetic architecture of a socially-affected trait. The power to detect SNP associations was relatively low and thus we expect that many effects on DGE and IGE remained undetected. Yet, GWAS results revealed SNPs with large DGE and a link of DGE and IGE for survival time in layers with the GABAergic system, which supports existing evidence for the involvement of GABA in the development of abnormal behaviors.

ACS Style

Tessa Brinker; Piter Bijma; Addie Vereijken; Esther D. Ellen. The genetic architecture of socially-affected traits: a GWAS for direct and indirect genetic effects on survival time in laying hens showing cannibalism. Genetics Selection Evolution 2018, 50, 38 .

AMA Style

Tessa Brinker, Piter Bijma, Addie Vereijken, Esther D. Ellen. The genetic architecture of socially-affected traits: a GWAS for direct and indirect genetic effects on survival time in laying hens showing cannibalism. Genetics Selection Evolution. 2018; 50 (1):38.

Chicago/Turabian Style

Tessa Brinker; Piter Bijma; Addie Vereijken; Esther D. Ellen. 2018. "The genetic architecture of socially-affected traits: a GWAS for direct and indirect genetic effects on survival time in laying hens showing cannibalism." Genetics Selection Evolution 50, no. 1: 38.

Journal article
Published: 23 November 2016 in Journal of Animal Breeding and Genetics
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Mortality of laying hens due to cannibalism is a major problem in the egg-laying industry. Survival depends on two genetic effects: the direct genetic effect of the individual itself (DGE) and the indirect genetic effects of its group mates (IGE). For hens housed in sire-family groups, DGE and IGE cannot be estimated using pedigree information, but the combined effect of DGE and IGE is estimated in the total breeding value (TBV). Genomic information provides information on actual genetic relationships between individuals and might be a tool to improve TBV accuracy. We investigated whether genomic information of the sire increased TBV accuracy compared with pedigree information, and we estimated genetic parameters for survival time. A sire model with pedigree information (BLUP) and a sire model with genomic information (ssGBLUP) were used. We used survival time records of 7290 crossbred offspring with intact beaks from four crosses. Cross-validation was used to compare the models. Using ssGBLUP did not improve TBV accuracy compared with BLUP which is probably due to the limited number of sires available per cross (~50). Genetic parameter estimates were similar for BLUP and ssGBLUP. For both BLUP and ssGBLUP, total heritable variance (T2), expressed as a proportion of phenotypic variance, ranged from 0.03 ± 0.04 to 0.25 ± 0.09. Further research is needed on breeding value estimation for socially affected traits measured on individuals kept in single-family groups.

ACS Style

T. Brinker; B. Raymond; P. Bijma; A. Vereijken; E.D. Ellen. Estimation of total genetic effects for survival time in crossbred laying hens showing cannibalism, using pedigree or genomic information. Journal of Animal Breeding and Genetics 2016, 134, 60 -68.

AMA Style

T. Brinker, B. Raymond, P. Bijma, A. Vereijken, E.D. Ellen. Estimation of total genetic effects for survival time in crossbred laying hens showing cannibalism, using pedigree or genomic information. Journal of Animal Breeding and Genetics. 2016; 134 (1):60-68.

Chicago/Turabian Style

T. Brinker; B. Raymond; P. Bijma; A. Vereijken; E.D. Ellen. 2016. "Estimation of total genetic effects for survival time in crossbred laying hens showing cannibalism, using pedigree or genomic information." Journal of Animal Breeding and Genetics 134, no. 1: 60-68.

Journal article
Published: 05 January 2016 in Evolution
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Indirect genetic effects (IGEs) are the basis of social interactions among conspecifics, and can affect genetic variation of nonsocial and social traits. We used flour beetles (Tribolium castaneum) of two phenotypically distinguishable populations to estimate genetic (co)variances and the effect of IGEs on three life-history traits: development time (DT), growth rate (GR), and pupal body mass (BM). We found that GR was strongly affected by social environment with IGEs accounting for 18% of the heritable variation. We also discovered a sex-specific social effect: male ratio in a group significantly affected both GR and BM; that is, beetles grew larger and faster in male-biased social environments. Such sex-specific IGEs have not previously been demonstrated in a nonsocial insect. Our results show that beetles that achieve a higher BM do so via a slower GR in response to social environment. Existing models of evolution in age-structured or stage-structured populations do not account for IGEs of social cohorts. It is likely that such IGEs have played a key role in the evolution of developmental plasticity shown by Tenebrionid larvae in response to density. Our results document an important source of genetic variation for GR, often overlooked in life-history theory.

ACS Style

Esther D. Ellen; Katrijn Peeters; Merel Verhoeven; Rieta Gols; Jeffrey A. Harvey; Michael J. Wade; Marcel Dicke; Piter Bijma. Direct and indirect genetic effects in life-history traits of flour beetles (Tribolium castaneum). Evolution 2016, 70, 207 -217.

AMA Style

Esther D. Ellen, Katrijn Peeters, Merel Verhoeven, Rieta Gols, Jeffrey A. Harvey, Michael J. Wade, Marcel Dicke, Piter Bijma. Direct and indirect genetic effects in life-history traits of flour beetles (Tribolium castaneum). Evolution. 2016; 70 (1):207-217.

Chicago/Turabian Style

Esther D. Ellen; Katrijn Peeters; Merel Verhoeven; Rieta Gols; Jeffrey A. Harvey; Michael J. Wade; Marcel Dicke; Piter Bijma. 2016. "Direct and indirect genetic effects in life-history traits of flour beetles (Tribolium castaneum)." Evolution 70, no. 1: 207-217.

Journal article
Published: 28 September 2015 in Genetics Selection Evolution
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Minimizing bird losses is important in the commercial layer industry. Selection against mortality is challenging because heritability is low, censoring is high, and individual survival depends on social interactions among cage members. With cannibalism, mortality depends not only on an individual’s own genes (direct genetic effects; DGE) but also on genes of its cage mates (indirect genetic effects; IGE). To date, studies using DGE–IGE models have focussed on survival time but their shortcomings are that censored records were considered as exact lengths of life and models assumed that IGE were continuously expressed by all cage members even after death. However, since dead animals no longer express IGE, IGE should ideally be time-dependent in the model. Neglecting censoring and timing of IGE expression may reduce accuracy of estimated breeding values (EBV). Thus, our aim was to improve prediction of breeding values for survival time in layers that present cannibalism. We considered four DGE–IGE models to predict survival time in layers. One model was an analysis of survival time and the three others treated survival in consecutive months as a repeated binomial trait (repeated measures models). We also tested whether EBV were improved by including timing of IGE expression in the analyses. Approximate EBV accuracies were calculated by cross-validation. The models were fitted to survival data on two purebred White Leghorn layer lines W1 and WB, each having monthly survival records over 13 months. Including the timing of IGE expression in the DGE–IGE model reduced EBV accuracy compared to analysing survival time. EBV accuracy was higher when repeated measures models were used. However, there was no universal best model. Using repeated measures instead of analysing survival time increased EBV accuracy by 10 to 21 and 2 to 12 % for W1 and WB, respectively. We showed how EBV and variance components estimated with repeated measures models can be translated into survival time. Our results suggest that prediction of breeding values for survival time in laying hens can be improved using repeated measures models. This is an important result since more accurate EBV contribute to higher rates of genetic gain.

ACS Style

Tessa Brinker; Esther D. Ellen; Roel F. Veerkamp; Piter Bijma. Predicting direct and indirect breeding values for survival time in laying hens using repeated measures. Genetics Selection Evolution 2015, 47, 75 .

AMA Style

Tessa Brinker, Esther D. Ellen, Roel F. Veerkamp, Piter Bijma. Predicting direct and indirect breeding values for survival time in laying hens using repeated measures. Genetics Selection Evolution. 2015; 47 (1):75.

Chicago/Turabian Style

Tessa Brinker; Esther D. Ellen; Roel F. Veerkamp; Piter Bijma. 2015. "Predicting direct and indirect breeding values for survival time in laying hens using repeated measures." Genetics Selection Evolution 47, no. 1: 75.

Review article
Published: 11 November 2014 in Frontiers in Genetics
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Social interactions between individuals living in a group can have both positive and negative effects on welfare, productivity, and health of these individuals. Negative effects of social interactions in livestock are easier to observe than positive effects. For example, laying hens may develop feather pecking, which can cause mortality due to cannibalism, and pigs may develop tail biting or excessive aggression. Several studies have shown that social interactions affect the genetic variation in a trait. Genetic improvement of socially-affected traits, however, has proven to be difficult until relatively recently. The use of classical selection methods, like individual selection, may result in selection responses opposite to expected, because these methods neglect the effect of an individual on its group mates (social genetic effects). It has become clear that improvement of socially-affected traits requires selection methods that take into account not only the direct effect of an individual on its own phenotype but also the social genetic effects, also known as indirect genetic effects, of an individual on the phenotypes of its group mates. Here, we review the theoretical and empirical work on social genetic effects, with a focus on livestock. First, we present the theory of social genetic effects. Subsequently, we evaluate the evidence for social genetic effects in livestock and other species, by reviewing estimates of genetic parameters for direct and social genetic effects. Then we describe the results of different selection experiments. Finally, we discuss issues concerning the implementation of social genetic effects in livestock breeding programs. In our opinion, this review demonstrates that selection for socially-affected traits, using methods that target both the direct and social genetic effects, is a promising, but sometimes difficult to use in practice, tool to simultaneously improve production and welfare in livestock.

ACS Style

Esther D. Ellen; T. Bas Rodenburg; Gerard A. A. Albers; J. Elizabeth Bolhuis; Irene Camerlink; Naomi Duijvesteijn; Egbert F. Knol; William M. Muir; Katrijn Peeters; Inonge Reimert; Ewa Sell-Kubiak; Johan A. M. Van Arendonk; Jeroen Visscher; Piter Bijma. The prospects of selection for social genetic effects to improve welfare and productivity in livestock. Frontiers in Genetics 2014, 5, 1 .

AMA Style

Esther D. Ellen, T. Bas Rodenburg, Gerard A. A. Albers, J. Elizabeth Bolhuis, Irene Camerlink, Naomi Duijvesteijn, Egbert F. Knol, William M. Muir, Katrijn Peeters, Inonge Reimert, Ewa Sell-Kubiak, Johan A. M. Van Arendonk, Jeroen Visscher, Piter Bijma. The prospects of selection for social genetic effects to improve welfare and productivity in livestock. Frontiers in Genetics. 2014; 5 ():1.

Chicago/Turabian Style

Esther D. Ellen; T. Bas Rodenburg; Gerard A. A. Albers; J. Elizabeth Bolhuis; Irene Camerlink; Naomi Duijvesteijn; Egbert F. Knol; William M. Muir; Katrijn Peeters; Inonge Reimert; Ewa Sell-Kubiak; Johan A. M. Van Arendonk; Jeroen Visscher; Piter Bijma. 2014. "The prospects of selection for social genetic effects to improve welfare and productivity in livestock." Frontiers in Genetics 5, no. : 1.

Journal article
Published: 01 January 2014 in Genetics Selection Evolution
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Feather pecking is a major welfare issue in laying hen industry that leads to mortality. Due to a ban on conventional cages in the EU and on beak trimming in some countries of the EU, feather pecking will become an even bigger problem. Its severity depends both on the victim receiving pecking and on its group mates inflicting pecking (indirect effects), which together determine plumage condition of the victim. Plumage condition may depend, therefore, on both the direct genetic effect of an individual itself and on the indirect genetic effects of its group mates. Here, we present estimated genetic parameters for direct and indirect effects on plumage condition of different body regions in two purebred layer lines, and estimates of genetic correlations between body regions.

ACS Style

Tessa Brinker; Piter Bijma; Jeroen Visscher; T B Rodenburg; Esther D Ellen. Plumage condition in laying hens: genetic parameters for direct and indirect effects in two purebred layer lines. Genetics Selection Evolution 2014, 46, 33 -33.

AMA Style

Tessa Brinker, Piter Bijma, Jeroen Visscher, T B Rodenburg, Esther D Ellen. Plumage condition in laying hens: genetic parameters for direct and indirect effects in two purebred layer lines. Genetics Selection Evolution. 2014; 46 (1):33-33.

Chicago/Turabian Style

Tessa Brinker; Piter Bijma; Jeroen Visscher; T B Rodenburg; Esther D Ellen. 2014. "Plumage condition in laying hens: genetic parameters for direct and indirect effects in two purebred layer lines." Genetics Selection Evolution 46, no. 1: 33-33.

Journal article
Published: 31 July 2013 in Physiology & Behavior
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Severe feather pecking (SFP) in laying hens is a detrimental behavior causing loss of feathers, skin damage and cannibalism. Previously, we have associated changes in frontal brain serotonin (5-HT) turnover and dopamine (DA) turnover with alterations in feather pecking behavior in young pullets (28–60 days). Here, brain monoamine levels were measured in adult laying hens; focusing on four brain areas that are involved in emotional behavior or are part of the basal ganglia-thalamopallial circuit, which is involved in obsessive compulsive disorders. Three behavioral phenotypes were studied: Severe Feather Peckers (SFPs), Victims of SFP, and Non-Peckers (NPs). Hens (33 weeks old) were sacrificed after a 5-min manual restraint test. SFPs had higher 5-HIAA levels and a higher serotonin turnover (5-HIAA/5-HT) in the dorsal thalamus than NPs, with intermediate levels in victims. NPs had higher 5-HT levels in the medial striatum than victims, with levels of SFPs in between. 5-HT turnover levels did not differ between phenotypes in medial striatum, arcopallium and hippocampus. DA turnover levels were not affected by feather pecking phenotype. These findings indicate that serotonergic neurotransmission in the dorsal thalamus and striatum of adult laying hens depends on differences in behavioral feather pecking phenotype, with, compared to non-pecking hens, changes in both SFP and their victims. Further identification of different SFP phenotypes is needed to elucidate the role of brain monoamines in SFP.

ACS Style

Marjolein S. Kops; Elske N. de Haas; T. Bas Rodenburg; Esther D. Ellen; Gerdien A.H. Korte-Bouws; Berend Olivier; O. Güntürkün; J. Elizabeth Bolhuis; S. Mechiel Korte. Effects of feather pecking phenotype (severe feather peckers, victims and non-peckers) on serotonergic and dopaminergic activity in four brain areas of laying hens (Gallus gallus domesticus). Physiology & Behavior 2013, 120, 77 -82.

AMA Style

Marjolein S. Kops, Elske N. de Haas, T. Bas Rodenburg, Esther D. Ellen, Gerdien A.H. Korte-Bouws, Berend Olivier, O. Güntürkün, J. Elizabeth Bolhuis, S. Mechiel Korte. Effects of feather pecking phenotype (severe feather peckers, victims and non-peckers) on serotonergic and dopaminergic activity in four brain areas of laying hens (Gallus gallus domesticus). Physiology & Behavior. 2013; 120 ():77-82.

Chicago/Turabian Style

Marjolein S. Kops; Elske N. de Haas; T. Bas Rodenburg; Esther D. Ellen; Gerdien A.H. Korte-Bouws; Berend Olivier; O. Güntürkün; J. Elizabeth Bolhuis; S. Mechiel Korte. 2013. "Effects of feather pecking phenotype (severe feather peckers, victims and non-peckers) on serotonergic and dopaminergic activity in four brain areas of laying hens (Gallus gallus domesticus)." Physiology & Behavior 120, no. : 77-82.

Journal article
Published: 26 July 2013 in Genetics Selection Evolution
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Through social interactions, individuals affect one another’s phenotype. In such cases, an individual’s phenotype is affected by the direct (genetic) effect of the individual itself and the indirect (genetic) effects of the group mates. Using data on individual phenotypes, direct and indirect genetic (co)variances can be estimated. Together, they compose the total genetic variance that determines a population’s potential to respond to selection. However, it can be difficult or expensive to obtain individual phenotypes. Phenotypes on traits such as egg production and feed intake are, therefore, often collected on group level. In this study, we investigated whether direct, indirect and total genetic variances, and breeding values can be estimated from pooled data (pooled by group). In addition, we determined the optimal group composition, i.e. the optimal number of families represented in a group to minimise the standard error of the estimates.

ACS Style

Katrijn Peeters; Esther Dorien Ellen; Piter Bijma. Using pooled data to estimate variance components and breeding values for traits affected by social interactions. Genetics Selection Evolution 2013, 45, 27 -27.

AMA Style

Katrijn Peeters, Esther Dorien Ellen, Piter Bijma. Using pooled data to estimate variance components and breeding values for traits affected by social interactions. Genetics Selection Evolution. 2013; 45 (1):27-27.

Chicago/Turabian Style

Katrijn Peeters; Esther Dorien Ellen; Piter Bijma. 2013. "Using pooled data to estimate variance components and breeding values for traits affected by social interactions." Genetics Selection Evolution 45, no. 1: 27-27.

Journal article
Published: 01 October 2012 in Physiology & Behavior
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Fearfulness of an individual can affect its sensitivity to stress, while at the same time the social situation in which an animal lives can affect its fear level. It is however unknown what the long-term effects of high fearfulness on sensitivity to stress are, on individual or group level in laying hens. We hypothesize that increased fearfulness at a young age results in increased sensitivity to stress at an adult age, and that this relation can differ between groups, due to differences in group composition. Therefore, we studied the relation between fearfulness in an Open Field (OF) test at six weeks of age and plasma-corticosterone (CORT) levels after a 5-min Manual Restraint test (MR) at 33 weeks of age, and assessed behavior in the home pen. We used birds from a low mortality line, selected for four generations on low mortality due to feather pecking and cannibalism and a control line (n=153 in total, eight pens/line). These lines are known to differ in fearfulness and stress physiology. Chicks from the low mortality line were more active in the OF compared to chicks from the control line. Chicks that showed a fearful response (no walking, no vocalizing) in the OF test had higher CORT at 33 weeks of age than chicks that walked and/or vocalized in the OF test and had higher activity in the home pen as adults. On group level, a passive response in the OF was related to high CORT levels after MR. Presence of at least one fearful bird in a group led to higher CORT in the other group mates compared to birds from groups with no fearful birds present. Birds from groups in which more than 50% of birds had severe comb lesions had higher CORT levels compared to birds from groups with less than 50% of birds affected. High fearfulness of laying hen chicks can on individual level have a long-term effect on stress sensitivity. The presence of fearful birds in a group as well as signs of social instability in a group, indicated by comb lesions, can affect sensitivity to stress of birds from the same group. The mechanism by which this occurs can lie in social transmission of (fear related) behavior, but this suggestion needs further investigation.

ACS Style

Elske N. De Haas; Marjolein S. Kops; J. Elizabeth Bolhuis; Ton G. G. Groothuis; Esther D. Ellen; Bas Rodenburg. The relation between fearfulness in young and stress-response in adult laying hens, on individual and group level. Physiology & Behavior 2012, 107, 433 -439.

AMA Style

Elske N. De Haas, Marjolein S. Kops, J. Elizabeth Bolhuis, Ton G. G. Groothuis, Esther D. Ellen, Bas Rodenburg. The relation between fearfulness in young and stress-response in adult laying hens, on individual and group level. Physiology & Behavior. 2012; 107 (3):433-439.

Chicago/Turabian Style

Elske N. De Haas; Marjolein S. Kops; J. Elizabeth Bolhuis; Ton G. G. Groothuis; Esther D. Ellen; Bas Rodenburg. 2012. "The relation between fearfulness in young and stress-response in adult laying hens, on individual and group level." Physiology & Behavior 107, no. 3: 433-439.

Journal article
Published: 31 May 2011 in Applied Animal Behaviour Science
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Rebecca Nordquist; Jasper L.T. Heerkens; Bas Rodenburg; Sabine Boks; Esther D. Ellen; F. Josef van der Staay. Laying hens selected for low mortality: Behaviour in tests of fearfulness, anxiety and cognition. Applied Animal Behaviour Science 2011, 131, 110 -122.

AMA Style

Rebecca Nordquist, Jasper L.T. Heerkens, Bas Rodenburg, Sabine Boks, Esther D. Ellen, F. Josef van der Staay. Laying hens selected for low mortality: Behaviour in tests of fearfulness, anxiety and cognition. Applied Animal Behaviour Science. 2011; 131 (3-4):110-122.

Chicago/Turabian Style

Rebecca Nordquist; Jasper L.T. Heerkens; Bas Rodenburg; Sabine Boks; Esther D. Ellen; F. Josef van der Staay. 2011. "Laying hens selected for low mortality: Behaviour in tests of fearfulness, anxiety and cognition." Applied Animal Behaviour Science 131, no. 3-4: 110-122.

Journal article
Published: 07 July 2010 in Genetics Selection Evolution
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Mortality due to cannibalism in laying hens is a difficult trait to improve genetically, because censoring is high (animals still alive at the end of the testing period) and it may depend on both the individual itself and the behaviour of its group members, so-called associative effects (social interactions). To analyse survival data, survival analysis can be used. However, it is not possible to include associative effects in the current software for survival analysis. A solution could be to combine survival analysis and a linear animal model including associative effects. This paper presents a two-step approach (2STEP), combining survival analysis and a linear animal model including associative effects (LAM).

ACS Style

Esther D Ellen; Vincent Ducrocq; Bart J Ducro; Roel F Veerkamp; Piter Bijma. Genetic parameters for social effects on survival in cannibalistic layers: Combining survival analysis and a linear animal model. Genetics Selection Evolution 2010, 42, 27 -10.

AMA Style

Esther D Ellen, Vincent Ducrocq, Bart J Ducro, Roel F Veerkamp, Piter Bijma. Genetic parameters for social effects on survival in cannibalistic layers: Combining survival analysis and a linear animal model. Genetics Selection Evolution. 2010; 42 (1):27-10.

Chicago/Turabian Style

Esther D Ellen; Vincent Ducrocq; Bart J Ducro; Roel F Veerkamp; Piter Bijma. 2010. "Genetic parameters for social effects on survival in cannibalistic layers: Combining survival analysis and a linear animal model." Genetics Selection Evolution 42, no. 1: 27-10.

Journal article
Published: 07 December 2009 in Physiology & Behavior
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The aim of the present study was to investigate the effect of brooding and group selection for low mortality on post-stress corticosterone and peripheral serotonin in laying hens. Birds in the experiment originated from the same population and were either group-selected for low mortality (low mortality line) or randomly selected (control line) for two generations. Twelve groups of seven birds from each line were used. Within each line, six groups were brooded by a foster mother and six groups were non-brooded. At 33 weeks of age, birds (n = 42/treatment) were manually restrained for 5 min, during which their behavioral response (number of struggles) was studied. Fifteen minutes after the start of the manual restraint, blood samples were drawn for assessment of plasma corticosterone and whole blood serotonin (5-HT) concentration. In the low mortality line, 80% of the birds struggled and vocalized vs. 72% in the control line (non significant). Birds from the control line had a higher plasma corticosterone concentration after manual restraint than birds from the low mortality line (7.7 vs. 6.0 nmol ml− 1). Furthermore, birds from the control line that were reared without a mother had a lower whole-blood 5-HT concentration than birds from the other treatments (45 vs. 48 nmol ml− 1). These results indicate that both brooding and selection for low mortality affect post-stress corticosterone and peripheral serotonin concentration, which may result in a reduced propensity to develop feather pecking.

ACS Style

T. Bas Rodenburg; J. Elizabeth Bolhuis; Rudie E. Koopmanschap; Esther D. Ellen; Eddy Decuypere. Maternal care and selection for low mortality affect post-stress corticosterone and peripheral serotonin in laying hens. Physiology & Behavior 2009, 98, 519 -523.

AMA Style

T. Bas Rodenburg, J. Elizabeth Bolhuis, Rudie E. Koopmanschap, Esther D. Ellen, Eddy Decuypere. Maternal care and selection for low mortality affect post-stress corticosterone and peripheral serotonin in laying hens. Physiology & Behavior. 2009; 98 (5):519-523.

Chicago/Turabian Style

T. Bas Rodenburg; J. Elizabeth Bolhuis; Rudie E. Koopmanschap; Esther D. Ellen; Eddy Decuypere. 2009. "Maternal care and selection for low mortality affect post-stress corticosterone and peripheral serotonin in laying hens." Physiology & Behavior 98, no. 5: 519-523.

Journal article
Published: 22 June 2009 in Physiology & Behavior
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Severe feather pecking is a maladaptive behavior in laying hens that may result in cannibalism and ultimately death of the victims. Selection methods in which the genetic effect of an animal on the survival of its group members is taken into account, i.e. ‘group selection’, have been shown to be very effective in reducing mortality due to feather pecking and cannibalism in laying hens. It has been suggested that fearfulness and serotonergic functioning are involved in the causation and development of feather pecking. We investigated effects of selection based on survivability in non-beak trimmed groups on fear-related behavior and peripheral 5-HT concentration and uptake in hens with trimmed or intact beaks, in a 2 × 2 factorial arrangement. Hens from the second generation of the low mortality line showed less fear-related behavior than control line hens. In addition, they displayed higher whole blood 5-HT concentrations and a lower platelet 5-HT uptake, indicating differences in functional activity of the 5-HT system. Beak trimming resulted in lowered levels of fear, and in a reduction of feather damage. Hens with trimmed and intact beaks did, however, not differ in peripheral 5-HT. The results imply that fearfulness and 5-HT activity are related to feather pecking without distinguishing between cause and effect. However, given that selection altered fear-related behaviors and peripheral 5-HT concentration and uptake, whereas beak trimming affected fearfulness and feather damage, but not 5-HT parameters, we suggest that peripheral 5-HT activity might reflect the predisposition to develop severe feather pecking under adverse conditions in laying hens.

ACS Style

J. Elizabeth Bolhuis; Esther D. Ellen; Cornelis G. Van Reenen; Johanna De Groot; Jan Ten Napel; Rudie E. Koopmanschap; Ger De Vries Reilingh; Koen A. Uitdehaag; Bas Kemp; Bas Rodenburg. Effects of genetic group selection against mortality on behavior and peripheral serotonin in domestic laying hens with trimmed and intact beaks. Physiology & Behavior 2009, 97, 470 -475.

AMA Style

J. Elizabeth Bolhuis, Esther D. Ellen, Cornelis G. Van Reenen, Johanna De Groot, Jan Ten Napel, Rudie E. Koopmanschap, Ger De Vries Reilingh, Koen A. Uitdehaag, Bas Kemp, Bas Rodenburg. Effects of genetic group selection against mortality on behavior and peripheral serotonin in domestic laying hens with trimmed and intact beaks. Physiology & Behavior. 2009; 97 (3-4):470-475.

Chicago/Turabian Style

J. Elizabeth Bolhuis; Esther D. Ellen; Cornelis G. Van Reenen; Johanna De Groot; Jan Ten Napel; Rudie E. Koopmanschap; Ger De Vries Reilingh; Koen A. Uitdehaag; Bas Kemp; Bas Rodenburg. 2009. "Effects of genetic group selection against mortality on behavior and peripheral serotonin in domestic laying hens with trimmed and intact beaks." Physiology & Behavior 97, no. 3-4: 470-475.

Journal article
Published: 01 February 2008 in Poultry Science
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Mortality due to cannibalism is a major problem in laying hens. Due to prohibition of beak-trimming in the European Union, this problem will increase in the near future. One solution to reduce mortality due to cannibalism is to use genetic selection. Mortality due to cannibalism, however, differs from conventional breeding traits, because it depends on social interactions among individuals. Selection strategies aiming to reduce cannibalism, therefore, should consider both the direct effect of an individual on its own survival and the social effect of the individual on the survival of its group members (the so-called associative effect). Traditional breeding, however, accounts for only the direct effect. Recently, methods have been proposed to estimate variance components and breeding values for both direct and associative effects. This paper presents estimated genetic parameters for direct and associative effects on survival days in 3 purebred laying lines. For the analysis, 16,780 hens with intact beaks were used. When considering only direct effects, heritabilities ranged from 2 through 10%. When considering both direct and associative effects, the total heritable variance, expressed as a proportion of phenotypic variance, ranged from 6 through 19%. These results show that heritable variation in survival days is substantially larger than suggested by conventional direct effects models. This means that prospects for reducing mortality by means of genetic selection are good and may lead to substantial reduction of 1 of the major welfare problems in egg production.

ACS Style

E.D. Ellen; J. Visscher; J.A.M. van Arendonk; P. Bijma. Survival of Laying Hens: Genetic Parameters for Direct and Associative Effects in Three Purebred Layer Lines. Poultry Science 2008, 87, 233 -239.

AMA Style

E.D. Ellen, J. Visscher, J.A.M. van Arendonk, P. Bijma. Survival of Laying Hens: Genetic Parameters for Direct and Associative Effects in Three Purebred Layer Lines. Poultry Science. 2008; 87 (2):233-239.

Chicago/Turabian Style

E.D. Ellen; J. Visscher; J.A.M. van Arendonk; P. Bijma. 2008. "Survival of Laying Hens: Genetic Parameters for Direct and Associative Effects in Three Purebred Layer Lines." Poultry Science 87, no. 2: 233-239.

Journal article
Published: 24 October 2007 in Journal of Agricultural and Environmental Ethics
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The combination of breeding for increased production and the intensification of housing conditions have resulted in increased occurrence of behavioral, physiological, and immunological disorders. These disorders affect health and welfare of production animals negatively. For future livestock systems, it is important to consider how to manage and breed production animals. In this paper, we will focus on selective breeding of laying hens. Selective breeding should not only be defined in terms of production, but should also include traits related to animal health and welfare. For this we like to introduce the concept of robustness. The concept of robustness includes individual traits of an animal that are relevant for health and welfare. Improving robustness by selective breeding will increase (or restore) the ability of animals to interact successfully with the environment and thereby to make them more able to adapt to an appropriate husbandry system. Application of robustness into a breeding goal will result in animals with improved health and welfare without affecting their integrity. Therefore, in order to be ethically acceptable, selective breeding in animal production should accept robustness as a breeding goal.

ACS Style

L. Star; E. D. Ellen; K. Uitdehaag; F. W. A. Brom. A plea to implement robustness into a breeding goal: poultry as an example. Journal of Agricultural and Environmental Ethics 2007, 21, 109 -125.

AMA Style

L. Star, E. D. Ellen, K. Uitdehaag, F. W. A. Brom. A plea to implement robustness into a breeding goal: poultry as an example. Journal of Agricultural and Environmental Ethics. 2007; 21 (2):109-125.

Chicago/Turabian Style

L. Star; E. D. Ellen; K. Uitdehaag; F. W. A. Brom. 2007. "A plea to implement robustness into a breeding goal: poultry as an example." Journal of Agricultural and Environmental Ethics 21, no. 2: 109-125.