Genetic characterization of stress responsiveness in Japanese quail. 1. Analyses of line effects and combining abilities by diallel crosses

Individual variation, personality, and the ability of animals to cope with climate change

The Sixth Assessment of the Intergovernmental Panel on Climate Change describes negative effects of climate change on animals occurring on a larger scale than previously appreciated. Animal species are increasingly experiencing more frequent and extreme weather in comparison with conditions in which the species evolved. Individual variation in behavioural and physiological responses of animals to stimuli from the environment is ubiquitous across all species. Populations with relatively high levels of individual variation are more likely to be able to survive in a range of environmental conditions and cope with climate change than populations with low levels of variation. Behavioural and physiological responses are linked in animals, and personality can be defined as consistent individual behavioural and physiological responses of animals to changes in their immediate environment. Glucocorticoids (cortisol and corticosterone) are hormones that, in addition to metabolic roles, are released when the neuroendocrine stress system is activated in response to stimuli from the environment perceived to be threatening. The size of a glucocorticoid response of an animal is an indication of the animal’s personality. Animals with reactive personalities have relatively high glucocorticoid responses, are relatively slow and thorough to explore new situations, and are more flexible and able to cope with changing or unpredictable conditions than animals with proactive personalities. Animals with reactive personalities are likely to be better able to cope with environmental changes due to climate change than animals with proactive personalities. A reaction norm shows the relationship between phenotype and environmental conditions, with the slope of a reaction norm for an individual animal a measure of phenotypic plasticity. If reaction norm slopes are not parallel, there is individual variation in plasticity. Populations with relatively high individual variation in plasticity of reaction norms will have more animals that can adjust to a new situation than populations with little variation in plasticity, so are more likely to persist as environments change due to climate change. Future studies of individual variation in plasticity of responses to changing environments will help understanding of how populations of animals may be able to cope with climate change.

Does selection for behavioral and physiological performance traits alter glucocorticoid responsiveness in bank voles?

One of the key elements of an animal's Darwinian fitness is its ability to adequately respond to and cope with challenging situations. Glucocorticoid hormones, such as corticosterone, affect an organism's ability to overcome such challenges. We hypothesized that changes in the glucocorticoid response curve contribute to the evolution of increased performance during challenging conditions, and tested it on bank voles (Myodes glareolus) from a multidirectional artificial selection experiment, which involves lines selected for high aerobic exercise metabolism achieved during swimming (A - Aerobic), predatory behavior towards a cricket (P - Predatory) and ability to maintain body mass on a low-quality herbivorous diet (H - Herbivorous), as well as unselected control lines (C - Control). We elicited a glucocorticoid response either by restraining the animal or by maximum pharmacological stimulation, and measured plasma corticosterone levels at baseline, during the response and during the recovery phase. Response-level corticosterone was higher in females, and recovery from maximal level was faster than that of males. Selection did not affect baseline or stress-induced corticosterone levels, but it decreased the maximum corticosterone level in Aerobic and Predatory lines, reducing the difference between stress-induced and maximum levels. Recovery from restraint-induced corticosterone level tended to be slower in the Herbivorous than in the other lines, an effect that was stronger in females than in males. In conclusion, successful selection for increased performance in challenging conditions was not associated with changes in absolute values of the glucocorticoid response to stress, but can affect other characteristics of the glucocorticoid response curve.

Carcass and meat quality of crossbreds of Thai indigenous chickens and Rhode Island Red layer chickens as compared with the purebreds and with broilers

Context In order to maintain the availability of meat from indigenous chicken types in remote Asian regions with their special meat quality, novel ways of increasing efficiency are needed. One way could consist of crossbreeding with layer type chickens that are genetically quite distant from indigenous breeds. Aim The three hypotheses tested were as follows: that the meat quality of indigenous chickens differs from that of broilers; that the meat quality of male layer chickens resembles that of indigenous chickens rather than that of broilers; and that crossbreds of indigenous chickens and layer types overall are superior to the respective purebreds. Methods We studied carcass and meat quality of crossbreds of Thai indigenous Pradu Hang Dam (PD) and Rhode Island Red (RR) layers, and compared them with the corresponding purebreds and a commercial broiler type (Ross) in a complete randomised design. Chickens were reared in 4 × 5 pens with 10 chickens each for 120 days (Ross: 45 days). Key results The crossbreds were superior to PD and RR in body and carcass weight, as well as breast meat percentage, but in Ross the latter was 1.7 times higher. The Ross meat was lighter, more yellow and less red and had a higher intramuscular fat content and drip loss and a lower thawing loss and shear force than that of the three other types. Nucleotide content was either similar in all chicken types or lower in Ross meat. Ross meat was more susceptible to lipid oxidation than that of the three other types although the Ross muscles lipids contained less polyunsaturated fatty acids. Conclusion Considering the better carcass yield and breast meat proportion, crossbreeding of indigenous chickens with a layer breed likely is be economically advantageous. Implications Overall, fattening of crossbreds turned out to be a valid alternative to improve fattening systems and to preserve the specific meat quality of indigenous chickens.

Effects of genotype on hematological and serum biochemical responses of turkey hens to stress

Abstract. Stress accompanying animal production is both an indicator of welfare and a factor that affects economic parameters. Dynamic development of alternative poultry production systems such as outdoor, free range or ecological, strives to achieve best-quality products and to improve the living conditions of birds. Apart from the type and intensity of the external stimuli, the response to stress is determined genetically. Poultry rearing in the aforementioned systems requires selecting the appropriate genotype of birds, often including crosses of fast-growing and slow-growing lines. The objective of this study was to demonstrate differences in the physiological response to stress of fast-growing (FG) and slow-growing (SG) turkeys and their crosses: SF (SG  ×  FG) and FS (FG  ×  SG), based on hematological and biochemical blood analyses. Blood was sampled from 30 turkey hens from each of four genotypes, aged 14 weeks, subjected to standard pre-slaughter handling procedures. Compared to FG and FS turkeys, the SG and SF birds had a high total protein concentration, a higher heterophil (H) ∕ lymphocyte (L) ratio and a higher concentration of cortisol. In turn, the FG turkeys had the highest activity of enzymes: alanine transaminase, aspartate transaminase, lactate dehydrogenase, creatine kinase. Conversely, the FS turkeys had the highest concentrations of total cholesterol and low-density lipoprotein (LDLC) and the lowest concentration of cortisol. Significant positive effects of crossing were reported for total protein, cholinesterase and cortisol. Effects of crossbreeding on the percentage of H, concentrations of total cholesterol, and LDLC and activity of aspartate transaminase in blood of the crosses were significant but negative and more dependent on the sire line. Except for albumins, whose concentration in blood of crosses was higher compared to birds of pure lines, there were no advantages of heterosis. Negative heterosis was estimated for creatinine, the enzymes alanine transaminase and lactate dehydrogenase, and for cortisol. The most similar regarding creatinine, bilirubin, albumins, total protein, H, L and H ∕ L were the FS and SF groups. The greatest differences were in the following parameters: triglycerides, total cholesterol, high-density lipoprotein (HDLC), LDLC, glucose and lactate, which occurred between the pure lines of turkeys. Study results demonstrate various responses to stress in the analyzed groups of turkeys, with the level of stress measured with hematological and biological blood markers being mostly determined by additive genetic variation, and to a lesser extent by the maternal and sire effects.

Effect of hybridization on carcass traits and meat quality of erlang mountainous chickens

Native chickens hold a significant share of the market in China. In response to the huge demand from the market, the productivity of Chinese native chickens needs to be improved. Cross breeding is an effective method to increase productivity, although it might affect meat quality. In this study, two pure lines (SD02 and SD03) of Erlang mountainous chickens were hybridized with a yellow feather and faster growing line (SD01). The effect of hybridization on carcass and meat quality (physiochemical and textural traits) was measured in the F1 population at d 91 of age. The hybrids exhibited higher body weight and dressed weight, and amount of semi-eviscerated, eviscerated, breast muscle and abdominal fat (p<0.05). Abdominal fat yield also increased (p<0.05) compared to the offspring of the two pure-lines. Meanwhile, there was no significant difference in meat quality traits except for the myofiber diameter and density and the shear force of the breast muscle. Overall, the offspring of cross-lines were similar to pure lines in meat color, pH value, inosinic acid, crude protein, crude fat, dry matter, moisture content and amino acid composition in the breast muscle. These results suggest that productivity can be improved via cross-breeding while maintaining meat quality of the Erlang mountainous chicken.

Genetic analysis of an F2 intercross between two strains of Japanese quail provided evidence for quantitative trait loci affecting carcass composition and internal organs

The purpose of this study was to identify genomic regions, quantitative trait loci (QTL), affecting carcass traits on chromosome 1 in an F2 population of Japanese quail. For this purpose, two white and wild strains of Japanese quail (16 birds) were crossed reciprocally and F1 generation (34 birds) was created. The F2 generation was produced by intercrossing of the F1 birds. Phenotypic data including carcass weight, internal organs and carcass parts were collected on F2 animals (422 birds). The total mapping population (472 birds) was genotyped for 8 microsatellite markers on chromosome 1. QTL analysis was performed with interval mapping method applying the line-cross model. Significant QTL were identified for breast weight at 0 (P < 0.01), 172 (P < 0.05) and 206 (P < 0.01), carcass weight at 91 (P < 0.05), carcass fatness at 0 (P < 0.01), pre-stomach weight at 206 (P < 0.01) and uropygial weight gland at 197 (P < 0.01) cM on chromosome 1. There was also evidence for imprinted QTL affecting breast weight (P < 0.01) on chromosome 1. The proportion of the F2 phenotypic variation explained by the significant additive, dominance and imprinted QTL effects ranged from 1.0 to 7.3%, 1.2 to 3.3% and 1.4 to 2.2%, respectively.

Response of restraint stress-selected lines of Japanese quail to heat stress and Escherichia coli challenge

Japanese quail selected for divergent corticosterone response to restraint stress were evaluated for their susceptibility to heat stress and challenge with Escherichia coli. These quail lines are designated as high stress (HS), low stress (LS), and the random-bred control (CS) lines. Heat stress (35°C, 8 h/d) began at 24 d until the end of the study at 39 d. Birds were challenged with an aerosol spray containing 2 × 10(9) cfu of E. coli at 25 and 32 d. At 38 d, the surviving birds were necropsied and the intestinal tract was screened for both Salmonella and Campylobacter. Body weights of the CS birds were higher than both HS and LS at 17, 25, and 32 d. At 32 d, there was no difference in mortality between males and females and the CS line had higher mortality compared with the LS line with the HS line being intermediate. At 38 d, females of the CS line that were both heat stressed and challenged had a mortality incidence of 25%, which was significantly higher than male birds of the same line and treatment (5.3%). There was an increased incidence in Salmonella enterica serotype Agona isolation after heat stress, with the LS birds having less isolation than the HS birds. Mean corticosterone levels of male birds were not significantly affected by line, heat stress, or E. coli challenge; however, the LS line subjected to heat stress had one-third the level of the HS line, a difference identical to that seen in the original selection for response to restraint stress.

Individual variation in glucocorticoid stress responses in animals

When stimuli from the environment are perceived to be a threat or potential threat then animals initiate stress responses, with activation of the hypothalamo-pituitary-adrenal axis and secretion of glucocorticoid hormones (cortisol and corticosterone). Whilst standard deviation or standard error values are always reported, it is only when graphs of individual responses are shown that the extensive variation between animals is apparent. Some animals have little or no response to a stressor that evokes a relatively large response in others. Glucocorticoid responses of fish, amphibian, reptiles, birds, and mammals are considered in this review. Comparisons of responses between animals and groups of animals focused on responses to restraint or confinement as relatively standard stressors. Individual graphs could not be found in the literature for glucocorticoid responses to capture or restraint in fish or reptiles, with just one graph in mammals with the first sample was collected when animals were initially restrained. Coefficients of variation (CVs) calculated for parameters of glucocorticoid stress responses showed that the relative magnitudes of variation were similar in different vertebrate groups. The overall mean CV for glucocorticoid concentrations in initial (0 min) samples was 74.5%, and CVs for samples collected over various times up to 4 h were consistently between 50% and 60%. The factors that lead to the observed individual variation and the extent to which this variation is adaptive or non-adaptive are little known in most animals, and future studies of glucocorticoid responses in animals can focus on individual responses and their origins and significance.

Fecal corticosterone metabolites and plasma corticosterone in Japanese quail selected for low or high plasma corticosterone responses to brief restraint

Fecal corticosterone metabolites and plasma corticosterone in Japanese quail selected for low- or high-plasma corticosterone responses to brief mechanical restraint (low- and high-stress lines), and in a line of unselected quail, were measured in this study. No line differences were observed in baseline plasma corticosterone concentrations, but fecal corticosterone metabolite concentrations and daily fecal corticosterone metabolite production were 20% higher in quail of the high-stress line than in unselected or low-stress quail for males and females living together in group cages (P < 0.05). No differences were observed between lines in corticosterone metabolite concentrations and production for male birds in individual cages. Baseline plasma corticosterone concentrations, fecal corticosterone metabolite concentrations, and production appeared to be higher for males and females in group cages compared with males in individual cages. This difference might have been because of greater corticosterone secretion by male quail living in mixed sex groups than living individually. Correlations between baseline plasma corticosterone concentrations and fecal corticosterone metabolite concentrations in low-stress and high-stress quail, and for all birds combined, were r = 0.521 (P = 0.038), r = 0.604 (P = 0.013), and r = 0.431 (P = 0.002), respectively. The low- and high-stress lines that have been selected for low- and high-corticosterone responses differ in other characteristics, including growth and reproductive performance, and the current results are consistent with the assumption that these other differences are a consequence of greater daily corticosterone secretion in quail of the high-stress line.

The European experience in poultry welfare--a decade ahead

Farm animal welfare is a major issue in Europe, which resulted in regulations and development of research dedicated to animal welfare, especially on standard poultry production, which is often considered as resulting in very poor welfare. The effect of selection is also often questioned. Indeed, capacities of adaptation have been very little considered during the first years of commercial selection and thus have been reduced. Nowadays, a much greater importance is given to welfare-related traits and genomic selection should alleviate the need for their measurements in the short-term. However, the choice of the fittest selection criteria is still to be made. Because behavioral traits are highly dependent on environment, general reactivity may be more efficient. For example, selection against undesirable behavior such as feather pecking has been proven to be efficient, but selection for reduced mortality rates in collective cages proved to be preferable. Most often, selection should not exacerbate extreme values, which are most often detrimental, as in the case of social motivation, which, when increased to too large of an extent, results in increased aggressivity. Moreover, a general propensity will not result in overall improvement; for example, reducing fearfulness has positive effects but does not modify response to social stress. Detrimental effects on other traits may also be observed: although genetic resistance to diseases should increase animal welfare, it may also result in increased frequency of silent carriers and in turn to human transmission. Indeed, an optimum must be found. Studying lines selected for or against these traits will be of great help to choose the best strategy of selection. Another and longer term concern should be on links with other production traits but also on sustainability, which will probably be of greater importance in the coming years.

Integrated maps in quail (Coturnix japonica) confirm the high degree of synteny conservation with chicken (Gallus gallus) despite 35 million years of divergence

BACKGROUND

By comparing the quail genome with that of chicken, chromosome rearrangements that have occurred in these two galliform species over 35 million years of evolution can be detected. From a more practical point of view, the definition of conserved syntenies helps to predict the position of genes in quail, based on information taken from the chicken sequence, thus enhancing the utility of this species in biological studies through a better knowledge of its genome structure. A microsatellite and an Amplified Fragment Length Polymorphism (AFLP) genetic map were previously published for quail, as well as comparative cytogenetic data with chicken for macrochromosomes. Quail genomics will benefit from the extension and the integration of these maps.

RESULTS

The integrated linkage map presented here is based on segregation analysis of both anonymous markers and functional gene loci in 1,050 quail from three independent F2 populations. Ninety-two loci are resolved into 14 autosomal linkage groups and a Z chromosome-specific linkage group, aligned with the quail AFLP map. The size of linkage groups ranges from 7.8 cM to 274.8 cM. The total map distance covers 904.3 cM with an average spacing of 9.7 cM between loci. The coverage is not complete, as macrochromosome CJA08, the gonosome CJAW and 23 microchromosomes have no marker assigned yet. Significant sequence identities of quail markers with chicken enabled the alignment of the quail linkage groups on the chicken genome sequence assembly. This, together with interspecific Fluorescence In Situ Hybridization (FISH), revealed very high similarities in marker order between the two species for the eight macrochromosomes and the 14 microchromosomes studied.

CONCLUSION

Integrating the two microsatellite and the AFLP quail genetic maps greatly enhances the quality of the resulting information and will thus facilitate the identification of Quantitative Trait Loci (QTL). The alignment with the chicken chromosomes confirms the high conservation of gene order that was expected between the two species for macrochromosomes. By extending the comparative study to the microchromosomes, we suggest that a wealth of information can be mined in chicken, to be used for genome analyses in quail.

Japanese quail selected for high plasma corticosterone response deposit high levels of corticosterone in their eggs

Poor habitat quality or body condition often correlates with high responsiveness of the hypothalamo-pituitary-adrenal (HPA) axis rather than with elevated baseline levels of glucocorticoids. We hypothesized that, for egg-laying vertebrates, high responsiveness of the HPA axis would correspond to high concentrations of corticosterone in yolk. We tested the prediction that Japanese quail (Coturnix coturnix japonica) selected for high plasma corticosterone response to brief immobilization (HS quail) would lay eggs with higher yolk corticosterone concentrations than birds selected for low response (LS quail). Quail from both lines were left undisturbed, outside of the stressors associated with daily management, before a first round of egg collection. In a second experiment, quail of both lines were experimentally stressed during the week before egg collection. In both cases we found quail from the HS line to lay eggs with significantly higher yolk corticosterone concentrations than quail of the LS line. After exposure to added experimental stressors, the line difference was more pronounced (increasing from 62% to 96%). There was no line difference in concentrations of yolk testosterone. Our results suggest that (1) genetic differences underly differences in the transfer of maternal corticosterone to yolk and (2) females may be able to control deposition of corticosterone into yolk through a mechanism independent of baseline corticosterone titers.

Genetic characterization of stress responsiveness in Japanese quail. 2. Analyses of maternal effects, additive sex linkage effects, heterosis, and heritability by diallel crosses

Diallel crosses were used to investigate the genetic inheritance of stress responsiveness through examination of population effects in progeny of randombred (RB) quail and quail selected for reduced (low stress, LS) or exaggerated (high stress, HS) plasma corticosterone (CS) response to brief immobilization. The three genotypes were crossed in a 3 x 3 factorial arrangement of treatments that allowed all possible crosses between RB, LS, and HS males with RB, LS, and HS females. The nine crosses produced 479 progeny that were, at 28 d of age, stressed by immobilization, and a sample of blood was collected. The following quantitative genetic parameters were estimated for plasma CS: heritability, heterosis, maternal effects, sex-linkage effects, and heterosis due to the sex chromosomes. Genotypic-phenotypic correlations within RB quail and quail of the two selected lines were also obtained. Maternal effects were different (P < 0.05) from zero for the plasma CS responses of all three genotypes. Additive sex linkage effects on plasma CS responses were variable and of much less importance than maternal effects. The correlations between plasma CS response and genotype were: 0.22 for RB quail and 0.37 and 0.55 for quail of the LS and HS lines, respectively. Heterosis effects were low and most likely due to either an increase in homozygozity of genes on the sex chromosomes or an increase of maternal effects within reciprocal crosses. Heritability, estimated for the post-immobilization plasma CS response, was 0.05 for RB quail and 0.14 and 0.30 for quail of the LS and HS lines, respectively.