Motivated by consumer concerns for animal welfare, several European countries have recently banned the culling of day-old male chicks from layer lines. Germany and France were the first countries to enact this binding prohibition, and in Germany, Article 1 § 4c of the Tierschutzgesetz (TierSchG) makes it a punishable offence to kill a vertebrate animal without reasonable cause. Economic unprofitability, which is the key reason for killing day-old male chicks from layer lines, whose genetically determined productivity is insufficient for commercial meat production, is explicitly excluded as a sufficient justification for the taking of animal life. Consequently, alternative systems such as dual-purpose poultry, in which both males and females are reared for commercial use, have gained importance. However, knowledge on the management and productivity of dual-purpose chickens is still limited. This study assessed the potential of selected dual-purpose chicken genotypes as an alternative to single-purpose poultry in organic production systems. Three genotypes with different performance profiles were reared and compared to commercial layer and broiler types as controls under organic husbandry guidelines. Due to biosecurity measures for avian influenza, males had access only to a covered outdoor run, while females were restricted to covered areas from 18 to 28 and 60-72 weeks, with full pasture access between 28 and 60 weeks of age. In the fattening trial, dual-purpose males required 37-50% longer to reach a target weight of 2.1 kg compared to the control, but exhibited more balanced growth of valuable cuts, whereas the control showed disproportionately high breast meat yield. Meat quality in dual-purpose males was not compromised relative to the control. Laying performance in dual-purpose hens was 19-25% lower than the control, with feed conversion ratios of 2.62-3.43 vs 2.14 in the control. However, due to their dual-purpose nature, the meat yield in these hens was 17-27% higher. While significant differences were observed in performance, egg quality remained similar across genotypes, and meat quality varied slightly. Economic evaluations indicated scenarios of short-, medium-, and long-term profitability depending on production goals and market context. Overall, dual-purpose poultry may represent a promising alternative for farming systems prioritising ethical considerations and product quality.
The rainbow trout is the most widely farmed freshwater species in Europe. Early research on the genetic basis of egg production began in the 1970s, but with several generations of selective breeding now established-mainly focused on body weight-understanding the genetic relationships between growth and spawning performance has become necessary. This study investigated a commercial line of rainbow trout, monitoring about 1600 females from 656 families, from portion size (355 g) to maturity (2600 g), to assess egg production traits at first spawn (total spawn weight and egg number, mean egg weight, relative fecundity, and gonado-somatic index). Thermal growth coefficients (TGCs) were calculated across six periods until spawning. Fillet fat content was measured, and carcass yield was predicted non-invasively through ultrasound tomography. Heritabilities and genetic correlations between growth, carcass quality and spawning traits were estimated using linear animal models. Genetic correlations between body weight at different ages and spawning traits were either nonsignificant or positive (0.05 to 0.70). Comparable trends were observed for TGCs (-0.20 to 0.63) and carcass yield at 16 months (-0.03 to 0.24). In contrast, predicted carcass yield at 20 months showed negative genetic correlations with spawning traits (-0.16 to-0.47). These findings indicate that selection for growth up to 20 months should not adversely affect and may improve spawning performance. However, improving carcass yield after 20 months may compromise egg production. Monitoring spawning performance in selective breeding programs is advised to anticipate shifts in genetic correlations and to optimize selection strategies all along the life cycle.
Extending the productive lifespan of laying hens is a key objective for sustainable egg production. Achieving this goal requires improving egg production and quality traits expressed late in life. Genomic selection offers opportunities to increase accuracy of selection for such traits, while shorter generation intervals can accelerate genetic progress. However, both strategies may affect inbreeding, and their combined impact in the context of extended laying cycles has not yet been quantified. Stochastic simulations were performed to evaluate seven breeding programs for layers, based on real genotype data and six quantitative traits (egg weight, egg shell strength, and laying rate, each at 60 and 90 weeks). Programs differed by generation interval (L, 60, 45, or 30 weeks) and two selection method were applied to each scenario: single-step GBLUP using male genotypes (ssGBLUPm), or single-step GBLUP using both male and female genotypes (ssGBLUPmf). A control PBLUP based scenario with a 60 weeks L was also performed. Each scenario was replicated 30 times, and results were compared for annual genetic gain (∆G), prediction accuracy (r), and inbreeding rate (∆F). Genomic evaluations using a generation interval of 60 weeks improved both ∆G and ∆F, especially when both sexes were genotyped. Reducing the generation interval to 30 weeks maximized ∆G (up to 1.17 SD/year) but increased ∆F above 1%/year. Overlapping generation schemes (45-week interval) provided an intermediate outcome, improving ∆G compared with conventional 60-week generation interval schemes while limiting ∆F compared with 30-week generation interval schemes. Including female genotypes was particularly beneficial for late-recorded traits at 90 weeks, where accuracy increased by up to 38%. Shortening generation interval and implementing genomic selection substantially increased annual genetic gain, especially for persistency traits expressed late in life. However, these strategies also raised inbreeding, with overlapping generations offering a valuable compromise. Full genotyping of both sexes enhanced accuracy and reduced the increase in ΔF per ΔG unit, highlighting the relevance of genomic selection in breeding programs aiming to extend laying periods sustainably.
This study focuses on genetic resistance to infectious pancreatic necrosis (IPN), a highly contagious disease caused by an aquatic birnavirus (IPNV) which especially affects salmonids worldwide. The objectives were to estimate the heritability of IPN resistance and to fine map quantitative trait loci (QTL) using a Bayesian Sparse Linear Mixed Model to identify candidate genes possibly linked to IPN resistance in two successive generations from a French commercial strain of rainbow trout. For each generation, 2000 fish were experimentally exposed by bath to IPNV and mortalities were monitored daily during 5 weeks. All fish were genotyped using a medium-density 57 K single nucleotide polymorphism (SNP) chip and imputed to high-density genotypes (665 K SNPs). The mean survival rate was 70
La spectrométrie portable et miniaturisée (proche et moyen infrarouge, Raman), couplée à des modèles chimiométriques performants, offre des potentialités pour la détection sélective de polluants agricoles et la caractérisation des acides gras en aquaculture et aviculture, avec des mesures rapides, fiables et applicables à la sélection génétique et à l’agro-industrie.
