Assessment of trade-offs between feed efficiency, growth-related traits, and immune activity in experimental lines of layer chickens

Abstract

Background In all organisms, life-history traits are constrained by trade-offs, which may represent physiological limitations or be related to energy resource management. To detect trade-offs within a population, one promising approach is the use of artificial selection, because intensive selection on one trait can induce unplanned changes in others. In chickens, the breeding industry has achieved remarkable genetic progress in production and feed efficiency over the last 60 years. However, this may have been accomplished at the expense of other important biological functions, such as immunity. In the present study, we used three experimental lines of layer chicken—two that have been divergently selected for feed efficiency and one that has been selected for increased antibody response to inactivated Newcastle disease virus (ND3)—to explore the impact of improved feed efficiency on animals’ immunocompetence and, vice versa, the impact of improved antibody response on animals’ growth and feed efficiency. Results There were detectable differences between the low (R+) and high (R−) feed-efficiency lines with respect to vaccine-specific antibody responses and counts of monocytes, heterophils, and/or T cell population. The ND3 line presented reduced body weight and feed intake compared to the control line. ND3 chickens also demonstrated an improved antibody response against a set of commercial viral vaccines, but lower blood leucocyte counts. Conclusions This study demonstrates the value of using experimental chicken lines that are divergently selected for RFI or for a high antibody production, to investigate the modulation of immune parameters in relation to growth and feed efficiency. Our results provide further evidence that long-term selection for the improvement of one trait may have consequences on other important biological functions. Hence, strategies to ensure optimal trade-offs among competing functions will ultimately be required in multi-trait selection programs in livestock.

Caecal microbiota composition of experimental inbred MHC-B lines infected with IBV differs according to genetics and vaccination

“…Intense selection may also have compromised the host immune response to Escherichia coli vaccination 5 or increased the susceptibility to Marek’s disease 6 , 7 . Potential trade-offs between productivity and immunity are often hypothesized to explain such results 8 .…”

Mitochondrial and Glycolytic Capacity of Peripheral Blood Mononuclear Cells Isolated From Diverse Poultry Genetic Lines: Optimization and Assessment

“…The significantly increased OCR, a measure of mitochondrial respiration, observed in the L8, dual-purpose line (inbred line since 1925) compared with modern commercial layer and broiler lines was an unanticipated outcome (Figure 5A) that may provide insight into consequences of intense genetic selection in modern commercial breeds. It has been established that selection for economic-focused traits in broilers has reduced diversity of immune system genetics (33) and that laying hens selected for feed efficiency show reduced antibody response to Newcastle disease virus (10). However, given that the L8 is highly inbred, its genetics is expected to be primarily fixed at the alleles in highest frequency at its founding.…”

“…In terms of glycolysis, Bovans layer PBMCs tended to show greater ECAR than broiler PBMCs, with a 32.4% increase. Broiler selection for weight gain has decreased immune system resources, an established phenomenon (10), likely to a greater extent than selection for high egg production has affected the immune response of the hen. Animal behavior may provide confirmation of this: broiler locomotion decreases over development; this is believed to be due in part to energy allocation toward significant weight gain that takes away from metabolic costs of standing, walking, perching, etc.…”

“…Chicken immune cells make for a particularly interesting model, as chicken populations in the last 60-70 years have been genetically selected from what were once multipurpose birds to two divergent, highly feed-efficient commercial lines: fast-growing broilers (8) or egg-producing layers (9). Ultimately, stringent artificial genetic selection for production traits of muscle accretion or egg production comes at the cost of other natural, biological functions that are also energetically expensive, i.e., the immune system (10). Baseline metabolic rates and immune cell pathway preferences between modern broiler and layer lines vs. legacy lines of chickens are, thus, of interest but have not been evaluated using an advanced metabolic assay.…”

Genetic and phenotypic correlations among feed efficiency, immune and production traits in indigenous chicken of Kenya

“…Such genetic advantage could be exploited to improve feed efficiency and immune-competence in this population. However, in cases of resource scarcity, trade-offs between different functions in the body may be expected when a negative dependency between resource acquisition and resource allocation exists ( Zerjal et al, 2021 ). Even in environments where ad libitum feed resources are available, Rauw (2012) indicates that there is a limited amount of feed an individual can ingest, assimilate, use, and share among various functions in the body with preferential partitioning of resources to functions of interest.…”