Immune parameters in two different laying hen strains during five production periods

Abstract

During life, the number and function of immune cells change with potential consequences for immunocompetence of an organism. In laying hens, studies have primarily focused on early development of immune competence and only few have investigated systemic and lymphatic distribution of leukocyte subsets during adolescence and the egg-laying period. The present study determined the number of various leukocyte types in blood, spleen, and cecal tonsils of 10 Lohmann Brown-Classic and 10 Lohmann LSL-Classic hens per wk of life 9/10, 15/16, 23/24, 29/30, and 59/60, encompassing important production as well as developmental stages, by flow cytometry. Although immune traits differed between the 2 hen strains, identical patterns of age-related immunological changes were found. The numbers of all investigated lymphocyte types in the spleen as well as the numbers of blood γδ T cells increased from wk 9/10 to 15/16. This suggests an ongoing release of lymphocytes from primary lymphoid tissues and an influx of blood lymphocytes into the spleen due to novel pathogen encounters during adolescence. A strong decrease in the number of CTL and γδ T cells and an increase in innate immune cells within blood and spleen were found between wk of life 15/16 and 23/24, covering the transition phase to egg-laying activity. Numbers of peripheral and splenic lymphocytes remained low during the egg-laying period or even further decreased, for example blood CD4 + T cells and splenic γδ T cells. Functional assessments showed that in vitro IFN-γ production of mitogen-stimulated splenocytes was lower in wk 60. Taken together, egg-laying activity seems to alter the immune system toward a more pronounced humoral and innate immune response, with probable consequences for the immunocompetence and thus for productivity, health and welfare of the hens.

Jejunal transcriptomic profiling of two layer strains throughout the entire production period

“…In this regard, the transcription factor encoding genes STAT2 , STAT3 , STAT5A and STAT6 were enriched in profile #9, indicating the transmission of effects at the level of gene expression represented by this pathway. The onset of laying in particular has been shown to have effects on the immune system as analyzed in the blood, spleen, and cecal tonsils of LB and LSL laying hens 12 . Moreover, corresponding analyses in the same individuals highlighted regulatory roles of miRNA within the JAK/STAT signaling 53 .…”

“…Both LB and LSL strains have been improved for egg production performance and have been extensively monitored at the levels of bone quality, egg quality and behaviour 7 . Their egg production performance is approximately identical, however, LB and LSL layer strains significantly differ in gene expression profiles of cerebrum, egg quality parameters (egg and eggshell weights), mineral metabolism (bone-breaking strength, phytate degradation, trans- and paracellular transport), and immune responsiveness 8 – 12 . Importantly, the attainment of sexual maturity in pullets (~ 18 weeks) through to the onset of laying (~ 24 weeks) represents a significant physiological shift within the layers’ metabolic demand.…”

The dynamics of molecular, immune and physiological features of the host and the gut microbiome, and their interactions before and after onset of laying in two hen strains

“…In our previous studies, animals of 2 laying hen strains (Lohmann Brown-Classic [ LB ], Lohmann LSL-Classic [ LSL ]) were studied over 5 developmental stages. These studies focused on individual data sets at various biological levels, such as physiological, endocrine, metabolic, immune, and transcriptomic ( Sommerfeld et al, 2020a ; Gonzalez-Uarquin et al, 2021 ; Omotoso et al, 2021 ; Ponsuksili et al, 2021 ; Schmucker et al, 2021 ). All data sets were obtained with the same animals.…”

“…The microbial community differed significantly between strains and gut sections. The marked changes in nutrients, especially Ca, from pre-laying to laying between 16 and 24 wk of age, resulted in the most striking difference not only in metabolic, endocrine, immunological and transcriptomic traits, but also in the gut's microbial community ( Sommerfeld et al, 2020b ; Gonzalez-Uarquin et al, 2021 ; Omotoso et al, 2021 ; Ponsuksili et al, 2021 ; Schmucker et al, 2021 ).…”

A significant quantitative trait locus on chromosome Z and its impact on egg production traits in seven maternal lines of meat-type chicken

“…The complement system plays an important role in the process of inflammation and infection, and also provides a link between innate and adaptive immunities. Immune capacity can affect the reproductive performance, health, and welfare of hens [ 38 ].…”