Effect of Intermittent and Mild Cold Stimulation on the Immune Function of Bursa in Broilers

Abstract

Cold stress causes growth performance to decrease and increases production costs. Cold adaptation can enhance immune function and alleviate the negative impact caused by the stress condition. The study investigated the effect of intermittent and mild cold stimulation on the immune function of the bursa of Fabricius in broilers. A total of 400 healthy one-day-old broilers were divided into the control group (CC) and cold stimulation (CS) groups. The CC group was raised at a conventional raising temperature of broilers, while the CS groups were raised at 3°C below the temperature of the CC for three-, four-, five-, or six-hour periods at one-day intervals from 15 to 35 days of age (D35), denoted CS3, CS4, CS5, and CS6, respectively. Subsequently, they were raised at 20°C from 36 to 49 days of age (D49). The expression levels of TLRs, cytokines, and AvBDs were determined to access the immune function of bursa in broilers. After 21-day IMCS (at D36), the expression levels of TLR1, TLR15 and TLR21, interleukin (IL)-8, and interferon (IFN)-γ, as well as AvBD8 in CS groups, were lower than those in CC (p < 0.05). The expression levels of TLR3, TLR4 and TLR7, were decreased in the CS3, CS5, and CS6 groups (p < 0.05), but there were no significant differences in both the CC and CS4 groups (p > 0.05). When the IMCS ended for 14 days (at D49), the expression levels of TLR2, TLR3, TLR5, TLR7, TLR15, and TLR21, and IL-8, as well as AvBD2, AvBD4 and AvBD7 in CS groups, were lower than those in CC (p < 0.05). In addition to CS4, the expression levels of TLR1, IFN-γ, and AvBD8 in CS3, CS5, and CS6 were still lower than those in CC (p < 0.05). We concluded that the intermittent and mild cold stimulation could regulate immunoreaction by modulating the production of TLRs, cytokines, and AvBDs in the bursa, which could help broilers adapt to low ambient temperature and maintain homeostasis.

Toll-Like Receptor as a Potential Biomarker in Renal Diseases

“…It is pointed out that intracellular localization is important not only for ligand recognition but also for avoiding TLR contact with self-nucleic acids, which could cause autoimmunity. A high number of TLR receptors on cells of the immune system, such as monocytes, macrophages, dendritic cells, or lymphocytes, enables the thesis that they constitute a network allowing rapid cooperation of leukocytes and cells present at the site of infection or in the immediate vicinity of damaged host cells [23,24]. TLR synthesis begins in the rough endoplasmic reticulum, from where it goes to the Golgi apparatus and then to its destinations, in other words to the cell surface or to the intercellular compartments [22].…”

Effect of mild intermittent cold stimulation on thymus immune function in broilers

“…Negative effects of low temperature pressure on poultry production ( Hangalapura et al, 2004 ; Zhao et al, 2013 ; Tsiouris et al, 2015 ). Previous studies have shown that intermittent cold stimulation training in early growth response can improve immunity and cold resistance in late growth growth response ( Wei et al, 2018 ; Su et al, 2019 ; Liu et al, 2020 ). We still need more results from different organizations in order to evaluate cold stimulus programs comprehensively.…”

“…In particular, it has been demonstrated that the use of a 21-d IMCS at feeding temperature, with 1-d or 6-h intervals, did not affect broiler's performance but improved antioxidant capacity ( Wei et al, 2018 ; Su et al, 2019 ). Our previous experiment found that IMCS at 3°C below normal feeding temperature for 3 h, 4 h, 5 h, and 6 h for 21 d was beneficial to the development of bursal in fabricius, spleen and intestine of broilers, in addition 5 h was the optimal solution ( Li et al, 2020 ; Liu et al, 2020 ; Xue et al, 2021 ). However, it is necessary to further study the spatiotemporal differences in the expression levels of immune-related genes in different organs.…”

“…Recent studies found that cold acclimation could reduce chilling injury in broilers by increasing antioxidant capacity and disease resistance ( Tsiouris et al, 2015 ; Mohammed et al, 2019 ). In this context, cold training during early stages of development could improve adaptability in late stages of growth ( Bukowiecki et al, 1986 ; Liu et al, 2020 ; Xue et al, 2021 ). Intermittent and mild cold stimulation ( IMCS ) has been suggested as an energy efficient strategy which could achieve the goal of enhancing immune capacity to withstand cold stress.…”

“…As sentinels of the immune system, Toll-like receptors ( TLRs) sense specific microbial ligands and primarily participate in the activation of the adaptive immune response of vertebrate hosts ( Ramasamy et al, 2011 ). In response to drastic temperature changes, cells maintain homeostasis by modulating the expression of TLRs genes ( Li et al, 2020 ; Liu et al, 2020 ; Xue et al, 2021 ). In addition, TLRs triggers activation cascades to mediate inflammatory and immune responses by recognizing and responding to pathogen-associated molecular patterns ( PAMPs ) ( Takeda et al, 2003 ; Kawai and Akira, 2010 ).…”