Immediate and transgenerational effects of thymol supplementation, inactivated Salmonella and chronic heat stress on representative immune variables of Japanese quail

Abstract

Environmental challenges are integrated in the inmunoneuroendocrine interplay, impacting the immune system of the challenged individuals, and potentially implying transgenerational effects on their offspring. This study addressed whether dietary supplementation with thymol can modulate the immune response of adult Japanese quail when simultaneously exposed to an inoculum of inactivated Salmonella Enteritidis and a chronic heat stress (CHS). We also evaluated whether the experienced situations by adults can affect the immune response of their undisturbed offspring. In the parental generation, supplemented quail exposed to CHS had a higher inflammatory response and similar values of the heterophil/lymphocyte (H/L) ratio than those that were not supplemented. In their offspring, those chicks whose parents were exposed to CHS showed higher inflammatory response and lower antibody production. Regarding the H/L ratio, chicks whose parents were supplemented showed lower H/L ratio values. Dietary supplementation with thymol partially and positively modulated the inflammatory response and avoided H/L ratio alteration in the parental generation exposed to high environmental temperatures, suggesting these adults were better at dealing with the challenge. The lower H/L ratio values in the offspring suggests that chicks are more capable to deal with potential stressful situations associated with conventional breeding conditions.

Figure 1

Effects of sex on the antibody titers against sheep red blood cells (a), sex and the inactivated Salmonella Enteritidis inoculum on the heterophil/lymphocyte ratio (b), thymol dietary supplementation and the environmental challenges on percentage of inflammation against PHA-P (c) and the heterophil/lymphocyte ratio (d) of 83 pair male–female adult Japanese quail. Dietary supplementation started at 103 days of age and lasted until the end of the study (130 days of age). Quail received a thymol dose equivalent to 80 mg/quail per day. At 115 days of age, quail were inoculated with Salmonella Enteritidis (SE) by an intramuscular injection. Chronic heat stress was achieved increasing room temperature from 24 to 34 °C during 9 consecutive days (121–129 days of age). Considering that no main effects of SE inoculation were detected, both SE and non-SE animals were pooled within the figures (c) and (d). Bars represent the mean value and lines represent standard error. ^A,BDifferent letters represent statistical differences (P < 0.05) between groups.

Figure 2

Effects of thymol dietary supplementation and the environmental challenges on the antimicrobial activity (a) and the agglutinant activity (b) in quail eggs. Dietary supplementation started at 103 days of age and lasted until the end of the study (130 days of age). Quail received a thymol dose equivalent to 80 mg/quail per day. At 115 days of age, quail were inoculated with Salmonella Enteritidis by intramuscular injection. Chronic heat stress was achieved increasing room temperature from 24 to 34 °C during 9 consecutive days (121–129 days of age). A total of 40 eggs (5 per treatment) collected on the 9th day of chronic heat stress were analysed. Bars represent the mean value and lines represent standard error. ^A–B/a–bDifferent letters represent statistical differences (P < 0.05) between groups.

Figure 3

Effects of thymol dietary supplementation and the environmental challenges in the parental generation on the percentage of inflammation against PHA-P (a), titters against SRBC (b) and heterophil/lymphocyte ratio (c) in their undisturbed offspring. Number of chicks per treatment ranged from 15 to 25. Bars represent the mean value and lines represent standard error. In the parental generation: Dietary supplementation started at 103 days of age and lasted until the end of the study (130 days of age). Quail received a thymol dose equivalent to 80 mg/quail per day. At 115 days of age, quail were inoculated with Salmonella Enteritidis (SE) by an intramuscular injection. Chronic heat stress was achieved increasing room temperature from 24 to 34 °C during 9 consecutive days (121–129 days of age). Considering that no main effects of SE inoculation were detected, both SE and non-SE animals were pooled within the figure. ^A–B/a–bRepresents statistical differences (P < 0.05) between groups.

Figure 4

Timeline scheme. Dietary supplementation began at 103 days of age and continued until after blood samples were taken (130 days of age). Quail received a thymol dose equivalent to 80 mg/quail per day. At 115 days of age, quail were inoculated with Salmonella Enteritidis by intramuscular injection. Heat stress protocol was applied during 9 consecutive days (119–127 days of age) and achieved by increasing room temperature from 24 to 34 °C during daylight hours.