Effects of thermal manipulation during late incubation period on post-hatch thermotolerance in ostrich

Abstract

ABSTRACT:The effects of thermal manipulation (TM) during late ostrich embryonic development on hatchability, body weight, biochemical and hormonal changes, and the ability of hatching chicks to cope with thermal challenge in days 6-8 of age were examined. At 35 days of incubation, two hundred fertile eggs were weighed and divided into two equal groups with five replicates. The first group was exposed to 36.5°C and 25% relative humidity (RH) (control), while the second group was exposed to 38.5°C and 45% RH for 3 h daily in days 35-37 of incubation (thermal manipulation). At days 6-8 of age, the hatched chicks from each treatment were randomly divided into two groups: control group (exposed to 32 ± 1°C), and thermal challenge group (exposed to 40 ± 1°C for 3 h daily). Hatchability rate was significantly lower with high incubation temperature as compared to the normal incubation temperatures. Embryonic TM and thermal challenge in days 6-8 of age reduced significantly total protein, albumin, and triiodothyronin concentrations and elevated uric acid, creatinine, triglycerides, and glucose concentrations as compared with the control. The level of corticosterone was significantly higher in the thermal challenge group as compared to the control. In conclusion, exposing the ostrich embryos to TM (38.5°C) during late embryonic development induced physiological changes that may represent epigenetic adaptation to TM. The same mechanisms are employed for increasing the ability to improve thermotolerance post-hatch.

Thermal manipulation of the broilers embryos: expression of muscle markers genes and weights of body and internal organs during embryonic and post-hatch days

“…This confliction can be attributed to the incubation period differences in the current study contrasted with other reports. The significant increase in weights of liver and heart tissues as a result of TM in the current study disagrees with previours reports in ostrrish [26] and Egyptian chickens [27] exposed to high incubation temperature during their late embryonic life. The significant increase in the breast muscles of birds exposed to TM of the current study are in the line with that obesreved earlier [10, 28] in the broiles chickens.…”

HSF3 and Hsp70 Expression during Post-Hatch Cold Stress in Broiler Chickens Subjected to Embryonic Thermal Manipulation

“…Compared to controls, TM chicks were found to have a reduced hatchability rate in the current study. In other avian species like ostriches and Japanese quail, TM resulted in a similarly decreased hatchability rate [39,40]. However, mixed findings were reported for the effect of TM on broiler hatchability, as some studies found that TM positively or negatively affected the hatchability rate [31,[41][42][43], while others reported no effect [36,[43][44][45][46].…”

Juvenile growth, thermotolerance and gut histomorphology of broiler chickens fed Curcuma longa under hot-humid environments

“…Generally, the respiratory rate of the birds appeared to be dose-dependent. Body temperature is an excellent measure of metabolic rate and is associated with acclimatization [ 55 ]. An increase in respiration rate in birds exposed to heat stress has been reported to decrease the blood HCO3- and PCO2 and increase blood pH, resulting in respiratory alkalosis [ 56 ].…”