Effect of prenatal temperature conditioning of laying hen embryos: Hatching, live performance and response to heat and cold stress during laying period

Abstract

This study was designed to determine the effect of prenatal temperature conditioning on hatching and live performance of laying chickens, and response to heat and cold stress during laying period. A total of 3600 eggs obtained from ATAK-S brown parent stock were incubated at control (37.5 °C, CONT-Inc), cyclic low (36.5 °C/6 h/d from 10 to 18 d of incubation, LOW-Inc) or high (38.5 °C/6 h/d from 10–18 d of incubation, HIGH-Inc) incubation temperatures. Hatched chicks per incubation temperature were reared under standard rearing conditions up to 26 wk. From 27 to 30 wk, hens from each incubation temperature were divided into 3 environmentally controlled rooms and reared at control (20±2 °C, CONT-Room), low (12±2 °C, COLDS) or high (32±2 °C, HEATS) temperatures. Hatching performance, body weight, egg production, and plasma triiodothyronine (T₃) and thyroxine (T₄) levels and oxidant and antioxidant activities were evaluated.

The highest hatchability was for LOW-Inc chicks while HIGH-Inc chick had similar hatchability to CONT-Inc. There was no effect of incubation temperatures on plasma MDA, GSH-Px, activities and T₄ concentrations on day of hatch. LOW- Inc chicks had higher SOD activities and T₃ concentrations compared to the other groups. Although chick weight was similar among incubation temperature groups, CONT-Inc chicks were heavier than those cyclic incubation temperature groups until 12 wk of age. Incubation temperature had no effect on sexual maturity age and weight and egg production of laying hens. From 27 to 30 wk, regardless of incubation temperature, HEATS hens lost weight from day 0 to 10, had the highest cloacal temperatures and lowest feed consumption and egg production while COLDS hens had the lowest cloacal temperatures. At day 5, T₄ level was higher in LOW-Inc hens at COLDS but it was higher in HIGH-Inc hens at HEATS compared to CONT-Inc. These data may suggest a modification in thyroid activity of hens that were conditioned during the incubation period. Moreover under COLDS condition, SOD production of LOW-Inc hens was higher than those of CONT- and HIGH-Inc hens indicating an induction in antioxidant enzyme activity. Nonetheless, prenatal temperature conditioning of laying hen embryos had no advantage on laying performance of hens under temperature stress conditions.