Research Note: Hatching Time, Body Weight, and Thyroid Hormones in Male and Female Chicks from Lines Selected for High or Low Juvenile Body Weight

Comparisons between males and females were made for length of time from start of incubation to perinatal stages of hatching, body weight, and thyroid hormones in lines of chickens selected for high (HW) or low (LW) juvenile body weight. Although males appeared to pip through the air cell and through the shell earlier than females in Line LW, there were no consistent differences between the sexes in time to hatch in either line. Body weights and plasma triiodothyronine and thyroxine were not different for males and females at any stage.