The thermal biology of the growing broiler having access to a means of conductive heat transfer in a hot environment

Four studies were conducted to investigate the productive, behavioral and physiological performance of growing broilers provided water cooled perches as a means of conductive heat transfer in a hot ambient environment. All perches were constructed from steel pipe and cooling was achieved by maintaining a constant water flow rate. In a small scale field study, broilers (3-7 wks of age) were provided either water cooled floor perches or air-equilibrated floor perches in a hot ambient environment. Occupation of water cooled perches was 8x greater than that of air-equilibrated perches, demonstrating a purposeful thermoregulatory use of water cooled perches. Use of water cooled perches increased with increasing duration of heat exposure. Broilers provided water cooled perches experienced greater body weight gain, increased feed consumption and greater efficiency of gain than their counterparts provided air-equilibrated perches. The largest treatment differences were observed during the fourth week of heat exposure. Behavioral preferences for diameter and height of water cooled perch were investigated in two age groups (3 wk and 6 wk) of perch naive broilers exposed to a hot ambient environment. Floor level perches proximal to the water supply within the pen were preferred by both age groups. A direct relationship was observed between diameter of perch preferred and age. Further study, demonstrated that water cooled perch use increased with increasing ambient temperature for both 3 wk and 6 wk of age broilers. Duration of perching bouts and methods of water cooled perch use by broilers were dependent upon ambient temperature, age, height, diameter, and position of perches within the pen. The physiological responses of broilers to perch cooling in a hot ambient environment were investigated. Peripheral vasomotion in the feet of broilers provided water cooled perches in a hot ambient environment spared the energy expenditure for thermoregulatory effort and permitted blood flow to be directed to organs not involved in heat dissipation. Furthermore, cooling of perches prior to, or at the onset of heat exposure minimizes physiological disruption and maximizes thermoregulatory benefit in growing broilers exposed to hot ambient temperatures.U of I OnlyETDs are only available to UIUC Users without author permissio