Date of this Version
Thesis (M.S.)—University of Nebraska—Lincoln, 1972. Department of Agricultural Engineering.
The purpose of this research was to determine the convective, radiative and evaporative heat losses of White Leghorn layers as affected by bird densities of one, two and three birds per cage, 8 x 16 inches.
The University of Nebraska Partitional Calorimeter was used to measure the heat losses of White Leghorn layers.The partitional calorimeter had a gradient layer thermopile that continuously measured the sensible heat loss of the birds, and a 4-Pi radiometer that continuously measured the radiative heat loss of the birds.The conductive heat loss of the birds was made negligible by suspending the cage with the birds inside the calorimeter. Therefore, the convective heat loss of the birds was approximated by subtracting the radiative heat loss from the sensible heat loss.An infrared moisture analyzer was used to continuously determine the evaporative heat loss of the birds.
A group of 120 White Leghorn layers were caged at densities of one, two and three birds per cage, 8 x 16 inches, for at least 8 months and were acclimated to an environmental temperature of 73°F for at least 3 months.From each bird density, hens were selected for uniformity of body weight and egg production.The selected birds from each bird density were subjected to environmental temperatures of 73°F, 83°F and 93°F inside the partitional calorimeter.
The heat losses on a per bird basis were relatively constant at all bird densities for each environmental temperature.This was unexpected and was probably caused by an increase in the shell conductance of the birds as the bird density per cage increased.The increase in shell conductance was probably a result of the change in the feather condition of the birds.
A post-experiment was designed to investigate the effect of feather condition of the different bird densities on the sensible, convective and radiative heat losses at environmental temperatures of 83°F and 93°F.There was an increase in the number of feathers that were broken or missing as the bird density per cage was increased from one of one bird per cage to one of two birds per cage.This deterioration of feather condition caused the sensible heat loss to increase 13.7%.There was an additional increase in the number of feathers that were broken and missing as the bird density increased from one of two birds per cage to one of three birds per cage.This additional deterioration in feather condition caused the sensible heat loss to increase 15.3%
Advisor:James A. DeShazer