FACTOR-ANALYSIS OF GROWING PIGS RESPONSES TO HIGH CYCLIC AND CONSTANTTEMPERATURES

A multivariate factor analysis was used to explore associations among five measured energetic responses for growing pigs as an improved anal ysis method to an analysis of predictions from an energetic mathematic al model. The response variables were feed consumption water vapor pro duction, heat production, water consumption, and respiratory quotient. In one treatment, groups of four 36 kg pigs were housed in a calorime ter at temperatures cycling between a minimum of 26 degrees C to a max imum of 40 degrees C. In another treatment, groups of four 36 kg pigs were housed in a calorimeter at a constant temperature of 33 degrees C . Three factors were extracted from the energetic data in each of the environmental treatments. These common factors described homeothermy, energy intake, energy retained and more clearly reflected the differen ces between the environments than any of the individual variables. Hom eothermy was described by hear and water vapor production in the const ant temperature treatment; while it was predominately described by wat er vapor production and water consumption in the cyclic temperature tr eatment. This factor represents heat loss as both sensible and latent heat in the constant temperature treatment but, primarily as latent he at in the cyclic temperature treatment. Cyclic temperatures caused hig her than average homeothermy scores during the time of low energy rete ntion and low energy intake scores (during peak temperatures), whereas constant temperatures caused high homeothermy scores during the time of high energy retention and high energy intake scores.