This study aimed to evaluate the effect of temperature and dietary fat level on growth
performance, heat production, nutrient oxidation and nitrogen balance in growing pigs. Thirty-two
pigs (Duroc × Landrace × Large White) with initial weight of 25±1.91 kg were assigned to treatments
in 2×4 factorial design. All pigs were fed with two isoenergetic and isoproteic diets of different
fat levels (low fat level: 3.68% fat of dry matter (DM) and high fat level: 8.39% fat of DM) under
four environmental temperatures (23, 18, 13 and 8 ºC). Heat production (HP) and nutrient oxidation
were calculated from gas exchange via measurement with respiration chambers. The results showed
that there was no interaction effect on growth performance by the temperature and dietary fat level.
The average daily feed intake (ADFI) was lower (P < 0.001), the average daily gain (ADG) was
higher (P < 0.001) and feed utilization was more efficient at 23 ºC than 13 and 8 ºC (P < 0.001).
Dietary fat had no effect on growth performance and feed utilization at the four different temperatures.
A significant interaction (P < 0.001) between temperature and dietary fat level on oxidation of
carbohydrate (OXCHO) and fat (OXF) was observed. HP, OXF and OXCHO were significantly
increased (P < 0.001) as environment temperatures decreased. Increasing dietary fat generated an
increase in the OXF and decrease in the OXCHO (P < 0.001). No significant difference was observed
in protein oxidation (OXP) of two factors. The intakes of nitrogen, nitrogen excretion in feces
(FN) and urine (UN) by the pigs kept in 8 ºC environment were highest. Nitrogen digestibility decreased
as environmental temperature decreased, with the most efficient gains obtained at 23 ºC.
However, nitrogen retention was not influenced by environmental temperature. Dietary fat level did
not affect nitrogen balance. No significant interaction between temperature and dietary fat level was
observed for nitrogen balance. These results indicated that the rate of growth and nutrition utilization
in pigs fed ad libitum are influenced by the environmental temperatures in which they are maintained,
and the oxidation of nutrition utilization of the pig to different environmental temperatures is
altered by the dietary fat supplementation.
Keywords: Environment temperature, dietary fat, heat production, nutrient oxidation, carbohydrate oxidation, nitrogen balance.
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