The effect of environmental heat stress
on N metabolism was studied using 7 gilts (50.5 ± 1.7
kg initial BW). Pigs were housed in metabolism cages
in a climate-controlled room. After a 4-d adaptation,
two 14-d experimental periods followed during
which the animals were exposed to thermo-neutral
temperature (NT; 20.61 ± 0.1°C) or high environmental
temperature (HT; 30.41 ± 0.4°C). In each experimental
period, two 24-h balance periods were carried out to
collect feces and urine (via bladder catheters) for N
analysis. Based on N intake and N excretion, N balance
was calculated. At HT conditions, N intake was lower
(P = 0.028), urinary N excretion increased (P = 0.040),
and N retention decreased (P = 0.001) in comparison
with NT conditions. Exposure of pigs to HT tended to
reduce (P = 0.070) digestibility of N as compared to
NT conditions. When pigs are exposed long term to
continuous HT, N retention decreases presumably due
to decreased use of ME during respiration.