Energy metabolism of growing pigs after transportation, regrouping, and exposure to new housing conditions as affected by feeding level.

An experiment was performed to evaluate alterations of energy metabolism with time in 10 groups of 16 barrows just after transportation. Ten-week-old pigs were fed at once (four groups; LF) or twice (three groups; MF) maintenance level (35 and 75 g.kg-.75.d-1, respectively), or allowed ad libitum access to feed (three groups; HF). The 13.5-d experimental period was divided into two balance periods. Heat production (HP) decreased with time. The changes in HP with time were different among feeding level groups (P < .001); the LF group had the greatest decrease. Metabolizable energy intake remained constant with time for the LF and MF groups and decreased for the HF group. Requirements for maintenance energy and efficiency of ME for growth decreased with time. Feeding level influenced (P < .001) energy retention (ER) during the total experimental period. The LF group had a negative ER (-65 kJ.kg-.75.d-1), whereas in the MF and HF groups positive values for ER were obtained (346 and 757 kJ.kg-.75.d-1, respectively). At all feeding levels, animals had a positive protein gain. The level differed between feeding levels (P < .001). Differences among groups (P < .001) were observed in energy retained as fat. Data from the present experiment show that young pigs are not in a steady state of energy metabolism during the 2 wk after transportation. During this period, the relationship between metabolic rate and feed intake alters with time.