Sensitivity to lipopolysaccharide (LPS) administration
Responses in performance test traits and in predicted energy utilisation to lipopolysaccharide
(LPS) administration in Large White pigs divergently selected for daily food intake (DFI) or lean
growth rate (LGS) were examined. The allocation of energy was predicted using energy utilisation
equations: energy required for maintenance, protein and lipid deposition and excretion of excess
protein. The difference between energy intake and predicted energy utilisation was termed
energy balance. At total of 160 animals, with 40 animals per selection line, were performance
tested with ad-libitum feeding from 40 kg for a 56 day period, with LPS administration on the
basis of 0, 5, 10 or 15 mg/kg live weight on days 1, 28 and 42. Performance test traits and blood
samples were measured at the start of test and at 14 day intervals. There was no effect of level of
LPS administration on predicted energy utilisation on the DFI or LGS selection lines throughout
the performance test. Throughout the performance test of the LGS lines, there was no change in
the predicted allocation of energy 0.33, 0.21 and 0.39 MJ DE/daily energy intake for energy
required for maintenance, protein and lipid deposition. However, following the second
administration of LPS on day 28, predicted energy for lipid deposition decreased in the DFI lines
from 0.41 to 0.23 (s.e. 0.05) MJ DE/daily energy intake such that predicted energy balance
increased from 0.01 to 0.16 (s.e. 0.05) MJ DE/daily energy intake. The magnitude of the changes
in energy utilisation were similar in the high and low DFI lines. Given that there was no detectable
effect of LPS administration level on predicted energy utilisation, the responses in energy
utilisation in the DFI lines may be energetic cost of the adjuvant acting on the immune system.
The DFI lines may have been more sensitive to the adjuvant than the LGS lines, when LPS was
administered with an adjuvant.
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