Leptin concentrations and the immune-mediated reduction of feed intake in sheep infected with the nematode Trichostrongylus colubriformis.

摘要

The hypothesis that increases in the concentration of the anorectic peptide leptin may be responsible for the immune-mediated reduction in feed intake (FI) during gastrointestinal parasitism in sheep was investigated. In a 2x2x2 factorial design, the first factor was age at the start of infection (5 months old v. 17 months old). The second factor was parasite infection (no infection v. administration of eighty L3 infective Trichostrongylus colubriformis larvae/kg live weight (LW) per d three times per week for 77 d). The third factor was immunosuppressive therapy with a corticosteroid (no therapy or weekly intramuscular injection of 40 mg methylprednisolone acetate/30 kg LW). Relative to their uninfected counterparts, a 20% reduction in FI per unit LW (FI/LW; g DM/kg LW) was observed in infected non-suppressed 5-month-old lambs from 21 to 63 d post-infection (P<0.001) but not in comparable 17-month-old ewes or in corticosteroid-treated lambs or ewes (P