Metabolic effects of infection by the stomach worm Obeliscoides cuniculi in rabbits fed diets varying in nutritive quality.

Rabbits parasitized by Obeliscoides cuniculi were used as models for stomach worm parasitism in ruminants. A 3 X 4 randomized complete block design containing three levels of of infection (NI, no infection; LI and HI, infections produced by 1,800 and 30,000 larvae, respectively) and four levels of diet (PC, high protein and carbohydrate; pc, low protein and carbohydrate; Pc, high protein, and low carbohydrate; pC, low protein and high carbohydrate) was replicated four times. Mean weight gains for rabbits on diets pc or PC were not influenced by infection level, whereas LI rabbits on diets Pc and pC gained as well as the NI animals and more than the HI ones. Only HI rabbits exhibited anorexia. NI and LI rabbits has positive feed conversion efficiencies, whereas those of HI rabbits were negative. The apparent digestibilities of organic matter, protein, and ash in rabbits with different infection levels varied with diet. Daily nitrogen balances were positive. The changes in concentrations of amino acids in the plasma typically associated with systemic, fever-producing infections or with starvation or protein-calorie malnutrition did not occur in infected rabbits. Only the high level infections produced adverse effects on productivity. These effects occurred on diets pc, Pc and pC and were mediated by anorexia.