Fig. 1

Experimental data integrated in this study to infer the energy cost of immunity. A Data represent responses to a parasitic challenge (10,000 third-stage larvae of Haemonchus contortus per animal given orally) observed in growing female sheep resistant (R; n = 21) or susceptible (S; n = 21) to infection with H. contortus. It supports a trade-off between host resistance (i, ii) and the gain in fat reserves (iv), possibly mediated by feed intake in early infection (v). In addition, an energy cost of parasite-specific immunity may contribute to the trade-off between lines (hypothesis H1), or not (hypothesis H0). B To test hypotheses H0 and H1, a dynamic mechanistic model of energy budget coupled with host–pathogen interaction was fitted individually to the observed data. Fig Ai-v were modified from [32]. Points represent adjusted means with their error bars representing 95% confidence interval and asterisks indicate statistical difference between lines (ns: p > 0.1; †: p < 0.1; *: p < 0.05; **: p < 0.01; ***: p < 0.001)