Table 1. Analysis of the effect of ectoparasite load manipulation (parasites), methionine supplementation (methionine) and interaction between these treatments on physiological traits of blue tit nestlings.

Factor	PHA-response N = 376			Ig level N = 273			Haematocrit N = 344
	df	F	p	df	F	p	df	F	p
parasites	1, 39	0.00	1.00	1, 34	0.76	0.39	1, 39	9.69	0.004
methionine	1, 333	4.26	0.04	1, 235	2.93	0.09	1, 301	0.17	0.67
interaction	1, 333	5.42	0.02	1, 235	0.05	0.83	1, 301	0.001	0.97

Statistics of a linear mixed model with brood nested in parasite treatment fitted as a random effect; variance component, its standard error and percentage of variance explained by brood effect nested in the parasite treatment is shown. N equals the number of nestlings assayed.