Table 3.

Meta-analysis of 94 trials on the estimated effect of parasitic infection on sheep performance

Production trait	Infection type	Number of trials	Ratio production infected/control	95 % C.I.	Number of trials reporting egg excretion	Mean number of eggs per gram faeces in infected animals
Weight gain	Mixed speciesa	30	0.74	0.71–0.77	22	2336
Weight gain	H. contortus	20	0.79	0.71–0.87	20	4019
Weight gain	T. colubriformis	12	0.78	0.71–0.87	12	1070
Weight gain	T. circumcincta	8	0.81	0.66–0.99	4	296
Wool production	Mixed speciesa	14	0.9	0.86–0.93	11	3788
Wool production	H. contortus	2	1.04	0.96–1.13	2	7585
Wool production	T. colubriformis	2	1.02	0.95–1.1	2	1359
Wool production	T. circumcincta	1	0.83	0.81–0.86	1	201
Milk yield	Mixed speciesa	5	0.78	0.73–0.84	1	527

^aMain species were of the genus Haemonchus, Teladorsagia, Trichostrongylus, Cooperia and Nematodirus