Table 7.

Nongenetic terms significantly associated with parasite resistance

Terms	Data type	d.f.	Δdeviance	P value
August lamb FEC (Null model n = 386, deviance = 582.62)
Cohort*	Factor	6	73.38	<0.001
Sex	Factor	1	17.66	<0.001
Treatment†	Factor	1	0.57	0.449
Weight	Continuous	1	15.63	<0.001
Weight × sex	Interaction	1	8.81	0.003
Cohort × sex	Interaction	6	15.17	0.019
Treatment × weight	Interaction	1	6.31	0.012
Residual	—	369	432.30	—
August yearling FEC (Null model n = 207, deviance = 293.54)
Cohort*	Factor	6	12.13	0.059
Sex	Factor	1	35.84	<0.001
Treatment‡	Factor	2	9.46	0.009
Weight	Continuous	1	6.87	0.009
Residual	—	197	229.55	—

Nongenetic terms fitted to lamb FEC and yearling FEC in a generalized linear models assuming a negative binomial error distribution. Significance of terms was determined by deletion testing. Change in deviance for lower order terms are calculated by deletion from models not containing higher order terms. 

^*1988–1994 cohorts. 

^†Progesterone treated vs. untreated. 

^‡Antihelminthic treated vs. progesterone treated vs. untreated.