Figure 4.

Key components of variation in faecal egg counts from five-month-old lambs from a single commercial farm in central Scotland. Each year from 1992 to 1996, a cohort of 200 lambs was followed but deaths, lost tags, missing or incorrect records meant that only 902 lambs were included in the analysis. Genetic refers to additive genetic variation which accounts for 30% of the variance. DoB is date of birth which accounts for 1% of the variance. Earlyfec is the faecal egg count at one month of age. Young lambs with high egg counts have lower than average egg counts at five months of age. Twin lambs have higher egg counts than singletons. Merror is measurement error, i.e. the discrepancy between replicate counts on the same aliquot. Unique means factors specific to each individual while mce refers to maternal genetics and the maternal common environment.