Data management

Adult body weight, PCV and percentage time parasitaemic or treated

Mean values of body weight, PCV and the percentage of occasions found to be parasitaemic or to be treated were calculated for each 6-monthly period from 1987 to 1997.

This was done for each animal that was 36 months of age or over on 1st March or 1st September, respectively, and recorded at least 3 times over the next six months. The choice of 3 was arbitrary but it was felt that mean values calculated with fewer observations would tend to give an imprecise estimate of a mean value. Part of the SAS program used for this is shown in CS10SAS.

A subset of data from 1989 onwards for animals with actual or estimated dates of birth was first analysed to determine the effect of age on these variables. Precise ages of animals older than five years of age that entered the study in 1986 were unknown.

From this preliminary analysis five age classes were defined: 3-4, >4-5, >5-7, >7-10 and >10 years of age. These classes represented suitable proportions of variation associated with age.

The results are stored in CS10Data2 and documented in CS10Doc2.