SIL – Sheep Improvement Limited

Kikitangeo was a foundation member of the first ‘National Recording Scheme’ in 1967.  This scheme subsequently became known as ‘Sheeplan’ and even later, ‘Animalplan’.  It is now known as SIL - Sheep Improvement Limited.  In this recording plan, the stud breeder measures all production traits – number of lambs born, weaning and growth rates, wool weights, survivability, worm resistance, FE tolerance and several other traits.  Along with the performance of near relatives, this results in a ‘Breed Value’ (BV) and a ranking for all traits.  These are then combined with appropriate value weighting, to given an overall index known as a DPO (Dual Purpose Overall).  The animal then has an overall ranking within the group.  These figures should be seen as a guide to selection rather than absolute measure of an animal’s worth.

There are three factors which affect the merit of the production figures.  They are:

Firstly, production figures, breed value and ranking to not include some important factors.  For instance, feet, bone, jaws and teeth, wool quality, freedom from black fibre, udder shape and teat placement and temperament are not covered by these index figures, nor is constitution and longevity.

Secondly, any recording plan assumes that all animals have equal treatment.  In the dairy world where all cows stay in the same mob for most of the year, especially over the production period, comparing cows production figures are reasonably accurate and is a good measure of an animal’s worth.  In the sheep world where stud ewes are singularly mated in different paddocks, and lambed in a number of paddocks where stocking rates, soil fertility and the incidence of parasites will vary, all sheep do not have equal opportunity.  In more favourable sheep farming areas where farms have one soil type with quality pasture, sheep will have a more equal opportunity and production assessments will be more accurate.  However, on farms where there is a variation in soil types and the quality of pasture, and health problems are a major issue, then the figures are a less accurate measure of an animal’s worth.  In other words, environmental factors can have a negative effect on the accuracy of production figures and rankings.

Thirdly, it is assumed that the production figures, be they good or bad, reflect the genes that an animal may carry.  Generally this is so.  However, some animals will ‘throw back’ to attributes further back in the pedigree.  In the past, we have found the odd animal, in spite of having excellent production and physical attributes, has failed badly in passing on these traits to their offspring.  Conversely, on some occasions, we have found some animals that perform beyond our expectations.