a1 Department of Animal Husbandry, Faculty of Veterinary Medicine, Aristotle University, 54006 Thessaloniki, Greece
a2 Scottish Agricultural College, West Mains Road, Edinburgh EH9 3JG
The objective of this study was to evaluate the influences of age and condition score on the live weight of ewes of three Greek dairy breeds. Boutsko (no. = 225), Serres (no. = 292) and Karagouniko (no. = 301) ewes from individually recorded purebred flocks were weighed (±0·5 kg) and condition scored, on a six-point scale, to the nearest 0·5 unit. Within each breed and age group the relationship between live weight and condition score was derived by linear regression. There was a highly significant relationship between condition score and live weight in all of the groups (P < 0·01). Live weight, adjusted to a standard condition score, increased with increasing age up to 3·5 years; beyond this age there was no effect of age on condition score. The live weight and condition score data for ages 3·5 years and upwards were used to derive a single regression between live weight and condition score for each breed. This provides a means to estimate adult live weights standardized to a given condition score. The values of the regression coefficients were directly proportional to the breed mature weight; on average the increase in live weight associated with a unit of condition score was 0·129 kg/kg of mature weight for the three breeds studied. Mature weight was estimated as the weight at a condition score of 5. Using published information, a similar value was found to apply to a wide range of sheep breeds and also to cattle. This robust value permits the live-weight change associated with a unit of condition score to be calculated, for any breed.
(Received May 08 1996)
(Accepted September 05 1996)