The comparison of predictive methods for the determination of fatness and condition in sheep

Summary

Condition scoring by manual palpation of fat and muscle over the loin (short ribs) has been used to us or nutritional well-being of adult ewes. Alternatively, fat scoring by manual palpation at the midside over the long ribs has been used to estimate the yield of saleable meat (%) of young sheep being marketed for meat; whole scores 1 to 5 are related to 5 mm ranges in total tissue ( fat + muscle) at the GR site over the 12th rib. MLA, which continues to advocate the use of fat score for prime lamb marketing and has also endorsed fat score as a method for ewe management, was concerned that the increased use of both terminologies is confusing producers and may actually be discouraging the application of either technique. Hence, MLA commissioned an experiment to test: 1. That skilled industry personal can repeatability assess condition score or fat scores 2. That the relationship between condition score and fat score is such that industry can confidently convert flock estimates between the two methods. 3. That the relationship will be similar in hogget and adult sheep 4. That methods of subjective assessment bear a statistically significant relationship with measured ultrasonic C site fat and eye muscle depth and carcase GR site tissue depth (as measured on hot carcase by a GR knife). In the experiment the condition score, fat score and C-site ultrasound fat and C-site ultrasound eye muscle depth were recorded for a group of 92 live Merino sheep in 6 months wool (45 young and 47 mature). All scores and measurements were done by two to four experienced assessors and repeated three times (runs) in a random order. Approximately 24 hr after the above measurements, the sheep were slaughtered at an abattoir (WAMMCO, Katanning) where the GR site tissue depth (fat + muscle) was recorded on the hot carcass for 89 of these sheep. This measurement was also done by two experienced assessors using standard GR knives and repeated three times in random order.