A comparison between lamb drafters and the Phillips Fat
Displacement Meter (PFDM) for predicting GR, hot carcass weight and
class in live lambs
A.H. Kirton, A.E. Uljee, G.J.K. Mercer
MAF Technology, Ruakura Agricultural Centre, Hamilton, New
Zealand
Proceedings of the New Zealand Society of Animal Production.
1991, 51: 309-314
A trial was undertaken in which 11 meat company lamb drafters
estimated the GR carcass fatness, hot carcass weight and carcass class
on 26 live lambs. In addition the Phillips Fat Displacement Meter (PFDM)
was used to estimate GR fatness these live animals. The average hot
carcass weight of the lambs was 21.9kg and mean GR on the left and right
sides were 14.2mm and 14.5mm respectively. The best two drafter
estimates correlated more highly (0.89 and 0.83) than the PFDM (0.81)
with lamb carcass GR (mm) on the left sides of these carcasses. On the
right sides these two drafters correlations were respectively 0.91 and
0.84 while the PFDM correlation was 0.85. The correlations of the
poorest drafter were 0.62 and 0.57 for the left and right sides,
respectively. While the best drafters were accurate in ranking live
lambs for fatness, in absolute terms all drafters underestimated GR on
average by 2.2mm whereas the PFDM underestimated by 1.1mm on the left
side and 0.8mm on the right. So for actually drafting lambs for
slaughter, the PFDM is less likely to select lambs in the penalty
payment ranges, or is more likely to select lambs before they reach
these penalty fatness levels than the company drafters. These results
highlight the need for drafter training courses with feedback on their
results. On average the drafters underestimated carcass weight by
4.0kg.
Keywords: NZSAPAB;
Lamb fatness; GR estimation; drafters; fat displacement meter;
grading
Download abstract in text format
Last Updated 25-01-1997
