Hostname: page-component-78c5997874-dh8gc Total loading time: 0 Render date: 2024-11-05T12:19:58.909Z Has data issue: false hasContentIssue false
  • English
  • Français

Path analysis and robust prediction of lamb carcass composition

Published online by Cambridge University Press:  02 September 2010

G. L. Bennett
G. L. Bennett
Affiliation:
Ruakura Animal Research Station, Private Bag, Hamilton, New Zealand
Get access

Abstract

Path analysis was applied to correlations among lamb carcass measurements. Correlations were obtained from lamb carcasses averaging 15·7 kg and 270 g fat per kg carcass weight. Correlations were adjusted to represent within breed, sex and management group relationships. The purpose of the analysis was to study the relationships of carcass weight with carcass measurements and to identify carcass measurements that are independent other than through their relationships with carcass chemical fat concentration and carcass weight. The direct effect of live weight on all carcass measurements was positive. Thus, heavier carcasses with the same fat concentration had larger fat and tissue depths, muscle measurements, leg measurements and kidney fat weights. The results of correlations among the residuals suggest that fat depths C and J, specific gravity, muscle width A and kidney fat weight are nearly independent estimates of carcass composition in the sense that they are only correlated through their relationships with carcass weight and carcass fat composition. Robust predictors of carcass composition were developed by first adjusting carcass measurements for the direct effects of carcass weight and then computing regressions on the adjusted measurements. These predictors appeared to be better predictors of environmental and genetic differences than least-squares multiple regression yet reduced the accuracy of within group prediction only slightly.

Type
Research Article
Information
Animal Production , Volume 48 , Issue 1 , February 1989 , pp. 139 - 148
Copyright
Copyright © British Society of Animal Science 1989

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Bennett, G. L., Meyer, H. H. and Kirton, A. H. 1988a. Effect of average carcass fat concentration on correlations among lamb carcass measurements. Animal Production 47: 369–377.Google Scholar
Bennett, G. L., Meyer, H. H. and Kirton, A. H. 1988b. Effects of selection for divergent ultrasonic fat depth in rams on progeny fatness. Animal Production 47: 379–386.Google Scholar
Gill, J. L. 1987. Biases in regression when prediction is inverse to causation. Journal of Animal Science 64: 594–600.CrossRefGoogle Scholar
Jarvis, H. F. T. 1971. The thermal variation of the density of beef and the determination of its coefficient of cubical expansion. Journal of Food Technology 6: 383–391.CrossRefGoogle Scholar
Kirton, A. H., Barton, R. A. and Rah, A. L. 1962. The efficiency of determining the chemical composition of lamb carcasses. Journal of Agricultural Science, Cambridge 58: 381–386.CrossRefGoogle Scholar
Kirton, A. H., Woods, E. G. and Duuanzich, D. M. 1984. Predicting the fatness of lamb carcasses from carcass wall thickness measured by ruler or by a Total Depth Indicator (TDI) probe. Livestock Production Science 11: 185–194.CrossRefGoogle Scholar
Li, C. C. 1975. Path Analysis — A Primer. The Boxwood Press, Pacific Grove, Ca.Google Scholar
Paksson, H. 1939. Meat qualities in the sheep with special reference to Scottish breeds and crosses. I. Journal of Agricultural Science, Cambridge 29: 544–574.CrossRefGoogle Scholar
Simm, G., Young, M. I. and Beatson, P. R. 1987. An economic selection index for lean meat production in New Zealand sheep. Animal Production 45: 465–475.Google Scholar
Wright, S. 1921. Correlation and causation. Journal of Agricultural Research 20: 557–585.Google Scholar