Hostname: page-component-586b7cd67f-dsjbd Total loading time: 0 Render date: 2024-11-28T07:09:51.771Z Has data issue: false hasContentIssue false
  • English
  • Français

Selection for high or low backfat depth in Coopworth sheep: juvenile traits

Published online by Cambridge University Press:  02 September 2010

C. A. Morris ,
J. C. McEwan ,
P. F. Fennessy ,
W. E. Bain ,
G. J. Greer  and
S. M. Hickey
C. A. Morris
Affiliation:
Ag Research, Ruakura Agricultural Research Centre, Private Bag 3123, Hamilton, New Zealand
J. C. McEwan
Affiliation:
AgResearch, Invermay Agricultural Centre, Private Bag 50034, Mosgiel, New Zealand
P. F. Fennessy
Affiliation:
AgResearch, Invermay Agricultural Centre, Private Bag 50034, Mosgiel, New Zealand
W. E. Bain
Affiliation:
Ag Research, Ruakura Agricultural Research Centre, Private Bag 3123, Hamilton, New Zealand
G. J. Greer
Affiliation:
Ag Research, Ruakura Agricultural Research Centre, Private Bag 3123, Hamilton, New Zealand
S. M. Hickey
Affiliation:
Ag Research, Ruakura Agricultural Research Centre, Private Bag 3123, Hamilton, New Zealand
Get access

Abstract

A selection experiment was established in Coopworth sheep in 1981 to breed for increased or reduced ultrasonic backfat depth (scan C). Foundation females came from four flocks recorded for scan C and live weight, with weight-adjusted scan C data within flock being used for initial screening and subsequent selection. Three groups of animals per source flock, comprising proportionally the fattest 0·12, a random sample, and the leanest 0·12, were used to establish the F, control and L lines, respectively. Ewe flock numbers from 1981 to 1992 averaged 51 per line. Foundation rams were selected in the same manner from four different farms (two sources each in 1981 and 1982) to provide F line (proportionally the fattest 0·04), control line and L line (leanest 0·04) rams for use in 1981 and 1982, with four mated per line per year. Thereafter homebred rams were selected, with 41 or 42 homebred rams being used per line until 1992. Average generation intervals were 2·13 years and annual inbreeding rates per line 0·004. Bivariate heritability estimates for log scan C and log live weight, and a univariate estimate for log scan C using restricted maximum likelihood with an animal model, were 0·28, 0·22 and 0·38, respectively (all with s.e. 0·03). There was a suggestion of lower heritabilities in the L line for log scan C after adjustment for live weight. Realized heritabilities in the F and L lines were 0·34 (s.e. 0·07) and 0·26 (s.e. 0·03), respectively. Deviations of back-transformed weight-adjusted scan C in the last 2 years ofF and L data analysed (1991 and 1992 birth years) from the control flocks were 2·08 and −0·85 mm, which corresponded to responses of +2·50 and −1·03 phenotypic standard deviations, respectively. In addition there were relatively large responses in live weight taken at scanning, with F and L lines averaging 34·0 and 40·2 kg, compared with 38·0 kg for controls in the 1991 and 1992 birth years. The genetic and phenotypic correlations between log scan C and log live weight at scanning were 0·16 (s.e. 0·07) and 0·46 (s.e. 0·01) respectively.

Keywords

backfatleannessselectionsheepultrasonics
Type
Research Article
Information
Animal Science , Volume 65 , Issue 1 , August 1997 , pp. 93 - 103
Copyright
Copyright © British Society of Animal Science 1997

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

Bass, J. J. 1979. Relationships between ultrasonic measurements taken on live cattle and their carcass composition. Proceedings of the New Zealand Society of Animal Production 39: 217–222.Google Scholar
Bennett, G. L., Meyer, H. H. and Kirton, A. H. 1988. Effects of selection for divergent ultrasonic fat depth in rams on progeny fatness. Animal Production 47: 379–386.Google Scholar
Bishop, S. C. 1993. Selection for predicted carcass lean content in Scottish Blackface sheep. Animal Production 56: 379–386.Google Scholar
Brinks, J. S., Clark, R. T. and Rice, F. J. 1961. Estimation of genetic trends in beef cattle. Journal of Animal Science 20: 903 (abstr.).Google Scholar
Cameron, N. D. and Bracken, J. 1992. Selection for carcass lean content in a terminal sire breed of sheep. Animal Production 54:367–377.Google Scholar
Clarke, J. N., Waldron, D. F. and Rae, A. L. 1991. Selection objectives and criteria for terminal lamb sires. Proceedings of the Australian Association of Animal Breeding and Genetics 9: 265–271.Google Scholar
Conington, J., Bishop, S. C., Waterhouse, A. and Simm, G. 1995. A genetic analysis of early growth and ultrasonic measurements in hill sheep. Animal Science 61:85–93.CrossRefGoogle Scholar
Fennessy, P. F., Bain, W. E., Greer, G. J. and Johnstone, P. D. 1992. Carcass characteristics of progeny from ram lambs selected for high or low ultrasonic backfat thickness. New Zealand Journal of Agricultural Research 35:177–183.CrossRefGoogle Scholar
Fennessy, P. F., Greer, G. J. and Bass, J. J. 1982. Progeny test of selected lean and fat rams. Proceedings of the New Zealand Society of Animal Production 42:137–140.Google Scholar
Fisher, A. V. and Boer, H. de. 1994. The EAAP standard method of sheep carcass assessment. Carcass measurements and dissection procedures. Report of the EAAP working group on carcass evaluation, in cooperation with the CIHEAM Instituto Agronomico Mediterraneo of Zaragoza and the CEC Directorate General for Agriculture in Brussels. Livestock Production Science 38:149–159.CrossRefGoogle Scholar
Gooden, J. M., Beach, A. D. and Purchas, R. W. 1980. Measurement of subcutaneous backfat depth in live lambs with an ultrasonic probe. New Zealand Journal of Agricultural Research 23:161–165.CrossRefGoogle Scholar
Johnson, D. L. and Thompson, R. 1995. Restricted maximum likelihood estimation of variance components for univariate animal models using sparse matrix techniques and average information. Journal of Dairy Science 78: 449–456.CrossRefGoogle Scholar
Kirton, A. H. and Johnson, D. L. 1979. Interrelationships between GR and other lamb carcass fatness measurements. Proceedings of the New Zealand Society of Animal Production 39: 194–201.Google Scholar
Lawes Agricultural Trust. 1990. Statistical package: Genstat 5, release 2.2. Rothamsted Experimental Station, Harpenden.Google Scholar
Lewis, R. M., Simm, G., Dingwall, W. S. and Murphy, S. V. 1996. Selection for lean growth in terminal sire sheep to produce leaner crossbred progeny. Animal Science 63: 133–142.CrossRefGoogle Scholar
McEwan, J. C., Clarke, J. N., Hickey, S. M. and Knowler, K. J. 1993. Heritability of ultrasonic fat and muscle depths in Romney sheep. Proceedings of the New Zealand Society of Animal Production 53:347–350.Google Scholar
McEwan, J. C., Clarke, J. N., Knowler, M. A. and Wheeler, M. 1989. Ultrasonic fat depths in Romney lambs and hoggets from lines selected for different production traits. Proceedings of the New Zealand Society of Animal Production 49:113–119.Google Scholar
McEwan, J. C., Fennessy, P. F., Greer, G. J., Bain, W. E. and Bruce, G. D. 1990. Effects of selection for ultrasonic backfat depth on carcass growth and composition in sheep. Proceedings of the Australian Association of Animal Breeding and Genetics 8: 323–326.Google Scholar
Palsson, H. 1939. Meat qualities in sheep with special reference to Scottish breeds and crosses. Journal of Agricultural Science, Cambridge 29: 544–626.CrossRefGoogle Scholar
Purchas, R. W., Rae, A. L., Barton, R. A. and Beach, A. D. 1981. The repeatability of ultrasonic fat-depth measurements made on sheep up to 18 months of age. Proceedings of the New Zealand Society of Animal Production 41: 133–139.Google Scholar
Simm, G. 1992. Selection for lean meat production in sheep. In Progress in sheep and goat research (ed. Speedy, A. W.), pp. 193–215. Commonwealth International, Wallingford.Google Scholar
Solis-Ramirez, J., Blair, H. T. and Purchas, R. W. 1993. Direct and correlated responses to selection for high or low ultrasonic backfat depth in Southdown sheep. New Zealand Journal of Agricultural Research 36: 133–141.CrossRefGoogle Scholar
Waldron, D. F., Clarke, J. N., Rae, A. L., Kirton, A. H. and Bennett, G. L. 1992. Genetic and phenotypic parameter estimates for selection to improve lamb carcass traits. New Zealand Journal of Agricultural Research 35:287–298.CrossRefGoogle Scholar