Free Standard AU & NZ Shipping For All Book Orders Over $80!
Register      Login
Animal Production Science Animal Production Science Society
Food, fibre and pharmaceuticals from animals
Shopping Cart: ( empty )
You are here: Home > Journals > AN > EA02225
RESEARCH ARTICLE
Contents Vol 44(8)

Genetic and phenotypic trends and parameters in reproduction, greasy fleece weight and liveweight in Merino lines divergently selected for multiple rearing ability

S. W. P. Cloete A B E , A. R. Gilmour C , J. J. Olivier D and J. B. van Wyk A
+ Author Affiliations
- Author Affiliations

A University of the Free State, PO Box 339, Bloemfontein 9300, South Africa.

B Elsenburg Agricultural Centre, Private Bag X1, Elsenburg 7607, South Africa.

C NSW Agriculture, Orange Agricultural Institute, Forest Road, Orange, NSW 2800, Australia.

D ARC Animal Improvement Institute, Private Bag X5013, Stellenbosch 7599, South Africa.

E Author for correspondence; e-mail: schalkc@elsenburg.com

Australian Journal of Experimental Agriculture 44(8) 745-754 https://doi.org/10.1071/EA02225
Submitted: 29 November 2002  Accepted: 17 October 2003   Published: 17 September 2004

Abstract

Genetic and phenotypic trends and parameters were estimated for reproduction, fleece weight and liveweight in a South African Merino population, divergently selected from 1986, either for (H line) or against (L line) maternal multiple rearing ability. Annual reproduction, ewe greasy fleece weight and pre-joining liveweight data were recorded on 809 Merino ewes, from 1986 to 2002. Phenotypic trends indicated divergence in reproduction traits between the H and L lines. The direct additive variance ratio (h2 ± s.e.) for day of lambing was 0.08 ± 0.02. Estimates of h2 for reproduction traits were: 0.10 ± 0.02 for number of lambs born per ewe; 0.04 ± 0.02 for number of lambs weaned per ewe; and 0.04 ± 0.02 for weight of lamb weaned per ewe, corrected for the gender of the lamb. Corresponding h2 estimates for annual production were 0.57 ± 0.06 for greasy fleece weight and 0.48 ± 0.06 for ewe liveweight at joining. Service sire only exerted a significant (P<0.05) effect on day of lambing, but it accounted for merely 2% of the overall phenotypic variation. Ewe permanent environment variance ratios (c2ewe) for the reproduction traits were: 0.07 ± 0.03 for number of lambs born per ewe; 0.11 ± 0.03 for number of lambs weaned per ewe; and 0.11 ± 0.03 for total weight of lamb weaned per ewe. Corresponding c2ewe estimates for annual production traits were 0.14 ± 0.05 for greasy fleece weight and 0.27 ± 0.06 for ewe joining weight. Genetic and ewe permanent environmental correlations between measures of reproduction exceeded 0.7. Genetic correlations of reproduction traits with greasy fleece weight were low and variable in sign. Genetic correlations of reproduction traits with ewe joining weight were positive and particularly high for weight of lamb weaned. Permanent environmental correlations of reproduction traits with greasy fleece weight and joining weight were generally low to moderate. Genetic trends for the H and L lines (derived from averaged direct breeding values within birth years) were divergent (P<0.01) for all reproduction traits. Expressed as percentage of the overall least squares means of the respective traits, breeding values in the H line increased annually, with 1.3% for lambs born per ewe, 1.5% for lambs weaned per ewe and by 1.8% for weight of lamb weaned per ewe. Corresponding trends in the L line were, respectively, –0.6%, –1.0% and –1.2% per year. Substantial genetic progress in annual lamb output was attainable, despite relatively small h2 estimates. This response was achieved without unfavourable genetic changes in wool and liveweight.

Additional keywords: ewe productivity, repeated records.


Acknowledgments

We thank all those responsible for the maintenance and recording of the experimental animals (Miss E. du Toit at Tygerhoek, as well as Mr J. E. Fourie and Miss A. J. Scholtz at Elsenburg). The maintenance of the animals was partially enabled by a grant from the South African Wool Industry.


References


Apps R, Brown DJ, Ball A, Banks R, Field S (2003) Genetic opportunities to improve lamb weaning rates in Merinos. Proceedings of the Association for the Advancement of Animal Breeding and Genetics 15, 249–252. open url image1

Atkins KD (1980) Selection for skin folds and fertility. Proceedings of the Australian Society of Animal Production 13, 174–176. open url image1

Brash LD, Fogarty NM, Gilmour AR (1994) Reproductive performance and genetic parameters for Australian Dorset sheep. Australian Journal of Agricultural Research 45, 427–441.
| Crossref |
open url image1

Brash LD, Fogarty NM, Gilmour AR (1994) Genetic parameters for Australian maternal and dual-purpose meatsheep breeds. 2. Liveweight, wool and reproduction in Corriedale sheep. Australian Journal of Agricultural Research 45, 469–480.
| Crossref |
open url image1

Brien FD, Konstantinov KV, Greeff JC (2002) Comparison of linear and threshold models for predicting direct and maternal genetic effects on number of lambs weaned in Western Australian Merinos. In ‘Proceedings of the 7th world congress on genetics applied to livestock production’. Volume 32. pp. 307–310. (Montpellier, France)

Bromley CM, Snowder GD, Van Vleck LD (2000) Genetic parameters among weight, prolificacy, and wool traits of Columbia, Polypay, Rambouillet, and Targhee sheep. Journal of Animal Science 78, 846–858.
| PubMed |
open url image1

Bromley CM, Van Vleck LD, Snowder GD (2001) Genetic correlations for litter weight weaned with growth, prolificacy, and wool traits in Columbia, Polypay, Rambouillet, and Targhee sheep. Journal of Animal Science 79, 339–346.
| PubMed |
open url image1

Burfening PJ, Davis KC (1996) Effect of service sire on ewe reproductive rate and estimated breeding values for reproductive rate in Rambouillet sheep. Sheep and Goat Research Journal 12, 89–93. open url image1

Charlick AJ, Arnold GW (1990) Effect of bearing and rearing lambs on Merino wool production. Australian Journal of Experimental Agriculture 30, 591–594.
| Crossref |
open url image1

Cloete SWP (1986) ‘A study of phenotypic and genetic aspects of reproduction in the Tygerhoek Merino flock.’ MSc Thesis, University of Stellenbosch, Stellenbosch, South Africa.

Cloete SWP (2002) ‘Studies on the behavioural and genetic aspects of ewe rearing ability and lamb survival in South African sheep flocks.’ PhD Dissertation, University of the Free State, Bloemfontein, South Africa.

Cloete SWP, Gilmour AR, Olivier JJ, Van Wyk JB (2003) Genetic parameters and trends in Merino lines divergently selected for multiple rearing ability. Proceedings of the Association for the Advancement of Animal Breeding and Genetics 15, 253–256. open url image1

Cloete SWP, Greeff JC, Lewer RP (2002) Direct and maternal genetic (co)variances for hogget live weight and fleece traits in Western Australian Merino sheep. Australian Journal of Agricultural Research 53, 271–279.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Cloete SWP, Greeff JC, Lewer RP (2002) Heritability estimates and genetic and phenotypic correlations of lamb production parameters with hogget live weight and fleece traits in Western Australian Merino sheep. Australian Journal of Agricultural Research 53, 281–286.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Cloete SWP, Greeff JC, Lewer RP (2002) Genetic and environmental variances in lamb production traits of Merino ewes in a Mediterranean environment. Wool Technology and Sheep Breeding 50, 395–400. open url image1

Cloete SWP, Olivier JJ (1998) Direct and correlated responses to selection for multiple rearing ability in South African Merinos. In ‘Proceedings of the annual congress of the South African Society for Animal Science’. Volume 36. pp. 65–68.

Cloete SWP, Olivier JJ, Du Toit E (2001) Blowfly strike of Merino sheep in relation to selection strategy, as well as to objective and subjective wool traits. In ‘Proceedings of the flystrike and lice IPM control strategy conference’. pp. 395–401.

Cloete SWP, Olivier JJ, Snyman MA, du Toit E (1998) Genetic parameters and trends in a selection experiment for increased clean fleece weight involving South African Merinos. Australian Journal of Experimental Agriculture 38, 427–432.
| Crossref |
open url image1

Cloete SWP, Scholtz AJ (1998) Lamb survival in relation to lambing and neonatal behaviour in medium wool Merino lines divergently selected for ewe multiple rearing ability. Australian Journal of Experimental Agriculture 38, 801–811.
| Crossref |
open url image1

Cloete SWP, Van Niekerk FE, Rust JM (1998) Application of embryo transfer for the improvement of multiple rearing ability in medium wool Merino ewes. Sheep and Goat Research Journal 14, 173–179. open url image1

Corbett JL (1979) Variation in wool growth with physiological state. In ‘Physiological limitations to wool growth’. (Eds JL Black, PJ Reis) pp. 79–98. (University of New England Publishing Unit: Armidale, NSW)

Ercanbrack SK, Knight AD (1998) Responses to various selection protocols for lamb production in Rambioullet, Targhee, Columbia and Polypay sheep. Journal of Animal Science 76, 1311–1325.
| PubMed |
open url image1

Fogarty NM (1995) Genetic parameters for live weight, fat and muscle measurements, wool production and reproduction in sheep: a review. Animal Breeding Abstracts 63, 101–143. open url image1

Gilmour AR, Cullis BR, Welham SJ, Thompson R (1999) ‘ASREML — reference manual.’ NSW Agriculture, Biometric Bulletin No. 3, Orange, NSW.

Greeff JC, Davidson R, Skerritt JW (2003) Genetic relationships between carcass quality and wool production in Australian Merino rams. Proceedings of the Association for the Advancement of Animal Breeding and Genetics 15, 330–333. open url image1

Heydenrych HJ, Du Plessis JJ, Cloete SWP (1984) Increasing the wool production of Merino sheep in the South Western Districts of South Africa by direct and indirect selection. In ‘Proceedings of the 2nd world congress on sheep and beef cattle breeding’. (Eds JH Hofmeyr, EHH Meyer) pp. 399–412. (South African Stud Book and Livestock Improvement Association: Bloemfontein, South Africa)

Ingham VM, Ponzoni RW (2001) A progress report on the development of a meat Merino line in South Australia (the Meat Fibre Plus). Proceedings of the Association for the Advancement of Animal Breeding and Genetics 14, 433–436. open url image1

Jorgensen JN (1994) Estimation of genetic parameters for litter size in sheep using a non-linear method. Acta Agriculturae Scandinavica. A. Animal Science (Penicuik, Scotland) 44, 8–11.
| Crossref |
open url image1

Lamberson WR, Thomas DL (1984) Effects of inbreeding in sheep: a review. Animal Breeding Abstracts 52, 278–291. open url image1

Lee GJ, Atkins KD (1995) Consequences of reproduction on live weight, fat depth, wool growth, and intake of grazing Merino ewes in the short and long term. Australian Journal of Experimental Agriculture 35, 153–159.
| Crossref |
open url image1

Olivier JJ (1999) The South African Merino performance testing scheme. In ‘Rising to the challenge — breeding for the 21st century customer’. Beef Industry and CRC for Premium Quality Wool Industry Symposia. Supplement to the Proceedings of the Association for the Advancement of Animal Breeding and Genetics 13, 119–124. open url image1

Olivier WJ, Snyman MA, Olivier JJ, Van Wyk JB, Erasmus GJ (2001) Direct and correlated responses to selection for total weight of lamb weaned in Merino sheep. South African Journal of Animal Science 31, 115–121. open url image1

Purvis IW, Hillard M (1997) Biology and genetics of reproduction. In ‘The genetics of sheep’. (Eds L Piper, A Ruvinsky) pp. 375–394. (CAB International: Wallingford, UK)

Snyman MA, Cloete SWP, Olivier JJ (1998) Genetic and phenotypic correlations of total weight of lamb weaned with body weight, clean fleece weight, and mean fibre diameter in three South African Merino flocks. Livestock Production Science 55, 157–162.
| Crossref | GoogleScholarGoogle Scholar | open url image1

Snyman MA, Erasmus GJ, Van Wyk JB, Olivier JJ (1998) Genetic and phenotypic correlations among production and reproduction in Afrino sheep. South African Journal of Animal Science 28, 74–81. open url image1

Snyman MA, Olivier JJ, Olivier WJ (1996) Variance components and genetic parameters for body weight and fleece traits of Merino sheep in an arid environment. South African Journal of Animal Science 26, 11–14. open url image1

Swan AA, Piper LR, Brewer HG, Purvis IW (2001) Genetic variation in reproductive performance of fine wool Merinos. Proceedings of the Association for the Advancement of Animal Breeding and Genetics 14, 417–420. open url image1

Turner HN (1977) Australian sheep breeding research. Animal Breeding Abstracts 45, 9–31. open url image1

Verbyla AP, Cullis BR, Kenward MG, Welham SJ (1999) The analysis of designed experiments and longitudinal data using smoothing splines. Journal of the Royal Statistical Society Series C 48, 269–311.
| Crossref | GoogleScholarGoogle Scholar | open url image1