Cumulative reproductive performance effect on overall lifetime productivity in Merino sheep
J. S. Richards A C , M. A. Sladek A and G. J. Lee BA Orange Agricultural Institute, NSW Department of Primary Industries, Orange, NSW 2800, Australia.
B Formerly Orange Agricultural Institute, NSW Department of Primary Industries, Orange, NSW 2800, Australia.
C Corresponding author. Email: jessica.richards@dpi.nsw.gov.au
Animal Production Science 58(8) 1470-1480 https://doi.org/10.1071/AN17794
Submitted: 10 November 2017 Accepted: 30 March 2018 Published: 9 May 2018
Abstract
Reproduction is an important driver of profitability in commercial sheep flocks. Historically, Merino flocks have been run with a fixed age structure, ignoring individual merit and casting for age at a specific age. More recently, research has focussed on utilising the variation within age groups by keeping productive older ewes longer and culling less productive ewes earlier. Previous studies have also examined the effect of age on reproduction and the impact of reproduction status on productivity, but little research has been conducted on cumulative effects of reproductive performance on later productivity, reproduction and health. The present study examined the impact of higher lifetime reproduction on other key production and fitness traits in older ewes run under commercial conditions. Data were collected from two commercial wool-producing properties in the South West Slopes and the Central West Plains of New South Wales during 2009–2011. Reproduction, fleece measurements, bodyweight and condition and dental health were recorded during the study. The results showed that age had a bigger effect on productivity and dental health than did cumulative lifetime reproduction. Environment and genetics determined the level of impact, with minimal loss in productivity from increased age of animals occurring in the South West Slopes flock, whereas the Central West Plains flock would appear to require closer monitoring of productivity as ewes aged. The data collected did not allow separation of the genetic and environmental influences within the study. Retaining animals with a higher reproductive performance past normal culling age does not necessarily result in reduction of productivity or ewe health, but this must be monitored.
Additional keywords: age, fertility, scanning, teeth, weaning, wellbeing.
References
Brown GH, Turner HN, Young SSY, Dolling CHS (1966) Vital statistics for an experimental flock of Merino sheep III. Factors affecting wool and body characteristics, including the effect of age of ewe and its possible interaction with method of selection. Australian Journal of Agricultural Research 17, 557–581.| Vital statistics for an experimental flock of Merino sheep III. Factors affecting wool and body characteristics, including the effect of age of ewe and its possible interaction with method of selection.Crossref | GoogleScholarGoogle Scholar |
Cannon DJ, Napier K, Hanrahan PD (1971) Some sheep-wheat men could reduce costs. Victorian Journal of Agriculture 69, 154–156.
Cloete SWP, Gilmour AR, Olivierr JJ, van Wyk JB (2003) Age trends in economically important traits of Merino ewes subjected to 10 years of divergent selection for multiple rearing ability. South African Journal of Animal Science 33, 43–51.
| Age trends in economically important traits of Merino ewes subjected to 10 years of divergent selection for multiple rearing ability.Crossref | GoogleScholarGoogle Scholar |
Clutton-Brock TH, Stevenson JS, Marrow P, MacColl AD, Houston AI, McNamara JM (1996) Population fluctuations, reproductive costs and life-history tactics in female Soay sheep. Journal of Animal Ecology 65, 675–689.
| Population fluctuations, reproductive costs and life-history tactics in female Soay sheep.Crossref | GoogleScholarGoogle Scholar |
Curtis K (2009) ‘Recent changes in the Australian sheep industry (the disappearing flock).’ (Department of Agriculture and Food, Western Australia: Perth) Available at http://archive.sheepcrc.org.au/files/pages/information/publications/australias-declining-sheep-flock/Recent_changes_ in_the_Australian_sheep_industy.pdf [Verified 7 November 2017]
Ernst and Young (2017) State of the industry report: the Australian red meat and livestock industry. Meat and Livestock Australia. Available at http://rmac.com.au/wp-content/uploads/2017/10/State-of-the-Industry-2017.pdf [accessed 7 November 2017]
Gilmour AR, Gogel BJ, Cullis BR, Thompson R (2006) ‘ASReml user guide release 2.0.’ (VSN International: Hemel Hempstead, UK)
Hamel S, Côté SD, Gaillard J-M, Festa-Bianchet M (2009) Individual variation in reproductive costs of reproduction: high-quality females always do better. Journal of Animal Ecology 78, 143–151.
Langlands JP, Donald GE, Paull DR (1984) Effects of different stocking intensities in early life on the productivity of Merino ewes grazed as adults at two stocking rates. 1. Wool production and quality, lamb growth rate, and size and liveweight of ewes. Australian Journal of Experimental Agriculture 24, 34–46.
| Effects of different stocking intensities in early life on the productivity of Merino ewes grazed as adults at two stocking rates. 1. Wool production and quality, lamb growth rate, and size and liveweight of ewes.Crossref | GoogleScholarGoogle Scholar |
Lee GJ, Atkins KD (1995) Consequences of reproduction on the liveweight, fat depth, wool growth, and intake of grazing Merino ewes in the short and long term. Australian Journal of Experimental Agriculture 35, 153–159.
| Consequences of reproduction on the liveweight, fat depth, wool growth, and intake of grazing Merino ewes in the short and long term.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DyaK2MXnslajt7Y%3D&md5=878fab9409f4dc47ecc1859cf0ea8e22CAS |
Lee GJ, Atkins KD, Sladek MA (2009) Heterogeneity of lifetime reproductive performance, its components and associations with wool production and live weight of Merino ewes. Animal Production Science 49, 624–629.
| Heterogeneity of lifetime reproductive performance, its components and associations with wool production and live weight of Merino ewes.Crossref | GoogleScholarGoogle Scholar |
Lee GJ, Sladek MA, Hatcher S, Richards JS (2014) Using partial records to identify productive older ewes to retain in the breeding flock to increase the flock net reproduction rate. Animal Production Science 54, 1631–1634.
| Using partial records to identify productive older ewes to retain in the breeding flock to increase the flock net reproduction rate.Crossref | GoogleScholarGoogle Scholar |
McGregor BA (2011) Incisor development, wear and loss in sheep and their impact on ewe production, longevity and economics: a review. Small Ruminant Research 95, 79–87.
| Incisor development, wear and loss in sheep and their impact on ewe production, longevity and economics: a review.Crossref | GoogleScholarGoogle Scholar |
Mullaney PD, Brown GH (1969) The influence of age on reproductive performance of sheep in Australia. Australian Journal of Agricultural Research 20, 953–963.
| The influence of age on reproductive performance of sheep in Australia.Crossref | GoogleScholarGoogle Scholar |
Ponzoni RW, Azzarini M, Walker SK (1979) Production in mature Corriedale ewes first mated at 7 to 11 or 18 months of age. Animal Production 29, 385–391.
| Production in mature Corriedale ewes first mated at 7 to 11 or 18 months of age.Crossref | GoogleScholarGoogle Scholar |
Richards JS, Atkins KD (2007) Determining pedigree by association in Merino flocks. Proceedings of the Association for the Advancement of Animal Breeding and Genetics 17, 403–406.
Safari E, Fogarty NM, Gilmour AR, Atkins KD, Mortimer SI, Swan AA, Brien FD, Greeff JC, van der Werf JHJ (2007) Across population genetic parameters for wool, growth, and reproduction traits in Australian Merino sheep. 1. Data structure and non-genetic effects. Australian Journal of Agricultural Research 58, 169–175.
| Across population genetic parameters for wool, growth, and reproduction traits in Australian Merino sheep. 1. Data structure and non-genetic effects.Crossref | GoogleScholarGoogle Scholar |
Weladji R, Loison A, Gaillard J-M, Holand Ø, Mysterud A, Yoccoz N, Nieminen M, Stenseth N (2008) Heterogeneity in individual quality overrides costs of reproduction in female reindeer. Oecologia 156, 237–247.
| Heterogeneity in individual quality overrides costs of reproduction in female reindeer.Crossref | GoogleScholarGoogle Scholar |
