Pregnancy scanning of sheep in southern Australia. 1. Scanning for litter size was profitable across all modelled regions, times of lambing and genotypes
John M. Young
A , David J. Brown B and Forbes D. Brien C *
A
B
C
Abstract
Pregnancy scanning allows ewes to be separately managed by litter size class to: (1) meet recommended condition score targets to enhance survival and progeny productivity, (2) prioritise allocation of multiple-bearing ewes to smaller mobs or more sheltered lambing paddocks, and (3) select replacement ewes based on birth type. However, 70% of Australian sheep producers are not scanning for litter size.
To establish the profitability of pregnancy scanning in southern Australia, to build a stronger business case to address the key perception by non-adopters that the case is weak.
The profitability of pregnancy scanning was modelled, across three regions (long, medium and short growing seasons in southern Australia), three different genotypes (Merino, Merino × terminal and a maternal flock) and three lambing times (autumn, winter and spring) using the Australian Farm Optimisation Model. A simpler gross margin analysis was used to include the summer rainfall regions.
Implementing optimal ewe nutritional management, paddock allocation and replacement strategies based on litter size was profitable in all the scenarios of region, genotype, time of lambing and price tested. The increase in profitability in the winter rainfall zone averaged across the scenarios tested was A$5.75/ewe scanned. In the summer rainfall zone, the average increase in profit was A$4.44/ewe scanned. Profitability was sensitive to sheep meat prices, but not sensitive to wool and supplement prices, nor overall reproductive rate.
There is a strong business case for pregnancy scanning ewes for litter size via: (1) selling of non-pregnant ewes (A$1.75/ewe), (2) better allocation of feed based on litter size (A$2.00/ewe), (3) allocating multiple-bearing ewes to the best lambing paddocks and/or reducing mob size to enhance lamb survival (A$1.00/ewe), and (4) accounting for birth type when selecting breeding replacements (A$1.00/ewe).
Pregnancy scanning for litter size is a relatively low-cost, high-profit and vital tool for improving reproductive rate, lamb and ewe survival rates, and lamb growth rates. Our findings extend previous, more limited studies, in terms of their reach across different regions, genotypes and production systems.
Keywords: AFO, Australian Farm Optimisation model, breeds, fecundity, genotypes, lambing dates, litter size, pregnancy scanning, profit, sheep.
References
Abadi GKA, Pannell DJ (1991) Economic trade-off between pasture production and crop weed control. Agricultural Systems 36(1), 1-15.
| Crossref | Google Scholar |
Behrendt R, Van Burgel AJ, Bailey A, Barber P, Curnow M, Gordon DJ, Edwards JEH, Oldham CM, Thompson AN (2011) On-farm paddock-scale comparisons across southern Australia confirm that increasing the nutrition of Merino ewes improves their production and the lifetime performance of their progeny. Animal Production Science 51(9), 805-812.
| Crossref | Google Scholar |
Behrendt R, Hocking Edwards JE, Gordon D, Hyder M, Kelly M, Cameron F, Byron J, Raeside M, Kearney G, Thompson AN (2019) Offering maternal composite ewes higher levels of nutrition from mid-pregnancy to lambing results in predictable increases in birthweight, survival and weaning weight of their lambs. Animal Production Science 59(10), 1906-1922.
| Crossref | Google Scholar |
Bowman PJ, Fowler DG, Wysel DA, White DH (1989) Evaluation of a new technology when applied to sheep production systems: Part II–real-time ultrasonic-scanning of ewes in mid-pregnancy. Agricultural Systems 29(4), 287-323.
| Crossref | Google Scholar |
Brien FD, Refshauge G, Hatcher S, Bunter KL, Dickson H, Young J, Petrovski K, Collins A, Cousins M, Graetz, T (2023) Increasing lamb percentages through better use of pregnancy scanning technology. Final Report to Meat Livestock Australia for L.LSM.0021. Available at https://www.mla.com.au/contentassets/a1760e8d3cb04e48b2746214e4d49739/increasing-lambing-percentages-through-better-use-of-pregnancy-scanning-technology---l.lsm.0021---final-report.pdf [verified 7 February 2025]
Corner-Thomas RA, Kenyon PR, Morris ST, Ridler AL, Hickson RE, Greer AW, Logan CM, Blair HT (2015) Influence of demographic factors on the use of farm management tools by New Zealand farmers. New Zealand Journal of Agricultural Research 58(4), 412-422.
| Crossref | Google Scholar |
Elliott J, Sneddon J, Lee JA, Blache D (2011) Producers have a positive attitude toward improving lamb survival rates but may be influenced by enterprise factors and perceptions of control. Livestock Science 140(1–3), 103-110.
| Crossref | Google Scholar |
Fowler DG, Wilkins JF (1984) Diagnosis of pregnancy and number of foetuses in sheep by real-time ultrasonic imaging. I. Effects of number of foetuses, stage of gestation, operator and breed of ewe on accuracy of diagnosis. Livestock Production Science 11(4), 437-450.
| Crossref | Google Scholar |
Freer M, Moore AD, Donnelly JR (2012) The GRAZPLAN animal biology model for sheep and cattle and the GrazFeed decision support tool. CSIRO Plant Industry Technical Paper. Available at https://grazplan.csiro.au/wp-content/uploads/2007/08/TechPaperMay12.pdf [verified 7 February 2025]
Hatcher S, Dominik S, Richards JS, Young J, Smith J, Tearle R, Brien FD, Hermann N (2018) Ewe culling and retention strategies to increase reproductive rates in Merino sheep. Animal Production Science 58(8), 1545-1551.
| Crossref | Google Scholar |
Hebart ML, Brien FD, Jaensch KS, Smith DH, Walkom SF, Grimson RJ (2010) Genetics of reproductive efficiency: a study of Merino resource flocks in South Australia. In ‘Proceedings of the 9th world congress on genetics applied to livestock production’, held 1–6 August, 2010 Leipzig, Germany. (German Society of Animal Science) Communication 0685.
Holmes P, Sackett D (2008) Pregnancy scanning ewes. On Farm 113, 11-14.
| Google Scholar |
Howard K, Beattie L (2018) A national producer survey of sheep and cattle husbandry practices. Project E.AWW.1501 Final Report to MLA. Available at https://www.mla.com.au/contentassets/c6b8854d3bb6421aab1a94baf9496b9a/e.aww.1501_final_report_-_sheep.pdf [verified 7 February 2025]
Kleemann DO, Walker SK, Ponzoni RW, Gifford DR, Walkley JRW, Smith DH, Grimson RJ, Jaensch KS, Walkom SF, Brien FD (2016) Effect of previous reproductive performance on current reproductive rate in South Australian Merino ewes. Animal Production Science 56(4), 716-725.
| Crossref | Google Scholar |
Lee GJ, Atkins KD, Sladek MA (2009) Heterogeneity of lifetime reproductive performance, its components and associations with wool production and liveweight of Merino ewes. Animal Production Science 49(7), 624-629.
| Crossref | Google 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(10), 1631-1634.
| Crossref | Google Scholar |
Lockwood A, Hancock S, Kearney G, Thompson A (2019) Reducing mob size increases the survival of twin-born Merino lambs when feed-on-offer from pasture is limited and ewes are supplementary fed during lambing. Small Ruminant Research 173, 65-69.
| Crossref | Google Scholar |
Lockwood A, Trompf J, Hancock S, Kubeil L, Thompson A, Young J (2020) Factors influencing the optimum mob size of ewes at lambing and the economic benefit of lambing ewes in smaller mobs to increase lamb survival across southern Australia. Agricultural Systems 184, 102916.
| Crossref | Google Scholar |
Lockwood A, Allington T, Blumer SE, Boshoff J, Clarke BE, Hancock SN, Kearney GA, Kenyon PR, Krog J, Kubeil LJ, Refshauge G, Trompf JP, Thompson AN (2023) Decreasing mob size at lambing increases the survival of triplet lambs born on farms across southern Australia. Animals 13(12), 1936.
| Crossref | Google Scholar | PubMed |
Masters DG, Blache D, Lockwood AL, Maloney SK, Norman HC, Refshauge G, Hancock SN (2023) Shelter and shade for grazing sheep: implications for animal welfare and production and for landscape health. Animal Production Science 63(7), 623-644.
| Crossref | Google Scholar |
McGrath S, Virgona J, Allworth B (2016) The cost of hitting lifetime ewe targets in scanned and unscanned Merino flocks – a simulation using a dynamic model, AusFarm. Available at https://researchoutput.csu.edu.au/en/publications/the-cost-of-hitting-lifetime-ewe-targets-in-scanned-and-unscanned [verified on 20 August 2021]
Mecardo (2022) Merino fleece micron premiums and discounts. 1 Nov 2022. Available at https://mecardo.com.au/merino-fleece-micron-premiums-discounts/ [verified on 7 February 2025]
Mecardo (2023) Percentiles – April 2023. 14 Apr 2023. Available at https://mecardo.com.au/percentiles-april-2023/ [verified on 7 February 2025]
Monjardino M, Revell D, Pannell DJ (2010) The potential contribution of forage shrubs to economic returns and environmental management in Australian dryland agricultural systems. Agricultural Systems 103(4), 187-197.
| Crossref | Google Scholar |
Oldham CM, Thompson AN, Ferguson MB, Gordon DJ, Kearney GA, Paganoni BL (2011) The birthweight and survival of Merino lambs can be predicted from the profile of liveweight change of their mothers during pregnancy. Animal Production Science 51(9), 776-783.
| Crossref | Google Scholar |
SSF (2022) Sheep sustainability framework: on-farm insights from the National Producer Survey – October 2022. Available at https://www.sheepsustainabilityframework.com.au/globalassets/sheep-sustainability/media/ssf-on-farm-insights-report-web-25oct2022.pdf [verified on 7 July 2023]
SSF (2024) Sheep sustainability framework. Annual Report 2024. Available at https://www.sheepsustainabilityframework.com.au/globalassets/sheep-sustainability/media/240731-ssf-2024-annual-report---web.pdf [verified on 24 January 2024]
Thompson AN, Ferguson MB, Gordon DJ, Kearney GA, Oldham CM, Paganoni BL (2011) Improving the nutrition of Merino ewes during pregnancy increases the fleece weight and reduces the fibre diameter of their progeny’s wool during their lifetime and these effects can be predicted from the ewe’s liveweight profile. Animal Production Science 51(9), 794-804.
| Crossref | Google Scholar |
Young JM, Thompson AN, Curnow M, Oldham CM (2011) Whole-farm profit and the optimum maternal liveweight profile of Merino ewe flocks lambing in winter and spring are influenced by the effects of ewe nutrition on the progeny’s survival and lifetime wool production. Animal Production Science 51(9), 821-833.
| Crossref | Google Scholar |
Young JM, Saul G, Behrendt R, Byrne F, McCaskill M, Kearney GA, Thompson AN (2014) The economic benefits of providing shelter to reduce the mortality of twin lambs in south-western Victoria. Animal Production Science 54(6), 773-782.
| Crossref | Google Scholar |
Young JM, Behrendt R, Curnow M, Oldham CM, Thompson AN (2016) Economic value of pregnancy scanning and optimum nutritional management of dry, single- and twin-bearing Merino ewes. Animal Production Science 56(4), 669-678.
| Crossref | Google Scholar |
Young M, Young J, Kingwell RS, Vercoe PE (2023) Improved whole-farm planning for mixed-enterprise Systems in Australia using a four-stage stochastic model with recourse. Australian Farm Business Management Journal 20, 37-54.
| Google Scholar |
Young M, Young J, Kingwell RS, Vercoe PE (2024) Identifying high-value tactical livestock decisions on a mixed enterprise farm in a variable environment. Animal Production Science 64, AN23407.
| Crossref | Google Scholar |
Young JM, Kenyon PR, Kubeil LJ, Thompson AN, Trompf J, Lockwood A (2025) The economic optimum mob size at lambing for triplet-bearing Maternal and Merino ewes across southern Australia. Animal Production Science 65(2), AN24334.
| Crossref | Google Scholar |
