Evaluating seasonal risk and the potential for windspeed reductions to reduce chill index at six locations using GrassGro
J. C. Broster A B C , S. M. Robertson A B , R. L. Dehaan A , B. J. King A B and M. A. Friend A B
+ Author Affiliations
- Author Affiliations
A EH Graham Centre for Agricultural Innovation (NSW Department of Primary Industries and Charles Sturt University), Locked Bag 588, Wagga Wagga, NSW 2678, Australia.
B Co-operative Research Centre for Future Farm Industries, Nedlands, WA 6009, Australia.
C Corresponding author. Email: jbroster@csu.edu.au
Animal Production Science 52(10) 921-928 https://doi.org/10.1071/AN12066
Submitted: 5 September 2011 Accepted: 5 April 2012 Published: 16 July 2012
Abstract
The death of newborn lambs is a major factor influencing the reproductive efficiency of sheep enterprises. Adverse weather conditions (wind, precipitation and low temperature), either alone or in combination (chill index), can increase the level of newborn lamb mortality to over 50% of births for short periods through increased heat loss. The provision of shelter to reduce wind speed and therefore chill index (heat loss) has been shown to reduce lamb mortality; however, the reduction in mortality has been variable. This study used the decision support tool GrassGro to determine the likelihood of adverse weather conditions occurring at six locations across south-eastern Australia which varied widely in climate. Data were extracted for 24 consecutive weekly periods between May and October over 39 years (1968–2006) to evaluate daily precipitation, temperature, radiation, wind speed and chill index. The minimum, maximum and median values were calculated for all climatic factors for every week and year combination. The effectiveness of reducing wind speed to reduce the occurrence of a high chill index was also evaluated. The severity of these weather events varied between locations with the median weekly chill index rarely exceeding 1000 kJ/m2.h at Temora, but at both Hamilton and Orange this occurred in over two-thirds of the weeks examined. Reducing wind speed by 50% reduced the number of weeks with a median chill index exceeding 1000 kJ/m2.h in twice as many weeks at Hamilton and Yass compared with Orange. These results show that the potential for shelter to reduce chill index will vary according to the location and time of year. In locations where another climatic factor, such as low temperature or rainfall, has a greater influence on the chill index, shelter which only reduces wind speed, will be less effective than at locations where wind speed is the driver of chill index.
References
Alexander G (1962) Temperature regulation in the new-born lamb. IV. The effect of wind and evaporation of water from the coat on metabolic rate and body temperature. Australian Journal of Agricultural Research 13, 82–99.| Temperature regulation in the new-born lamb. IV. The effect of wind and evaporation of water from the coat on metabolic rate and body temperature.Crossref | GoogleScholarGoogle Scholar |
Alexander G (1974) Heat loss from sheep. In ‘Heat loss from animals and man’. (Eds JL Monteith, LE Mount) pp. 173–203. (Butterworths: London)
Alexander G, Lynch JJ (1976) Phalaris windbreaks for shorn and fleeced lambing ewes. Proceedings of the Australian Society of Animal Production 11, 161–164.
Alexander G, Lynch JJ, Mottershead BE, Donelly JB (1980) Reduction in lamb mortality by means of grass wind-breaks: results of a five-year study. Proceedings of the Australian Society of Animal Production 13, 329–332.
Alexander G, Stevens D, Kilgour R, de Langen H, Mottershead BE, Lynch JJ (1983) Separation of ewes from twin lambs: incidence in several sheep breeds. Applied Animal Ethology 10, 301–317.
| Separation of ewes from twin lambs: incidence in several sheep breeds.Crossref | GoogleScholarGoogle Scholar |
Alexander G, Bradley LR, Stevens D (1993) Effect of age and parity on maternal behaviour in single-bearing Merino ewes. Australian Journal of Experimental Agriculture 33, 721–728.
| Effect of age and parity on maternal behaviour in single-bearing Merino ewes.Crossref | GoogleScholarGoogle Scholar |
Atkins KD (1980) The comparative productivity of five ewe breeds. 1. Lamb growth and survival. Australian Journal of Experimental Agriculture 20, 272–279.
| The comparative productivity of five ewe breeds. 1. Lamb growth and survival.Crossref | GoogleScholarGoogle 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, 805–812.
| 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.Crossref | GoogleScholarGoogle Scholar |
Bird PR (1998) Tree windbreaks and shelter benefits to pasture in temperate grazing systems. Agroforestry Systems 41, 35–54.
| Tree windbreaks and shelter benefits to pasture in temperate grazing systems.Crossref | GoogleScholarGoogle Scholar |
Bird PR, Lynch JJ, Obst J (1984) Effect of shelter on plant and animal production. Proceedings of the Australian Society of Animal Production 15, 270–273.
Bird PR, Bicknell D, Bulman PA, Burke SJA, Leys JF, Parker JN, Van Der Sommen FJ, Voller P (1992) The role of shelter in Australia for protecting soils, plants and livestock. Agroforestry Journal 20, 59–86.
| The role of shelter in Australia for protecting soils, plants and livestock.Crossref | GoogleScholarGoogle Scholar |
Bird PR, Jackson TT, Kearney GA, Roache A (2007) Effects of windbreak structure on shelter characteristics. Australian Journal of Experimental Agriculture 47, 727–737.
| Effects of windbreak structure on shelter characteristics.Crossref | GoogleScholarGoogle Scholar |
Brien FD, Hebart ML, Smith DH, Edwards-Hocking JE, Greeff JC, Hart KW, Refshauge G, Bird-Gardiner TL, Gaunt G, Behrendt R, Robertson MW, Hinch GN, Geenty KG, van der Werf JHJ (2010) Opportunities for genetic improvement of lamb survival. Animal Production Science 50, 1017–1025.
| Opportunities for genetic improvement of lamb survival.Crossref | GoogleScholarGoogle Scholar |
Brown D, Mount LE (1987) Convective and radiative components of wind chill in sheep: estimation from meteorological records. International Journal of Biometeorology 31, 127–140.
| Convective and radiative components of wind chill in sheep: estimation from meteorological records.Crossref | GoogleScholarGoogle Scholar |
Bureau of Meteorology (2009) About frost. Available at http://www.bom.gov.au/climate/map/frost/what-is-frost.shtml#form [verified 30 May 2012]
Cleugh HA (Ed.) (2003) ‘Trees for shelter: a guide to using windbreaks on Australian farms.’ (RIRDC: Barton, ACT)
Croker K, Curtis K, Speijers J (2009) ‘Wool desk report – February 2009. Times of lambing in Australian flocks – 2005 to 2007.’ (Department of Agriculture and Food, Western Australia: Perth)
Dai A, Trenberth KE, Karl TR (1999) Effects of clouds, soil moisture, precipitation, and water vapor on diurnal temperature range. Journal of Climate 12, 2451–2473.
| Effects of clouds, soil moisture, precipitation, and water vapor on diurnal temperature range.Crossref | GoogleScholarGoogle Scholar |
Donnelly JR (1984) The productivity of breeding ewes grazing on Lucerne or grass and clover pastures on the Tablelands of southern Australia.III. Lamb mortality and weaning percentage. Australian Journal of Agricultural Research 35, 709–721.
| The productivity of breeding ewes grazing on Lucerne or grass and clover pastures on the Tablelands of southern Australia.III. Lamb mortality and weaning percentage.Crossref | GoogleScholarGoogle Scholar |
Donnelly JR, Moore AD, Freer M (1997) GRAZPLAN: decision support systems for Australian grazing enterprises – 1. Overview of the GRAZPLAN project, and a description of the MetAccess and LambAlive DSS. Agricultural Systems 54, 57–76.
| GRAZPLAN: decision support systems for Australian grazing enterprises – 1. Overview of the GRAZPLAN project, and a description of the MetAccess and LambAlive DSS.Crossref | GoogleScholarGoogle Scholar |
Egan JK, McLaughlin JW, Thompson RL, McIntyre JS (1972) The importance of shelter in reducing neonatal lamb deaths. Australian Journal of Experimental Agriculture and Animal Husbandry 12, 470–472.
| The importance of shelter in reducing neonatal lamb deaths.Crossref | GoogleScholarGoogle Scholar |
Egan JK, Thompson RL, McIntyre JS (1976) An assessment of overgrown Phalaris tuberosa as shelter for newborn lambs. Proceedings of the Australian Society of Animal Production 11, 157–160.
Ferguson BD (1982) Perinatal lamb mortality. Proceedings of the Australian Society of Animal Production 14, 23–26.
Fogarty NM (1972) Crossbreeding for lamb production. 1. Survival and growth of first cross lambs. Australian Journal of Experimental Agriculture 12, 234–239.
| Crossbreeding for lamb production. 1. Survival and growth of first cross lambs.Crossref | GoogleScholarGoogle Scholar |
Freer M, Dove H, Nolan JV (Eds) (2007) ‘Nutrient requirements of domesticated ruminants.’ (CSIRO: Melbourne)
Genstat (2008) ‘Genstat Release 11.1.’ (Lawes Agricultural Trust, Rothamsted Experimental Station: Hemel Hempstead, UK)
Hatcher S, Atkins KD, Safari E (2009) Phenotypic aspects of lamb survival in Australian Merino sheep. Journal of Animal Science 87, 2781–2790.
| Phenotypic aspects of lamb survival in Australian Merino sheep.Crossref | GoogleScholarGoogle Scholar | 1:CAS:528:DC%2BD1MXhtFSqu7nJ&md5=7e3b12ce6b6a90cb0a750575b4c26de0CAS |
Haughey KG (1981) Perinatal lamb mortality In ‘Refresher Course on Sheep. Proceedings of a Reference Course for Veterinarians. Proceedings No. 58’. pp. 657–673. (The Post Graduate Foundation in Veterinary Science, University of Sydney: Sydney)
Hight GK, Jury KE (1970) Hill country sheep production II. Lamb mortality and birth weights in Romney and Border Leicester x Romney flocks. New Zealand Journal of Agricultural Research 13, 735–752.
| Hill country sheep production II. Lamb mortality and birth weights in Romney and Border Leicester x Romney flocks.Crossref | GoogleScholarGoogle Scholar |
Kleemann DO, Walker SK (2005) Fertility in South Australian commercial Merino flocks: relationships between reproductive traits and environmental cues. Theriogenology 63, 2416–2433.
| Fertility in South Australian commercial Merino flocks: relationships between reproductive traits and environmental cues.Crossref | GoogleScholarGoogle Scholar |
Knight TW, Oldham CM, Smith JF, Lindsay DR (1975) Studies in ovine infertility in agricultural regions in Western Australia: analysis of reproductive wastage. Australian Journal of Experimental Agriculture 15, 183–188.
| Studies in ovine infertility in agricultural regions in Western Australia: analysis of reproductive wastage.Crossref | GoogleScholarGoogle Scholar |
Lindsay DR (1988) ‘Breeding the flock: modern research and reproduction in sheep.’ (Inkata Press: Melbourne)
Lynch JJ, Alexander G (1976) The effect of gramineous windbreaks on behaviour and lamb mortality among shorn and unshorn merino sheep during lambing. Applied Animal Ethology 2, 305–325.
| The effect of gramineous windbreaks on behaviour and lamb mortality among shorn and unshorn merino sheep during lambing.Crossref | GoogleScholarGoogle Scholar |
Lynch JJ, Alexander G (1977) Sheltering behaviour of lambing Merino sheep in relation to grass hedges and artificial windbreaks. Australian Journal of Agricultural Research 28, 691–701.
| Sheltering behaviour of lambing Merino sheep in relation to grass hedges and artificial windbreaks.Crossref | GoogleScholarGoogle Scholar |
Lynch JJ, Mottershead BE, Alexander G (1980) Sheltering behaviour and lamb mortality amongst shorn Merino ewes lambing in paddocks with a restricted area of shelter or no shelter. Applied Animal Ethology 6, 163–174.
| Sheltering behaviour and lamb mortality amongst shorn Merino ewes lambing in paddocks with a restricted area of shelter or no shelter.Crossref | GoogleScholarGoogle Scholar |
McCaskill M (2007) Tall wheatgrass hedges cut wind speeds. In ‘48th Conference of the Grasslands Society of Southern Australia, Murray Bridge, SA’. (Ed. J Hirth) p. 104. (Grassland Society of Southern Australia: Tooborac, Vic.)
McEachern S, Sackett D (2008) ‘Economic analysis of management options to improve reproductive performance in Merino ewes.’ (Holmes, Sackett & Associates Pty Ltd: Wagga Wagga)
McLaughlin JW, Egan JK, Poynton WM, Thompson RL (1970) The effect upon neonatal lamb mortality of lambing systems incorporating partial and complete shelter. Proceedings of the Australian Society of Animal Production 8, 337–343.
Miller BV (1991) Pregnancy and lambing. In ‘Australian sheep and wool handbook’. (Ed. DJ Cottle) pp. 119–143. (Inkata Press: Melbourne)
Mount LE, Brown D (1983) Wind chill in sheep: its estimation from meteorological records. Agricultural Meteorology 29, 259–268.
| Wind chill in sheep: its estimation from meteorological records.Crossref | GoogleScholarGoogle Scholar |
Nixon-Smith WF (1972) The forecasting of chill risk ratings for new born lambs and off-shears sheep by the use of a cooling factor derived from synoptic data. Working paper 150, 40/145 of April 1972, Bureau of Meteorology, Canberra, Australia.
Obst JM, Day HR (1968) The effect of inclement weather on mortality of Merino and Corriedale lambs on Kangaroo Island. Proceedings of the Australian Society of Animal Production 7, 239–242.
Obst JM, Evans JV (1970) Genotype–environment interactions in lamb mortality with particular reference to birth coat and haemoglobin type. Proceedings of the Australian Society of Animal Production 8, 149–153.
Osczevski RJ (1995) The basis of wind chill. Arctic 48, 372–382.
Owens JL, Bindon BM, Edey TN, Piper LR (1985) Behaviour at parturition and lamb survival of Booroola Merino sheep. Livestock Production Science 13, 359–372.
| Behaviour at parturition and lamb survival of Booroola Merino sheep.Crossref | GoogleScholarGoogle Scholar |
Robertson SM, Friend MA, Broster JC, King BJ (2011) Survival of twin lambs is increased with shrub belts. Animal Production Science 51, 925–938.
| Survival of twin lambs is increased with shrub belts.Crossref | GoogleScholarGoogle Scholar |
Scales GH, Burton RN, Moss RA (1986) Lamb mortality, birthweight and nutrition in late pregnancy. New Zealand Journal of Agricultural Research 29, 75–82.
| Lamb mortality, birthweight and nutrition in late pregnancy.Crossref | GoogleScholarGoogle Scholar |
Schofield NJ (1992) Tree planting for dryland salinity control in Australia. Agroforestry Systems 20, 1–23.
| Tree planting for dryland salinity control in Australia.Crossref | GoogleScholarGoogle Scholar |
Slee J (1979) Response of sheep to cold exposure in relation to selection for survival ability. In ‘The management and diseases of sheep’. (Eds JMM Cunningham, JT Stamp, WB Martin) pp. 100–113. (Commonwealth Agricultural Bureaux: London)
Watson RH, Alexander G, Cumming IA, McDonald JW, McLaughlin JW, Rizzoli D, Williams D (1968) Reduction of perinatal loss of lambs in winter in western Victoria by lambing in sheltered individual pens. Proceedings of the Australian Society of Animal Production 7, 243–249.
