Simple and robust model to estimate liveweight of Ethiopian Menz sheep
Jane Wamatu A C , Ashraf Alkhtib A B and Barbara Rischkowsky AA International Center for Agricultural Research in Dry Areas (ICARDA), PO Box 5689, Addis Ababa, Ethiopia.
B Nottingham Trent University, School of Animal, Rural and Environmental Sciences, PO Box NG25 0QF, Brackenhurst Lane, Southwell, Nottinghamshire, UK.
C Corresponding author. Email: j.wamatu@cgiar.org
Animal Production Science 59(12) 2265-2272 https://doi.org/10.1071/AN18006
Submitted: 4 January 2018 Accepted: 16 February 2019 Published: 26 September 2019
Abstract
Heart girth (HG) bands have been predominantly used in Ethiopia by smallholder farmers, traders and extension workers to estimate liveweight (LW) of livestock. They are produced using recommended and published predictive models from Ethiopia. More recently, some farmers and traders have abandoned the bands due to perceived inaccuracy of LW estimation and reverted to eye-ball estimations. The present study generated a novel algorithm using multiple criteria to develop a robust predictive model for LW estimation of Ethiopian Menz sheep by using HG. Subsequently, recommended models currently in use in Ethiopia were evaluated for accuracy in predicting LW, using data of the present study. Liveweight and HG of 420 Menz sheep were measured. Simple linear model (SLM), Box–Cox (SLM with LW0.75), quadratic and allometric models were used to describe the relationship between LW and HG. Algorithms used to validate the models included data exploration, model construction and model redeployment. Results showed that all models had similar R2 (≈0.82). All models fitted the criteria of residual analysis and robustness against extreme values. However, only Box–Cox was robust against data redeployment, with 95th percentile of prediction error (PE) less than 10%. Accordingly, a Box–Cox model (LW0.75 = –9.71 + 0.289 (HG)) is robust and can be used to accurately predict LW of Menz sheep. The 95th percentile of PE of existing, recommended models was higher than 10; thus, they cannot be recommended to accurately predict LW of Menz sheep. The present study concludes that an approach based on regressing LW on HG, and then selecting models with the highest R2, is inadequate to generate accurate and robust prediction models. This highlights the importance of model redeployment to generate accurate prediction models. Calibrated HG bands are suitable alternatives to weighing scales in rural areas of Ethiopia because they are cheaper and not subject to maintenance. Thus, their accuracy and robustness in estimation of LW is vital for sustainable use.
Additional keywords: heart girth, linear, liveweight prediction, non-linear, prediction error.
References
Atta M, El Khidir O (2004) Use of heart girth, wither height and scapuloischial length for prediction of liveweight of Nilotic sheep. Small Ruminant Research 55, 233–237.| Use of heart girth, wither height and scapuloischial length for prediction of liveweight of Nilotic sheep.Crossref | GoogleScholarGoogle Scholar |
Berhe W (2017) Relationship and prediction of body weight from morphometric traits of indigenous highland sheep in Tigray, northern Ethiopia. Journal of Biotechnology and Bioinformatics 3, 1–5.
Box G, Cox D (1964) An analysis of transformations. Journal of the Royal Statistical Society. Series B. Methodological 26, 211–252.
| An analysis of transformations.Crossref | GoogleScholarGoogle Scholar |
Buvanendran V, Umoh J, Abubakar B (1980) An evaluation of body size as related to weight of three West African breeds of cattle in Nigeria. The Journal of Agricultural Science 95, 219–224.
| An evaluation of body size as related to weight of three West African breeds of cattle in Nigeria.Crossref | GoogleScholarGoogle Scholar |
Francis J, Sibanda S, Kristensen T (2004) Estimating body weight of cattle using linear body measurements. Zimbabwe Veterinary Journal 33, 15–21.
| Estimating body weight of cattle using linear body measurements.Crossref | GoogleScholarGoogle Scholar |
Galall E (1980) ‘A contribution towards a plan for sheep and goat research and development in Ethiopia.’ (Institute of Agricultural Research: Addis Ababa, Ethiopia)
Galall E (1983) Sheep germ plasm in Ethiopia. Animal Genetic Resources Information 1, 5–12.
| Sheep germ plasm in Ethiopia.Crossref | GoogleScholarGoogle Scholar |
Getachew T, Haile A, Tibbo M, Sharma AK, Solkner J, Wurzinger M, Terefe E (2009) Use of linear body measurements for performance recording and genetic evaluation of Menz and Afar sheep breeds under village condition. In ‘Proceedings of the 17th annual conference of the Ethiopian Society of Animal Production (ESAP)’, 24–26 September 2009, Addis Ababa, Ethiopia. pp. 113–121.
Gizaw S, Aschalew T, Lemma W, Beneberu T, Shenkute G, Wamatu J, Thorpe W, Duncan A (2012) ‘Characterization of the farming and livestock production systems and the potentials to enhance productivity through improved feeding in the subalpine highlands of Amhara region, Ethiopia.’ (Addis Ababa, Ethiopia)
Goopy JP, Pelster DE, Onyango A, Marshall K, Lukuyu M (2017) Simple and robust algorithms to estimate liveweight in African smallholder cattle. Animal Production Science
| Simple and robust algorithms to estimate liveweight in African smallholder cattle.Crossref | GoogleScholarGoogle Scholar |
Kmenta J (1986) ‘Elements of econometrics.’ (Macmillan: New York)
Leach T, Roberts C (1981) Present status of chemotherapy and chemoprophylaxis of animal trypanosomiasis in the eastern hemisphere. Pharmacology & Therapeutics 13, 91–147.
| Present status of chemotherapy and chemoprophylaxis of animal trypanosomiasis in the eastern hemisphere.Crossref | GoogleScholarGoogle Scholar |
Lesosky M, Dumas S, Conradie I, Handel IG, Jennings A, Thumbi S, Toye P, de Clare Bronsvoort BM (2012) A live weight–heart girth relationship for accurate dosing of east African shorthorn zebu cattle. Tropical Animal Health and Production 45, 311–316.
| A live weight–heart girth relationship for accurate dosing of east African shorthorn zebu cattle.Crossref | GoogleScholarGoogle Scholar | 22923040PubMed |
Machila N, Fèvre E, Maudlin I, Eisler M (2008) Farmer estimation of live bodyweight of cattle: implications for veterinary drug dosing in East Africa. Preventive Veterinary Medicine 87, 394–403.
| Farmer estimation of live bodyweight of cattle: implications for veterinary drug dosing in East Africa.Crossref | GoogleScholarGoogle Scholar | 18586339PubMed |
McDonald JH (2009) ‘Handbook of biological statistics.’ (Sparky House Publishing: Baltimore, MD)
Nesamvuni A, Mulaudzi J, Ramanyimi N, Taylor G (2000) Estimation of body weight in Nguni-type cattle under communal management conditions. South African Journal of Animal Science 30, 97–98.
ReliaSoft (2015) ‘Experiment design & analysis reference.’ (ReliaSoft Corporation: Tucson, AZ)
SAS (2012) ‘SAS/STAT 12.1. User’s guide.’ (SAS Inc.: Cary, NC)
Sawyer G, Barker D, Morris R (1991) Performance of young breeding cattle in commercial herds in the south-west of Western Australia. 2. Liveweight, body condition, timing of conception and fertility in first-calf heifers. Australian Journal of Experimental Agriculture 31, 431–441.
| Performance of young breeding cattle in commercial herds in the south-west of Western Australia. 2. Liveweight, body condition, timing of conception and fertility in first-calf heifers.Crossref | GoogleScholarGoogle Scholar |
Sowande O, Sobola O (2008) Body measurements of west African dwarf sheep as parameters for estimation of live weight. Tropical Animal Health and Production 40, 433–439.
| Body measurements of west African dwarf sheep as parameters for estimation of live weight.Crossref | GoogleScholarGoogle Scholar | 18575971PubMed |
Tadesse A, Gebremariam T (2010) Application of linear body measurements for live body weight estimation of highland sheep in Tigray region, north-Ethiopia. Journal of the Dry Lands 3, 203–207.
Veerkamp R (1998) Selection for economic efficiency of dairy cattle using information on live weight and feed intake: a review. Journal of Dairy Science 81, 1109–1119.
| Selection for economic efficiency of dairy cattle using information on live weight and feed intake: a review.Crossref | GoogleScholarGoogle Scholar | 9594400PubMed |
Wood M (2004) Statistical inference using bootstrap confidence intervals. Significance 1, 180–182.
| Statistical inference using bootstrap confidence intervals.Crossref | GoogleScholarGoogle Scholar |
