Body weight estimation of yaks using body measurements from image analysis. (July 2019)

• Record Type: Journal Article
• Authors: Yan, Qi; Ding, Luming; Wei, Haiyan; Wang, Xianju; Jiang, Cuixia; Degen, Allan
• Is Part Of: Measurement. Volume 140(2019)
• Page Start: 76
• Page End: 80
• Publication Date: 2019-07
• Subjects: Yak -- Live body weight -- Linear measurements -- Image analysis -- Regression model; Weights and measures -- Periodicals; Measurement -- Periodicals; Measurement; Weights and measures; Periodicals; 530.8
• DOI: 10.1016/j.measurement.2019.03.021
• Languages: English
• ISSNs: 0263-2241

Abstract

Highlights: Withers height, body diagonal length and body side area of yaks were determined from photographs. Using simple regressions, each body measurement accurately estimated liveweight of the yaks. Multiple regression analysis improved the accuracy of the estimation. Abstract: Traditionally, yaks graze only natural pasture on the Qinghai-Tibetan Plateau year around without any supplementary feed. Weighing these animals is extremely difficult because of the general wild nature of yaks and the lack of proper weighing equipment on the plateau. The aim of this study was to determine whether body measurements of yaks could be used to estimate their live body weight (LBW). Photographs were taken of 39, 52 and 55 yaks, aged 1 to 8 years, in summer (July), winter (November) and spring (April), respectively. Each yak was weighed and, from its photograph, withers height (WH), body diagonal length (BDL) and body side area (BSA) were calculated. Simple regression analyses between LBW and each of the linear measurements within each season were all highly significant and explained 78.3% to 94.6% of the variance in LBW. Multiple linear regressions between LBW and body measurements improved the predictive power within each season and explained 86.3% to 97.2% of the variance in LBW. We concluded that body measurements could be used to estimate LBW of yaks; to improve the estimate, calibrations of LBW on linear measurements should be done in each season.