ACCURACY OF DIFFERENT METHODS OF ESTIMATING THE WEIGHT OF HORSES

Six hundred horses of different ages, heights and breeds were weighed on a weighbridge and had their weights estimated by two weigh tapes, 1 and 2, by a formula, and by a visual estimate. For the population as a whole, the most accurate method was the formula (mean [sd] 98.6 [10. 6] per cent) closely followed by weigh tape 2 (98.1 [8.1] per cent). T ape 1 and the visual estimate were the least accurate (112.0 [9.3] and 88.3 [20.1] per cent respectively). When the population was divided i nto two height groups, the formula and weigh tape 2 were the most accu rate for horses <15 hh (99.6 [5.2] per cent and 99.0 [5.6] per cent re spectively), and weigh tape 1 and the visual estimate were 113.5 (6.5) per cent and 88.4 (16.3) per cent accurate respectively. For horses g reater than or equal to 15 hh weigh tape 1 was most accurate (103.5 [9 .1] per cent) and the formula, tape 2 and the visual estimate were 95. 5 (13.1) per cent, 91.8 (9.2) per cent, and 89.3 (22.2) per cent accur ate respectively. Overall the formula appeared to be the most accurate estimator of a horse's weight. However, owing to individual variation , it is recommended that the weights of horses <15 hh are estimated by the formula or weigh tape 2, and that the weights of those greater th an or equal to 15 hh are estimated with weigh tape 1.