Star Milling

Mules: Estimating Body Weight

Traditionally, weight tapes have been designed for horses. Field studies and research in the Sierra Mountains required our research team to develop a practical method to accurately estimate the body weight of mules. Knowledge of true body weights is obviously useful in determining the proper feeding program. Drugs, de-worming-compounds, feed supplements and additives are also administered on a body-weight basis.

The study consisted of 85 female and 52 male mules, ranging in body weights from 250 to 1400 pounds. Three commercially available weight tapes were compared to a calibrated livestock scale. The tapes were placed around the heart girth of the mule. The reference point for the heart girth is approximately 4 inches behind the point of elbow. Proper position of the weight tape included the dorsal (top) and ventral (bottom) surfaces of the weight tape being bisected by a line that was perpendicular to the ground.

Each of the commercial weight tapes underestimated the true body weight of the mules. There were no differences between the weight tapes when comparing "Molly Mules" to "John Mules". However, the degree of differences observed to be greater with the heavier animals when comparing the weight tapes to the actual mules body weights.

In the table below the mules heart-girth circumference measurements were used to develop the weight table. Schematics on the proper use of the strap used to measure circumference are also provided.

Using a non-stretchable material, such as a nylon strap, measure the mule's heart-girth (inches) and compare the measurement to the corresponding weight provided in the table. Example: If the heart girth circumference was 70 in (inches), then the estimated body weight would be 986 lb (pounds). If the heart girth circumference was 73 in, then you would average the weights for 72 and 74 in which would approximate 1103 lb (1063 + 1144 = 2207 2 = 1103.5).

Estimating Mule’s Body Weight from Heart Girth Circumference

Mule Weight
Heart Girth (inches) Body Weight (lbs)
50.0 402
52.0 447
54.0 494
56.0 544
58.0 597
60.0 654
62.0 714
64.0 776
66.0 843
68.0 913
70.0 986
72.0 1063
74.0 1,144
76.0 1,228
78.0 1,316
80.0 1,408