Having an accurate way to obtain weights for your dairy herd is important for medication dosages, ration balancing and monitoring growth. However, many producers don’t have access to a scale or are often in need of a quick weight and don’t want to take the time to get the animal to the scale, especially if the scale is in a different barn.
In situations like these it’s necessary to have an alternative way, such as a weight tape or a weight estimation formula, to get an accurate weight without using a scale, because visual observation is highly inaccurate.
A study conducted by Pennsylvania State University found a high correlation between body weight and a single body measurement including heart girth, wither height, hip width, and body length. Heart girth had the highest correlation for Holstein cattle ranging from 1 to 2 years of age. They also found that correlating body weight with two body measurements increased the accuracy, but added little benefit as the precision already was so high with just a single measurement.
Weight tapes are an inexpensive way to accurately estimate body weight without having to calculate it using a formula. Most of the time weight tapes are used by measuring the animal’s heart girth, which then will give an estimation of the animal’s weight. Proper technique is important for accurately using a weight tape:
(1) Make sure the animal’s head is up, as the chest expands when its head is down.
(2) Measure the heart girth region just behind the shoulders, not the abdomen (see photo).
(3) Be sure the tape is in contact with the animal’s body surface all the way around, but do not “cinch” it tighter. Pulling the tape too tight will cause an underestimation of weight; leaving it too loose will cause an overestimation of weight.
Weight tapes are available for various breeds of dairy cattle and are specifically developed for calves, heifers and cows. It is important to use the proper tape because different breeds and ages of animals grow differently and have various body conformations.