Bodyweight estimation – Which method is best?

Bodyweight estimation—which method is best?

Having an accurate bodyweight for your horse is critical when formulating your horse’s diet. Overestimating your horse’s bodyweight may mean you feed too much, resulting in weight gain and wasted money on feed that is surplus to your horse’s needs. Underestimating could result in underfeeding your horse, possibly causing weight loss and nutrient deficiencies.

How to do it … better!

Weighing your horse on a set of livestock scales is by far the most accurate method of obtaining your horse’s bodyweight. However, few of us have the luxury of a set of scales. Thus we turn to various methods that allow us to estimate our horse’s bodyweight. There are 3 generally well accepted methods for estimating your horse’s bodyweight:

    1. Weight tapes – you place a specially marked tape around your horse’s girth and it gives you an estimated weight.
    2. Height and Condition score – using your horse’s height and body condition score and a published weight table, you can look up your horse’s estimated weight.
    3. Girth and Length measurements – measure your horse’s girth and length from point of the shoulder to point of the buttock and then enter them into the equation:

kg of bodyweight = [ girth (cm)2 x length (cm) ] ÷ 11,880

But how accurate are these methods?

We ran a very small test on the accuracy of the 3 methods and compared them against actual bodyweights of horses here at Equilize Horse Nutrition. Our results showed the following:

Method of Weight Estimation
Horse Actual Bodyweight Weight Tape Height / Condition Score Girth and Length
Poet 475 kg 500 kg 490 kg 468 kg
Quilla 444 kg 500 kg 463 kg 446 kg
Cass 430 kg 460 kg 437 kg 422 kg

The weight tape was the least accurate method, overestimating the weight of these horses by an average of 8.3% (meaning all nutrient requirements will also be overestimated by 8.3%). The Height/Condition Score method was a bit better, only overestimating the weight by 3%. The Girth and Length method is the best, underestimating the bodyweights by an average of 1%.

Take home message…

An accurate bodyweight is essential if you want to balance your horse’s diet correctly. Be very careful when estimating your horse’s bodyweight. If you cannot weigh your horse on livestock scales we recommend you use the Girth and Length method to estimate your horse’s bodyweight as it will give you the closest estimate to your horse’s actual bodyweight. This is the method we use to help you estimate your horse’s bodyweight in FeedXL.

 

Dr. Nerida Richards is FeedXL’s resident equine nutrition specialist and horse nut. With a degree in Rural Science, a doctorate degree in equine nutrition and going on 13 years of full time, on the ground experience in feeding all types of horses Nerida is able to help FeedXL members solve any problem they may come up against with feeding their horses.

This newsletter by Dr. Nerida Richards was originally posted to the FeedXL user forums for FeedXL subscribers in April, 2009. If you would like be among the first to receive our newsletters then please consider subscribing to our email list.

QUESTIONS? COMMENTS?

Click here to join us on our Facebook Page