Bodyweight Estimation From Linear Measures of Growing Warmblood Horses by a Formula

Highlights

• We observed 13 body measurements, body mass index, and bodyweight of warmblood horses.

• We evaluate the influence of 13 body measurements on the horse bodyweight.

• Four body measurements were selected to be used for weight estimation.

• Formula that corresponds with the physiology of warmblood horses was developed.

• A comparison of weight estimation on the basis of other authors' formulas was made.

Abstract

Formulas for the estimation of bodyweight (BW) are generally used when no scale is available. The objective of this study was to develop a suitable formula for the BW estimation of warmblood horses of different age that were based on linear relations. Five hundred twenty-four warmblood horses from 97 to 1,290 days were weighed, and 13 body measurements, BW, and body mass index were taken. Because of the closest linear correlation with weight, four measurements were selected for weight estimation: body length (BL), heart girth (HG), sternum height (SH), and front pelvis width (FPW). The formula value = [(2 × SH + HG) × 2 × BL × BL × FPW]/10,000,000 was developed from the four selected parameters. Taking into account the variable growth intensity during horse maturation, four age groups with boundary values of 365, 650, and 950 days were created. Using the coefficients of linear correlation between the value and actual weight, the formula for BW estimation was adjusted for each age group: mass = coefficient_1 × value + coefficient_2 (horse age < 365 days: coefficient_1 = 4.46, coefficient_2 = 91.12; 365 days < horse age < 650 days: coefficient_1 = 3.83, coefficient_2 = 135.87; 651 days < horse age < 950 days: coefficient_1 = 3.60, coefficient_2 = 168.09; horse age > 950 days: coefficient_1 = 3.23, coefficient_2 = 221.55). In comparison with past BW estimation formulas, the new equation is the most suitable for BW estimation in warmblood horses of different age (P value < .001).

Introduction

Horse bodyweight (BW) is not always a parameter which horse owners and breeders are able to accurately estimate. However, it is an important parameter describing body development and is a rough equivalent of physiological functions of an organism [1]. A horse's BW can be an important health indicator. Knowing how much a horse weighs and whether it is currently gaining or losing weight can help identify health issues. Low BW in a horse can be caused by health problems (disease or hormone imbalance), old age, parasites, overwork, an unbalanced diet, insufficient feed access (sometimes caused by a low pecking order in the herd), or genetics [2]. Knowing the BW of a horse is important in many facets of horse care, including designing feeding programs and administering medication. However, horse owners and veterinarians working in the field do not generally have access to a livestock scale for the purpose of obtaining a horse's weight [3]. Drugs and anthelmintic preparations are potentially toxic and should be limited to the dosages dictated by the weight of the animal [4], [5]. Sendel [2] found that incorrect BW estimation may result in overdosing or underdosing the animal. Overdosing medicinal products may cause toxicity and colic or other serious complications, including death [2]. Underdosing will not produce the desired effects and, in the case of antibiotics, may lead to antibiotic resistance [2]. Johnson et al [6] found that 88% of horse owners underestimated actual BW by an average of 84.37 kg.

Several researchers have developed BW estimation formulas using body measurements of adult horses [3], [4], [5], [7], [8], [9], [10], [11], [12], [13], [14] and ponies [15], [16], [17]. Stanier et al [18] predicted BW of growing Thoroughbreds. Bodyweight of foals at 2 months of age is reaching 25% to 30% of the weight of the adult animal and after the 6 months of age 45%. Height at withers (HWs) of yearlings is corresponding to 91% to 93% of adults, but their weight corresponds to only 62% to 76% of the weight in adulthood. In the second year of life, the growth rate slows down. Two-year-old horses reach 84% to 90% of BW of adult animals [19], [20], [21]. Dušek et al [1] described changes in the body constitution of growing horses. Body framework of foals is similar to standing rectangle because HW is greater than body length (BL). Within 12 to 18 months of age, the body framework is changing into the square format. During further growth, BL is increasing faster than HW, so the body frame is similar to a rectangle lying on the longer side.

The objective of this research was to develop a simple formula to estimate the BW of different age groups of warmblood horses based on body measurements.