The energy requirements of performance horses in training

Abstract

The aim of this study was to estimate the energy requirements of performance horses in active, variable training in the field. Sixty horses in England and Switzerland were measured over 2-wk periods and, for 15 of these, the measurement period was extended, ranging from 21 to 42 wk. Energy intake was estimated by measuring daily feed consumption. Energy output was measured using heart rate (HR) monitors during 608 training sessions, relating HR to volume of oxygen (VO₂) and converting VO₂ to energy. Field maintenance requirements were calculated by deducting the marginal energy cost of training from energy input. The mean field maintenance expenditure for performance horses with a normal temperament was found to be 0.118 MJ of metabolizable energy (ME) per kilogram of body weight (BW) per day (SD = 0.008, CI = 0.005, n = 60 horses). This result is between 1.9% (P = 0.086) and 20.9% (P < 0.001) greater than the official guidance found in the United States, France, Germany, and Holland. Heart rate monitoring of training revealed a mean energy expenditure (EE) per ridden session of 0.023 MJ ME (SD = 0.001, CI = 0.001, n = 175 training sessions). The mean daily EE for exercise based on a full week’s training was 0.018 MJ ME/kg BW/d (SD = 0.005, CI = 0.001, n = 60 horses), representing a multiple of maintenance of 15.3%. This implies that the official guidance in the United States and France may overstate expenditure for exercise by 111% and 15%, respectively (P < 0.01). Daily EE between countries and within disciplines was consistent, allowing for the creation of user-friendly tables that can be used in budgeting the energy component of diets.

Where Are We Now? Feeds, Feeding Systems and Current Knowledge of UK Horse Owners When Feeding Haylage to Their Horses

“…Eighty-three percent fed a complementary feed (coarse mixes or compound nuts), which was generally given in two meals/day. The surveys did not identify how much feed was being fed and the exact content of the diet, nor the exact energy requirements for each individual horse or their body weights, but given the persistent high levels of obesity in the UK equine population, it is perhaps concerning that such a high proportion of our surveyed owners were feeding more than just a balancer (or low energy-fortified fibre-based feed) with their fresh or preserved forage [ 10 , 11 , 12 , 30 ]. More in depth investigations are required to explore the reasons behind this.…”

“…It is also worth noting that, when stabled horses are just standing, eating and not moving around to forage, their energy expenditure will be lower than when continually moving during grazing [ 32 ]. In the field study of Ebert and Moore-Colyer based on 175 recorded training sessions over 45 weeks, the commonly used system in the UK, i.e., NRC (2007) recommendations, were found to overestimate the energy requirements for mild exercise by 11% [ 33 , 34 ]. Coupled with this is the challenge faced by many owners of how to accurately determine the exercise level of their horses [ 35 ].…”

“…Failing this, weigh tapes, although not an accurate means of obtaining body weight, can be used to monitor changes in shape, provided it is placed correctly on each repetition [ 36 ]. In addition, nutritionists and veterinarians could actively promote and demonstrate simple energy requirement calculations, so that requirements are based on the individual horse’s actual energy expenditure, a value that is easily determined using a heartrate monitor and the user-friendly equation of Ebert and Moore-Colyer [ 33 ].…”

“…Digestive and mental health issues have also received attention [ 9 ]. However, despite all these advances, the prevalence of obesity in the UK equid population remains very high, indicating a mismatch between energy intake (and, therefore, dietary choice) and energy requirements [ 10 , 11 , 12 ].…”