Effects of training distance on feed intake, growth, body condition and muscle glycogen content in young Standardbred horses fed a forage-only diet

Abstract

This study examined feed intake, growth, body condition, muscle glycogen content and nutrition-related health in 16 Standardbred horses fed a high-energy, forage-only diet ad libitum and allocated to either a control training programme (C-group) or a training programme with the high-intensity training distance reduced by 30% (R-group), from January as 2-year olds until December as 3-year olds. Feed intake was recorded on 10 occasions during 3 consecutive days. Body weight was recorded once in a week and height, body condition score (BCS), rump fat thickness and thickness of the m. longissimus dorsi were measured at 7±3-week intervals throughout the study. Muscle biopsies of the m. gluteus medius were taken in December as 2-year olds and in November as 3-year olds and analysed for glycogen content. Nutrition-related health disorders were noted when they occurred. Horses consumed 1.7% to 2.6% dry matter of BW, corresponding to 19 to 28 MJ metabolisable energy/100 kg BW. There were no differences between training groups in feed intake or any of the body measurements. The pooled weekly BCS was maintained between 4.8 and 5.1 (root mean square error (RMSE)=0.4). Muscle glycogen content was 587 and 623 mmol/kg dry weight (RMSE=68) as 2- and 3-year olds, respectively, and there was no difference between training groups. When managed under normal conditions, no nutrition-related health disorders or stereotypic behaviours were observed. It was concluded that the training programme did not affect feed intake, growth, BCS or muscle glycogen content. In addition, the forage-only diet did not appear to prohibit muscle glycogen storage, growth or maintenance of body condition, and seemed to promote good nutrition-related health.

Increased body fat content in horses alters metabolic and physiological exercise response, decreases performance, and increases locomotion asymmetry

“…in the proportion of fat accumulated subcutaneously, intramuscular and visceral. Nevertheless, the method has earlier been shown useful in for example Standardbred horses (Klein et al, 2020) and in the same breed rump fat thickness has also been negatively correlated with VLa 4 (Ringmark et al, 2017).…”

Parasites in Horses Kept in A 2.5 Year-Round Grazing System in Nordic Conditions without Supplementary Feeding

“…Body condition is reported to be negatively correlated with parasite burden in feral horses [39]. The lower limit of body condition score set for horses to remain in the present study was 4 (scale 1-9), which is still 'healthy' condition (corresponding to the fat content of equine athletes [40,41]). The results indicate that at this body condition, horses may still invest energy in resistance to parasites, which may not be the case in horses in poorer body condition [42][43][44].…”

Straw as an Alternative to Grass Forage in Horses—Effects on Post-Prandial Metabolic Profile, Energy Intake, Behaviour and Gastric Ulceration

“…Feed changes have been associated with increased risk of colic during the following subsequent 2 weeks [ 44 ]. However, the same study setup (abrupt feed changes or changes within 4 days) have been used in many studies with forage-only diets without problems being encountered [ 21 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 ]. This is in contrast to the field observations by Hudson et al [ 44 ] and may be due to that our feed changes have been between feeds of good hygienic quality and “balanced” (as in the present study), i.e., diets have had similar energy and nutrient contents, with a few exceptions where crude protein content differed substantially [ 45 , 47 , 48 , 50 , 52 ].…”