Physiological responses to training and racing in two year-old Quarter Horses fed Sodium Zeolite A

Abstract

Fifty-three Quarter Horse yearlings were fed 0, .92, 1.86 or 2.80% Sodium Zeolite A (SZA) in the total diet. Beginning at approximately 18 mo of age, the horses were trained to ride, conditioned and run in nine match races--three races each at 274 m, 320 m and 366 m. During the last long slow distance workout (LSD), the last LSD with sprints workout prior to racing, and each race, blood samples were collected and heart rates (HR), respiration rates (RR) and rectal temperatures (RT) were measured at rest, after the warm-up, and at 1, 2, 5, 10, 20, 30, 60 and 120 min of recovery. Blood samples were analyzed for packed cell volume (PCV) and plasma ionized calcium (Ca++), sodium (Na+), potassium (K+), lactate (LA-) and glucose. Data were analyzed by ANOVA using the repeated measures GLM of SAS Scheffe's multiple comparison test to compare means by treatment, race and sample (time). Results were considered significant at P<.l. The horses were able to run increasingly longer races without corresponding changes in HR, Na+, K+, Ca++, glucose, or PVC . Pre-race excitement was responsible for most of the change from resting HR in the races. However, maximum HR were not as high as is commonly reported in TB horses running longer distances. Mean RR and RT were higher during recovery with increasing race distance. Plasma silicon concentrations were elevated in treated horses, proving the bioavailability of silicon in SZA. There were no detected harmful effects and no important physiological advantages due to feeding SZA. There were no differences in HR, RR, RT, PCV, Ca++, Na+, K+, LA- or glucose between treated and untreated horses. With the Student's t test, fillies were found to be shorter at the withers and hip and smaller in heartgirth and external cannon bone circumference than geldings. However, there were no differences between genders in weight, condition score, rump- fat, soundness or race times. These results suggest that the routine decision to select against good fillies as race horses is not beneficial.