Various Factors Affecting Plasma Free Amino Acid Concentrations in the Horse
Russell, Mark Allen
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https://hdl.handle.net/2142/70005
Description
Title
Various Factors Affecting Plasma Free Amino Acid Concentrations in the Horse
Author(s)
Russell, Mark Allen
Issue Date
1982
Department of Study
Animal Sciences
Discipline
Animal Sciences
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Agriculture, Animal Culture and Nutrition
Abstract
A series of trials was conducted to determine the effects of various factors including meal schedule, fasting, age and sex of the animal, protein level and quality, exercise, training, length of time on the diet and sample location, on the resulting plasma free amino acid (PFAA) concentrations in the horse. Six horses were individually fed a complete pelleted diet of 15.1% C.P. at a rate of 1.75% of body weight in either one, two or six meals daily. Horses receiving six meals had more constant level of PFAA than horses fed one or two meals. Feeding one or two meals per day produced large PFAA peaks at five and three h after beginning the meal, respectively. Following the absorptive peak at five h, PFAA declined to a constant level at 20-30 h, then rose to near absorptive levels when the fat was continued for 48 h. There was no plateau of PFAA, indicating that a steady state fasting level was not attained.
When the effect of age on plasma arginine (ARG), lysine (LYS), histidine (HIS) and ornithine (ORN) was investigated in weanling, yearling and mature mares receiving a 16.8% C.P. diet, it was observed that PFAA were lower in weanlings than in the yearlings or mature mares. The yearlings were lower in ARG than the mature mares. There was no effect of sex on any of the PFAA except ORN which was higher in males.
Although PFAA increased with age when horses were fed the 16.8% C.P. diet, there was no effect of age on PFAA when horses were fed the 8.5% C.P. diet. The higher amino acid/protein content of the 16.8% C.P. diet was reflected in higher PFAA in horses of all ages. On the first day following the change from the 8.5% C.P. diet to the 16.8% C.P. diet, plasma LYS, ARG and HIS levels were lower than on day four, eight or 12, indicating that one day is not time enough for the PFAA pool to adapt. There was no apparent effect of protein source on plasma LYS during hours one to four after eating the meal when weanlings were fed diets containing either soybean oil meal or cottonseed meal with crystalline lysine.
The effects of an aerobic training program and a single exercise bout on PFAA were examined in six mature mares. PFAAs sampled at rest and while trotting were not different; however training increased plasma leucine and aspartic acid. Samples taken from the jugular vein, pulmonary artery and carotid artery were not different in their PFAA concentrations.
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