Determine Turnover Rates Research Articles

Evaluation of rare-earth markers using an in vitro ruminal fermentation system and effect of processing method on ruminal turnover of sized corn particles.

A two-stage in vitro ruminal fermentation experiment was conducted to determine the extent of marker migration and the effects of marker addition on digestibility. Fermentation studies were terminated either at the end of stage I, the fermentation phase, or stage II, the pepsin digestion phase. Treatment diets contained ytterbium-marked corn plus chopped Coastal bermudagrass hay and nonmarked corn plus chopped hay. After stage I of the in vitro ruminal fermentation, 90% of ytterbium was recovered. Of this, 8.8% of the ytterbium had migrated to the hay, 2% was recovered in the supernatant and 89.2% remained bound to the corn. After completion of both stages, 72% was recovered, of which 7.9% was bound to corn, 33.6% was bound to the hay, 1.1% was recovered in the stage I supernatant and 57.4% was associated with the acid pepsin supernatant. Dry matter digestion was not affected after stage I but after stage II, digestibility was decreased 7% due to marker addition. A ruminal-cannulated Holstein steer weighing approximately 680 kg was used to determine turnover rates from the rumen of liquid and five different particle sizes of corn. Corn from each of two processing methods was fractionated into five particle sizes by dry-sieving. The corn particles included steam-rolled corn (SRC) retained on a 4-mm sieve and marked with dysprosium, SRC retained on a 2-mm sieve and marked with erbium, cracked corn (CC) retained on a 4-mm sieve and marked with yttrium, CC retained on a 2-mm sieve and marked with ytterbium, and CC retained on a 1-mm sieve and marked with samarium.(ABSTRACT TRUNCATED AT 250 WORDS)

A microcomputer program for determining turnover rates before and after intervention in a single animal

A set of three programs to calculate the turnover of biomolecules whose metabolism follows a steady-state precursor-product relationship and follows the open, single-compartment kinetics model has been written in MS-BASIC. The programs comprise a system for determining two values of turnover, before and after an intervention which may alter the turnover rate, in a single animal. The programs have been extensively tested in our laboratory for the determination of norepinephrine turnover under differing physiological and pharmacological conditions. The utility of the programs lies in their ability to readily adapt to turnover determinations for any substance whose metabolic pathway conforms to the model constraints. This includes the biogenic amine neurotransmitters, peptides and proteins, and many small biological molecules or pharmacological agents.

Theory of use of the turnover rates of body water for measuring energy and material balance

The theory is developed for the use of the isotopically determined turnover rates of the hydrogen and oxygen of body water for measurement of total energy and material balance of an animal. After a consideration of several simplifying assumptions, a summary is given of tests of the extent to which theoretical expectations are realized. The results of these appear to be in general accord with theoretical expectations.