The Effect of Change of Ration on the Required Length of Preliminary Feeding Period in Digestion Trials with Sheep

Abstract

Four sheep were fed a field-cured all-roughage ration immediately upon their removal from pasture, and a hay plus grain ration immediately following the all-roughage ration. By extending the length of preliminary feeding period it was found that the apparent digestibility of the dry matter, crude protein, crude fiber, ether extract and nitrogen-free extract of both rations showed rhythmic fluctuations. Because of these fluctuations, it seemed highly improbable that constant and maximum digestibility of the nutrients studied is biologically normal. A statistical analysis of the individual apparent digestion coefficients of each of the nutrients calculated for preliminary feeding periods of from zero to 60 days indicated that following the “standard” 10-day preliminary feeding period, and with the exception of ether extract, the effect of time on the variation of these digestion coefficients was of minor significance. Since constant digestion coefficients were not obtained for certain nutrients even when the length of preliminary feeding period was extended to 60 days, and since any increase in precision thereby realized was shown to be insignificant in practice, there does not appear to be any justification for increasing the length of preliminary feeding period in sheep digestion trials beyond 10 days. Copyright © . .