The cxpcriments to be reported in this paper wcrc planned with
two objects in view: one, to obtain quantitative information con-
cerning the relative biological values for maintenance and growth
of the proteins of whole wheat, egg, and pork, as determined by
investigation of the utilization by growing rats of their content of
t.otal nitrogen, and the other, to test out the method adopted in
this laboratory (1) of conducting such investigations and of inter-
preting the results secured. It was desired, in particular, to dis-
cover whether the order in which a series of foods was tcstcd influ-
ences in any way the biological values obtained, and whether the
utilization of food proteins is increased if fed immediately after
a 10 day period in which the experimental subjects are greatly
depleted in nitrogen by subsistence on a low nitrogen diet.
A litter of nine rats, weighing from 70 to 80 gm. each, was
divided into two groups, one of five and one of four rats. The
first group was fed the different rations in the following order:
protein-free, wheat, egg, pork, and protein-free. The order of
feeding for the second group was as follows: protein-free, egg,
pork, wheat, and protein-free. The feeding periods were of 10
days duration, on the last 7 days of which collections of feces and
urine were made. The only change in procedure from that
already reported was that the rat, instead of resting directly on
the filter paper mat in the bottom of the crystallizing dish, was
supported about h inch above the filter paper on a circular disc
of $ inch mesh wire screen, resting on a bent heavy glass rod (SW
Fig. 1). By this means consumption of feces and filter paper by
the rat was practically entirely avoided.
To maintain the appetite of the rats throughout the experiment,
each rat was given, aside from its food, 25 mg. daily, in all periods,
of a commercial vitamin B product (yeast vitamin-Harris powder),
prepared according to the method of Osborne and Wakeman.
This amount contained by analysis 2.34 mg. of nitrogen, 16 per
cent of which was free amino nitrogen, and 28 per cent free and
combined amino nitrogen. The possible vitiating effect of this
small amount of nitrogen on the estimations of biological value
has been discussed elsewhere (2).
The figures given in the tables
or nitrogen intakes and biological values do not include or involve
n any way this amount of nitrogen.
Untuk lebih lanjut lihat di : www.jbc.org/cgi/reprint/60/3/613.pdf
two objects in view: one, to obtain quantitative information con-
cerning the relative biological values for maintenance and growth
of the proteins of whole wheat, egg, and pork, as determined by
investigation of the utilization by growing rats of their content of
t.otal nitrogen, and the other, to test out the method adopted in
this laboratory (1) of conducting such investigations and of inter-
preting the results secured. It was desired, in particular, to dis-
cover whether the order in which a series of foods was tcstcd influ-
ences in any way the biological values obtained, and whether the
utilization of food proteins is increased if fed immediately after
a 10 day period in which the experimental subjects are greatly
depleted in nitrogen by subsistence on a low nitrogen diet.
A litter of nine rats, weighing from 70 to 80 gm. each, was
divided into two groups, one of five and one of four rats. The
first group was fed the different rations in the following order:
protein-free, wheat, egg, pork, and protein-free. The order of
feeding for the second group was as follows: protein-free, egg,
pork, wheat, and protein-free. The feeding periods were of 10
days duration, on the last 7 days of which collections of feces and
urine were made. The only change in procedure from that
already reported was that the rat, instead of resting directly on
the filter paper mat in the bottom of the crystallizing dish, was
supported about h inch above the filter paper on a circular disc
of $ inch mesh wire screen, resting on a bent heavy glass rod (SW
Fig. 1). By this means consumption of feces and filter paper by
the rat was practically entirely avoided.
To maintain the appetite of the rats throughout the experiment,
each rat was given, aside from its food, 25 mg. daily, in all periods,
of a commercial vitamin B product (yeast vitamin-Harris powder),
prepared according to the method of Osborne and Wakeman.
This amount contained by analysis 2.34 mg. of nitrogen, 16 per
cent of which was free amino nitrogen, and 28 per cent free and
combined amino nitrogen. The possible vitiating effect of this
small amount of nitrogen on the estimations of biological value
has been discussed elsewhere (2).
The figures given in the tables
or nitrogen intakes and biological values do not include or involve
n any way this amount of nitrogen.
Untuk lebih lanjut lihat di : www.jbc.org/cgi/reprint/60/3/613.pdf
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