Biomedical Engineering Reference
In-Depth Information
Requirement
Protein requirements for adult nonhuman primates are
fairly typical of other adult noncarnivorous mammals that
have been investigated. Maintenance requirements for adult
animals translate to less than 10% of ME in the diet coming
from protein. Protein requirements are increased for young,
growing animals and for gestating and lactating females,
even after accounting for the likely increase in energy
intake among these animals ( National Research Council,
2003 ). The actual level of protein that will satisfy
requirements depends upon the quality of the protein,
which in turn depends upon its amino acid composition and
factors that affect its digestibility. The NRC ( National
Research Council, 2003 ) recommends that protein in the
total diet (accounting for all foods) be in the range of
15 e 22% of dry matter ( Table 10.1 ). This should be suffi-
cient for all life stages, assuming energy intake is sufficient.
A consistent statement in the literature is that the small
New World callitrichid monkeys (marmosets and tamarins)
have a higher protein requirement than do the larger
monkeys. However, there are no data to substantiate this
claim, and common marmosets have been successfully
maintained on diets with 15 e 16% protein on a dry matter
basis for years with normal health, growth, and reproduc-
tion ( Tardif et al., 1998 ), albeit the protein source was high
quality (lactalbumin). Thus, diets within the NRC sug-
gested protein range are appropriate for the callitrichid
primates. It is true that the protein content of milk from
some of the small New World monkeys (e.g. common
marmosets, squirrel monkeys) contributes a greater
proportion of energy (approximately 20%) ( Milligan et al.,
2008; Power et al., 2008 ) compared to the protein content
of macaque milk (approximately 13%) ( Hinde et al., 2009 ),
suggesting that hand rearing formulas for these monkeys
should contain a higher proportion of energy from protein.
However, even the milk of callitrichid primates is within
the NRC range, suggesting that the life stage with likely the
highest protein requirement
et al., 1976 ). In common marmosets fed very low protein
diets (6% of dry matter) the animals lost weight initially but
reached nitrogen balance after 2 weeks. However,
a consistent finding in that study was extensive coprophagy
( Flurer and Zucker, 1988 ), which may have served to
recycle protein.
Protein Sources and Quality
Protein can be supplied in the diet from a variety of
sources. In purified and semi-purified diets used in highly
controlled research trials, the primary proteins are gener-
ally lactalbumin, casein, or isolated soy protein. In non-
purified diets, primary protein sources are grains and
their byproducts (e.g. corn gluten meal), legume meals
(e.g. soybean meal), seeds and byproducts (e.g. flaxseed
meal), and animal and fish protein sources. Insects may be
provided as enrichment or training items to appropriate
species. Two major factors affect quality of protein. First,
the digestibility of the protein source varies; protein
digestibility in five species of monkeys was shown to be
63 e 88%, and higher protein intakes are associated with
higher digestibility ( National Research Council, 2003 ).
Second, each protein source has a particular amino acid
profile, and the deviation of this profile from the animals'
requirement is a major factor affecting the quality of the
protein. Casein, lactalbumin, and whole egg are often used
as optimal protein quality sources by which other sources
are compared. Using those references, soy protein isolate
provides lower quality (41 e 69% that of lactalbumin for
growth, 80% for maintenance) due to limiting methionine
concentration. Wheat protein (gluten) is generally a poor
protein source (15% of the quality of lactalbumin for
growth) ( National Research Council, 2003 ). In addition,
gluten protein found in wheat, barley, and rye can lead to
celiac disease, with about 1% of humans showing signs of
gluten sensitivity. Gluten is a composite protein, consist-
ing of a prolamin and a glutelin protein. In wheat, the
prolamin protein is gliadin, in barley it is hordein, and in
rye it is secalin. Gluten sensitivity is actually an immune
reaction to gliadin, hordein, or secalin. Sensitivity to these
prolamin proteins may be implicated in some intestinal
pathologies of nonhuman primates, particularly for tama-
rins and other callitrichids ( Brack et al., 1999; Smith et al.,
2006 ), but also in rhesus macaques ( Bethune et al., 2008 ).
Antibodies to gliadin have been detected in individuals
from all these species and have been associated with
diarrhea and intestinal inflammation. It is important to
note that other plant protein fractions termed “gluten,”
such as corn gluten meal, contain different prolamin
proteins and have not been linked to adverse reactions.
Oats have been implicated in celiac disease, but that is
thought to be due to significant contamination by wheat
either in oat fields or in processing plants.
is comfortably within the
15 e 22% recommendation.
Deficiency
Inadequate energy intake will exacerbate protein loss, as
lean tissue will be metabolized to meet maintenance energy
requirements. Macaques, squirrel monkeys, and capuchins
have been used in protein-calorie malnutrition studies.
Signs of protein deficiency include: decreased total serum
protein and albumin concentration, decreased serum amino
acid concentration, decreased serum transferin concentra-
tion, alopecia, anemia, and edema. It is associated with
weight loss, muscle weakness, and lethargy. Protein defi-
ciency can also have neurological effects. Protein defi-
ciency in pregnant rhesus macaques resulted in high
(40 e 50%) neonatal mortality ( Riopelle et al., 1975; Kohrs
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