Protein deprivation in primates. I. Nonpregnant adult rhesus monkeys

Postnatal protein deprivation in rhesus monkeys

We studied the growth of 97 rhesus monkeys (M. mulatta) that from birth until 120 days of age were fed a diet containing 13.4%, 6.7%, 3.35% protein or a commercial simulated human-milk formula (SMA) affording 9% protein. After 120 days, all animals were fed SMA. Females fed the diet lowest in protein, but not the other diets, were moderately affected, gaining less weight than their well-fed counterparts did, but they recovered their deficit during the repletion period, so that at 240 days no group differences remained. Males fed the two lowest-protein diets were severely and profoundly affected, in keeping with the depth of their protein deficiency. Moreover, unlike the females, they recovered none of their weight deficit during the repletion period. Food intake during deprivation was lower in the animals eating the low-protein diets. During SMA repletion, intakes followed no simple rule, but they did not converge. Except for the males fed the 3.35% protein diet, relative food intake (ml formula/kg body weight) did not differ substantially between diets or sexes at any time during the deprivation and diminished as the animals got older. Those males' relative intakes did not decline. During repletion, the SMA females ate the most in proportion to weight and the 13.4% group the least. The lowest-protein males, in contrast, ate the most in proportion to their weight during both deprivation and repletion. Males fed the lowest-protein diet gained little for what they ate; those fed the highest-protein diet gained much. Females were more efficient than males were when eating the low-protein diet and less efficient when eating the high-protein diet. When fed SMA during repletion, males' food efficiencies (grams gained/liter of diet) were nearly equal; females still differed: the SMA group was the least efficient and the low-protein group most efficient. Its counterpart, protein efficiency, was greatest (during deprivation) for females eating the low-protein diet and least (among females) for those eating the high-protein diet. Males were least protein efficient if eating the low-protein diet. Evidently, a 4 month bout of protein deprivation had prolonged effects on the amount of food the animals needed to produce a given gain in weight.

Intraday feeding patterns in infant rhesus monkeys and the effects of missing a meal

During the first month of life, infant rhesus monkeys (N = 96) were fed 7 times a day for the first 21 days and were fed 6 times a day thereafter. Fifty monkeys were fed SMA, a formula designed for human infants (9% protein, 43% carbohydrate, and 48% fat); 46 were fed one of three laboratory-confected diets varying in the amount of protein and carbohydrates provided. Although the diets had differential effects on weight gain, overall daily consumption was practically unaffected. A characteristic pattern was evident soon after birth: The first meal of the day (8:00 AM) was one of the largest, and the following two meals were usually the smallest; the next peak spanned the 4:00 PM and 8:00 PM feedings. The meal following a missed meal was slightly larger than normal. To some extent, the large meal at 8:00 AM can be attributed to the 10-hr absence of food during the night, but the peak at 4:00 PM and 8:00 PM cannot be so accounted for. The adult bicuspid pattern of eating hence appears to develop very early in life.

Scotopic thresholds of rhesus monkeys at different grating densities under normal and low-protein diets

Scotopic thresholds of rhesus monkeys were determined over a range of luminance levels, from 1138 to 17.8 x 10(-9) cd/cm2, and grating densities, from .132 to 1.58 lines per cm. The effects of a low-protein diet on these thresholds were also investigated, and standard stimulus objects within the discrimination learning situation were employed. Obtained thresholds decreased systematically from about 350 to 20 x 10(-9) cd/cm2, and there were no significant differences due to dietary protein level.

Chronic tubulointerstitial nephritis and wasting disease in marmosets (Callithrix jacchus)

Six marmosets (Callithrix jacchus), 20 months to 16 years old, died from a disease characterized by weakness and paralysis of the hind legs, weight lose, anemia and transient diarrhea. The lesions most prominent at necropsy were subacute to chronic tubulointerstitial nephritis, subacute to chronic pancreatitis, and generalized hemosiderosis. Chronic protein deficiency is believed to be the underlying pathogenic mechanism, since the diet contained no more than 15% animal protein during the last two years, and increasing the amount of protein was accompanied by disappearance of the syndrome.

Protein deprivation in primates. VIII. Early behavior of progeny

Infant rhesus monkeys whose mothers were fed diets providing 1, 2, or 4 g of protein/kg body weight/day during pregnancy were tested on 13 behavioral tests during their first 60 days of life. (The diets had been shown to affect significantly the weights and blood protein concentrations of both pregnant and nonpregnant females.) The tests samples a wide range of behaviors, including visual and auditory perception, feeding reflexes, and locomotion. Despite the maternal dietary differences, the performances of infants on all tests were comparable in all groups. These data contrast with the finding of persistent deficit in rats born of protein-deprived mothers.

Protein deprivation in primates. 3. Cage activities and chain-pulling behavior of adult rhesus monkeys maintained on low-protein diets

Three groups of adult female rhesus monkeys, maintained on low-protein diets (.5-gm, 1-gm, and 2-gm protein per kg body weight) were compared with a control group (4-gm protein per kg body weight) on a number of spontaneous cage activities and chain-pulling behavior. Although the deprived animals lost body weight and muscle tissue and they became deficient in essential amino acids and plasma albumin, they maintained their normal posture and continued to move about, vocalize, eat, drink, etc., as such monkeys usually do in their home cages. However, several specific behavioral deficiencies were revealed: reduced face and head movements, fewer eye contacts, and less chain pulling. It was concluded that the level of protein deprivation induced in this study depletes the animals' energy resources and produces a lowered anxiety threshold, so that certain additional behavioral demands cannot be supported even though routine cage activities are not impaired.