Infant Formula - To Use or Not to Use
Are the Potential Risks Worth the Price?


Too often we don't have access to documented information when faced with important decisions. We end up relying on other people's personal experiences and can only hope that our own experiences have a positive outcome. Such seems to be the case when infant formula for non-human primates comes up in conversations between primate caretakers.

It is generally agreed upon that "Mother's Milk" (no matter what species of mother is being referred to) is the most nutritious, easily digested form of nourishment for that mother's infant. In reality, there are times when a mother is not able to breast feed their infant and choosing a formula that is mixed specifically for that species is most important, not only for optimal development but to minimize possible negative side-effects (short and long term). Non-human primates develop ideally when left in their mother's care. "Work with non-human primate infants has shown that contact with mother, of which nipple-contact is an important component, not only reduces behavioral stress, but also reduces the infant's adrenocortical response to stressors such as disruption of the social group, capture and handling, and rehousing in novel environments"  (Coe et al., 1978; Gunnar et al., 1981b). When this is not an option, it is imperative you feed a supplement that comes closest to the natural contents of a non-human primate's milk.

Human infant formula is usually not the supplement of choice, if you want the best start for the non-human infant. Studies are being done to document a possible correlation in risks associated with feeding non-human primates with human infant formulas, such as diabetes. Late weaning of non-human primates is believed to be associated with obesity in their later years. There fore this is another factor to be taken into consideration when hand-rearing an infant non-human primate.

From "The Composition of Primates' Milk and Its Importance in Selecting Formulas for Hand-Rearing" by Exequiel M. Patiño and Juan T. Borda Universidad Nacional del Nordeste, (found in the Laboratory Primate Newsletter, VOLUME 36 NUMBER 2 APRIL 1997) the following information may help you make a more informed decision regarding non-human infant formulas.



Very little is known about the composition of primates' milk. Of the approximately 166 species of primates in existence, the milks of only 19 have been studied, and those only incompletely (Oftedal, 1984). The milk of humans is the only one that has been analyzed with the frequency necessary to establish an average composition that is trustworthy (Packard, 1982). In nonhuman primates, milk composition has been studied in the great apes (e.g. Ben Shaul, 1962; Tailor & Tomkinson, 1975); Old World monkeys (e.g., Buss, 1968; Buss & Cooper, 1970); New World monkeys (e.g. Buss, 1970; Patiño & Ruiz, 1993); and prosimians (e.g., Buss et al., 1976).

Milk composition is known for only four of the 76 known species of New World monkeys (Mittermeier et al., 1988): Saimiri sp. (Buss, 1970; Buss & Cooper, 1972; Patino & Ruiz, 1993); Leontopithecus rosalia (Buss, 1975); Saguinus oedipus (Glass & Jenness, 1971); and Callithrix jacchus (Turton et al., 1978).

In general, milk of the order Primates, compared with that of other orders, is characterized by moderate amounts of solids and fats, low levels of proteins, and high levels of sugar (Oftedal, 1980). Knowing the composition of primates' milk is of fundamental importance in selecting formulas for feeding infants that are being raised by hand.

Composition of Primates' Milk

Primate milks contain on the average 13% solids, of which 6.5% is lactose, 3.8% lipids, 2.4% proteins, and 0.2% ash. Lactose is the largest component of the solids, and protein is a lesser one (Table 1). The milks of humans and Old World monkeys have the highest percentages of sugar (an average of 6.9%), while those of New World monkeys have the highest content of solids in general and also of proteins and lipids. Comparing the milk of humans with those of non-human primates, we see that they have similar proportions of solids, but the former is richer in sugar and lipids, the latter richer in proteins (Table 2). In fact, human milk has the lowest concentration of proteins (1.0%) of all the species of primates.


Primates     Total Solids Protein  Fat  Sugar  Ash 

                 (%)        (%)    (%)   (%)   (%)


Human (1)       12.5        1.0    4.4   6.9   0.2 



Apes (2)        11.5        2.8    3.0   5.5   0.2                                


Old World   

Monkeys (3)     12.8        1.7    4.0   6.9   0.2                                 


New World   

Monkeys (4)     17.1        4.6    5.4   6.6   0.5                             


Prosimians (5)  11.2        1.9    2.3   6.7   0.3 


Mean            13.0        2.4    3.8   6.5   0.2 


Table 1: The composition of primate milks. (1) Homo sapiens, Packard, 1982; (2) Pongo pygmaeus, Pan troglodytes, Ben Shaul, 1962; Gorilla gorilla, Tailor & Tomkinson, 1975; (3) Cercopithecus talapoin, Buss & Cooper, 1970; Papio anubis, Papio cynocephalus & Papio papio, Buss, 1968; (4) Saimiri sciureus, Buss & Cooper, 1972; Leontopithecus rosalia, Buss, 1975; (5) Lemur spp., Buss et al., 1976.


Order        Total Solids Protein  Fat  Sugar  Ash 

                 (%)        (%)    (%)   (%)   (%)



(Human)(1)      12.5        1.0    6.9   4.4   0.2 




(2,3,4,5)       13.0        6.4    2.7   3.6   0.3                                 



(Cow) (6)       12.2        3.2    3.7   4.6   0.7                             


  Table 2: The composition of primate and cow milks. (1-5) as in Table 1; (6) Bos taurus, Oftedal, 1984.

Milk Formulas for Hand Rearing

Selecting an appropriate milk formula is one of the most important aspects of hand rearing primates. Most systems of hand feeding use formulas for humans, which are based on cows' milk, the composition of which has been modified to make it as similar as possible to human milk. Although both primate and bovine milks have approximately the same percentage of solids, primate milk has more lactose, a similar amount of lipids, and smaller amounts of proteins and ash (Table 2).

The low protein content of primates' milk is correlated with infants' very slow rate of postnatal growth and long periods of dependence on their mothers' milk (Stathatos & Kirkwood, 1988).

The proteins of human milk have an average ratio of 40/60 of casein to whey protein (Kunz & Lonnerdal, 1990), a ratio very different from that of cows' milk, which is 82/18 (Tomarelli & Bernhart, 1962). The former ratio permits correct digestion in the human infant, since casein, when exposed to gastric acids and enzymes, precipitates in the stomach and forms a curd, the solidity of which depends on the proportion of casein in the ingested milk. Cows' milk, which has a high proportion of casein, produces firm, hard curds which are digested relatively slowly. Whey proteins, in contrast, pass rapidly through the stomach. This is why the casein/whey proteins ratio of milk is of fundamental importance in the nutrition of many nonhuman primates, and why Oftedal (1980) affirms that it is preferable to use those formulas which are modified to make them similar to human milk.

Kunz & Lonnerdal (1993) have found that the casein/whey protein ratio in the milk of Macaca mulutta is very similar to that of human milk.

The milk formula S26reg. fortified with iron from Wyeth Laboratory has been successfully used for hand feeding, during their first weeks of life, infants of the species Saimiri boliviensis (Patiño et al., 1995) and Cebus apella (Patiño et al., 1996). The proteins in this formula have a ratio 40/60 of casein to lactalbumin, similar to that in human milk, and very different from their proportions in bovine milk (Table 2).


Of all the species comprising the Order Primates, milk composition is known for only 11%; and of New World monkeys, for only 5%. One has to take into account that there are variations in milk composition due to the few samples obtained from each species, the methods of analysis used, and the state of lactation in which they were obtained. Therefore these results should only be regarded as preliminary. Better knowledge of milks' compositions, together with studies of lactation in non-human primates, are of vital importance for developing hand-rearing programs, which play a very important role in propagating both species in captivity and those in danger of extinction when the life of the neonate is threatened.


Authors' address: Grupo de Investigactiones Primatológicas, Proyecto P.I. SECyT - (UNNE), Fac. de Ciencias Veterinarias, Univ. Nacional del Nordeste (UNNE), Sgto. Cabral 2139, (3400) Corrientes, Argentina []
The authors would like to thank Elva Mathiesen and her sister, Juanita Watt, for translating this paper from Spanish.      The preceding information may be found at:



The Risks of Infant Formula Feeding

Formula feeding accounts for up to 26% of insulin dependent diabetes mellitus in children. Otitis media (middle ear infection) is up to 3-4 times as prevalent in formula-fed infants.  US Formula fed infants have a 10 fold risk of being hospitalized for any bacterial infection.

Scores on the Baley Mental Development Index were lower in formula-fed children at 1-2 years of age.  Scores were directly correlated with the duration of breastfeeding.  Formula fed preterm infants had lower IQ scores (8 points) at age 7-8 years than breastfed premies, even after adjustment for mother's education and social class.

Due to an excessive phosphate load in formula, formula fed infants face a 30-fold risk of neonatal hypocalcemic tetany (convulsions, seizures, twitching) during the first 10 days of life.  Formula fed infants are at a high risk of exposure to life-threatening bacterial contamination.  Enterobacter sakazakii is a frequent contaminant in powdered formula and can cause sepsis and meningitis in newborns.

Add the risk of formula recalls found at:   and then decide if using them is worth the risks you may be subjecting the non-human infant to. Cases of Salmonella contamination, glass particles found in formula bottles and labeling errors. "Several studies link formula feeding with rotavirus gastroenteritis, celiac disease, Crohn's Disease, ulcerative colitis in adulthood, childhood-onset insulin dependent diabetes mellitus, lymphomas."

Are you really willing to take the chance that the human infant formula you feed the non-human infant in your care is safe?

And more information about mother's milk versus formula:

"The evidence from animal experiments suggests that pre and post-natal nutrition have pronounced effects on brain lipid composition and learning (Gall) and Socini, 1983). Specific deficits of n-3 fatty acids influence neural integrity (Budowski, Leighfield and Crawford, 1987) and selectively affect learning and visual abilities (Wheeler, Benolken and Anderson, 1975; Lamptey and Walker, 1976; Bourre et al., 1989; Yamamoto et al., 1987). Studies with non-human primates confirm that n-3 deficiency depresses the development of retinal function and visual acuity (Neuringer, Anderson and Connor, 1988; Connor, Lin and Neuringer, 1990).

Data on brain composition provide a comparison of formula-fed versus breastmilk-fed babies and give further evidence that dietary fatty acids influence the developing brain of term infants (Farquharson et al., 1992). Eight year follow-up studies which compared premature babies who were fed human milk by tube with those fed formula showed an IQ which was eight points lower in those children who had been fed formula (Lucas et al., 1992)."

If you must substitute formula to feed a non-human infant, the following company comes highly recommended.

Bioserv has a product called Primilac infant formula (on their website:

"This outstanding milk substitute meets the special needs of both New and Old World non-human infant primate. It is a must for foster nursing when primates are rejected, abused, or exhibiting signs of illness. Increased levels of folic acid and ascorbic acid that can not be found in human milk substitutes help to meet the increased requirements of New World Monkeys. In addition, selenium, chromium, and fluoride, which cannot be found in human formulas, have proven to be essential elements that are provided in Primilac along with balanced vitamins and minerals.

Features & Advantages: 

Designed to meet higher metabolic rate and increased nutrient requirements for growth. Contains higher protein than the 8-10% of Kcal in human milk substitutes, which are required by most primates, particularly smaller species of New World Origin. Contains 120 mg. per liter of Vitamin C compared to 60 mg. per liter in human formulas. Both New and Old World monkeys have been shown to respond with increased weight gain when certain amino acids like those included in Primilac are introduced into their diet. Easy to prepare with new Shake & Pour formula - no blender needed. Manufactured according to GMP guidelines and can be approved for use in GLP studies

Powder Mixing Directions:
One Kg. of Primilac Powder makes 32, 6 ounce servings. (See caloric breakdown)

Shake & Pour Formula:
Simply mix with warm tap water and shake for approximately 1 minute until dissolved.
Refrigerate unused portion up to 3 days. Prepared diet should not be kept longer than 48 hours at room temperature.

Original Formula:
Mix with warm tap water and blend for approximately 1 minute.

Assays performed by independent laboratory on every lot of diet prior to shipment.
Actual certificate of analysis is sent to you after each shipment for documentation.

Nutritional Assays:
Ascorbic Acid, Protein, Fat, Fiber, Carbohydrate, Ash, Moisture

Caloric Profile:
Every 6 oz. serving contributes:
Protein          12.75 Kcal/6 oz.
Fat              71.90 Kcal/6 oz.
Carbohydrates    56.70 Kcal/6 oz.
TOTAL           140.35 Kcal/6 oz.

Shelf Life:
6 months refrigerated in sealed packages.

1 Kg. resealable mylar bags with measuring scoop. Packed with inert gas to preserve freshness.
1 Kg. makes 32, 6 oz. servings

Product #F0554SP-Primilac (Shake & Pour)
Product #F0554-Primilac (requires blender)

For more information on Primilac:
One 8th Street, Suite One
Frenchtown, NJ 08825

Please call 908-996-2155 between 8:30 a.m. and 5:00 p.m. EST  Monday through Friday. Fax orders, questions or comments to 908-996-4123

Veterinary Assistance:
Technical Assistance:
Sales Assistance: 


(Published Summer 2000 issue of "The Primate Care Journal)


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