TABLE 7-4 Estimates of Vitamin B6 Requirement

Species

Age

Body Weight

Daily AirDry Diet Consumption

Type of Diet

Vitamin B6 Levels Studied

Criteria

Estimated Requirement

Reference

Macaca mulatta

Immature

1.3-3.0 kg

Not specified

Purified

50-1,000 µg·d-1

Growth of depleted animals

62 µg·BWkg-1·d-1

Rinehart and Greenberg, 1956

Macaca mulatta

Not specified

4.1 kg

60-170 g

Purified fat 220%

Pyridoxine HCl at 0.5-2.0

Growth of depleted animals

1.0-2.0 mg·d-1 or 0.24-0.49 mg·BWkg-1·d-1

Emerson et al., 1960 mg·d-1

 

1.0 mg·d-1 required to prevent all deficiency signs; 2.0 mg·d-1 supported faster growth

 

Cebus albifrons

Not specified

900-1,500 g

Not Specified

Purified

0-1,100 µg· BWkg-1· d-1

Weight gain and hematocrit recovery in depleted animals

50-100 µg·BWkg-1·d-1 for growth; 175-200 µg·BWkg-1·d-1 for optimum hematocrit

Mann, 1968

Papio hamadryas

Adolescent males

7-15 kg

Probably 190-378 g

Purified

1.11 mg·d-1

Control animals exhibit no deficiency signs.

 

Foy et al., 1974

although the baboons had received no carcinogenic substance. Serum vitamin B6 concentrations dropped from 200-350 ng·ml-1 to 5-10 ng·ml-1 (Foy et al., 1970; Foy et al., 1974). The urine of pyridoxine-deficient baboons had increased concentrations of the tryptophan metabolites xanthurenic acid, kynurenine, and 3-hydroxykynurenine (Foy et al., 1974; Verjee, 1971).

Control baboons in the investigations of Foy et al. (1974) received a daily oral supplement of 1.0 mg of pyridoxine hydrochloride and an additional 0.11 mg from ingredients in the diet. That dosage level was equivalent to 74-158 µg·BWkg-1·d-1, or about 3.1 mg·kg-1 of dietary DM, and apparently exceeded the requirement.

A syndrome similar to vitamin B6 deficiency has been observed after chronic administration of isoniazid, a drug used for prevention of and treatment for tuberculosis. Although evidence of an induced B6 deficiency was equivocal, urinary vitamin B6 was increased when the drug was administered to humans (Levy et al., 1967). Manning and Clarkson (1971) did not observe a decrease in vitamin B6 concentrations in the serum of rhesus monkeys receiving isoniazid when fed a diet containing vitamin B6at 21 mg·kg-1. That is a high dietary intake of vitamin B6 and suggests that supplemental vitamin B6 should be considered for primates receiving this drug even though the pathogenesis of the syndrome induced by isoniazid is not understood.

The dietary vitamin B6 requirement has been estimated to be 4.4 mg·kg-1 of DM. The preponderance of evidence suggests that that level is adequate to meet the needs of rhesus and capuchin monkeys. However, if the details of the study by Emerson et al. (1960) were correctly reported, the dietary requirement under some conditions could be as high as 9.6 mg·kg-1 of DM.

Biotin

Biotin serves as a cofactor in carboxylation and decarboxylation reactions. It is concerned with introduction of bicarbonate, as a carbonyl group, into metabolic steps involved in gluconeogenesis, fatty acid synthesis, and amino acid metabolism (Mock, 1996, 1999). Substantial amounts of biotin can be synthesized by the microbial flora in the intestinal tract. Signs of biotin deficiency have been produced experimentally by feeding raw egg white. Raw egg white contains the protein avidin, which binds biotin and prevents its absorption (Bonjour, 1991). Biotin is widely distributed in natural feedstuffs. However, the biologic availability of biotin in wheat, wheat byproducts, barley, and oats is low (Frigg, 1976; Anderson et al., 1978).

Biotin deficiency has been produced in rhesus monkeys (Macaca mulatta) by feeding deficient diets and by feeding deficient diets containing raw egg white. A more severe deficiency is produced by feeding sulfa drugs (sulfguanidine or sulfasuxidine) to prevent production of biotin by the intestinal microflora (Lease et al., 1937; Waisman and Elvehjem, 1943; Waisman et al., 1945). Animals fed a biotin-deficient purified diet, without egg white or sulfa drugs, showed a gradual loss of fur color followed by loss of fur. These deficiency signs could be reversed or prevented by the daily administration of 20 µg of biotin. Rhesus monkeys receiving 12 µg of biotin daily did not show deficiency signs, whereas those receiving 1.7-9.0 µg per day showed



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