Synthetic Diets for Herbivora

Abstract

Synthetic diets for herbivora present two special problems, first, because these species are accustomed to diets containing large amounts of cellulose, and second, they are accustomed to high levels of inorganic elements that tend to keep the urine alkaline. The chief problem in selecting a suitable source of pure cellulose is one of physical composition. We attempted to maintain goats upon synthetic diets in which the cellulose portion was furnished by paper, but never succeeded in maintaining the animals upon such a ration. They usually refused the feed entirely after a period of 2 weeks. On the other hand, we have found both goats and rabbits eat regenerated cellulose as readily as the rats, discussed in our earlier report. 1 In devising suitable inorganic mixtures for herbivora we have adopted the plan of imitating the ash constituents of a diet of natural feedstuff s known to be satisfactory for goats and sheep. Such a mixture, however, is rich in the element, silicon. Although it has long been recognized that skin, hair and wool are relatively rich in silicon, we know little of the nutritional requirements for this element. Furthermore, we know little about the form in which it occurs in plants and almost nothing concerning its metabolism in the animal body.

During the past year we have maintained an adult male goat upon a synthetic diet of the following composition, for a period of 152 days: regenerated cellulose 20 30, corn starch 30, casein 15, sucrose 10, yeast 5, salt mixture 7, and lard 3. The salt mixture was made by mixing together the following salts and acids: K₂CO₃, 219.0, Na₂CO₃ 1.9, CaCO₃ 192, MgCO₃ 96.6, Fe citrate 20.0, H₂SO₄ 30, H₃PO₄ 41.8, Na₂SiO₃ 97.0, HCl 28.5, CuSO₄ 0.2, KI 0.03, MnSO₄ 0.12, NaF 0.37, K alum 0.037.