6.115 Not all vegetables produce such high yields, but without improving present figures, 6 m 2 will produce 500 g/day of high-yield vegetables. With sufficient research on optimization, assuming a wide mixture of vegetables with varying yields, it seems probable that production could be brought to the required 750 g/person-day (6.4). VI.11.5.3: Animal Protein: Most humans are happily accustomed to eating meat, and the colony has no intention of requiring that everyone become a vegetarian. Various substitute meat-like foods can be made from soybeans, and their taste is continually being improved. Indeed, soybean substitutes are not ruled out but they are not regarded as the primary meat source. The requirements for meat animals in the colony are high productivity, low mass, low food intake, feed that does not compete with human food, and a high reproduction rate. Table 6.14 compares some candidates (6.4). Rabbits are the most likely choice. Dr. Kenneth Olson of the University of Arizona has shown that alfalfa, with a little salt, is acceptable as a complete rabbit feed. Because of palatability and yield losses, it is not feasible to utilize straight alfalfa protein for humans (6.4). One square meter can house a doe rabbit and her litters. The average litter of 3.5 young are produced every two months, and the doe-and-litter unit yields about 143g of low-fat, boneless meat per day on a food intake of 700 g/day dry weight (which requires 10 m 2 planted). A comparison of protein production per m 2 -day shows rabbits and grain each produce 4g, and soybeans produce 6g (6.4). However, few Americans consume rabbits on a regular basis and though it may come to be a space colony specialty, the study group would rather sacrifice some mass and efficiency factors and investigate other animals as well. Cattle, sheep, hogs, chicken and fish could probably be available to some extent. Assuming one broiler feeds four and allowing for a chicken dinner once a week requires 1000 broilers every three months. Other chickens, producing eggs basically from leftovers, can provide each person with four eggs per week on a work force of 762 hens (6.17). Fish could be raised in decorative ponds; their food requirements are modest.
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