Isolation of IgE from reaginic rat serum

Small black goats (12 to 25 kg) are herded by Bedouins in the hot, arid Middle Eastern deserts. Total body water of these goats (measured as HTO space) amounted to 75-80% of their weight. When vegetation and water are scarce, the goats are watered only once every 4 days. They continued to eat during water deprivation, even when they had lost 30% of their initial body weight. The loss of body weight was equal to the reduction in body water content, and it was fully replenished during one short visit (2 min) to a water point. Thus the high water content of Bedouin goats appears to act as a 'reservoir' which enables goats to prolong the interval between drinking; to graze further from water; and to exploit a larger area of desert pasture. In lactating nannies body water increased to 85% of body weight and milk yield was exceptionally high (up to 97 ml Kg^-1 day ^-1). This high milk yield was maintained in the face of intermittent water deprivation and it fully satisfied the fluid requirements of the kids in the desert.