Interrelationships between water, food and digestible energy intake in desert and temperate goats

Intra- and interspecific relationships between energy intake and digestible energy intake (DEI) and water turnover (WTO) in Black Bedouin and temperate (Swiss Saanen) goats were analyzed. Available data from other species of mammals were also evaluated. A highly significant linear relationship between WTO and DEI holds within breeds of goats under different levels of DEI and between breeds which vary considerably in their body weight and metabolic expenditure (WTO ml/kg per day = -5.4 + 0.911 DEI kcal/kg per day, n = 34, r2 = 0.99, Sb = 0.057). In lactating goats the relation between WTO rate (minus water secreted in milk) and DEI is the same as that measured in non-lactating ones. Mammals with quite a different body weight have the same WTO per unit of metabolism--about 1 mol of water per 5 mol of oxygen--although their absolute turnover is very different. Furthermore, the above relationship is similar to the relationship between WTO:DEI found in goats here. (WTO ml/kg per day = 5.8 + 0.849 x kcal/kg per day, n = 8, r2 = 0.99, Sb = 0.030, where x is the caloric equivalent of oxygen consumption.