Urinary Creatinine as an Indicator of Water Intake in Sheep and Goats Sustainably Farmed in Tropical Climates

Mathematical models are valuable tools for predicting water intake in small ruminants, enhancing water use efficiency, reducing environmental pollution, alleviating competition for water with human consumption, and improving productive performance, ultimately leading to increased revenues and promoting sustainability. This study aims to evaluate creatinine as a metabolic marker for estimating water intake in sheep and goats and to develop predictive models for tropical conditions. Five Santa Inês crossbred sheep and five Boer crossbred goats were used in a replicated 5 × 5 Latin square design. Treatments consisted of titanium dioxide supplementation at 1.0, 1.75, 2.5, 3.25, and 4.0 g/day. A species effect was observed on dry matter intake. Significant correlations were identified between water intake, urinary volume, body weight, metabolic weight, and creatinine concentration. Negative correlations were observed between water intake and both dry matter intake and metabolic measures. Five mathematical models were developed to predict water intake, all of which demonstrated good predictive capacity. Among them, the equation Ŷ H2Og/kgBW = 164.72 − 6.60 × MBW + 0.025 × Creat (mg/L) proved most reliable. This model enables accurate estimation of water intake in sheep and goats, supporting more efficient water management and sustainability in tropical regions where water resources are limited.