Influence of dietary fat on some metabolic responses of cattle to fasting

Metabolic responses were compared in Brahman cross and British cattle to 96 hours fasting from two maintenance diets; low fat (2.5 per cent fat) and high fat (9.2 per cent fat), which were isocaloric and isonitrogenous. Within breeds, the plasma concentrations of non-esterified fatty acids were increased (P less than 0.01) and the amounts of urinary urea nitrogen and creatinine excreted and respiratory quotient lowered (P less than 0.01) by feeding the high fat diet beforehand. Within dietary groups, the Brahman crosses showed a higher adaptation to a lipid fuel economy with a concomitant greater conservation of body nitrogen than the British animals. The results point to a role for dietary lipid in ameliorating bodyweight loss in cattle during periods of inadequate nutrition.