Modelling the growth of preruminant calves

摘要: The emphasis in meat production has shifted from maximizing volume to the efficient of lean meat. Body composition can a large extent be manipulated by nutritional means. It does, however, require integrated knowledge protein and energy metabolism. Two experiments were performed with male, preruminant calves, quantify relationship between nutrient intake (protein, energy) rate gain live weight, fat weight range 80 240 kg. These showed that calves this respond increased increasing their deposition rates. utilization digested decreased 60% at low levels 35% high levels. Extra protein-free results mainly extra deposition, but also increases rate, even intakes. Subsequently, these used for construction dynamic, mechanistic growth simulation model. model predicts rates body (in several tissues) intake. predict amino acid requirements. Protein accretion obtained independent could simulated satisfactorily. Additional measurements, muscle degradation, measured urinary excretion 3-methylhistidine, Furthermore, it was shown plasma triiodothyronine strongly hardly In contrast, thyroxine insulin-like factor-1 intake, unaffected