Untersuchungen zum Energieerhaltungsbedarf und zum Energiebedarf für den Proteinansatz an wachsenden Ratten und Broilern

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Abstract
In 4 experiments with 3 times 3 male Wistar rats each, which received rations with different protein contents (10, 25 and 40% crude protein in the dry matter), between .apprx. 65 and 180 g live weight and with an environmental temperature of 30.degree. C, a total of 226 measurements of total metabolism were carried out on the energy level maintenance, partly with a fasting day added. On the energy level maintenance with the simultaneous catabolization of body fat there was considerable protein energy retention, which amounted to between 30 and 40% of the retention achieved in the growth periods. The energy maintenance requirement can be determined with good reproducibility (mean SD: .+-. 6%). The average energy requirement directly measured at the feeding level maintenance of 437 kJ metabolizable energy (ME)/kg live weight0.75 day-1 (n = 224) differs insignificantly from the average value obtained by means of multiple regression analysis from experimental periods, with feeding for growth of 423 kJ ME/kg live weight0.75 day-1 (n = 437). It is not necessary to differentiate between energy requirement for maintenance and energy requirement connected correlatively with the live weight (metabolic weight of the body) under conditions of growth. Energy maintenance requirement was insignificantly dependent on the amount of protein in the feed. The relative values of protein quotas of 10, 25 and 40% in the feed were 100, 101 and 103%, respectively; the expected values (derived from the efficiency of ATP synthesis in the oxidation of carbohydrates and protein) were 100, 104 and 109%. The problem of the thermogenous effect of protein, which is also of great importance to human nutrition, urgently requires further experimental investigation. For growing rats the best adaptation of the energy maintenance over the investigated period of development was achieved if the 2/3 potence of the live weight is chosen as the expression of the metabolic body weight. With high probability this can also be transferred to the characterization of protein metabolization.