GROWTH-STUDIES WITH BLACK-AND-WHITE DAIRY BULLS AT A LOW FEEDING LEVEL .3. NUTRIENT AND ENERGY RETENTION IN THE EMPTY BODY-WEIGHT

In two long-term individual feeding experiments with rations very rich in roughage, nutrient and energy retention in the course of live weight development of black-and-white dairy bulls were determined. For this purpose, a total of 123 animals were slaughtered at the age of 5, 9, 12, 15, 18, 21 and 24 months, and the total body was analysed of 97 animals. The ascertained protein, fat and energy retention per day showed a clear dependence of the implemented level of nutrition. The results received compare well with the findings of earlier studies (PIEPER et al., 1984a). At a nutrition level (maintenance = 1.0) of 1.38 = 473 g gain of empty body weight/day 97 g protein/day 83 g fat/day 5.4 MJ/day and at a nutrition level of 1.48 546 g/gain of empty body weight 107 g protein/day 110 g fat/day 6.8 MJ/day were retained in the live weight range between 150 and 450 kg. The dynamics of the nutrient and energy retention in the course of live weight development is depicted in tables.