[Energy requirement of growing bulls]

The series of experiments concerning the utilisation of feed energy by growing bulls (482 total metabolism periods) as described in this periodical in four articles (Schiemann and others 1976; Jentsch and Schiemann 1976; Jentsch and others, 1976; Hoffmann and others, 1977), has undergone further statistical processing in order to test possibilities of factorial analysis for the derivation of values for the energy requirement of growing bulls. Square equations for the characterisation of the maintenance requirement of metabolisable energy and net-energy-fat in kJ/kg live weight 0.75 and day were derived for the live weight range between 50 and 335 kg (see equations (2) and (4)). Beyond this live weight range the maintenance requirement of growing bulls-- related to the metabolic body weight -- corresponds to that of fullgrown oxen (410--420 kJ metabolisable energy/kg live weight 0,75 and day). The analysis of the energy content for the live weight increase in dependence on the live weight resulted in the statistical generalisation characterised by equation (5) for live weights above 200 kg. Up to 200 kg live weight the energy content of the live weight gain is between 8 and 10 MJ/kg live weight gain. Above that, equations for the characterisation of the energy requirement of fattening bulls in ad libitum feeding were derived for the live weight ranges between 200 and 335 kg as well as 335 and 550 kg (cf. equations (2) and (3)). The significance of the factorial analysis of the energy metabolism of growing animals is discussed comparatively to previous assessments.