The rearing of female twin cattle using only feed pellets in comparison with straw pellets plus a concentrate mixture. 2. Weight gain and feed consumption as well as rumen fermentation in the 1st half of the 2d year of life

In investigations with 30 young cows (twin cattle) the applicability of straw materials as sole roughage was tested during the first half of their second year of life (183 feeding days). In the course of the experiment sole feed pellets (I) and partly pelleted rations of dried feed (straw pellets plus loose wheat and loose wheat straw resp.; II) were used. Approximately 72% of the dry matter intake was provided from straw materials in both groups and on an average of the test period. Weight gain and feed expenditure were ascertained and at the end of the test period also the parameters of rumen fermentation and of the concentration of some metabolism parameters in the blood serum. With feed supply being restrictive (2.2 kg dry matter/100 kg live weight), a high dry matter intake from straw (1.6 kg/100 kg live weight or 4.8 kg/animal and day resp.) and average weight gains of between 574 (I) and 582 g (II) were achieved. The standard expenditure of energy (kEFUcattle) and protein stated in the GDR feed evaluation system for this period of development was undercut by 27 (II) and 29 (I)% and 12 (II) and 18 (I)% resp. On average the expenditure of kEFUcattle/kg weight gain was 4.75 (I) and 4.98 (II) and that of digestible crude protein/kg weight gain 679 (I) and 733 g (II). Compared to standard values the expenditure of energy and feed expenditure from concentrates was 80%. Rumen fermentation conditions corresponded to those of a high cellulolytic activity (C2: C3 ratio of greater than 4: 1). The only significant differences between the groups at the time of sampling were to be observed in the total concentration of volatile fatty acids and in the pH-value in the rumen. The absolute (1/animal) and relative (1/kg dry matter intake) volume of rumen fluid varied between 65 and 70 and between 10.5 and 12.5 1. The ascertained concentration of selected metabolism parameters were within the physiologic standard range.