[Effect of graduated vitamin D3 doses and different ration composition on the 25OH-vitamin D3 plasma concentration and fattening and slaughter production of bulls].

In a individual feeding experiment (348 days) 24 fattening bulls were given either a ration high in roughage (2.8 kg concentrate mixture, wheat straw ad libitum: group I) or high in concentrate (5.6 kg concentrate mixture, wheat straw ad libitum group II) supplemented with various levels of vitamin D3 (0, 250, 500, 1,000, 2,000, 4,000 and 8,000 IU per 100 kg body weight (bw) and day) and minerals as required.

[The effectiveness of oral and parenteral vitamin A doses in growing cattle with different vitamin A supplies].

The effect of one single oral or parenterally administered dose of 1 million IU vitamin A on the vitamin A depot in the liver and on blood plasma vitamin A concentrations was investigated in 3 individual feeding experiments with involvement of 18 and 24 calves or 24 fattening bulls. 50% of all animals in each of the 3 experiments received feed without any vitamin A through 108 or 112 or 209 days, prior to vitamin A administration, or received 10.000 IU/100 kg live weight and day.

[The effect of avoparcin on apparent digestibility, characteristics of rumen fermentation and fattening and slaughter output of growing cattle].

Four digestion experiments with 5 wethers each (0, 15, 30 or 60 mg avoparcin per animal and day), three individual feeding experiments (28, 18 or 56 bulls per experiment; 0 and 150/200; 0, 250 and 500 or 0 and 200 mg avoparcin per animal and day in the experiments 1, 2 or 3) and two group feeding experiments (60 bulls and 161 heifers per experiment; salt lick stones without or with 2.5 g avoparcin per kg) were carried out in order to investigate the influence of avoparcin on apparent digestibility, figures of rumen fermentation, fattening and slaughtering results as well as protein, fat and energy retention. Avoparcin supplementation did not significantly influence the apparent digestibility of organic matter and crude nutrients.

[The effect of a monensin-containing bolus on the live weight increase and characteristics of rumen fermentation of growing cattle].

Eight feeding experiments (4 on pasture and indoors each) with 401 growing cattle were carried out in order to measure the influence of a monensin device on daily weight gain. The monensin device effected on the average 7 g (1.4%) and 37 g (4.

[The vitamin A requirement and the vitamin A status of growing cattle. 1. Studies of calves].

Five experiments with 18 to 36 male calves each of the black and white dairy cattle breed (age: 14-21 days, initial live weight: approximately 45 kg per animal) were carried out in order to investigate the influence of various vitamin A supply (0-80,000 IU per 100 kg LW and day) on dry matter intake and weight gain as well as the vitamin A status of liver and blood plasma over 84 days. The calves consumed a diet free of carotene and vitamin A consisting of milk replacer, concentrate and chopped wheat straw. The calves were fed in three experiments for a longer time in order to observe the further vitamin A depletion.