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Summary The role of β-carotene in reproduction was investigated in gilts assigned to three dietary supplementations: VA (4000 IU vitamin A); VA + VA (4000 IU + 8300 IU); VA + BC (4000 IU + 100 mg β-carotene) per kg diet for 14 weeks. Gilts were slaughtered at day 12 of gestation. In the VA + BC group, number of corpora lutea was lowest, but the number of embryos was greatest, resulting in a non-significant decreased prenatal mortality(p

Investigations with 15N'-labelled urea were carried out to find out the influence of the amount of fibre on the reflux of 15N' into the caecum to take part in the caecal metabolism. Two pelleted diets, containing 9.7% (group 1 with 23% oat hulls) and 2.2% (Group 2 without oat hulls) crude fibre, with urea with 60 atom% 15N-excess (15N) used as marker were given to three White New Zealand rabbits each group. Group 1 and 2 consumed 109 and 72 g fresh matter per rabbit and day, respectively. Daily 15N'-intake per rabbit was 307 mg in group 1 and 279 mg in group 2. Most of 15N' was eliminated directly via the urine. The daily faecal excretion in group 1 and 2 was 5.3 and 2.3 mg 15N', respectively. Only about 20 to 30% of 15N' and volatile fatty acids in the caecum and higher amounts of 15N' in muscles were found. The animals of this group consumed nearly the total amount of faeces by caecotrophy. Therefore 24 g of group 2 was still satisfying compared to 33 g live weight gain/rabbit and day of group 1. It is concluded that the animals of group 2 could compensate the low fibre level within a period of about 20 days by a more efficient utilization, the consumption of crude protein and starch being 18 and 12% lower than in group 1, respectively. Feed intake and health status were not evidently affected. The results are in contradiction to the common knowledge.

In commercial pig fattening, copper is added to the feed in amounts that greatly exceed the requirements of the animals. On the one hand, this improves weight gain, but on the other, as we were able to recently prove, the retention of the heavy metal cadmium rises in the kidney, in the liver and in muscle. In a feeding experiment with female and male castrated piglets, we tried to counter the copper-induced rise in cadmium (175 mg Cu/kg feed) by adding zinc or vitamin C to the diet. While addition of 100 or 200 mg zinc per kg of diet had no influence, the addition of 1000 mg vitamin C reduced the elevated cadmium values in the kidneys and livers to values only determined with a low copper supplementation of 35 mg copper per kg of feed. This positive vitamin C effect not only occurs in cases of high copper supplementation (175 mg Cu/kg feed); when the pigs were given only 35 mg copper per kg of feed, vitamin C also reduced the cadmium content in the organs by 35 to 40%. This indicates that vitamin C improves the quality of food gained from animals for human consumption in both conditions.