Reproductive health for rats

Summary

In the present paper the feeding experiment with laboratory rats, conducted at the Ludwig Boltzmann Institute for Biological Agriculture from 1987-1989 is described in more detail to show the advantages, but also the difficulties of the method (Velimirov et al. 1992).
Two groups of rats (Long Evans strain), each consisting of 20 pairs, were fed with products from organic resp. conventional growing systems. After chemical analyses of all products, vitamins, minerals and trace elements were added if needed to provide nutritionally balanced diets. With 2 harvests 3 generations (6 litters) were investigated. In the first litters significantly fewer offspring were born dead or died within the first week of their lives. The survival rate until weaning time at the age of 28 days and the weight development were slightly more successful. The weight gain of the female rats in connection with litter size and pup weight during lactation was significantly higher. But the change from the feed mixture of the 1st to the 2nd harvest showed a reverse tendency in the 2nd litters of the 2nd generation, although the same diet components were used. After the adaptation to the new diet the “organic” group again displayed better results. Contradictory results are difficult to explain, because the overall impact of diets from different production systems is investigated, not effects of single components at different levels. The results are not unequivocally accepted by the scientific community, but are easily understood by the public, since the method reflects reality. The linear resp. synergistic perception of biological systems corresponds with the research objective, which is inherently different. Analysis is focussed on objects and their material nature, whereas the systemic approach tries to reveal the interactions (system dynamics) between the objects in the course of time. For a profound understanding of systems clearly both positions are needed, to compensate for the limitations of each method on its own.