The effects of organically and conventionally cultivated plant feed on fertility and health in two inbred rat strains

Summary

In this experiment we study the effects of various culturing methods of plant based foods on health and fertility parameters in a two-generation study in rats. The organic method of growing plants without pesticides and synthetic fertiliser will be compared to a conventional method of growing plants (using pesticides and artificial fertiliser). The diets have been supplemented with minerals and vitamins according to the recommendations of the National Research Council for rats (1995), in order to avoid deficiencies. A control group is fed with a standard breeding chow for rodents. Two inbred rat strains have been selected:  the BN/hsdCpb which is characterised by a relatively low fertility and the GK/mol, a model susceptible for the development of non-insulin dependant diabetes (diabetes type II).
One of the hypotheses for decreasing fertility and increasing frequency of testis cancer in humans in denmark, could be the use of certain pesticides.  However changes in type and amount of fertiliser may affect plant composition, and thus the efficiency of the preventive effect of plant foods on ex. cancer. With this study we hope to throw more light on a possible direct causal relationship between the type of diet and fertility parameters. While many different food components and contaminants show effects at high doses in single factor experiment, it is impossible to predict the combined effect of differences in low doses. This study hopes to provide answers to this, by showing if different ways of growing plants will result in differences in selected aspects of rat health. The results will thus provide a baseline for subsequent work to elucidate the relative importance of the different factors involved.
Several preference tests with different animal species show that animals often have a preference for organically grown food. Whether this preference indicates some nutritional benefits, that will increase health and fertility of the animals, is however not well documented. This work presents the preliminary results on food intake, on growth and female fertility measured by litter size, the number of stillborn pups at birth and the number of survivors at weaning, in addition to the female body weight development during lactation. The male fertility, estimated by testicular size, histology and semen quality have been measured as well. In addition, a macroscopical pathological evaluation of all rats at autopsy will be performed, after the reproductional phase of the first litter has been finished.