Endocrine Abstracts

The aim of the study was to analyze the influence of feed from different production systems on food intake, body chemical composition and plasma leptin concentrations in rats. It is expected, that organically produced feed influences positively rat organism, in that hormone balance. Leptin regulates energy intake and expenditure, as well as basic functions of many tissues.

The experiment was conducted in 104 Wistar male rats divided into 16 dietary groups (organic, conventional and two low input, all in four replications) and one control group (Labofeed H) consuming feed ad libitum for three months. Plasma leptin levels by RIA, body composition by standard chemical methods and total food intake and body weight gain were determined. Macronutrient and bioactive compounds intakes were also calculated. All procedures were approved by the Local Animal Care and Use Committee in Warsaw.

According to multifactorial statistical analyses, plasma leptin concentrations are observed to depend significantly on fertilization regime (P<0.02), while crop protection system does not influence significantly this parameter. At the same time, there is strong interaction between crop protection and fertilization regimes (P<0.001). Lowest plasma concentrations of leptin are observed in rats fed one of low input diets (feed from production system based on conventional fertilizers and organic protection) and standard diet (Labofeed H). Plasma leptin levels in other analyzed groups are statistically higher, however there are no significant differences between these groups. Moreover, the results show positive correlation between plasma leptin and β-carotene intake (r=0.32, P≤0.002) and negative correlation between plasma leptin and dietary fiber intake (r=−0.28, P≤0.01).

Presented results do not confirm unquestionably earlier hypothesis. However, analyzed parameter is only one of many parameters which can be taken into consideration to evaluate the influence of organically produced food on the organism.