Influence of Botanical Diversity in the Natural and Cultivated Pastures on the Lipid Content and Fatty Acid Composition of Grass in the Region of the Middle Rhodopes

The aim of the study concerns an estimation of the lipids and their fatty acid composition of the grass associations occupying natural and cultivated pastures at 1200m altitude. Plant samples are taken from the region of the Middle Rhodopes from natural meadows containing mainly Nardus stricta and cultivated meadows predominantly with Fastuca fallax, Lolium perenne L. and Poa pratensis during the period from 15 May to 15 July. The established differences in the molar concentration of SFA, MUFA and PUFA, as well as the changed proportions of the main fatty acids - palmitic, oleic, linoleic and linolenic are supposed to have influence on the milk fat in the ruminant animals. The content of SFA increases from May to July and reaches from 39.90mol% to 45.31mol% in the natural and from 31.19mol% to 40.86mol% in the cultivated grass. It is mostly due to the molar concentration of the 16:0 and 22:0 - p 0.05 which varies between 21.91mol% - 27.57 mol% and 0.88 mol% -1.47 mol%, respectively in the cultivated grasses. The study shows that the total content of MUFA is increased - p 0.01 during the experiment from 8.60mol% to 14.08 mol% in the cultivated meadows, while the differences are not significant in the grasses of the natural meadows. The concentrations of PUFA - 60% - 45% in the plant lipids at the examined altitude in the region of the Middle Rhodopes in May, June and July are connected with relatively higher levels of 18:3n-3 - 24mol% - 42mol% and 18:2 - 13mol% - 21 mol%. It has to be noted that the high PUFA level during the whole vegetation period is favorable for providing an optimal supply of essential fatty acids to grazing animals, especially for productive ruminants, as well as for the increased synthesis and secretion of CLA in milk lipids, which prevent human beings from atherosclerosis, obesity, diabetes and other diseases and stimulate the immune system.