BLOOD-PLASMA FATTY-ACID CONCENTRATIONS IN CATTLE DURING THE TRANSITIONAL FEEDING PERIOD (WINTER-SUMMER)

Changes of fatty acids levels in the blood plasma of heifers were stud ied in a locality with annual incidence of nutritional muscle dystroph y. Pinzgau breed heifers divided into 4 groups (6 animals per group) w ere used in the experiment. Groups I (with i.m. administered Selevit) and II (without treatment) were abruptly turned out to pasture. Groups III and IV were left indoors: group III was abruptly and group IV gra dually turned to green feeding. With regard to changes in proportions of major plasma fatty acids (those of about 5 % and higher) and essent ial plasma fatty acids of n-6 (linoleic acid) and n-3 series (linoleni c acid) as well as their higher metabolites, the differences between t he groups of animals during stabled period (Ist sampling) and on the 2 nd day on the pasture (2nd sampling) were not significant. At the foll owing samplings, significant differences were observed within the grou ps of animals with increasing proportion of total monounsaturated fatt y acids and n-3 polyunsaturated fatty acids (especially that of linole nic acid) and decreasing proportion of n-6 polyunsaturated fatty acids including linoleic acid as well as higher n-6 metabolites (especially dihomogamma-linoleic and arachidonic acids). In contrast to linolenic acid, a decrease of its higher n-3 metabolites was recorded. Although these changes were the most marked in the group II of animals (animal s abruptly turned to pasture without previous treatment), and in all g roups at the last but one sampling (8th day on pasture), similar tende ncy was recorded also in other groups. In conclusion, the results of t his study indicate that the observed changes are related to turning th e animals to green feeding.