Composition and Fatty Acid Profile of Bone Marrow in Farmed Fallow Deer (Dama dama) Depending on Diet

SIMPLE SUMMARY: The bone marrow is regarded as an indicator of the health status in ungulates, because it is not only a source of fat but also it contains minerals, vitamins, and fatty acids. These substances affect the functioning of the organism, especially in unfavorable conditions such as winter. However, the relevant concentrations of fatty acids for healthy deer bone marrow are not known; their contents can be modified by various nutrition, although for ruminants there are some limitations. Unfortunately, studies on the composition of bone marrow fatty acids or their changes are scarce, especially in relation to the youngest deer. Therefore, the aim of the study was to analyze the fatty acid composition of the bone marrow of farmed fallow deer fawns after the pasture period and the winter feeding. The results obtained in the study indicate that, notwithstanding inclement weather conditions in winter, providing the animals with appropriate housing conditions on the farm as well as their optimal feeding resulted in better condition and nutritional status of the animals, which is indicated by a more favourable composition and profile of fatty acids in bone marrow, compared to the optimal summer grazing period for ruminants. ABSTRACT: There are few studies on the composition of fatty acids and how they change the bone marrow fat of young animals depending on nutrition. Therefore, the proximate and fatty acid composition of metatarsal bone marrow from fawns of farm fallow deer after a summer of grazing and the winter feeding was compared. Due to the size and nature of the data, parametric or nonparametric tests were used. Fatty acid composition was determined by gas chromatographic analysis. After the winter feeding, bone marrow contained more fat (83.11% vs. 75.09%, p < 0.05) and less fat free dry matter (5.61% vs. 13.76%, p < 0.05) compared to the pasture period. Moreover, there was a significantly higher amount of saturated fatty acids (23.34% vs. 21.60%, p < 0.001), more trans fatty acids (2.99% vs. 2.34%, p < 0.005), and conjugated linoleic acid isomers (1.04% vs. 0.83%, p < 0.01), compared to post winter feeding, which in turn contained significantly more total cis-monounsaturated fatty acids (54.65% vs. 58.90%, p < 0.001). The percentage of polyunsaturated fatty acids (including n-3 and n-6) was not affected by feeding season. In conclusion, it was shown that young male farm fallow deer were better nourished after the winter period, during which they were kept in properly prepared rooms and fed fodder prepared by people.