The effect of adding herbs to the summer diet on the fatty acid profile of the lipid fraction of sheep milk

Abstract

The study was carried out on bulk milk samples collected at two-week intervals during the summer (June-August) and individually from ewes at the end of the experiment. The milk was obtained from ewes of the Koluda prolific dairy breed, housed indoors and fed green alfalfa forage and hay with a mixture of concentrate feeds. Three diet groups were established: group I – control (without the addition of herbs to the concentrate feed) and groups II and III, in which an herbal mixture was added to the concentrate feed in the amount of 10 and 20 g/sheep/day, respectively. The effect of the herb supplement in the sheep diet on the fatty acid profile of the milk fat was analysed. The results showed that the fat composition changed in all groups during the three-month milking period. In the first two months, an improvement was noted in the health-promoting properties of the milk fat (a decrease in SFA and an increase in MUFA and PUFA), but in the final period of the experiment they deteriorated. The unfavourable changes were smaller where the proportion of herbs in the diet was higher. As a consequence, in the final stage of research, lower SFA content was noted in the fat of the group III sheep than in the control group and II, by 6.0% (P≤0.01) and 4.1% (P≤0.05), respectively, lower content of OFA by 9.1% (P≤0.01) and 5.6% (P≤0.05), and higher content of UFA by 17.7% (P≤0.01) and 11.8%. (P≤0.05), including MUFA by 20.1% (P≤0.01) and 11.3% and PUFA by 11.7% (NS) and 15.0% (P≤0.05), as well as CLA, by 26.0% (P≤0.01) and 17.9% (ns) and DFA by 23.8% (P≤0.01) and 13.0% (P≤0.05). This also meant favourable changes in the UFA/SFA, PUFA/SFA and DFA/OFA ratios. The milk fat of group III also had higher content of n-3 PUFA (by 25.3%) than in group II, and thus a lower n-6/n-3 ratio.