Fatty Acid Profiles of Cow’s Milk and Cheese as Affected by Mountain Pasture Type and Concentrate Supplementation

SIMPLE SUMMARY: It is well-known that milk and cheese derived from grazing animals are beneficial for human health. Grazing dairy cows produce milk with high levels of unsaturated fatty acids and conjugated linoleic acid, which are able to reduce cardiovascular diseases and have some anticancer properties. The aim of this trial was to assess the effect of pasture type and concentrate supplementation levels on the fatty acid composition of milk and cheese obtained during summer grazing on mountain pasture. Seventy-two dairy cows, supplemented with 3.0 kg/head/d or 1.5 kg/head/d of energetic concentrate feed in the diet, grazed on a nutritionally rich Poion alpinae pasture, and subsequently a nutritionally poor Seslerion caeruleae pasture. In milk, the highest concentrate level reduced linolenic acid and total polyunsaturated fatty acids, while the pasture type influenced the monounsaturated fatty acids. In cheeses, these differences were markedly reduced. ABSTRACT: The aim of this trial was to assess the effect of pasture type and concentrate supplementation on the fatty acids (FA) composition of milk and cheese obtained during summer grazing on mountain pasture. Seventy-two Italian Simmental dairy cows were assigned to two groups that differed by the amount of concentrate supplementation: 3.0 kg/head/d (HIGH) vs. 1.5 kg/head/d (LOW). The dairy cows grazed on a Poion alpinae alliance pasture (PAST1), and subsequently they grazed on a Seslerion caeruleae alliance pasture (PAST2) for 10 d each. In the last three days of each experimental period, milk samples were collected immediately before each cheese-making event. Cheese samples were collected from each cheese loaf after 60 d of ripening. LOW showed higher isoFA, FA intermediates of the ruminal biohydrogenation, C18:3 c9,c12,c15, and total polyunsaturated fatty acid (PUFA) levels than HIGH. The pasture type had a more limited effect on FA composition of milk than concentrate level and was mainly related to monounsaturated fatty acids (MUFA), which were higher in PAST1 than PAST2 (p < 0.05). In cheeses, these differences were reduced. The phytanic acid and phytanic isomer ratio (SRR/RRR) in milk were not affected either by supplement level (p > 0.05) or by type of pasture (p > 0.05). Increasing the concentrate offered to dairy cows from 1.5 to 3.0 kg/d did not markedly influence the level of PUFA in cheeses produced during summer grazing on high mountain pasture.