Cardiovascular diseases represent 31% of deaths worldwide (World Health Organization, WHO, 2017). Among the controllable risk factors (such as diet, physical inactivity, and smoking), a high cholesterol intake from animal fats has been associated with the development of coronary artery disease and hypertension (Oggioni et al., 2015). In bovine milk, cholesterol (3-hydroxy-5,6-cholestene; the major sterol in whole milk) is a nonpolar compound present in concentrations of 10 to 30 mg/dl (Jensen, 2002). Lipids of milk are secreted in the form of fat globules, which are enveloped by a biological membrane (milk fat globule membrane; MFGM). Cholesterol is transported in milk fat globules and associates easily with phospholipids of the MFGM (MacGibbon & Taylor, 2006). Milk fat globules contain components that have beneficial properties for health such vitamins, conjugated linoleic acid, phos

The diet of dairy cows influences the fatty acid (FA) profiles of their milk and cheese, but how these are affected by different conditions during confinement in a mixed system (MS:grazing + total mixed ration:TMR) is not known. The aim of this study was to compare the FAs of the milk and cheese from MS in a compost-bedded pack barns (CB-GRZ) versus an outdoor soil-bedded pen (OD-GRZ) during confinement, and with a confinement system (100%TMR) in a compost-bedded pack barns (CB-TMR). Individual milk samples (n = 12 cows/group), cheese, and pooled milk (MilkP) samples were collected. The saturated FA percentages in the milk and the omega 6/omega 3 ratio in the MilkP and cheese were greater for the CB-TMR (p < 0.0001), while the unsaturated and monounsaturated FA percentages in the milk were lower for the CB-TMR than the MS (p < 0.001). The milk n-3, C18:3, and conjugated linoleic acid percentages were lower for the CB-TMR than the MS (p < 0.001). The milk n-3 and C18:3 were higher for the CB-GRZ than the OD-GRZ (p < 0.01), but no differences were observed between the MS in the MilkP and cheese. In conclusion, CB-GRZ cows during confinement produced better quality milk compared to OD-GRZ cows. However, the FA profiles of the milk, MilkP, and cheese were affected to a greater extent by the feeding management than by the conditions during confinement.

A study was carried out to determine the casein variation in milk along the year with season and herd feeding strategy as main source of variation. Monthly samples were taken from 30 dairy farms that sent milk to PILI SA (15 farms) and CLALDY SA (15 farms) during April 2012 -March 2013. A mixed model and a recursive partition of variance method were used. The protein content in milk was higher in autumn, and the casein content in milk was higher in autumn and winter probably due to the higher use of energy concentrated supplements with better synchronization with the protein contribution from pastures. It was possible to maintain high levels of casein content and a casein:true protein ratio in milk during spring with almost exclusively pastoral diets. Overall, the proportion of casein in relation to the total protein and the casein in relation to true protein in milk did not reach the values reported in the literature with more concentrated diets.