Changes in terpenoid composition of milk and cheese from commercial sheep flocks associated with seasonal feeding regimens throughout lactation.

Changes in the terpenoid content of milk and cheese from commercial sheep flocks monitored throughout lactation in the Cantabrian area of northern Spain were investigated. The flocks followed the same seasonal feeding strategy during lactation: indoor feeding in winter (early lactation) based on concentrate and forage; part-time grazing in the valley in early spring (mid lactation); and from mid spring on (late lactation), flocks were managed under extensive mountain grazing. In the present study design, seasonal feeding and lactation stage were intrinsically linked and could not be considered in isolation, and a holistic approach was necessary to consider the whole production management of the commercial flocks studied. Furthermore, the study focused on the identification of sesquiterpenoid ratios to differentiate milks and cheeses produced under extensive mountain grazing from those produced under other seasonal feeding regimens. Total abundance of mono- and sesquiterpenoids and that of individual compounds such as α-pinene, ß-caryophyllene, α-humulene, α-amorphene, and γ-cadinene significantly increased in milk and cheese from indoor feeding to mountain extensive grazing. Sesquiterpenoid ratios such as γ-cadinene/α-muurolene, γ-cadinene/δ-cadinene, ß-caryophyllene/α-muurolene, and (ß-caryophyllene + γ-cadinene)/α-muurolene were used to differentiate mountain milks and cheeses from those from indoor feeding and part-time grazing in the valley. Multivariate discriminant analysis applied to individual terpenoids and sesquiterpenoid ratios showed milk and cheese samples classified into 2 groups: samples from indoor feeding and part-time grazing in the valley were classified together, and clearly separated from mountain milks and cheeses. The results of the present study showed that the sesquiterpenoid ratios approach could help to differentiate mountain dairy products from others obtained under other specific feeding regimens in a local environment.

Commercial sheep flocks--fatty acid and fat-soluble antioxidant composition of milk and cheese related to changes in feeding management throughout lactation.

Fatty acids (FAs), tocopherols and retinoids were analysed in raw milk and cheese from six commercial sheep flocks monitored from early lactation in winter to late lactation in summer. In winter, animals received concentrate and forage indoors; in early spring, animals grazed part-time on cultivated or natural valley grasslands; and from mid spring on, animals were kept outdoors constantly on mountain natural pastures. Mountain grazing in late lactation significantly increased the amount of healthy desirable unsaturated FAs such as C18:1t11 (VA), C18:2c9t11 (RA), C18:2t11c13, C18:3c9c12c15 (ALA) and C20:5c5c8c11c14c17 (EPA), and those of α-tocopherol and α-tocotrienol of milk and cheese. Stepwise discriminant analysis was applied to classify cheese samples according to seasonal feeding management. The multivariate approach was able to discriminate beyond doubt mountain cheeses from those of indoor feeding and part-time valley grazing.

Simultaneous analysis of carotenoids and tocopherols in botanical species using one step solid-liquid extraction followed by high performance liquid chromatography.

Carotenoids and tocopherols from botanical species abundant in Atlantic mountain grasslands were simultaneously extracted using one-step solid-liquid phase. A single n-hexane/2-propanol extract containing both types of compounds was injected twice under two different sets of HPLC conditions to separate the tocopherols by normal-phase chromatography and carotenoids by reverse-phase mode. The method allowed reproducible quantification in plant samples of very low amounts of α-, ß-, γ- and δ-tocopherols (LOD from 0.0379 to 0.0720 µg g(-1) DM) and over 15 different xanthophylls and carotene isomers. The simplified one-step extraction without saponification significantly increased the recovery of tocopherols and carotenoids, thereby enabling the determination of α-tocopherol acetate in plant samples. The two different sets of chromatographic analysis provided near baseline separation of individual compounds without interference from other lipid compounds extracted from plants, and a very sensitive and accurate detection of tocopherols and carotenoids. The detection of minor individual components in botanical species from grasslands is nowadays of high interest in searching for biomarkers for foods derived from grazing animals.

Rapeseed and sunflower oilcake as supplements for dairy sheep: animal performance and milk fatty acid concentrations.

The influence of different amounts of oilseed cake (rapeseed and sunflower) on animal production parameters and fatty acid (FA) concentrations of the milk was studied in a Latxa dairy sheep experimental flock, both in winter (50% oilcakes; indoor feeding) and in spring (30% oilcakes; part-time grazing). The two different levels of the oilcakes tested did not affect animal production parameters or milk yield. Milk fat content and the fat/protein ratio decreased significantly with 30 and 50% sunflower cake. Yet, fat/protein ratio values were within the range for cheesemaking. Both levels of either type of oilcake tested significantly increased the concentrations of nutritionally interesting FA (CLA isomer C18:2cis-9, trans-11, vaccenic, oleic, and total unsaturated FA), while simultaneously decreasing the concentration of atherogenic FA. The atherogenicity indexes of milks from ewes fed 50 or 30% of either oilcake were significantly lower than those of their corresponding control. The use of cakes in winter increased the concentration of nutritionally interesting FA to the values obtained with part-time grazing.