Potential of milk fatty acid composition to predict diet composition and authenticate feeding systems and altitude origin of European bulk milk.

The aims of this work were to elucidate the potential of using milk fatty acid (FA) concentration to predict cow diet composition and altitude of bulk milk collected in 10 different European countries and to authenticate cow-feeding systems and altitude of the production area using a data set of 1,248 bulk cow milk samples and associated farm records. The predictions based on FA for cow diet composition were excellent for the proportions of fresh herbage [coefficient of determination (R2)=0.81], good for hay, total herbage-derived forages, and total preserved forages (R2>0.73), intermediate for corn silage and grass silage (R2>0.62), and poor for concentrates (R2<0.51) in the cow diet. Milk samples were assigned to groups according to feeding system, level of concentrate supplementation, and altitude origin. Milk FA composition successfully authenticated cow-feeding systems dominated by a main forage (>93% of samples correctly classified), but the presence of mixed diets reduced the discrimination. Altitude prediction reliability was intermediate (R2<0.62). Milk FA composition was not able to authenticate concentrate supplementation level in the diet (<58% of samples correctly classified). Similarly, the altitude origin was not successfully authenticated by milk FA composition (<76% of samples correctly classified). The potential of milk FA composition to authenticate cow feeding was confirmed using a data set representative of the diversity of European production conditions.

Prediction of bulk milk fatty acid composition based on farming practices collected through on-farm surveys.

The aim of this study was to predict the fatty acid (FA) composition of bulk milk using data describing farming practices collected via on-farm surveys. The FA composition of 1,248 bulk cow milk samples and the related farming practices were collected from 20 experiments led in 10 different European countries at 44°N to 60°N latitude and sea level to 2,000 m altitude. Farming practice-based FA predictions [coefficient of determination (R(2)) >0.50] were good for C16:0, C17:0, saturated FA, polyunsaturated FA, and odd-chain FA, and very good (R(2) ≥0.60) for trans-11 C18:1, trans-10 + trans-11 C18:1, cis-9,trans-11 conjugated linoleic acid, total trans FA, C18:3n-3, n-6:n-3 ratio, and branched-chain FA. Fatty acids were predicted by cow diet composition and by the altitude at which milk was produced, whereas animal-related factors (i.e., lactation stage, breed, milk yield, and proportion of primiparous cows in the herd) were not significant in any of the models. Proportion of fresh herbage in the cow diet was the main predictor, with the highest effect in almost all FA models. However, models built solely on conserved forage-derived samples gave good predictions for odd-chain FA, branched-chain FA, trans-10 C18:1 and C18:3n-3 (R(2) ≥0.46, 0.54, 0.52, and 0.70, respectively). These prediction models could offer farmers a valuable tool to help improve the nutritional quality of the milk they produce.

Component-resolved diagnosis with commercially available D. pteronyssinus Der p 1, Der p 2 and Der p 10: relevant markers for house dust mite allergy.

OBJECTIVE: To establish the prevalence and serum levels of IgE to commercial Der p 1, Der p 2, Der p 10 and the carbohydrate MUXF3 in house dust-mite allergic patients. To compare individual vs. allergen microarray methods. METHODS: Prevalence and serum levels of IgE to Dermatophagoides pteronyssinus extract and components Der p 1, Der p 2, Der p 10 and MUXF3, specific IgG4 to D. pteronyssinus, total serum IgE levels, and clinical features (age, asthma, rhinitis and atopic dermatitis) were determined in 123 patients (64 children) with the ImmunoCAP® method. ImmunoCAP ISAC® was performed in 24 patients. RESULTS: All patients had serum IgE to D. pteronyssinus. Prevalences of serum IgE to commercial components were Der p 1 93%, Der p 2 77% (Der p 1 or Der p 2 94%), Der p 10 28% and MUXF3 25%. Levels of D. pteronyssinus IgE strongly correlated with Der p 1 and Der p 2 IgE (r = 0.89 and 0.85 respectively), but not Der p 10 and MUXF3. ImmunoCAP® and ImmunoCAP ISAC® were concordant, but the quantitative correlation was poor. No clinical implication for the prevalence, levels, or molecular IgE reactivity profile to house dust mite components was found. CONCLUSIONS AND CLINICAL RELEVANCE: Commercially available Der p 1 and Der p 2 strongly correlate with IgE D. pteronyssinus. The lack of Der p 1 and Der p 2 IgE may help with differential diagnosis. Der p 10 serum IgE prevalence and levels suggest different patterns in food and mite-related tropomyosin sensitization. Serum IgE to carbohydrate MUXF3, although unexpectedly prevalent, were low and did not modify D. pteronyssinus IgE levels. Follow-up may be best carried out with individual rather than microarrayed components.

Authentication of cow feeding and geographic origin on milk using visible and near-infrared spectroscopy.

The ability of near-infrared spectroscopy to trace cow feeding systems and farming altitude was tested on 486 bulk milk samples from France and northwestern Italy. Milks were grouped into feeding systems according to the main forage in the diet. Partial least square discriminant analysis correctly classified 95.5, 91.5, and 93.3% of pasture versus maize silage, hay, and fermented herbage feeding systems, respectively. Discrimination was slightly less successful when diets with large proportions of the nondominant forage were included in each group. Near-infrared spectroscopy correctly discriminated no-pasture from pasture milk, even with only 30% of pasture in the diet (5.4% cross-validation error), and the error stabilized when pasture exceeded 70% (2.5% error). Near-infrared spectroscopy did not reliably trace milk geographic origin when the feeding system effect was isolated from the altitude effect. These findings may be usefully exploited for the authentication of dairy products.

Tanker milk variability according to farm feeding practices: vitamins A and E, carotenoids, color, and terpenoids.

The aim of this work was to study the variability in the composition of bulk milk mixtures of fat-soluble compounds (vitamins A and E, carotenoids, and terpenoids) and assess the links with milk production conditions. Milk from 10 collection trips in the French department of the Haute-Loire (10 to 36 herds per trip) was sampled in the tanker twice during the winter period and 3 times during the grazing season. The collection trips differed in their altitude (440 to 1,150 m) and the forage system (grass or based on corn silage). Vitamins A and E, carotenoids, and terpenoids of the 50 tanker loads of milk were analyzed. Data of milk production conditions in the 204 farms made it possible to constitute indicators for the collection trip and to define 50 mean herds. The relationships between mean herd characteristics (breed, stage of lactation, and feed) and milk characteristics were investigated. The constituents of tanker loads of milk were comparable to those observed in milk produced by groups of animals receiving contrasting diets (rich in concentrate or corn silage vs. pasture). The characteristics of the milk differed according to the period; those produced at grazing were more yellow (1.02 +/- 0.4; mean of difference) and richer in beta-carotene, lutein, vitamin E (2.0 +/- 1.2, 0.23 +/- 0.12, and 6.1 +/- 5.0 mug/g of fat, respectively), and sesquiterpenes (2.7 +/- 2.5) than winter. The variations observed for beta-carotene, lutein, and vitamin E were linked to the proportion of grazed grass or grass silage in the forage (r = 0.66, 0.69, and 0.51, respectively), unlike the vitamin A content. During grazing, 20 of the 32 terpenoids identified were associated with the proportion of permanent grassland available for grazing or cut. These results show that feeding is an effective way to modify the quality of dairy products, even in the case of bulk tank milk mixtures. Dairy plants could market different milks, which would contain specific compositions.

Using visible or near infrared spectroscopy (NIRS) on cheese to authenticate cow feeding regimes.

An experiment was conducted to evaluate the ability of two spectroscopy methods to distinguish between pasture and preserved-forage cheeses. The reflectance spectra of 308 fresh and freeze-dried samples of cow's milk cheeses were recorded at wavelengths in the range of the visible, using a portable MINOLTA CM-2002 spectrophotometer. The reflectance spectra of the same samples were also measured in near infrared range using a non-portable laboratory monochromator NIRSystem 6500. The proportion of cheeses correctly classified by NIRS and visible spectra was respectively 0.96 and 0.91 for pasture samples, and 0.96 and 0.79 for preserved-forage samples. No significant differences were found when fresh and freeze-dried cheeses were compared. We conclude that NIRS is able to classify cheese samples from different regimes (here, pasture vs. preserved-forage).

Effects of feeding practices on milk fat concentration for dairy cows.

Thirty-seven dairy farms, using high producing (7500 kg/yr per cow on average) Montbéliarde cows that were fed hay-based rations, were included in a detailed survey involving the structure of the farm and the herd, the quality of forage, the feeding practices in winter and summer, and genetic characteristics of the cows (breeding values and herd effects). These data were used to analyze variation in milk fat concentration among farms, particularly variation linked to environmental factors, as assessed by the herd effect. When farms were ranked according to herd effect of fat concentration, farms with the highest herd effects fed concentrate to cows in rolled form, distributed forage before or with the concentrate, and provided hay in the trough in summer. The effects of such practices on digestive phenomena in the rumen are discussed. This study supported the use of herd effects to identify factors related to variation in dairy cow performance.