This experiment was conducted to determine the variations in carotenoid, vitamins A and E concentrations, and color in the plasma and milk of dairy cows following a shift from a hay diet to diets containing increasing levels of carotenoids and vitamin E. This study was performed on 32 multiparous Montbéliarde dairy cows in midlactation. After a 6-wk preexperimental period on a diet based on hay and concentrates, the cows were allocated to 4 homogeneous groups, and thereafter fed for 6 wk on isoenergetic experimental diets where the hay was replaced by an experimental feed rich in carotenoids and vitamin E, consisting in 75% grass silage and 25% alfalfa protein concentrate (PX Agro Super Desialis, Châlons en Champagne, France). The hay-to-experimental feed ratios were 100/0 in group 1, 67/33 in group 2, 33/67 in group 3, and 0/100 in group 4, providing 1.6, 3.6, 5.4, and 7.4 g/d of total carotenoids, respectively. Variations in carotenoid, vitamins A and E concentrations as well as variations in color index (CI) were monitored from d -7 through to d 42 on the experimental diets. Zeaxanthin, lutein, 13-cis-beta-carotene, and all-trans-beta-carotene accounted for an average 3, 10, 9, and 78%, respectively, of total carotenoids in plasma and 0, 17, 12, and 71%, respectively, of total carotenoids in milk. The switch from preexperimental to experimental diets only slightly affected zeaxanthin, lutein, and vitamin A concentrations in plasma and milk. A rapid increase in vitamin E and beta-carotene (BC) was observed during the first week in both plasma and milk. For vitamin E, the time to reach a plateau was from 8 d (group 2) to 28 d (group 4) in plasma, and 5 d (groups 2-4) in milk. Plasma concentrations of BC had stabilized after 28 d in group 2 but were not stabilized after 42 d in groups 3 and 4, whereas milk concentrations of BC plateaued from d 21 in group 2 and d 28 in groups 3 and 4. At the end of the experimental period, BC and vitamin E concentrations in plasma and vitamin E concentrations in milk fat were linearly related to the proportion of experimental feed in the diet. In contrast, BC concentrations in milk fat did not differ between groups 2, 3, and 4, reflecting saturation at high levels of carotenoid intake (i.e., when plasma BC exceeded 5 mug/mL). These results suggested that under high-carotenoid diets, milk secretion of BC is not limited by the amount of plasma BC arriving to the mammary gland but by mechanisms involved in the BC transfer from plasma to milk. These mechanisms will need to be investigated. The BC concentrations were responsible for more than 80% of CI variations in plasma and 56% of CI variations in milk, where there was wide variability among individuals. Plasma CI appeared to be a more promising tool than milk CI as an indicator of the carotene content of the diets ingested by dairy cows.

The main aim of this work was to assess the effect of lactation period on the secretion of carotenoids in cow's milk. Our objective was to determine the variations in carotenoids in the plasma and milk of dairy cows from drying off to wk 12 of lactation, and to specify whether these variations depend on body stores of these micronutrients at calving. We also investigated the relationship between beta-carotene (BC) and color in plasma and milk to evaluate the methods based on direct or indirect characterization of these micronutrients for traceability of feeding management. The experiment was carried out on 18 dairy cows, which were dried off 8 wk before their expected date of parturition. They were then divided into 2 homogeneous groups and fed diets contrasting in carotenoid content, high (grass silage) vs. low (corn silage), from wk -7 until parturition. From parturition through wk 12 of lactation, both groups received a grass silage-based diet. Variations in concentrations of carotenoids and the color index (CI) in plasma and milk were monitored from drying off to wk 12 of lactation. Other components of nutritional interest (i.e., vitamins A and E) were also measured. Lutein, all-trans BC and cis-13 BC were the carotenoids found in plasma and milk. Plasma concentrations of carotenoids, vitamin A, and vitamin E decreased throughout the dry period and in the first week of lactation, then increased through the first 3 mo of lactation, parallel to grass silage intake. For both groups, carotenoid and vitamin concentrations in milk drastically decreased during the first week of lactation, then did not vary significantly throughout the remainder to the experiment (wk 12). Plasma concentrations of carotenoids and vitamins were higher in the high-carotenoid group than in the low-carotenoid group during the dry period. Those differences were also observed in colostrum and disappeared in both plasma and milk during the first 10 d of the lactation period. This work allowed us to conclude that, unlike in plasma, variations in carotenoids, vitamin A, and vitamin E in milk were only slight in early lactation. In both plasma and milk, the concentrations were only transitorily affected by the nature of forage fed during the dry period, showing that they depended mainly on the dietary supply, even during the lipid mobilization period. The relationship between concentrations of BC and the CI was linear in plasma (R2 = 0.51) and milk (R2 = 0.37) and reached a plateau in the milk + colostrum data set (R2 = 0.77). The changes in CI during the first 3 mo of lactation were not negligible compared with variations related to the nature of forage reported in previous studies. This implies that methods being developed for the traceability of feeding management of dairy cows based on direct or indirect characterization of these micronutrients in milk, plasma, or both will need to account for changes in relation to lactation stage, which requires further investigation.

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-Carotenoids are involved in the sensorial and nutritional values of dairy products. In grazing systems, both herbage maturity stage and grazing management may affect the amount of carotenoid ingested, thus these factors may affect carotenoid concentrations in milk. Two homogenous plots of mountain grassland (1.4 and 2.0 ha) were grazed during two cycles of growth by 6 dairy cows in mid lactation, in strip (SG) and rotational grazing (RG), respectively. We monitored the changes in carotenoid concentrations in sward and milk, measured by HPLC twice a week. Seven carotenoids were identified in the sward: violaxanthin, antheraxanthin, epilutein, lutein, zeaxanthin, ß-carotene and 13-cis ß-carotene. Forage quality decreased throughout the course of the first growth stage, but carotenoid concentration in sward did not significantly change. In early regrowth, forage quality was high and the concentration of ß-carotene and xanthophylls also tended to be higher. Carotenoid concentrations in sward were not affected by grazing management, averaging 350 µg per g DM. The carotenoids identified in milk were β-carotene (75%) and lutein (25%). A significant decrease in ß-carotene concentration in milk was observed throughout the course of the first growth stage, from 5.37 to 3.87 µg per g fat, whereas it increased to 4.91 µg per g fat in early regrowth. β-carotene concentration in milk was not affected by grazing management, averaging 4.72 and 5.03 µg per g fat for RG and SG, respectively. However, lutein concentration was slightly lower for RG than for SG, averaging 1.39 and 1.74 µg per g fat, respectively. It is concluded that carotenoids in milk were only slightly affected by herbage maturity stage, and to a lesser extent by grazing management. caroténoïdes du lait pourraient dépendre du stade de l'herbe et du mode de pâturage, qui conditionnent la quantité et la qualité de l'ingéré. Pour valider cette hypothèse, deux prairies naturelles de montagne homogènes, de 1,4 et 2,0 ha, ont été exploitées par 6 vaches en milieu de lactation, en pâturage tournant rapide (SG) et lent (RG), respectivement, pendant deux cycles de végétation. Nous avons suivi l'évolution des teneurs en caroténoides de l'herbe et du lait, déterminées par HPLC sur deux prélèvements par semaines. Dans l'herbe, sept caroténoïdes ont été identifiés : violaxanthine, anthéraxanthine, épilutéine, lutéine, zéaxanthine, ß-carotène et 13-cis ß-carotène. Au cours du premier cycle de végétation, la valeur nutritive de l'herbe a fortement diminué, mais sa teneur en caroténoïdes n'a pas été significativement modifiée. Les teneurs en ß-carotène et xanthophylles et la valeur nutritive de l'herbe étaient les plus élevées au début du deuxième cycle. La concentration en caroténoïdes de l'herbe n'a pas été affectée par le mode de pâturage, et était en moyenne de 350 µg par g MS. Dans le lait, les caroténoïdes identifiés ont été le ß-carotène (75 %) et la lutéine (25 %). La concentration en ß-carotène dans le lait a diminué significativement de 5,37 à 3,87 µg par g M...

Traditional methods to measure spatio-temporal variations in biomass rely on a labor-intensive destructive sampling of the crop. In this paper, we present a high-throughput phenotyping approach for the estimation of Above-Ground Biomass Dynamics (AGBD) using an unmanned aerial system. Multispectral imagery was acquired and processed by using the proposed segmentation method called GFKuts, that optimally labels the plot canopy based on a Gaussian mixture model, a Montecarlo based K-means, and a guided image filtering. Accurate plot segmentation results enabled the extraction of several canopy features associated with biomass yield. Machine learning algorithms were trained to estimate the AGBD according to the growth stages of the crop and the physiological response of two rice genotypes under lowland and upland production systems. Results report AGBD estimation correlations with an average of r = 0.95 and R 2 = 0.91 according to the experimental data. We compared our segmentation method against a traditional technique based on clustering. A comprehensive improvement of 13% in the biomass correlation was obtained thanks to the segmentation method proposed herein.