A mutation in the promoter of the chicken ß,ß-carotene 15,15'-monooxygenase 1 gene alters xanthophyll metabolism through a selective effect on its mRNA abundance in the breast muscle.

A polymorphism in the promoter of the ß,ß-carotene 15,15'-monooxygenase 1 (BCMO1) gene recently was identified in an experimental cross between 2 chicken lines divergently selected on growth rate and found to be associated with variations in the yellow color of the breast meat. In this study, the effects of the polymorphism on several aspects of carotenoid metabolism were evaluated in chickens sharing the same genetic background except for their genotype at the BCMO1 locus. We confirmed that BCMO1 mRNA abundance varied (P < 0.001) between the 2 homozygous genotypes (GG << AA) and in the pectoralis major muscle. By contrast, BCMO1 mRNA expression was not affected (P > 0.05) by the polymorphism in the duodenum, liver, or sartorius muscle. The breast meat of GG chickens was more (P < 0.001) yellow and richer in lutein (P < 0.01) and zeaxanthin (P < 0.05) compared to that of AA chickens whereas these variables did not differ (P > 0.05) in the other tissues tested. The GG were also characterized by reduced (P < 0.01) plasma lutein and zeaxanthin concentrations than AA without affecting plasma and tissue content of fat-soluble vitamins A and E. As lutein and zeaxanthin are usually not considered as substrates of the BCMO1 enzyme, the impact of BCMO1 polymorphism on the activity of other genes involved in carotenoid transport (SCARB1 and CD36 encoding the scavenger receptor class B type I and the cluster determinant 36, respectively) and metabolism (BCDO2 encoding ß,ß-carotene 9',10'-dioxygenase 2) was evaluated. The BCMO1 polymorphism did not affect mRNA abundance of BCDO2, SCARB1, or CD36, regardless of tissue considered. Taken together, these results indicated that a genetic variant of BCMO1 specifically changes lutein and zeaxanthin content in the chicken plasma and breast muscle without impairing vitamin A and E metabolism.

Simultaneous quantification of carotenoids, retinol, and tocopherols in forages, bovine plasma, and milk: validation of a novel UPLC method.

Simultaneous quantification of various liposoluble micronutrients is not a new area of interest since these compounds participate in the nutritional quality of feeds that is largely explored in human, and also in animal diet. However, the development of related methods is still under concern, especially when the carotenoid composition is complex such as in forages given to ruminants or in lipid-rich matrices like milk. In this paper, an original method for simultaneous extraction and quantification of all carotenoids, vitamins E, and A in milk was proposed. Moreover, a new UPLC method allowing simultaneous determination of carotenoids and vitamins A and E in forage, plasma and milk, and separation of 23 peaks of carotenoids in forages was described. This UPLC method using a HSS T3 column and a gradient solvent system was compared to a previously published reverse-phase HPLC using two C18 columns in series and an isocratic solvent system. The UPLC method gave similar concentrations of carotenoids and vitamins A and E than the HPLC method. Moreover, UPLC allowed a better resolution for xanthophylls, especially lutein and zeaxanthin, for the three isomers of beta-carotene (all-E-, 9Z- and 13Z-) and for vitamins A, an equal or better sensitivity according to gradient, and a better reproducibility of peak areas and retention times, but did not reduce the time required for analysis.

Discrimination of pasture-fed lambs from lambs fed dehydrated alfalfa indoors using different compounds measured in the fat, meat and plasma.

The last decade has seen important developments in the use of carotenoid pigments to authenticate pasture-feeding in ruminants. However, dehydrated alfalfa is sometimes incorporated in grain-based concentrates fed to stall-raised lambs, which may affect the reliability of the pasture-feeding authentication methods based on carotenoids in plasma and fat, due to significant residual carotenoid levels post-dehydration. The aim of this study was to examine whether other compounds can give additional information to authenticate diet and discriminate pasture-fed lambs from lambs fed high levels of alfalfa indoors. Two feeding treatments were compared: pasture-feeding (P) v. stall-feeding with dehydrated alfalfa (A). Each treatment group consisted of seven male Romanov × Berrichon lambs. Pasture-fed (P) lambs grazed a permanent graminaceae-rich pasture maintained at a leafy, green stage, offered ad libitum; they received no supplementation at pasture. A-group lambs were individually penned and fed dehydrated alfalfa and straw; their feed level was adjusted to achieve a similar growth pattern as for P-group lambs. Plasma carotenoid concentration was measured at slaughter by spectrophotometry. The reflectance spectrum of perirenal and subcutaneous caudal fat was measured at 24-h post mortem and used to calculate an index (absolute value of the mean integral (AVMI)) quantifying light absorption by carotenoid pigments present in the fat. The nitrogen (N) stable isotopes ratio (δ15N) in both feed and longissimus dorsi muscle was measured by isotopes ratio mass spectrometry (IRMS). Volatile compounds were analyzed in perirenal fat for five randomly chosen lambs per treatment, using dynamic headspace-gas chromatography-mass spectrometry. Plasma carotenoid concentration and AVMI of the fat did not differ significantly between P- and A-group lambs, but there were significant between-treatment differences in meat δ15N values and in the terpene profiles of perirenal fat. A discriminant analysis performed using three compounds in different animal tissues (δ-cadinene in perirenal fat, δ15N value of the meat and plasma carotenoid concentration) clearly separated pasture-fed lambs from lambs fed high levels of alfalfa indoors.

Variations in carotenoids, vitamins A and E, and color in cow's plasma and milk following a shift from hay diet to diets containing increasing levels of carotenoids and vitamin E.

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.

A dose-response study relating the concentration of carotenoid pigments in blood and reflectance spectrum characteristics of fat to carotenoid intake level in sheep.

This study was conducted to describe the dose-response curve relating the concentration of carotenoid pigments in plasma and reflectance spectrum characteristics of fat to the carotenoid intake level in sheep, and to investigate the extent to which incorporation of dehydrated alfalfa in the diet affects the reliability of the discrimination between concentrate-fed and pasture-fed lambs based on these measurements. In Exp. 1, 6 treatments were compared in individually penned lambs: feeding 0, 250, 500, 750, 1,000, or 1,250 g/d of dehydrated alfalfa for 60 d before slaughter. Each treatment (T0 to T1,250) consisted of 8 male Romanov x Berrichon lambs with an initial average BW of 24.8 kg (SD 2.6). All lambs received straw for ad libitum intake and T0 to T1,000 lambs received a concentrate free of green vegetative matter in amounts to produce similar ADG in all treatments. In Exp. 2, 33 male Romanov x Berrichon lambs grazed a natural pasture maintained in a leafy green vegetative stage for at least 59 d before slaughter. Initial BW when turning out to pasture was 14.2 kg (SD 2.3). Plasma carotenoid concentration was measured at slaughter by spectrophotometry. Reflectance spectrum, lightness, redness, and yellowness were measured after 24 h of shrinkage in subcutaneous caudal and perirenal fat. The spectra were translated to 0 reflectance at 510 nm, and the integral of the translated spectrum was calculated between 450 and 510 nm (i.e., the range of light absorption by carotenoids). Reflectance measurement was replicated 5 times, from which we calculated the absolute value of the mean integral (AVMI). In Exp. 1, plasma carotenoid concentration at slaughter (PCCS) increased linearly with mean daily carotenoid intake (P < 0.01). Both subcutaneous caudal and perirenal fat AVMI increased linearly (P < 0.01) with mean daily carotenoid intake and PCCS, the slopes of the regressions being greater for perirenal than for subcutaneous caudal fat. The mean PCCS was greater for lambs of Exp. 2 than for lambs on any treatment of Exp. 1 (P < 0.01). We established the dose-response curves relating PCCS and AVMI of subcutaneous and perirenal fat to carotenoid intake level. The combined use of PCCS and of perirenal fat AVMI enabled discrimination of pasture-fed lambs of Exp. 2 from the lambs of Exp. 1 that received up to 500 g/d of dehydrated alfalfa.

Variations in carotenoids, vitamins A and E, and color in cow's plasma and milk during late pregnancy and the first three months of lactation.

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.