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Background: beta-Carotene is an important precursor of vitamin A, and is associated with bovine fertility. beta-Carotene concentrations in plasma are used to optimize beta-carotene supplementation in cattle, but measurement requires specialized equipment to separate plasma and extract and measure beta-carotene, either using spectrophotometry or high performance liquid chromatography (HPLC).
Objective: The objective of this study was to validate a new 2-step point-of-care (POC) assay for measuring beta-carotene in whole blood and plasma.
Methods: beta-carotene concentrations in plasma from 166 cows were measured using HPLC and compared with results obtained using a POC assay, the iCheck-iEx-Carotene test kit. Whole blood samples from 23 of these cattle were also evaluated using the POC assay and compared with HPLC-plasma results from the same 23 animals. The POC assay includes an extraction vial (iEx Carotene) and hand-held photometer (iCheck Carotene).
Results: Concentrations of beta-carotene in plasma measured using the POC assay ranged from 0.40 to 15.84 mg/L (n = 166). No differences were observed between methods for assay of plasma (mean +/- SD; n = 166): HPLC-plasma 4.23 +/- 2.35 mg/L; POC-plasma 4.49 +/- 2.36 mg/L. Similar good agreement was found when plasma analyzed using HPLC was compared with whole blood analyzed using the POC system (n = 23): HPLC-plasma 3.46 +/- 2.12 mg/L; POC-whole blood 3.67 +/- 2.29 mg/L.
Conclusions: Concentrations of beta-carotene can be measured in blood and plasma from cattle easily and rapidly using a POC assay, and results are comparable to those obtained by the highly sophisticated HPLC method. Immediate feedback regarding beta-carotene deficiency facilitates rapid and appropriate optimization of beta-carotene supplementation in feed.
This study investigated vitamin A compounds in the plasma of healthy free-ranging Central European raptors with different feeding strategies. Plasma samples of nestlings of white-tailed sea eagle [white-tailed sea eagle (WTSE), Haliaeetus albicilla) (n = 32), osprey (Pandion haliaetus) (n = 39), northern goshawk (Accipiter gentilis) (n = 25), common buzzard (Buteo buteo) (n = 31), and honey buzzard (Pernis apivorus) (n = 18) and adults of WTSE (n = 10), osprey (n = 31), and northern goshawk (n = 45) were investigated with reversed-phase-high-performance liquid chromatography (RP-HPLC). In WTSE, northern goshawks and common buzzards retinol were the main plasma component of vitamin A, whilst in ospreys and honey buzzards, 3,4-didehydroretinol predominated. The median of the retinol plasma concentration in the nestlings group ranged from 0.12 to 3.80 mu M and in the adult group from 0.15 to 6.13 mu M. Median plasma concentrations of 3,4-didehydroretinol in nestlings ranged from 0.06 to 3.55 mu M. In adults, northern goshawks had the lowest plasma concentration of 3,4-didehydroretinol followed by WTSE and ospreys. The plasma of all investigated species contained retinyl esters (palmitate, oleate, and stearate). The results show considerable species-specific differences in the vitamin A plasma concentrations that might be caused by different nutrition strategies.
In this study, we investigated the alpha-tocopherol plasma concentrations in healthy free-ranging nestlings of the white-tailed sea eagle (Haliaeetus albicilla) (n=32), osprey (Pandion haliaetus) (n=39), northern goshawk (Accipiter gentilis) (n=25), common buzzard (Buteo buteo) (n=31), and honey buzzard (Pernis apivorus) (n=18) as well as of free-ranging adults of the white-tailed sea eagle (n=10), osprey (n=31), and northern goshawk (n=45). alpha-Tocopherol plasma concentrations were determined by reverse-phase high-performance liquid chromatography. alpha-Tocopherol plasma concentrations in nestlings of osprey, white-tailed sea eagle, and northern goshawk did not differ significantly amongst the species, but the common buzzard and honey buzzard nestlings had significantly lower alpha-tocopherol plasma concentrations than nestlings of the other species (both P<0.001). Adult male ospreys and white-tailed sea eagles had significantly higher alpha-tocopherol concentrations compared to adult females (both P<0.005). Adult ospreys and northern goshawks had significantly higher alpha-tocopherol plasma concentrations compared to their nestlings (both P<0.001). In adult female northern goshawks, plasma concentrations of alpha-tocopherol increased significantly before egg laying (P<0.001). These results demonstrate alpha-tocopherol plasma concentrations in birds of prey to be species specific and influenced by age and reproductive status.