[Manganese concentrations in whole blood, plasma and serum of adult warmblood horses from 3 locations in Germany]. / Mangankonzentrationen im Vollblut, Plasma und Serum adulter Warmblutpferde an 3 Standorten in Deutschland.

OBJECTIVE: This study aimed to establish reference intervals for Mn in whole blood, plasma and serum of healthy, adult warmblood horses with known dietary Mn intake and to compare 2 methods of analysis. MATERIAL AND METHODS: Between May 2018 and November 2019 a single blood sample was taken from a total of 270 clinically healthy horses (age: 3-25 years) in 3 stud farms. In lithium-heparin (LH) whole blood, LH plasma and serum Mn concentrations were analyzed by means of atomic absorption spectrometry (AAS) and inductively coupled plasma mass spectrometry (ICP-MS). The reference intervals were calculated according to the recommendations of the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) and the Clinical and Laboratory Standards Institute (CLSI) comprising the range between 2.5 and 97.5 percentile of the analyzed Mn concentrations. Concurrent to blood sampling feed samples were taken and analyzed in order to determine the Mn content of the corresponding feeding ration. RESULTS: The horses' whole-blood Mn levels were significantly (p < 0.0001) higher with a median Mn concentration of 12.4 µg/l (reference interval: 4.99-25.1 µg/l [AAS]; 5.99-25.3 µg/l [ICP-MS]) than in the corresponding serum (median: 1.65 µg/l, reference interval: 0.60-3.50 µg/l [AAS]; 1.11-2.96 µg/l [ICP-MS]) or LH plasma (median: 1.35 µg/l, reference interval: 0.22-2.68 µg/l [AAS]; 0.59-2.45 µg/l [ICP-MS]). In the comparison of methods, there were statistically significant differences in the Mn determinations for LH plasma and serum between AAS and ICP-MS, whereas they yielded comparable results for whole blood. CONCLUSION AND CLINICAL RELEVANCE: Whole blood shows an average of 10-fold higher Mn concentrations than serum or LH plasma. When evaluating blood Mn concentrations, consideration must be granted to the sample material under analysis as well as to which method is employed since relevant differences were found between AAS and ICP-MS in serum and LH plasma.

[Effects of oral manganese supplementation with different compounds on the manganese whole blood and serum concentrations of broodmares and their suckling foals]. / Effekte einer oralen Mangansupplementierung mit unterschiedlichen Verbindungen auf die Mangankonzentrationen in Vollblut und Serum von Stuten und Saugfohlen.

OBJECTIVE: This study aimed to examine the effects of an oral supplementation on manganese (Mn) concentrations in the blood of lactating warm-blood broodmares. Furthermore, the potential relationship between Mn supply of the lactating mare and its suckling foal was investigated. MATERIAL AND METHODS: During the 90-day trial, lactating mares were divided into 3 groups and daily received a daily dose of either a placebo (n = 11) or a Mn supplement of 560 mg Mn as Mn sulfate (n = 11) or Mn chelate (n = 11) in addition to the Mn intake from the basal ration (hay ad libitum, total mixed ration: Mn intake ~ 100 mg/kg dry matter). Blood samples were taken from the mares and their foals in 14-day intervals. The Mn determination in serum and whole blood as well as in the mare's milk was carried out by means of mass spectrometry with inductively coupled plasma. The Mn analysis in representative feed samples was performed by means of atomic absorption spectrometry. Data were assessed using the software IBM SPSS Statistics 27 (IBM Deutschland GmbH, Ehningen). RESULTS: During the trial period, the mares showed Mn concentrations 10-fold higher in whole blood (median: 15.6 µg/l; 25-75 percentile: 12.8-18.5 µg/l) than in serum (median: 1.54 µg/l; 25-75 percentile: 1.20-1.90 µg/l). The foals had Mn whole-blood concentrations 16.4-fold higher (median: 21.3 µg/l; 25-75 percentile: 16.7-28.1 µg/l) compared to their serum (median: 1.50 µg/l; 25-75 percentile: 1.30-1.70 µg/l). The Mn whole-blood levels of the foals corresponded to 1.6-fold the Mn concentration of their dams. The milk contained a median Mn concentration of 0.012 mg/kg fresh matter. Mn supplementation had no effect on the Mn blood levels of mares and their foals. CONCLUSION AND CLINICAL RELEVANCE: Blood Mn concentrations were not affected by the Mn supplementation. However, the Mn levels differed significantly between serum and whole blood. In addition, the Mn concentrations in whole blood of suckling foals were higher compared to their dams, although the Mn concentrations in the mare's milk were low regardless of Mn supplementation. Due to the low Mn content in milk, early Mn supply, preferably by forages, is necessary to ensure that the foals are supplied with Mn according to their requirement.