Ketone bodies in blood of dairy cows: Prevalence and monitoring of subclinical ketosis

The aim of this study was to investigate the relationship between concentration of non-esterified fatty acid and ketone bodies in blood of dairy cows, and to evaluate these concentrations for the detection of prevalence of subclinical ketosis. The second aim was to compare the concentration of β-hydroxybutyric acid determined by an electronic handheld meter Precision Xtra® with serum concentration of β-hydroxybutyric acid analysed in laboratory with izotachometric and photometric method, respectively. Blood samples were collected from jugular vein 4–6 h after morning feeding in three groups of Holstein cows (n = 909) according to the lactation phase from 51 different herds with similar husbandry characteristics. High lipomobilization (non-esterified fatty acid ≥ 0.35 mmol·l-1, mean concentration 0.34 ± 0.15 mmol·l-1) was detected in 30.3% of antepartum cows, while increased concentrations of β-hydroxybutyric acid (≥ 1.0 mmol·l-1, prevalence of subclinical ketosis) were detected in 18.5% and 14.1% of the early lactation and mid lactation cows, respectively. The correlation coefficient (r = 0.84, P < 0.001; r = 0.93, P < 0.001) was found between measurements of whole blood β-hydroxybutyric acid of 60 and 38 dairy cows determined with the Precision Xtra® test and plasma or serum β-hydroxybutyric acid concentration determined by isotachophoresis and photometrical method, respectively. Our results show that the monitoring of changes in the blood concentration of β-hydroxybutyric acid in high-yielding cows in the early postpartum period by the electronic handheld meter Precision Xtra® may be effective in reducing the incidence of ketosis and health problems associated with ketosis in dairy cattle herds.

Milk acetone determination by the photometrical method after microdiffusion and via FT infra-red spectroscopy

Milk acetone determination by the photometrical method after microdiffusion and via FT infra-red spectroscopyMilk acetone (AC) and betahydroxybutyrate (BHB) are important indicators of the energy metabolism of cows (ketosis occurrence) and an effective method for their determination, with reliable results, is of great importance. The goal of this work was to investigate the infrared method MIR-FT in terms of its calibration for milk AC and to develop a usable procedure. The microdiffusion photometric (485 nm; Spekol 11) method was used with salicylaldehyde as a reference (Re) and mid infrared spectroscopy FT (MIR-FT: Lactoscope FT-IR, Delta; MilkoScan FT 6000, M-Sc) as an indirect method. The acetone addition to milk had no recovery using MIR-FT (Delta). The reference AC set must have acceptable statistics for good MIR-FT calibration (M-Sc) and they were: 10.1 ± 9.74 at a geometric mean of 7.26 mg l-1, and a variation range from 1.98 to 33.66 mg l-1. The AC correlation between Re and MIR-FT (Delta) was low at 0.32 (P>0.05 but the Log AC relationship between Re and MIR-FT (M-Sc) was markedly better at 0.80 (P<0.01). The conversion of >10 mg l-1 as an AC subclinical ketosis limit could be > -0.80 (feedback 0.158 mmol l-1 = 9.25 mg l-1) and > -1.66. This could be important for ketosis monitoring (using M-Sc).

Reliability of results of milk urea analysis by various methods using artificial milk control samples

The milk urea concentration (MUC) is a respected indicator of the health and nutrition status of dairy cows. It is in relation to their reproduction performance, longevity and technological milk indicators. The accuracy of the interpretation of results depends on their reliability, which is so important. There are a lot of principles of MUC analyses. Their results can be affected by a number of interferential factors. Many disproportions were noticed for the above-mentioned reasons in laboratory practice. That is the reason why relevant result variation sources are studied. The goal of this paper was to search the relationships between different methods of MUC determination with the use of specifically modified samples on a milk basis with the absence of dissolved components such as lactose. The results of two methods (photometric BI with diacetylmonoxime and FT-MIR (mid infrared)) were disqualified for a large shift and variance of values, unsatisfactory recovery and paralysed relation to other methods (BI <I>r</I> = from 0.184 to 0.213; <I>P</I> > 0.05). Therefore the second BI method was retained in the evaluation, and it was probably a local defect in the performance at disqualification. Nevertheless, the procedure showed poorer recovery (75.5 ± 14.3%) and necessity for methodical modifications for support of result reliability such as increase in the number of calibration points as compared to the contemporary procedure. The results of FT-MIR method were strongly systematically displaced due to lactose absence in particular (by 33.824 ± 3.794 mg/100 ml). Nevertheless, the correlations with results of other relevant methods were tight (from 0.991 to 0.999; <I>P</I> < 0.001). The photometrical method with Ehrlich’s agent (para-dimethylaminobenzaldehyde, EH) showed acceptable values of all the evaluated indicators of reliability. The specific Ureakvant method (UR; with conductivity difference measurement) showed the most proper results in combination with all the reliability indicators (recovery as much as 93.2 ± 10.2%; correlation from 0.989 to 1.0; <I>P</I> < 0.001; acceptable ratio of systematic and random error components). It is possible to use the tested specific standard samples for the control or calibration of all methods (BI, EH and UR) with the exception of FT-MIR.

XIV. Researches on spectrum photography in relation to new methods of quantitative chemical analysis.—Part II

The first attempt to apply the spectroscope to the quantitative analysis of alloys seems to have been made by the late Dr. W. A. Miller, F. R. S., in the year 1862 (Phil. Trans., Vol. 152, p. 883,1863, and Jour. Chem. Soc., vol. xvii., p. 82, 1864). By taking photographs of the spectra of alloys of gold and silver of different degrees of fineness he obviously sought to apply this method of working to the assaying of gold. He was at the time an assayer to the Royal Mint. In 1870 M. Janssen proposed two methods of quantitative spectrum analysis. The first was based on measurements of the intensity of the most brilliant rays emitted by incandescent matter, while the second depended upon the time during which a substance emits visible rays during complete volatilisation in a flame (Comptes Bendus, Ixxvi., pp. 711–713). MM. P. Champion and H. Pellet, and also M. Grenier, applied the former spectro-photometrical method with some degree of success to the estimation of alkalies (Comptes Rendus, lxxvi., pp. 707–711). In 1874 Messrs. Lockyer and Roberts attempted and accomplished with a considerable amount of accuracy the determination of the composition of certain tolerably homogeneous alloys of gold and silver, and of lead and cadmium, by means of the spark passed between metallic electrodes, and examined by the spectroscope. The spectrum of the alloy was compared with certain check pieces of known composition. Others who have attempted to make use of emission spectra for the purposes of quantitative analysis are Sir J. G. N. Alleyne, who in 1875 communicated a paper to the Iron and Steel Institute “On the estimation of small quantities of Phosphorus in Iron and Steel by Spectrum Analysis” (Journal of the Iron and Steel Institute, 1875, pp. 62–72), and H. Ballman, who attempted the quantitative estimation of lithium with the spectroscope by observing the degree of dilution of a solution which seemed to cause the extinction of the red line. This is theoretically constant, but practically it varies slightly (Zeitschrift für Analytische Chemie, vol. xiv., pp, 297–301; also Journal Chem. Soc., 1876, p. 550, Abstract). Messrs. Liveing and Dewar have published notes on quantitative spectroscopic experiments (Proc. Roy. Soc., vol. xxix., pp. 482–489). Observing the emission spectrum of sodium vapour, they sought to estimate the quantity of substance present in a given space by measuring the width of the sodium lines.