Diurnal variation of milk fatty acids in early-lactation Holstein cows with and without hyperketonemia

Estimates of milk constituents by Fourier-transform mid-infrared (FTIR) analysis have been shown to be a useful tool in monitoring energy deficit in early-lactation dairy cows. Our objectives were to describe the diurnal variation in milk fatty acids (FAs) and estimate the association of hyperketonemia with concentrations and diurnal patterns of FTIR estimates of milk FA. Blood samples were collected via jugular catheters bihourly for 5 d from multiparous Holstein cows (n = 28) enrolled between 3 and 9 days in milk. Milk samples were collected thrice daily at 0600, 1400, and 2200 h for d 2, 3, and 4 of the study period. Cows were retrospectively classified as hyperketonemic (HYK; n = 13) or non-HYK (n = 15) based on blood beta-hydroxybutyrate (bBHB) concentrations analyzed during the study period. Cows were classified as HYK if bBHB was ≥ 1.2 mmol/l for ≥ 50% (22/44) of bihourly timepoints; cows were classified as non-HYK if bBHB was ≥ 1.2 mmol/l for < 50% of bihourly timepoints. The HYK cows had bBHB ≥ 1.2 mmol/l for 31.4 ± 6.8 timepoints while the non-HYK cows had bBHB ≥ 1.2 mmol/l for 8.0 ± 3.9 timepoints. We used generalized linear mixed models to analyze concentrations of milk FA over time and differences between HYK groups. The relative percentage of de novo, mixed, and preformed FAs all followed diurnal patterns, however only the yield of preformed FA diurnally cycled, reaching a nadir at 0600 h and peaking at 1400 h. The yield per milking of preformed FA was also greater in the HYK cows than in the non-HYK cows. Oleic acid in milk followed a similar diurnal pattern to the yield of preformed FA, likely driving the cyclical nature of preformed FA. Finally, stearic acid was greater in HYK cows. Our results suggest that FTIR estimates of milk FA offer the potential to provide insight on the energy status of early-lactation cows, and when interested in understanding the absolute concentrations and yields of milk FA, diurnal variation should be considered.     

Identification of natural and semisynthetic ω-cycloalkyl fatty acids

The experimental criteria, principally GLC behaviour and spectroscopic data, by which ω-cycloalkyl fatty acids (cyclobutyl to cycloheptyl, C₁₄ to C₂₁) can be identified, are described.     

Digestion of fatty acids in ruminants: a meta-analysis of flows and variation factors. 1. Total fatty acids

A database built from 95 experiments with 303 treatments was used to quantify the ruminal biohydrogenation (BH) of fatty acids (FA), efficiency of microbial protein synthesis (EMPS), duodenal flow and intestinal absorption of total FA and of FA with 12 to 18 C units, in response to variations in dietary FA content, source or technological treatment of fat supplement. Flows of FA were expressed relative to dry matter intake (DMI) to compile data from bovine and ovine species. BH tended to increase curvilinearly with FA intake, whereas dietary FA did not affect EMPS. A linear relationship between FA intake and duodenal flow of total FA was obtained, with a coefficient of 0.75 ± 0.06 g duodenal FA/kg DMI for each g FA intake/kg DMI. Between experiments, positive balances of total FA (intake - duodenum) were related to low EMPS. Relationships between duodenal flows of FA with 12 to 18 C units and their respective intakes were linear, with a coefficient that increased with the number of C units. Duodenal flow of bacterial FA was linearly related to FA intake (coefficient 0.33 ± 0.13), whereas contribution of bacterial lipid to duodenal flow decreased as FA intake increased. For each FA with 12 to 16 C units, prediction of FA absorption from its respective duodenal flow was linear. For total FA and FA with 18 C units, apparent absorption levelled off at high duodenal flows. All these relationships were discussed according to current knowledge on microbial metabolism in the rumen and on the intestinal digestibility of FA in the intestine.     

Signature fatty acids in the polar lipids of acid-producing Thiobacillus spp.: Methoxy, cyclopropyl, alpha-hydroxy-cyclopropyl and branched and normal monoenoic fatty acids

Abstract The polar lipids of 5 species of Thiobacillus were extracted and purified. An analysis of the fatty acid composition of the polar lipids documented the presence of methoxy, cyclopropyl, monounsaturated and hydroxycyclopropyl fatty acids of sufficiently unusual structure to serve as 'signatures' for the presence of these organisms in environmental samples. The structures of the unusual fatty acids of the polar lipids were confirmed by mass spectrometry (MS) after isolation by capillary gas chromatography (GC).     

Seasonal variation in plasma lipids and lipases in young healthy humans

Although intermediate metabolism is known to follow circadian rhythms, little information is available on the variation in lipase activities (lipoprotein and hepatic lipase, LPL and HL, respectively) and lipids throughout the year.

In a cross-sectional study, we collected and analysed blood from 245 healthy students (110 men and 135 women) between 18 and 25 years old from the University of Barcelona throughout the annual campaign (March, May, October and December) of the blood bank. All subjects gave their written informed consent to participate. All blood samples were taken after breakfast at 8:00 and 11:00 am.

Plasma glucose, total plasma protein, triacylglycerides (TAG), free fatty acids (FFA), free cholesterol and esterified cholesterol (FC and TC, respectively), cholesterol in low-density lipoproteins (cLDL), cholesterol in high-density lipoproteins (cHDL), phospholipids (PL) and lipase activities (LPL and HL) were determined. Cosinor analysis was used to evaluate the presence (significance of fit cosine curve to data and variance explained by rhythm) and characteristics of possible 12-month rhythms (acrophase, MESOR and amplitude).

Statistically significant seasonal rhythms were detected for all the variables studied except proteins, with most of them peaking in the winter season. The lowest value for cLDL and the HL occurs in summer, while for cHDL and the LPL it is in winter.

These findings demonstrate for the first time that in physiological conditions, plasma LPL and HL activities and lipids follow seasonal rhythms. The metabolic significance of this pattern is discussed.     

Specificity effects in the biosynthesis of fatty acids in Bacillus acidocaldarius

Addition to Bacillus acidocaldarius of acids which can act as primers for fatty acid synthesis promote the synthesis of corresponding fatty acids competitively. The effective acids are n?C₅ to -?₇ (not C₄ or C₈), iso- and anteiso-C, and ?C, (not C4), and a range of cyclic acids from cyclobutylacetic and cyclopentanecarboxylic to cycloheptylacetic. New non-natural ω-cyclobutyl-, ω-cyclopentyl-, and ω-cycloheptyl-fatty acids are obtainable. The range of acceptable primers and the range of fatty acids produced therefrom indicate, respectively, the substrate specificities of the transacylase which introduces acyl species into fatty acids synthesis and the one which removes them. The specificity of the primer transacylase may be similar to that in some rumen anaerobes.     

Digestion of fatty acids in ruminants: a meta-analysis of flows and variation factors: 2. C18 fatty acids

In ruminants, dietary lipids are extensively hydrogenated by rumen micro-organisms, and the extent of this biohydrogenation is a major determinant of long-chain fatty acid profiles of animal products (milk, meat). This paper reports on the duodenal flows of C18 fatty acids and their absorption in the small intestine, using a meta-analysis of a database of 77 experiments (294 treatments). We established equations for the prediction of duodenal flows of various 18-carbon (C18) fatty acids as a function of the intakes of their precursors and other dietary factors (source and/or technological treatment of dietary lipids). We also quantified the influence of several factors modifying rumen metabolism (pH, forage : concentrate ratio, level of intake, fish oil supplementation). We established equations for the apparent absorption of these fatty acids in the small intestine as a function of their duodenal flows. For all C18 unsaturated fatty acids, apparent absorption was a linear function of duodenal flow. For 18:0, apparent absorption levelled off for high duodenal flows. From this database, with fatty acid flows expressed in g/kg dry matter intake, we could not find any significant differences between animal categories (lactating cows, other cattle or sheep) in terms of rumen metabolism or intestinal absorption of C18 fatty acids.     

Seasonal variation of sexual differences in the volatile oil of Juniperus scopulorum

Very few differences between male and female trees were found in the volatile oil composition of Juniperus scopulorum Sarg. Differences were more apparent when the compounds were calculated as percent of total oil than as weight per g dry matter. Almost all of the sexual differences occurred in the growing season (March–May). Essentially no differences were observed during the rest of the year. The observed differences were very small and should not affect the choice of plant material used in revegetating efforts (when browse potential is important). These differences should not affect chemosystematic studies, particularly if sampling is done during the period of the year when the plants are dormant.     

Seasonal variation of bovine anti-J in the tropics*

Close to the Equator at an altitude of 1750 m above sea level a total of 27 cows of various breeds have been studied with regard to the fluctuation of their anti-J naturally occurring antibodies. Over 16 consecutive months the average total score of anti-J varied from a minimum of 20 in October to a maximum of 37 at. the end of December. Practically all the sera had the lowest level of anti-J in October. This is about two months after the lowest yearly maximum temperature. It is concluded that gradual changes in temperature can cause variation in anti-J titer, and that the magnitude of the seasonal temperature changes influences the fluctuation of the natural anti-J.     

Identification of fatty acids from Cladonia lichens

Fatty acids of eight lichen species belonging to the genus Cladonia were examined by GC-MS. Twenty-two saturated, 23 monoene, five diene, nine triene and eight tetra-, penta- and hexaene fatty acids were identified. Unusually for lichens, very long-chain fatty acids, 25:1, 26:0, 26:1, 26:3, 28:0, 28:1, and 30:1 were detected.     

Biochemistry of radioiodinated free fatty acids

Summary Radioiodinated free fatty acids have been developed to study myocardial metabolism non-invasively in man. In the present study the distribution of radiolabeled lipids in the myocardium and in arterial and coronary sinus blood was evaluated following injection of three commonly used iodinated fatty acids in fasted (n = 5) and lactate loaded (n = 3) dogs. Five minutes after simultaneous i.v. injection of radioiodinated 17-I-heptadecanoic acid (IHDA),15-(p-I-phenyl) pentadecanoic acid (IPPA) and 15-(p-I-phenyl)-3,3-dimethylpentadecanoic acid (DMIPPA) a biopsy specimen and samples of arterial and coronary sinus blood were taken. After extraction and TLC the relative distribution of radioactivity in the aqueous phase (containing the oxidation products), pellet and organic phase was calculated. The organic phase was further divided into phospholipids, diglycerides, free fatty acids, triglycerides and cholesterolesters. Seventy two percent of IHDA was oxidized, 36% of IPPA and 7% of DMIPPA. The organic phase consisted primarily of triglycerides and phospholipids. The ratios of triglycerides to phospholipids were about the same for IHDA, IPPA and DMIPPA (0.58, 0.65 and 0.50, respectively). Free IHDA in tissue samples was low (4%) and elevated for IPPA and DMIPPA, (17% and 37%). During lactate loading triglycerides were higher for all three fatty acids. For IHDA and IPPA this increase was paralleled by a decrease in the aqueous phase, in case of DMIPPA the aqueous phase remained the same. Five minutes after injection most of the organic phase of both arterial and coronary sinus blood consisted of the injected fatty acids, the aqueous phase contained oxidation products. There were only minor differences during lactate loading. During the evaluation of scintigraphic patterns of the radioiodinated fatty acids under normal conditions (eg at rest) and during elevated lactate levels (eg during exercise) the differences in distribution must therefore be considered.     

Seasonal changes in oleosomic lipids and fatty acids of perennial root nodules of beach pea

Seasonal changes in the fatty acid composition of phospholipids (PL), monoglycerides (MG), diglycerides (DG), free fatty acids (FA) and triglycerides (TG) separated from oleosomes (lipid bodies) of perennial root nodules of beach pea (Lathyrus maritimus) were analysed. Thin layer chromatography (TLC) revealed that PL and MG are the major lipids in nodule oleosomes. The fatty acid profile and overall double bond index (DBI) varied among lipid classes depending upon the season. High DBI in PL and MG found during late winter and early spring indicated that they may play a major role in winter survival and regeneration of perennial nodules. The DBI of DG was high at the end of the fall season and the DBI of FA and TG was high in summer months. The dominant fatty acids are C16:0 followed by C18:0 and C18:1. The levels of many unsaturated fatty acids such as C18:1, C18:2 and C18:3 increased while saturated fatty acid C18:0 decreased during winter. These unsaturated fatty acids possibly play an important role in the protection of nodule cells from cold stress. Nodules seem to retain some fatty acids and selectively utilize specific fatty acids to survive the winter and regenerate in spring.     

Seasonal variation in the terpenes of the foliage of black spruce

The changes in the relative amounts of the mono- and sesquiterpenes of the volatile oil of the leaves, buds and twigs of black spruce were determined at various intervals throughout the year. Major changes take place in the young leaves just after bud burst until mid-summer. Upon maturing the same quantitative composition as that of the mature leaves is reached. The composition of the latter, as well as that of the twigs, shows only minor changes from bud burst to mid-summer and none during the rest of the year. In contrast, large relative quantitative changes take place in the bud oil throughout the year. The relative changes of santene, tricyclene, camphene, bornyl acetate and limonene in the new growth follow similar curves, but those of α-pinene, β-pinene, myrcene, car-3-ene and the sesquiterpenes differ considerably. The sesquiterpenes, and possibly myrcene, appear to be metabolized at least in part as the young leaves mature.