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Biomedical subjects

Michael Kreuzer

Publications and source records attributed to Michael Kreuzer.

8 recordsLinked to original sources
PubMed2005

A study on the causes for the elevated n-3 fatty acids in cows' milk of alpine origin.

The influence of grass-only diets either from rye-grass-dominated lowland pastures (400 m above sea level) or botanically diverse alpine pastures (2000 m) on the FA profile of milk was investigated using three groups of six Brown Swiss cows each. Two groups were fed grass-only on pasture (P) or freshly harvested in barn (B), both for two experimental periods in the lowlands and, consecutively, two periods on the alp. Group C served as the control, receiving a silage-concentrate diet and permanently staying in the lowlands. Effects of vegetation stage or pasture vs. barn feeding on milk fat composition were negligible. Compared with the control, alpha-linolenic acid (18:3n-3) consumption was elevated in groups P and B (79%; P< 0.001) during the lowland periods but decreased on the alp to the level of C owing to feed intake depression and lower 18:3n-3 concentration in the alpine forage. Average 18:3n-3 contents of milk fat were higher in groups P and B than in C by 33% (P< 0.01) at low and by 96% (P < 0.001) at high altitude, indicating that 18:3n-3 levels in milk were to some extent independent of 18:3n-3 consumption. The cis-9, trans-11 CLA content in milk of grass-fed cows was higher compared with C but lower for the alpine vs. lowland periods whereas the trans-11, cis-13 isomer further increased with altitude. Long-chain n-3 FA and phytanic acid increased while arachidonic acid decreased with grass-only feeding, but none of them responded to altitude. Grass-only feeding increased milk alpha-tocopherol concentration by 86 and 134% at low and high altitude (P < 0.001), respectively. Changes in the ruminal ecosystem due to energy shortage or specific secondary plant metabolites are discussed as possible causes for the high 18:3n-3 concentrations in alpine milk.

Altitude↗
PubMed2005

Protein composition, plasmin activity and cheesemaking properties of cows' milk produced at two altitudes from hay of lowland and high-alpine origins.

The influence of high altitude, alpine origin of the forage and roughage-only diets on milk protein content and composition, plasmin activity and cheesemaking properties was investigated. There were four treatment groups, each consisting of six dairy cows in early to mid-lactation. Two groups were fed only with hay ad libitum either at 2000 m or at 400 m a.s.l. One group, kept in the lowlands, was pair-fed to the alpine-site group and another group received a mixed diet of silages, hay and concentrates. Two hay types, harvested either at the alpine site or in the lowlands, were offered to all cows fed with hay alone, following a change-over design in three periods each of 3 weeks. In the respective third week, milk was sampled at every milking. Hay of alpine origin significantly reduced milk protein, in particular whey proteins, which is why the casein number increased. kappa-Casein proportion in total casein was reduced and its glycosylation was increased by the alpine hay. The apparent plasminogen-derived activity was reduced when alpine hay was given, but apparent plasmin activity and rennet coagulation properties of the milk were not affected by hay type. Independent of hay type, the high altitude group showed a significantly reduced milk protein content, lower glycosylation of kappa-casein and impaired rennet coagulation properties. For several of the traits, the trend was the same in the pair-fed group. There was no effect of altitude on apparent plasmin activity. Hay-alone v. the mixed diet resulted initially in marked declines in milk protein content but did not impair cheesemaking properties. Thus the extensive diet without concentrates, typical of high-alpine conditions, contributed less to the overall effect of extensive alpine v. intensive lowland feeding systems than hay quality and altitude did. In conclusion, certain positive influences of the alpine sojourn of cows on cheese processing quality are overruled by the major adverse impact of lower milk protein content.

Altitude↗
PubMed2004

Rumen simulation technique study on the interactions of dietary lauric and myristic acid supplementation in suppressing ruminal methanogenesis.

The interactions of lauric (C12) and myristic acid (C14) in suppressing ruminal methanogenesis and methanogens were investigated with the rumen simulation technique (Rusitec) using bovine ruminal fluid. The fatty acids were added to basal substrates (grass hay:concentrate, 1:1.5) at a level of 48 g/kg DM, provided in C12:C14 ratios of 5:0, 4:1, 3:2, 2.5:2.5, 2:3, 1:4 and 0:5. Additionally, an unsupplemented control consisting of the basal substrates only was employed. Incubation periods lasted for 15 (n 4) and 25 (n 2) d. CH4 formation was depressed by any fatty acid mixture containing at least 40 % C12, and effects persisted over the complete incubation periods. The greatest depression (70 % relative to control) occurred with a C12:C14 ratio of 4:1, whereas the second most effective treatment in suppressing CH4 production (60 % relative to control) was found with a ratio of 3:2. Total methanogenic counts were decreased by those mixtures of C12 and C14 also successful in suppressing methanogenesis, the 4:1 treatment being most efficient (60 % decline). With this treatment in particular, the composition of the methanogenic population was altered in such a way that the proportion of Methanococcales increased and Methanobacteriales decreased. Initially, CH4 suppression was associated with a decreased fibre degradation, which, however, was reversed after 10 d of incubation. The present study demonstrated a clear synergistic effect of mixtures of C12 and C14 in suppressing methanogenesis, mediated probably by direct inhibitory effects of the fatty acids on the methanogens.

Animal Feed↗
PubMed2003

Methane-suppressing effect of myristic acid in sheep as affected by dietary calcium and forage proportion.

The efficiency of myristic acid (14 : 0) as a feed additive to suppress CH4 emissions of ruminants was evaluated under different dietary conditions. Six sheep were subjected to a 6 x 6 Latin square arrangement. A supplement of non-esterified 14 : 0 (50 g/kg DM) was added to two basal diets differing in their forage:concentrate values (1 : 1.5 and 1 : 0.5), which were adjusted to dietary Ca contents of 4.2 and 9.0 g/kg DM, respectively. Comparisons were made with the unsupplemented basal diets (4.2 g Ca/kg DM). The 14 : 0 supplementation decreased (P<0.001) total tract CH4 release depending on basal diet type (interaction, P<0.001) and dietary Ca level (P<0.05, post hoc test). In the concentrate-based diet, 14 : 0 suppressed CH4 emission by 58 and 47 % with 4.2 and 9.0 g Ca/kg DM, respectively. The 14 : 0 effect was lower (22 %) in the forage-based diet and became insignificant with additional Ca. Myristic acid inhibited (P<0.05) rumen archaea without significantly altering proportions of individual methanogen orders. Ciliate protozoa concentration was decreased (P<0.05, post hoc test) by 14 : 0 only in combination with 9.0 g Ca/kg DM. Rumen fluid NH3 concentration and acetate:propionate were decreased (P<0.05) and water consumption was lower (P<0.01) with 14 : 0. The use of 14 : 0 had no clear effects on total tract organic matter and fibre digestion; this further illustrates that the suppressed methanogenesis resulted from direct effects against methanogens. The present study demonstrated that 14 : 0 is a potent CH4 inhibitor but, to be effective in CH4 mitigation feeding strategies, interactions with other diet ingredients have to be considered.

Animal Feed↗
PubMed2003

UK developments.

As a new industry task force is established, hopes are high that access to medical technologies will be easier in the future.

Equipment and Supplies↗
PubMed2002

Health technology assessment for medical devices in Europe. What must be considered.

OBJECTIVE: To inform about the specifics of medical devices and the resulting consequences for health technology assessment (HTA) and to present the European industry position on this topic. METHODS: The paper is based on an intensive debate within Eucomed, the European trade association in the field of medical devices, informed by an HTA Experts Group, comprising experts from within and outside the medical device industry. RESULTS: Based on the specifics of medical devices, there are a number of methodologic considerations that require a tailored HTA, differing from the approach taken for, for example, pharmaceutical products. These differences have an impact on the selection of the technology, the timing of the assessment, the study design, and the patient population. CONCLUSION: The European medical device industry can commit to an HTA that takes into consideration the specifics of medical technologies, which is appropriate and fair, and which is done under full participation of industry. Under these circumstances HTA can be a useful tool to support rational decision making in health care.

Cooperative Behavior↗
PubMedDate not supplied

Effect of coconut oil and defaunation treatment on methanogenesis in sheep.

The present study was conducted to evaluate in vivo the role of rumen ciliate protozoa with respect to the methane-suppressing effect of coconut oil. Three sheep were subjected to a 2 x 2 factorial design comprising two types of dietary lipids (50 g x kg(-1) coconut oil vs. 50 g x kg(-1) rumen-protected fat) and defaunation treatment (with vs. without). Due to the defaunation treatment, which reduced the rumen ciliate protozoa population by 94% on average, total tract fibre degradation was reduced but not the methane production. Feeding coconut oil significantly reduced daily methane release without negatively affecting the total tract nutrient digestion. Compared with the rumen-protected fat diet, coconut oil did not alter the energy retention of the animals. There was no interaction between coconut oil feeding and defaunation treatment in methane production. An interaction occurred in the concentration of methanogens in the rumen fluid, with the significantly highest values occurring when the animals received the coconut oil diet and were subjected to the defaunation treatment. Possible explanations for the apparent inconsistency between the amount of methane produced and the concentration of methane-producing microbes are discussed. Generally, the present data illustrate that a depression of the concentration of ciliate protozoa or methanogens in rumen fluid cannot be used as a reliable indicator for the success of a strategy to mitigate methane emission in vivo. The methane-suppressing effect of coconut oil seems to be mediated through a changed metabolic activity and/or composition of the rumen methanogenic population.

Animals↗