Nitrogen and energy losses and methane emissions from beef cattle fed diets with gradual replacement of maize silage and concentrate with grass silage and corn-cob mix.

Diets based on large proportions of grassland-based feed are uncommon in forage-based intensive beef production, thus contradicting governmental or commercial strategies to promote the use of grassland-based feed in ruminant production systems. Compared with typical maize silage/concentrate diets, grassland-based diets are associated with impaired nitrogen (N) and energy utilisation because of the comparably lower energy and higher CP content of these feeds. However, quantitative studies concerning the effects of increased dietary proportions of grassland-derived feeds on N and energy losses and utilisation and on methane emissions are missing and the compensation potential of using a limited proportion of an energy-rich forage is unknown. Therefore, we tested five diets with varying types and proportions of forage and concentrate. Three diets consisted of grass silage, maize silage, and concentrate in ratios of, g/kg DM, 100:600:300 (G100; control), 300:500:200 (G300), and 500:300:200 (G500), respectively. Two diets were composed of grass silage, corn-cob mix (CCM), and concentrate in ratios of, g/kg DM, 500:300:200 (G500CCM), and 750:150:100 (G750CCM), respectively. A high-protein concentrate (270 g CP/kg DM) was fed to G100, whereas a low-protein concentrate (140 g CP/kg DM) was used in the remaining diets. Diets were fed throughout the entire fattening period to groups of six Limousin-crossbred bulls each. When weighing 246 ± 18 kg, each animal underwent a 7-day total daily faeces and urine collection, which was followed by measuring methane emissions in respiration chambers for 48 h. Total DM intake was similar across all diets, whereas the N intake varied (P < 0.05). Urinary N loss (g/day) was the highest for G750CCM (28.2) and G100 (26.6) and lowest for G500CCM (15.2) and G300 (16.9) (P < 0.001). Energy utilisation was comparable among all groups. Metabolisable energy intake decreased numerically only with increasing proportions of grass silage in the diet. Substituting maize silage with CCM counteracted the loss in metabolisable energy intake. Absolute methane emissions were not different across the groups, but methane emission intensity (mg/g body protein retention) varied (P < 0.05), being numerically lower for G100 (349) and G500CCM (401) compared with the other groups (488 on average). In conclusion, the results show that the grass silage proportion in beef cattle diets can be substantially increased when strategically combined with energy-dense forages, such as CCM. This also limits the need for concentrate and additional protein sources; in addition, the associated urinary N emissions, which are potentially noxious to the environment, are avoided.

Agonistic behaviour of dairy goats and sheep during feeding - A pilot study on Swiss farms with mixed rations.

INTRODUCTION: Feeding mixed rations is a widely used practice for cattle to ensure the intake of a balanced diet and to reduce competition for food. It is unknown, whether mixed rations have the same advantages for small ruminants because they differ from cattle in their feeding and social behaviour. In this observational pilot study, an array of feeding and social behaviour of dairy goats and sheep fed ad libitum with mixed rations on Swiss farms was investigated. Twelve dairy goat and 12 dairy sheep farms feeding mixed rations were visited once during the winter feeding period. Data on the feeding management, feeding place design and the composition of the mixed rations were collected. The number of animals feeding simultaneously and the number and type of agonistic interactions during feeding were assessed by direct observations for 6 hours after the morning feed-distribution. The feeding management and the composition of the mixed rations were very heterogeneous among farms. The feed rations were mostly well balanced in relation to energy and protein and covered the requirements for the daily production of about 2,5 kg of milk. In terms of feeding simultaneously, sheep were more synchronous than goats. The mean number of agonistic interactions per feeding place within 6 hours were 3,8 in goats and 1,8 in sheep; thus, the probability to observe agonistic behaviour is higher in goats than in sheep. Goats and sheep also differed in the frequency of types of agonistic interactions. Overall, the occurrence of agonistic interactions between animals during feeding decreased with higher numbers of feeding places per animal and longer periods of time since the feed distribution. To conclude, when feeding mixed rations, agonistic interactions related to feeding are more frequent in goats but also occur in sheep to a considerable extent. They can be decreased by offering more feeding places.

INTRODUCTION: L'alimentation avec des rations mixtes est une pratique largement utilisée pour les bovins afin de garantir l'apport d'une alimentation équilibrée et de réduire la concurrence pour la nourriture. On ignore si les rations mixtes présentent les mêmes avantages pour les petits ruminants, car ils diffèrent des bovins en matière de comportement alimentaire et social. Dans cette étude observationnelle pilote, un éventail de comportements alimentaires et sociaux de chèvres et de moutons laitiers nourris ad libitum avec des rations mixtes dans des fermes suisses a été étudié. Douze exploitations de chèvres laitières et 12 exploitations de moutons laitiers, utilisant des rations mixtes, ont été visitées une fois pendant la période d'alimentation hivernale. Des données sur la gestion de l'alimentation, la conception du lieu d'alimentation et la composition des rations mixtes ont été recueillies. Le nombre d'animaux s'alimentant simultanément et le nombre et le type d'interactions agonistiques pendant l'alimentation ont été évalués par des observations directes pendant 6 heures après la distribution matinale des aliments. La gestion de l'alimentation et la composition des rations mélangées étaient très hétérogènes entre les exploitations. Les rations alimentaires étaient généralement bien équilibrées en termes d'énergie et de protéines et couvraient les besoins pour la production quotidienne d'environ 2,5 kg de lait. En termes d'alimentation simultanée, les moutons étaient plus synchrones que les chèvres. Le nombre moyen d'interactions agonistiques par place d'alimentation dans les 6 heures était de 3,8 chez les chèvres et de 1,8 chez les moutons ; la probabilité d'observer un comportement agonistique est en conséquence plus élevée chez les chèvres que chez les moutons. Les chèvres et les moutons diffèrent également dans la fréquence des types d'interactions agonistiques. Dans l'ensemble, l'occurrence des interactions agonistiques entre les animaux pendant l'alimentation a diminué avec un nombre plus élevé de places d'alimentation par animal et des périodes plus longues depuis la distribution des aliments. En conclusion, lors de la distribution de rations mixtes, les interactions agonistiques liées à l'alimentation sont plus fréquentes chez les chèvres mais se produisent également dans une large mesure chez les moutons. Elles peuvent être réduites en offrant davantage de places d'alimentation.

Effects on performance, carcass and meat quality of replacing maize silage and concentrate by grass silage and corn-cob mix in the diet of growing bulls.

Grass silage is barely used in intensive beef production, but it is unclear if its lower energy supply compared to maize-silage feeding really impairs growth performance. Diets with 100, 300, 500 or 750 g grass silage/kg dry matter replacing maize silage and concentrate were tested with or without dried corn-cob mix (CCM). Performance, carcass and meat quality were studied in 30 Limousin-sired bulls. Feeding grass silage, CCM, and concentrate in a ratio of 500:300:200 allowed to maintain a similar animal performance, carcass and meat quality compared to a conventional maize silage/concentrate diet. Increasing the dietary grass silage proportion to 750 g/kg decreased the shear force of the meat. The proportion of n-3 fatty acids in intramuscular fat increased with dietary grass silage proportion. Consequently, a strategic combination of grass silage with energy-rich forages may facilitate grassland-based feeding strategies in intensive beef production with favourable meat fatty acid profiles and a performance comparable to that with maize-silage based diets.

Electronic structure study by means of x-ray spectroscopy and theoretical calculations of the "ferric star" single molecule magnet.

The electronic structure of the single molecule magnet system {M[Fe(L(1))(2)](3)}4CHCl(3) [M=Fe,Cr;L(1)=CH(3)N(CH(2)CH(2)O)(2) (2-)] has been studied using x-ray photoelectron spectroscopy, x-ray-absorption spectroscopy, soft-x-ray emission spectroscopy, as well as theoretical density-functional-based methods. There is a good agreement between theoretical calculations and experimental data. The valence band mainly consists of three bands between 2 and 30 eV. Both theory and experiments show that the top of the valence band is dominated by the hybridization between Fe 3d and O 2p bands. From the shape of the Fe 2p spectra it is argued that Fe in the molecule is most likely in the 2+ charge state. Its neighboring atoms (O,N) exhibit a magnetic polarization yielding effective spin S=52 per iron atom, giving a high-spin state molecule with a total S=5 effective spin for the case of M=Fe.

An object-oriented Monte Carlo simulator for 3D cylindrical positron tomographs.

Monte Carlo simulation is a very powerful tool in understanding performances of positron tomographs as well as in assessing image reconstruction algorithms and their implementations. We present an object-oriented Monte Carlo simulator developed for 3D positron tomography. Results from phantom simulation studies including absorption and scattering of the photons in the field-of-view are presented. Scatter fractions determined from these studies are in good agreement with measured scatter fractions published in the literature. Limitations and future prospects are discussed.

Reconstruçäo 3D rápida em tomografia por emissäo de pósitrons / Rapid 3D reconstruction in positrons emission tomography

O problema de tempos longos para reconstrução em PET foi abordado de várias formas, resultando em um sistema dedicado, capaz de efetuar reconstruções 3D rotineiras em poucos minutos por frame: a abordagem por hardware usa processadores rápidos e arquitetura paralela; a abordagem software utiliza a implementação eficiente de algoritmos mais rápidos.

The issue of long reconstruction times in PET has been addressed from severa! points of view, resulting in an affordable dedicated system capable ofhandling routine 30 reconstructions in a few minutes per frame: on the hardware side using fast processors and a parallel architecture, and on the software side, using efficient implementation of computationally less intensive algorithms.

Effects of different phosphodiesterase inhibitors on the antilipolytic action of insulin in human adipocytes.

The effects of two phosphodiesterase inhibitors, e.g. theophylline and D-4-(3-butoxy-4 methoxybenzyl)-2-imidazolidinone (RO-20-1724) on the antilipolytic action of insulin in human adipocytes were investigated. At a concentration of 1 mmol/l (theophylline) and 0.1 mmol/l (RO-20-1724) both inhibitors increased cyclic AMP to a similar extent. However, their effects on insulin action were different. Whereas addition of theophylline abolished the ability of insulin to inhibit lipolysis, insulin was fully functional in depressing glycerol release in the presence of RO-20-1724. The results suggest that the insulin-sensitive phosphodiesterase of human adipocytes may be relatively resistant to RO-20-1724 as has been shown for the enzyme system of 3T3-L1 adipocytes.

Influences of variation in total energy intake and dietary composition on regulation of fat cell lipolysis in ideal-weight subjects.

Weight-maintaining fat-rich, "prudent," carbohydrate-rich, as well as energy-restricted diets (300 kcal/d) were fed in succession for 7 d to 12 healthy males of ideal body weight under metabolic ward conditions. At the end of each period isolated fat cells were prepared from subcutaneous abdominal adipose tissue and incubated in vitro in the absence or presence of adenosine deaminase, either alone or in combination with various lipolytic or antilipolytic hormones and agents. Variations in total energy intake and dietary composition had characteristic and specific effects on fat cell lipolysis in vitro. High carbohydrate and prudent diets resulted in low rates of nonstimulated glycerol release and impaired insulin action in the presence of adenosine deaminase (320 mU/ml). High-fat and energy restricted diets were characterized by high rates of nonstimulated glycerol release. Sensitivity of antilipolysis to insulin and prostaglandin E2 was 10 to 200 times lower respectively on energy-restricted than on fat-rich diets. The effects of alpha 2- and beta-adrenergic catecholamines and of N6-phenylisopropyladenosine were not affected by the preceding diets.

Antilipolytic action of insulin in abdominal adipocytes of obese subjects before and during energy restriction. Influence of adenosine deaminase.

The influence of prolonged energy restriction (1250 kJ for 4 weeks) on insulin's antilipolytic action was investigated in abdominal adipocytes of obese subjects. An attempt was made to discriminate between dietary influences per se and indirect influences caused by changes in the concentration or action of adenosine. Prolonged energy restriction resulted in about a 3.5-fold increase in basal lipolytic rate which was associated with a corresponding increase in maximal response to insulin. Both these effects could be mimicked by adenosine deaminase (1.6 micrograms/ml) which increased glycerol release of adipocytes from fed donors to levels normally seen during starvation suggesting that the improvement of lipolytic responsiveness to insulin during energy restriction was an apparent one only, due to the fact that glycerol release was increased. To identify dietary influences that selectively affect insulin action the effects of insulin were compared with those of other antilipolytic agents in the presence of adenosine deaminase. Maximally effective concentrations of prostaglandin E2, clonidine and N6-phenylisopropyladenosine almost completely suppressed glycerol release before and during starvation. The extent of inhibition produced by these latter compounds was therefore related to basal activity by the same linear relationship in all experimental settings. By contrast insulin only partially depressed glycerol release and the relationships between basal activity and response to maximal concentrations of insulin were significantly different before and during starvation (P less than or equal to 0.01) in the presence of adenosine deaminase indicating that starvation selectively influences insulin action via mechanisms that are unrelated to the effects of other antilipolytic compounds. It is concluded that the main effect of energy restriction on insulin's antilipolytic action is an apparent one which is secondary increased lipolytic activity. Direct dietary effects on insulin action became apparent upon removal of endogenous adenosine. These tend to limit the maximal response to insulin and may be due to changes at the post-binding level but could also reflect an intrinsic property of insulin's antilipolytic action.

Pharmacologically induced changes in human beta-chorionic gonadotropin (beta-hCG) synthesis by human placenta in organ culture.

In organ cultures the regulation of beta-hCG formation in human placentas of early gestation (EG) and at term (T) was analyzed using the following test substances: dibutyryl cAMP (dbcAMP), theophylline, and by two drugs used to treat patients with premature labor, fenoterol hydrobromide and verapamil hydrochloride. The rapid increase in beta-hCG in culture medium beginning at 24-48 h corresponds to morphologic changes (proliferation of the cytotrophoblast). Beta-hCG synthesis of human placenta is related to an adenylate cyclase as could be shown by dose-dependent stimulation by dbcAMP (T) (after 72 h) (controls = 100%): 2 nM = 125%; 70 nM = 200%; 2 microM = 300%. Similar results were obtained using EG. First stimulation by dbcAMP was found after 2 h and may be caused by a release of intracellular beta-CG or by a direct stimulation of beta-hCG synthesis; late effects (after 48-72 h) are suspected to be due to changes in morphologic differentiation of the placenta in organ culture. Theophylline (0.1 and 1 mM) did not influence beta-hCG formation in EG, whereas in T a dose-dependent stimulation could be achieved (controls = 100%): 0.1 mM = 110%; 1 mM = 300%; and 10 mM = 160%. Fenoterol hydrobromide, a tocolytic beta 2-receptor stimulating agent showed a slight (130-160%) beta-hCG stimulation (after 72 h) (EG and T). The stimulatory effect of a high dose (1 microgram/ml) of fenoterol hydrobromide could be due to a stimulation of beta 2 receptors related to an adenylate cyclase. Dose-related changes in beta-hCG in T were found for the calcium antagonist verapamil hydrochloride (controls = 100%): 0.01 microgram/ml = 125% stimulation; 0.33 microgram/ml = 200% stimulation; 10 micrograms/ml = 100%. As indicated by verapamil tests, calcium ions may play a role in the regulation of beta-hCG production.