Kg Dry Matter (kg + dry_matter)

Distribution by Scientific Domains

Selected Abstracts

The use of endogenous nitrogen for microbial crude protein synthesis in the rumen of growing bulls

H. Kluth
Summary The objective of this study was to quantify endogenous nitrogen (N) recycled for microbial protein synthesis in the rumen. Four growing bulls (Schwarzbuntes Milchrind; bodyweight: 240,310 kg) with duodenal T-shaped cannulas were fed diets containing four levels of crude protein content (200, 156, 102 and 63 g/kg dry matter, respectively). The diets were based on wheat, barley, tapioca meal, soybean extracted meal, dried beet pulp, meadow hay and straw. The diets had an energy level of 11.1, 10.9, 10.2 and 9.6 MJ metabolizable energy/kg dry matter. Faeces and urine were collected in four 7-day balance periods. Duodenal flow rate was estimated by TiO2, pelleted with grain, as a marker. The relationship between urine N excretion, the amount of microbial N reaching the duodenum, ruminal N balance and N retention were examined and the amount of endogenous N available for microbial protein synthesis without negative effects on the N retention was determined. It can be concluded that up to 16% of the microbial N supply could be covered by recycled endogenous N, but N retention should not be decreased by more than 1.5 residual standard deviations of maximal N retention. [source]

Effect of dietary linoleic acid concentration and vitamin E supplementation on cell desquamation and susceptibility to oxidative damage of pig jejunal mucosa

C. J. López Bote
Sixty Large White × Great York pigs weighing approximately 60 kg were individually fed on six experimental diets. The experiment was organized in a 3 × 2 factorial arrangement design with three different fat sources and a basal or supplemented (200 mg/kg diet) level of ,-tocopheryl acetate. All diets contained the same concentration of saturated fatty acids (15 ± 0.2 g/kg dry matter) but differed in the concentration of C18 : 2 (14 ± 0.5, 18 ± 0.4 and 21 ± 0.6 g/kg) and monounsaturated fatty acids (19 ± 0.2, 15 ± 1.2 and 10 ± 1.3 g/kg). No effect of dietary treatment was observed on weight gain and feed consumption. A histological study of the jejunal mucosa showed lower cell desquamation in groups containing a supplemental level of ,-tocopheryl acetate (p=0.080). A higher cell desquamation was found in the groups fed diets containing the higher concentration of C18 : 2 (p=0.087). We also observed an interaction effect (p < 0.001) of dietary fat source and vitamin E supplementation on jejunal cell desquamation in which the effect of dietary vitamin E was lower when diets with a low concentration of C18 : 2 were administered. In vitro- induced oxidation of jejunal mucosa homogenates was lower in pigs fed diets supplemented with ,-tocopheryl acetate (p < 0.002). The dietary concentration of C18 : 2 significantly affected oxidation of pig jejunal mucosa (p < 0.002). [source]

The use of endogenous nitrogen for microbial crude protein synthesis in the rumen of growing bulls

H. Kluth
Summary The objective of this study was to quantify endogenous nitrogen (N) recycled for microbial protein synthesis in the rumen. Four growing bulls (Schwarzbuntes Milchrind; bodyweight: 240,310 kg) with duodenal T-shaped cannulas were fed diets containing four levels of crude protein content (200, 156, 102 and 63 g/kg dry matter, respectively). The diets were based on wheat, barley, tapioca meal, soybean extracted meal, dried beet pulp, meadow hay and straw. The diets had an energy level of 11.1, 10.9, 10.2 and 9.6 MJ metabolizable energy/kg dry matter. Faeces and urine were collected in four 7-day balance periods. Duodenal flow rate was estimated by TiO2, pelleted with grain, as a marker. The relationship between urine N excretion, the amount of microbial N reaching the duodenum, ruminal N balance and N retention were examined and the amount of endogenous N available for microbial protein synthesis without negative effects on the N retention was determined. It can be concluded that up to 16% of the microbial N supply could be covered by recycled endogenous N, but N retention should not be decreased by more than 1.5 residual standard deviations of maximal N retention. [source]

Fat Feeding Increases Equine Heparin-Released Lipoprotein Lipase Activity

Suzanne N.J. Geelen
The aim of this study was to establish the dose-response relationship between fat intake and heparin-released plasma lipoprotein lipase (LPL) activity in horses. Eight mature trotters were fed 4 rations with different fat levels (3.0, 5.0, 7.7, or 10.8% fat in the dry matter) according to a 4 × 4 Latin square design. The experimental rations consisted of hay and different concentrates; the concentrates and hay were given in a 3 :1 ratio on an energy basis. Soybean oil was added to the concentrates at the expense of isoenergetic amounts of glucose. Blood samples were taken at the end of each dietary period, which lasted 3 weeks. Fat feeding was found to increase heparin-released plasma LPL activity in a dose-dependent fashion. When the data from this study and previous studies were combined it was calculated that an increase in fat intake by 1 g/kg dry matter is associated with an increase in LPL activity by 0.98 ,mol fatty acid released.mL -1.h -1. Fat feeding raised the plasma concentrations of total cholesterol, high-density lipoprotein cholesterol, and phospholipids. Diet did not have a statistically significant effect on plasma triacylglycerol concentrations. The results are discussed in the light of the possible enhancing effect of fat feeding on the oxidative capacity of skeletal muscle. [source]

Herbage growth rates on heterogeneous swards as influenced by sward-height classes

ahin Demirba
Abstract The contribution of four classes of sward height to daily herbage growth rates of a heterogeneous sward in eight periods throughout a grazing season was investigated in two continuous cattle-grazing systems differing in intensity (moderate stocking rate: MC; lenient stocking rate: LC). At the beginning and end of periods of 12 to 28 d, the compressed sward height (CSH) was measured in exclusion cages at eighteen fixed points per cage to derive daily growth rates for the four classes of sward height. Stratified calibrations were made to relate sward height to herbage mass for each treatment in each period. Quadratic regressions described the relationship between herbage growth rate and initial CSH for each treatment in each period. For scaling up to the scale of the plot, CSH was measured monthly at 100 points per plot. Daily herbage growth rates declined from more than 100 kg dry matter (DM) ha,1 d,1 on both treatments at the beginning of the grazing season to 20 kg DM ha,1 d,1 or less, especially on treatment LC. This was due to the larger area covered by tall herbage on treatment LC than on treatment MC. On treatment MC, daily herbage growth rate was predominantly derived from short sward areas of up to 12 cm in height while sward areas taller than 12 cm contributed most to daily growth rates on treatment LC in early summer. The method used is considered suitable for estimating daily herbage growth rates of different classes of sward height in extensively managed pastures and can easily be adapted to deal with more heterogeneous swards than used in this study. [source]

Impact of seeding rate on annual ryegrass performance

B. C. Venuto
Abstract Annual ryegrass (Lolium multiflorum Lam.) is a primary forage resource for livestock producers throughout the south-eastern USA during the winter-growing season. It is important for livestock producers to begin grazing annual ryegrass as early as possible and any management practices maximizing early season production could be beneficial. To assess the impact of seeding rate on subsequent yield, yield distribution, quality, seedling density, and end-of-season plant and tiller density, a 2-year study was initiated at four locations in Louisiana. Three annual ryegrass cultivars, varying in seed size, were established at four seeding rates based on pure live seed (PLS) rates of 400, 800, 1200 and 1600 PLS m,2. There was no advantage in total yield from increasing seeding rates beyond 800 PLS m,2. However, first-harvest yields increased from 360 to 930 kg dry matter (DM) ha,1 as seeding rate increased from 400 to 1600 PLS m,2. Crude protein and neutral-detergent fibre concentrations, and in vitro DM digestibility, were not affected by seeding rate. Seedling density and end-of-season plant numbers increased as seeding rate increased. However, stems per plant decreased as seeding rate increased, indicating compensatory tillering for the reduced plant numbers observed at the lower seeding rates. These results indicate first-harvest yield can be increased by planting at higher seeding rates but total yields are not increased. [source]

Linseed (Linum usitatissimum L.) Cultivars and Breeding Lines as Stem Biomass Producers

H. S. Sankari
Linseed (Linum usitatissimum L.) stems, which contain bast fibres, make up a considerable part of the linseed biomass, but are considered a by-product of no value. The feasibility of cultivating existing linseed cultivars and breeding lines for dual-purpose use of stem and seed was studied in 1995,97 in Jokioinen, Finland. Finnish linseed cv. Helmi was compared with 10 linseed genotypes and one flax cultivar for stem yield, ratio of stem yield to seed yield, and plant stand height and density. The stem yield of cv. Helmi averaged 1317 kg dry matter ha -1. Significantly higher stem yields were produced by breeding lines Bor 15 and Bor 18 and cvs Gold Merchant, Norlin and Martta. The cv. Helmi produced lower stem yield than seed yield while breeding lines Bor 15 and Bor 18 and cvs Gold Merchant and Martta yielded more stem than seeds. The difference in the ratio of stem yield to seed yield between them and cv. Helmi was statistically significant. The mean plant stand height was 60.3 cm and the final plant density 594 plants m -2. No relationship was found between stem yield and height or density. Within 2 days of seed threshing, stems of early maturing Finnish genotypes dried up in the field to nearly 15 % moisture content, even in the middle of September (1996). The early maturing breeding lines Bor 15 and Bor 18, with their significantly higher stem yields relative to cv. Helmi, are recommended for dual-purpose use. Zusammenfassung Der bastfasernenthaltende Stengel des Ölleins (Linum usitatissimum L.) bildet einen Grossteil der oberirdischen Biomasse von Öllein, der häufig keiner Nutzung zugeführt wird. Um das Potential bestehender Ölleinsorten und -zuchtlinien für eine Doppelnutzung von Samen und Stengelbiomasse zu überprüfen, wurden in den Jahren 1995,97 in Jokioinen (Finland) Feldversuche durchgeführt. Die finnische Ölleinsorte Helmi wurde mit zehn Ölleinzuchtstämmen und einer Faserleinsorte angebaut, und der Stengelertrag, der Stengelertrag im Verhältnis zum Samenertrag und die Bestandeshöhe und -dichte wurden ermittelt. Der Stengelertrag betrug bei Helmi durchschnittlich 1317 kg Trockenmasse ha -1. Signifikant höhere Stengelerträge wurden von den Zuchtlinien Bor 15 und Bor 18, den Sorten Gold Merchant, Norlin und Martta produziert. Helmi produzierte im Mittel einen geringeren Stengel , als Samenertrag. Die Stengelerträge der Zuchtstämme Bor 15 und Bor 18 und der Sorten Gold Merchant und Martta waren höher als die Samenerträge. Zwischen diesen Genotypen und der Sorte Helmi ist der Unterschied des Ertragsverhältnisses signifikant. Die Bestandeshöhe lag im Durchschnitt bei 60,3 cm und die Bestandesdichte betrug im Mittel 594 Pflanzen m -2. Eine Korrelation zwischen dem Stengelertrag und der Bestandeshöhe bzw. -dichte konnte nicht nachgewiesen werden. Die Stengel der frühen finnischen Genotypen trockneten nach dem Dreschen auf dem Feld (Mitte September 1996) in zwei Tagen auf einen Feuchtegehalt von 15% ab. Die frühreifen Zuchtlinien Bor 15 und Bor 18 können aufgrund ihrer signifikant höheren Stengelerträge im Vergleich zu der Sorte Helmi für eine Doppelnutzung empfohlen werden. [source]

Cobalt requirement of beef cattle , feed intake and growth at different levels of cobalt supply

F. J. Schwarz
Summary In a study using a total of 36 German Simmental beef bulls weighing between 236 kg and about 620 kg the question of what constitutes an adequate Co supply was investigated with reference to the performance criteria growth, feed intake, energy intake, nutrient intake and carcass criteria. The bulls received a diet of corn silage ad libitum and 2.5 kg concentrate for a period of 280 days. Ten rations (R) with graduated Co supplements were fed with mean concentrations of 0.07 (R1), 0.09 (R2), 0.11 (R3), 0.15 (R4), 0.18 (R5), 0.26 (R6), 0.33 (R7), 0.42 (R8), 0.59 (R9) and 0.69 (R10) mg Co per kg dry matter (DM) intake. The Co supplement was added as CoSO47H2O. The diets with no or low Co supplementation produced either distinctly lower daily gains of 1045g (R1) and 1130g (R2) or lower daily gains of about 1260 g (R3, R4) than rations R5,R10, where daily gains averaged 1340 g. The mean daily feed intake per animal was also significantly or marginally affected with values of 6.0 kg DM (R1) rising to 7.7 kg DM (R2,R4) versus 7.9 kg DM on average (R5,R10). Calculations using the broken line model and the quadratic model show that the optimal Co supply for maximum growth is 0.12 mg/kg dietary DM and for maximum feed intake, 0.16,0.18 mg Co/kg dietary DM. After taking further biochemical criteria into account (Stangl et al. 2000), a level of 0.20 mg/kg dietary DM is recommended as an adequate Co supply for growing cattle. [source]

Phosphocreatine degradation in type I and type II muscle fibres during submaximal exercise in man: effect of carbohydrate ingestion

Kostas Tsintzas
1The aim of this study was to examine the effect of carbohydrate (CHO) ingestion on changes in ATP and phosphocreatine (PCr) concentrations in different muscle fibre types during prolonged running and relate those changes to the degree of glycogen depletion. 2Five male subjects performed two runs at 70 % maximum oxygen uptake (V,O2,max), 1 week apart. Each subject ingested 8 ml (kg body mass (BM)),1 of either a placebo (Con trial) or a 5.5 % CHO solution (CHO trial) immediately before each run and 2 ml (kg BM),1 every 20 min thereafter. In the Con trial, the subjects ran to exhaustion (97.0 ± 6.7 min). In the CHO trial, the run was terminated at the time coinciding with exhaustion in the Con trial. Muscle samples were obtained from the vastus lateralis before and after each trial. 3Carbohydrate ingestion did not affect ATP concentrations. However, it attenuated the decline in PCr concentration by 46 % in type I fibres (CHO: 20 ± 8 mmol (kg dry matter (DM)),1; Con: 34 ± 6 mmol (kg DM),1; P < 0.05) and by 36 % in type II fibres (CHO: 30 ± 5 mmol (kg DM),1; Con: 48 ± 6 mmol (kg DM),1; P < 0.05). 4A 56 % reduction in glycogen utilisation in type I fibres was observed in CHO compared with Con (117 ± 39 vs. 240 ± 32 mmol glucosyl units (kg DM),1, respectively; P < 0.01), but no difference was observed in type II fibres. 5It is proposed that CHO ingestion during exhaustive running attenuates the decline in oxidative ATP resynthesis in type I fibres, as indicated by sparing of both PCr and glycogen breakdown. The CHO-induced sparing of PCr, but not glycogen, in type II fibres may reflect differential recruitment and/or role of PCr between fibre types. [source]

Spatial variability of above-ground net primary production in Uruguayan grasslands: a remote sensing approach

S. Baeza
Abstract Question: How does above-ground net primary production (ANPP) differ (estimated from remotely sensed data) among vegetation units in sub-humid temperate grasslands? Location: Centre-north Uruguay. Methods: A vegetation map of the study area was generated from LANDSAT imagery and the landscape configuration described. The functional heterogeneity of mapping units was analysed in terms of the fraction of photosynthetically active radiation absorbed by green vegetation (fPAR), calculated from the normalized difference vegetation index (NDVI) images provided by the moderate resolution imaging spectroradiometer (MODIS) sensor. Finally, the ANPP of each grassland class was estimated using NDVI and climatic data. Results: Supervised classification presented a good overall accuracy and moderate to good average accuracy for grassland classes. Meso-xerophytic grasslands occupied 45% of the area, Meso-hydrophytic grasslands 43% and Lithophytic steppes 6%. The landscape was shaped by a matrix of large, unfragmented patches of Meso-xerophytic and Meso-hydrophytic grasslands. The region presented the lowest anthropic fragmentation degree reported for the Rio de la Plata grasslands. All grassland units showed bimodal annual fPAR seasonality, with spring and autumn peaks. Meso-hydrophytic grasslands showed a radiation interception 10% higher than the other units. On an annual basis, Meso-hydrophytic grasslands produced 3800 kg dry matter (DM) ha,1 yr,1 and Meso-xerophytic grasslands and Lithophytic steppes around 3400 kg·DM·ha,1·yr,1. Meso-xerophytic grasslands had the largest spatial variation during most of the year. The ANPP temporal variation was higher than the fPAR variability. Conclusions: Our results provide valuable information for grazing management (identifying spatial and temporal variations of ANPP) and grassland conservation (identifying the spatial distribution of vegetation units). [source]

Clinical acidosis in a Gippsland dairy herd

Objective: To report on spontaneous clinical and subclinical acidosis in a large dairy herd, to evaluate the diets and feeding strategies involved, and to report on measures of rumen function in the cows affected. Design: A Gippsland dairy herd was sampled as part of a wider randomised cross-sectional study that examined the prevalence, risk factors for, and effects of, acidosis on rumen function of dairy cattle. Three herds on the farm were involved in the study: the transition herd (cows 3 weeks prior to calving), the very fresh lactating herd (1kg dry matter triticale per cow per day and hay with an estimated total dry matter intake of 4.8 kg per cow per day. The lactating cow diet included 6.75 kg dry matter triticale per cow per day with total concentrate fed being 8.1 kg dry matter per cow per day in the milking parlour. Silage, lucerne cubes, hay and pasture (herd 2 only) was also fed to the lactating cows with the estimated total dry matter intake for cows in herds 1 and 2 being 13.7 kg and 20.8 kg per cow per day respectively. Three primiparous and five multiparous cows in early lactation (<100 days in milk) were randomly selected from each of two lactating herds: herds 1 and 2. Rumen fluid was sampled from each cow by both rumenocentesis and stomach tube. The rumenocentesis samples were tested for pH at the time of sampling. Stomach tube samples were frozen and subsequently tested for volatile fatty acid, ammonia, and D- and L-lactate concentration. Results: In the very fresh herd, there was a high prevalence of severe lameness and scouring, coupled with a mean rumen pH 5.67, low mean total volatile fatty acid concentration 71.0 mM and high mean concentrations of L- and D-lactate,(7.71 mM and 7.31 mM), respectively. Cows in the fresh herd had moderate signs of scouring and lameness. A lame herd comprising approximately 50 cows separated from the fresh herd was also present on the farm. The mean rumen pH of the fresh herd was 5.74 and mean rumen concentrations of volatile fatty acids, ammonia, L- and D-lactate were within ranges considered normal. Conclusions: The transition diet failed to supply sufficient energy and protein for maintenance of cows of this live weight in late gestation. The diet fed to the very fresh herd was low in effective fibre and contained an excessive content of non-structural carbohydrate in the form of processed, rapidly fermentable grain. The sudden change from the transition diet to the diet fed to the very fresh herd probably also precipitated the outbreak of acidosis. This case report provides unique detail, including information on diets and rumen parameters, of an outbreak of acidosis in a pasture-fed herd. [source]

In vitro fermentative characteristics of ruminant diets supplemented with fibrolytic enzymes and ranges of optimal endo-,-1,4-glucanase activity

E. González-García
Summary Effectiveness of fibrolytic enzymes supplementing a range of forage to concentrate (F:C) diets was assessed with goat (G) or cow (C) inoculum using the gas production (GP) technique. Four F:C diets were evaluated: forage (1:0), high forage (0.7:0.3), medium forage (0.5:0.5) and low forage (0.3:0.7) diets, supplemented or not with PromoteTM (PRO) at 1 or 2 ml/kg dry matter (DM). The GP kinetic was different between F:C (1:0 < 0.7:0.3 < 0.5:0.5 < 0.3:0.7) and inoculum. Responses to enzyme were positively related to forage level and differed with inoculum. The neutral detergent fibre and acid detergent fibre degradation were depressed by the concentrate in the substrates fermented with C and were not altered or even enhanced in G sets. Results confirm that increasing starch proportion modified the pattern of microbial fermentation, while no influences were detected in the improvement of cell wall degradation with fibrolytic enzymes. Another in vitro experiment was conducted to investigate factors by which endo-,-1,4-glucanase activity (EA) of PRO is compromised in a factorial design (3 × 4 × 3) for three pH (4.0, 5.5 and 6.5), four temperatures (30, 40, 50 and 70 °C) and three doses (1, 2 and 3 ml/kg DM of substrate). Maximum EA were obtained for pH 4.0, 50 °C and 3 ml/kg DM. Optimal conditions for PRO proved to be outside the normal ranges in ruminal environment. [source]

Is the intrinsic potassium content of forages an important factor in intake regulation of dairy cows?

F. Leiber
Summary Hay from intensively managed grassland with high nutrient density and digestibility containing 29 g potassium/kg dry matter (DM) and hay from an alpine pasture, clearly lower in energy, digestibility and potassium (12 g/kg DM) were offered as sole feeds to 18 lactating dairy cows following a change-over arrangement within three periods of 21 days each (schedule either alpine-lowland-alpine or lowland-alpine-lowland hay). Faeces and urine were quantitatively collected over 7 days. Dry matter intake was similar and neutral detergent fibre (NDF) intake was higher with alpine than with lowland hay (1.57 kg/100 kg vs. 1.43 kg/100 kg body weight). Potassium intake was approximately three times lower with alpine than with lowland hay. Urinary water output was closely correlated with potassium intake. It was also correlated with DM intake but only in animals receiving lowland hay, while it remained independent from intake when alpine hay was fed. Plasma osmolality was lower when alpine hay was fed. As energy requirements were not covered with either diet, the lower NDF intake with lowland hay was assumed to have been caused by higher ruminal osmolality because of the higher intrinsic potassium concentrations of this hay type. Further studies are necessary to determine potassium levels critical for feed intake. [source]

Hypolipidaemic effects of potato protein and fish protein in pigs

J. Spielmann
Summary This study was performed to assess the effects of potato protein and fish protein on concentrations of lipids in plasma and lipoproteins and the expression of genes involved in lipid metabolism in pigs used as an animal model. Therefore, 27 young male pigs with an average body weight of 22 kg were fed diets supplemented with protein extracted from potatoes (containing 849 g protein/kg dry matter), Alaska Pollack fillet as a source of fish protein (containing 926 g crude protein/kg dry matter) or casein which was used as control, for 3 weeks. Diets were formulated to supply identical amounts of each protein to the pigs by the three protein sources, namely 116 g/day in first week and 150 g/day in the second and third week. Pigs fed potato protein had lower concentrations of cholesterol in plasma and LDL than pigs fed casein (p < 0.05); no effect was observed on concentrations of HDL cholesterol and triglycerides. Pigs fed fish protein had lower cholesterol concentrations in plasma, LDL and HDL, and lower triglyceride concentrations in triglyceride-rich lipoproteins than pigs fed casein (p < 0.05). mRNA concentrations of genes involved in bile acid synthesis and cholesterol uptake were higher in pigs fed fish protein than in pigs fed casein (p < 0.05); no effect on these genes was observed in pigs fed potato protein. Expression of genes involved in lipogenesis and fatty acid oxidation was not altered by fish protein. In conclusion, this study shows that fish protein and potato protein lower plasma cholesterol concentrations in pigs. The hypocholesterolaemic effect of fish protein might be in part caused by a stimulation of bile acid synthesis; the reason for the hypocholesterolaemic effect of potato protein requires further elucidation. [source]

Effects of rumen-protected methionine in a low protein ration on metabolic traits and performance of early lactating cows as opposed to rations with elevated crude protein content

T. F. Kröber
Summary A 5-week experiment with 24 multiparous early lactating Brown Swiss cows was conducted to investigate the effects of supplementary rumen-protected methionine in conjunction with dietary protein reduction on metabolism and performance after 1 week of control measurement. Three rations containing 175, 150 and 125 g of crude protein/kg feed dry matter were supplemented with methionine. The fourth ration, also only containing 125 g of crude protein/kg dry matter, remained unsupplemented. The four treatment groups had a similar metabolic supply of other essential amino acids, protein and energy, as calculated by various approaches. The two low protein rations were, however, slightly deficient in ruminally degraded protein. Treatment effects remained low on feed intake, forage meal pattern, milk yield and fat as well as lactose content. In contrast, the content and yield of milk protein significantly declined only in the unsupplemented low protein ration relative to the initial value. Compared with this ration, the decline in milk protein yield was clearly delayed in the supplemented low protein ration. Blood plasma methionine tended to be reduced without supplementation and to be increased with additional methionine. Supplementation of methionine reduced other plasma amino acids. Plasma insulin, glucose, lactate, ketone bodies and aspartate amino transferase activity indicated a certain liver stress and a somewhat elevated energy requirement with high and particularly with low protein content (when unsupplemented). Methionine improved metabolic protein utilization, followed by the lowest plasma, urine and milk urea levels in the supplemented low protein diet. In conclusion, no major adverse effects were assessed under the conditions tested. Supplementation of methionine may nevertheless be useful in rations with particularly low protein content fed to early lactating cows in order to prevent negative long-term effects which were only visible here as trends. Zusammenfassung Auswirkungen von pansengeschütztem Methionin in einer Niedrigproteinration im Vergleich zu Rationen mit erhöhtem Rohproteingehalt auf Stoffwechselmerkmale und Leistung von frischlaktierenden Milchkühen In einem fünfwöchigen Experiment mit 24 frischlaktierenden Braunviehkühen wurden die Auswirkungen einer Ergänzung mit pansengeschütztem Methionin bei gleichzeitiger Reduktion der Proteinzufuhr nach einer einwöchigen Kontrollphase geprüft. Drei Rationen mit 175, 150 und 125 g Rohprotein/kg T wurden mit Methionin ergänzt. Eine weitere Variante, ebenfalls nur mit 125 g Rohprotein/kg T, wurde nicht supplementiert. Die vier Varianten stellten gemäß verschiedener Futterbewertungsysteme eine vergleichbare metabolische Versorgung mit den übrigen essentiellen Aminosäuren, Protein und Energie sicher. Die Niedrigproteinvarianten enthielten allerdings etwas zu wenig pansenabbaubares Protein. Futteraufnahme, Muster des Grundfutterverzehrs, Milchleistung sowie Fett-und Laktosegehalt der Milch zeigten nur geringe Reaktion auf die Behandlungen. Milchproteingehalt und -menge waren nur in der nicht ergänzten Niedrigproteinvariante relativ zum Ausgangswert signifikant verringert. Im Vergleich zur unsupplementierten Niedrigproteinration war dagegen der Abfall mit Ergänzung deutlich verzögert. Gegenüber dem Ausgangswert war die Methioninkonzentration im Blutplasma ohne Ergänzung tendenziell erniedrigt, mit Ergänzung erhöht. Es erfolgte eine Verringerung der Plasmakonzentration anderer Aminosäuren durch die Methioninergänzung der Niedrigproteinration. Die Plasmaniveaus von Insulin, Glucose, Laktat, Ketonkörpern und Aspartataminotransferase-Aktivität lassen auf eine gewisse Leberbelastung und einen etwas höheren Energiebedarf mit hohem und besonders mit niedrigem Proteingehalt (unsupplementiert) schließen. Die Zulage an Methionin verbesserte die metabolische Proteinverwertung, so dass die Harnstoffgehalte in Blut, Milch und Harn in dieser Niedrigproteinvariante am niedrigsten waren. Insgesamt ergaben sich keine grösseren ungünstigen Effekte unter den getesteten Bedingungen. Dennoch könnte die Ergänzung von Rationen mit besonders niedrigem Rohproteingehalt mit Methionin beim Einsatz an frischlaktierende Kühe hilfreich sein, um negative Langzeitwirkungen zu verhindern, die sich hier lediglich andeuteten. [source]