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Search Results: 1 - 10 of 144370 matches for " F. WITTWER "
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Incremento en la proteína no degradable en rumen de vacas lecheras: 2. Efectos sobre utilización y excreción del nitrógeno
Ibarra,D; Latrille,L; Wittwer,F;
Archivos de medicina veterinaria , 2006, DOI: 10.4067/S0301-732X2006000300004
Abstract: eight confined lactating cows at mid lactation fed diets based on silages were used in an incomplete latin square design to evaluate the effects of increasing rumen undegradable protein (rup) on nitrogen utilization and excretion. four diets were used. diets designed as a1 and b1 had, on a dm basis, 45% pasture silage and 20% alfalfa haylage, while diets a2 and b2 had 38% permanent pasture and 27% alfalfa silage. diets a and b differed mainly on the level of rup. diets a were formulated accepting up to a 20% rup deficit and included soybean meal, while b diets covered 100% of estimated rup requirements, using fish meal as a protein source. in spite of causing a lower n intake (p < 0.05), diets higher in rup (b diets) resulted in similar milk production. productive n (secreted as milk nitrogen plus n in daily gain, expressed as g day-1 and as g kg-1 of n intake) was improved significantly (p < 0.05) in higher rup diets. faecal and urinary n excretion were also lower (p < 0.05 and p < 0.01, respectively) in these diets. intake n used in productive functions was higher in b diets (p < 0.01). the relationship productive n v/s intake n and excreted n (faeces plus urine) per litre of milk produced, and productive n v/s excreted n were all improved with b diets. these data indicate that correcting a rup deficit of high silage diets with fish meal, increased the efficiency of the use of n for productive functions and decreased potential contamination through a reduced n excretion.
Incremento en la proteína no degradable en rumen de vacas lecheras: 2. Efectos sobre utilización y excreción del nitrógeno Increasing of rumen undegradable protein in dairy cows: 2. Effects on nitrogen utilization and excretion
D Ibarra,L Latrille,F Wittwer
Archivos de medicina veterinaria , 2006,
Abstract: El objetivo de este trabajo fue establecer los efectos de diferentes niveles de PNDR en dietas con alto contenido de ensilajes sobre la utilización y excreción del N consumido. El ensayo tuvo 2 períodos de 14 días, utilizándose 8 vacas en lactancia en un dise o de cuadrados latinos incompletos. Las dietas identificadas como A1 y B1 tenían: base materia seca (MS), un 45% de ensilaje de pradera permanente (PP), un 20% de ensilaje de alfalfa (EA) y un 35% de concentrado, y las A2 y B2 un 38% de ensilaje de PP, un 27% de EA y un 35% de concentrado. Las dietas B se ajustaron a las recomendaciones de PNDR de NRC (1989), mientras que en las dietas A se permitió un déficit de esta fracción de hasta un 20%. Las dietas B (suplementadas con harina de pescado) generaron un menor consumo de N sin afectar la producción de leche ni su composición. Sin embargo, las dietas adecuadas en PNDR redujeron la excreción de fecas y de orina así como de la cantidad de urea excretada en orina. Al evaluar la excreción de N, los grupos suplementados con PNDR excretaron menos N vía fecas y orina y utilizaron más N en funciones de producción (leche más ganancia de peso). Al evaluar la eficiencia de utilización del N consumido (expresado como g/kg de N consumido), los grupos suplementados con PNDR excretaron más N consumido en la leche y en ganancia de peso. Asimismo, el N excretado, expresado como N por litro de leche producida, fue menor en las dietas suplementadas con harina de pescado. Se concluye que al corregir un déficit de PNDR en dietas ricas en ensilaje con una adecuada suplementación con harina de pescado, ajustada a los requerimientos animales, se permite una buena utilización del N consumido, reduciendo las excreciones de N al medio ambiente. Eight confined lactating cows at mid lactation fed diets based on silages were used in an incomplete Latin square design to evaluate the effects of increasing rumen undegradable protein (RUP) on nitrogen utilization and excretion. Four diets were used. Diets designed as A1 and B1 had, on a DM basis, 45% pasture silage and 20% alfalfa haylage, while diets A2 and B2 had 38% permanent pasture and 27% alfalfa silage. Diets A and B differed mainly on the level of RUP. Diets A were formulated accepting up to a 20% RUP deficit and included soybean meal, while B diets covered 100% of estimated RUP requirements, using fish meal as a protein source. In spite of causing a lower N intake (P < 0.05), diets higher in RUP (B diets) resulted in similar milk production. Productive N (secreted as milk nitrogen plus N in daily gain, expressed as g day-
Efecto de la suplementación con selenio sobre la actividad sanguínea de glutation peroxidasa (GSH-Px) y ganancia de peso en bovinos selenio deficientes mantenidos a pastoreo
OBLITAS,F.; CONTRERAS,P. A.; B?HMWALD,H.; WITTWER,F.;
Archivos de medicina veterinaria , 2000, DOI: 10.4067/S0301-732X2000000100007
Abstract: an experiment was designed to study the effects of a selenium (se) supplementation with sodium selenite on the blood activity of glutathione peroxidase (gsh-px; ec 1.11.1.9) and live weight gain of selenium deficient grazing dairy heifers from two dairy farms from the south of chile. a total of 80 friesian heifers (40 growing heifers, 287 kg b:w; and 40 mating heifers, 358 kg b:w) managed at grazing on permanent pastures belonging to two selenium deficient herds (40 animals from each herd), were used. animals were allotted in similar groups, treated and control. the animals from the treated groups were administered with sodium selenite at 1.67% i.m., in a single dose of 5 mg of se/100 kg body weight. body weight change and gsh-px blood activity were determined previous to supplementation and every three months. the initial blood activity of gsh-px was 34 u/g hb in one herd and 116 u/g hb in the other (ref. value = > 130 u/g hb). a significant increase in the gsh-px activity up to 3 months after supplementation with selenium (p<0.05) was observed and the highest values were found at the 2nd month of the experiment. the percentage of increase of gsh-px at the second month in the treated animals, in comparison with both the initial values and the values of the control animals, was of 300% in one herd and 179% in the other herd. the live weight gain up the third month was slightly greater in the treated group than in the control (p<0.05) with a mean of 234 and 220 g/d in the growing and mating treated heifers, respectively in comparison with 169 and 148 g/d in the control groups. it was concluded that, under the conditions of this study, selenium supplementation increases the blood activity of the enzyme gsh-px for a period of at least three months and there is also evidence suggesting an increase in weight gain in selenium deficient grazing dairy heifers
Effect of source of carbohydrate in concentrate on the performance of high producing dairy cows during spring grazing
Pulido,R G; Berndt,S; Orellana,P; Wittwer,F;
Archivos de medicina veterinaria , 2007, DOI: 10.4067/S0301-732X2007000100003
Abstract: two experiments were conducted to evaluate two different sources of carbohydrate (fibrous and starchy) in concentrate supplement for high producing dairy cows fed spring pasture. in experiment 1, 12 friesian cows producing a daily milk yield of 33.0 kg were assigned to a 3x3 latin square design with 21 day periods each. in experiment 2, 27 friesian cows yielding 29.3 kg/d were assigned to a completely randomized design for 45 days. in both experiments, the treatments included: grazing only (go), grazing plus 6 kg/d of sugar beet pulp- based concentrate (beet pulp), and grazing plus 6 kg/d of cereal-based concentrate (barley). the cows were supplemented twice a day and managed under a strip grazing system on a pasture consisting mainly of perennial ryegrass. in experiment 1 and 2 the crude protein (cp) content of the concentrates was 17.0 and 11.9%, respectively. in experiment 1, average milk yield and milk composition were similar for the sugar beet pulp-based concentrate and the cereal-based concentrate. in experiment 2 average milk yield and milk fat were similar for the supplemented treatments. the type of concentrate did not affect body weight, bodyweight gain, or body condition score. concentrate supplementation increased average milk yield (5.0 and 6.0 kg/d for experiments 1 and 2, respectively) and milk protein concentration (0.12 and 0.15 percent units for experiments 1 and 2, respectively).these results were only significant in experiment 1, when compared to grazing only. in experiment 2 the starchy concentrate produced an increase in plasma glucose concentration and a decrease in plasma bhba and urea-n concentrations. under these conditions, the results suggest that carbohydrate source did not affect the productive performance of dairy cows but it did improve the metabolic condition.
Valores bioquímicos sanguíneos de equinos que tiran carretones en la ciudad de Valdivia (Chile)
TADICH,N.; MENDEZ,G.; WITTWER,F.; MEYER,K.;
Archivos de medicina veterinaria , 1997, DOI: 10.4067/S0301-732X1997000100005
Abstract: this study was carried out in order to establish glucose, lactic acid, b-hidroxibutirate (b-hba), urea, creatininkinase (ck), aspartate aminotransferase (ast), calcium (ca), inorganic phosphorus (pi) and magnesium (mg) blood concentrations in loadcart draught horses in valdivia, chile, and the degree of adaptation of these animals to the exercise performed. also, the relationship of these concentrations with the sex, age and parasite egg counts of the horses were determined. sixty serum and plasma samples obtained from clinically healthy, 3 to 20 years old, crossbred geldings and non pregnant mares, were used. before taking samples, the animals were left to rest for at least 30 minutes, and then subjected to a general clinical examination; name and address of the owner, race, sex, age and weight of the horses were recorded. after the examination, two blood samples were obtained by yugular venopuncture, using plain tubes and tubes with naf. blood mean concentrations were 7.31 ± 1.46 mmol/l, for urea; 0.15 ± 0.09 mmol/l, b-hba; 4.62 ± 0.55 mmol/l, glucose; 2.55 ± 0.92 mmol/l, lactate; 179.74 ± 85.81 u/1, ch; 390.27 ± 148.56 u/1, ast; 2.74 ± 0.17 mmol/l, ca; 1.03 ± 0.25 mmol/l, pi and 0.70 ± 0.07 mmol/1 for mg. no significant differences (p 0.05) were found when blood concentrations of the biochemical parameters analyzed were compared according to age, sex and parasite egg counts of the animals. it was concluded that loadcart draught horses in valdivia present mean blood concentrations of plasmatic lactic acid, serum b-hba and serum activity of ck above the ranges of reference established for the species, suggesting that they are not well adapted to the work they perform. blood concentrations of the different biochemical parameters analyzed showed no significant correlation (p 0.05) with the sex and age of the horses
Plasma retinol concentration in grazing heifers: First data obtained from a dairy herd in the south of Chile
Chihuailaf,RH; González,CS; Wittwer,F; Contreras,PA;
Archivos de medicina veterinaria , 2008, DOI: 10.4067/S0301-732X2008000100009
Abstract: there is no information available about plasma retinol concentration in grazing heifers in chile, for this reason the plasma retinol concentration was measured in dairy heifers grazing during the winter and spring seasons on paddocks in the south of chile. fifteen clinically healthy friesian heifers from a dairy farm located in the valdivia province, chile, aged between 16 and 18 months, were used. the animals were grazing on fertilized natural pastures from july to december. blood samples were taken monthly from each animal and plasma retinol concentrations were determined using reverse-phase high performance liquid chromatography. mean (± sd) plasma retinol concentration was 0.46 ± 0.09 μg/ml with values fluctuating between 0.18 - 0.69 μg/ml. plasma retinol concentration was lower in winter (0.42 ± 0.09 μg/ml, with values fluctuating between 0.18 to 0.57 hg/ml) and higher in spring (0.50 ± 0.09 μg/ml; with values fluctuating between 0.29 to 0.69 μg/ml). the average values obtained in this study constitute the first data currently available in chile regarding plasma retinol concentration in grazing cattle
Contenido de yodo en forrajes de predios lecheros de las Regiones IX y X de Chile
CONTRERAS,P. A.; CEBALLOS,A.; MATAMOROS,R.; WITTWER,F.;
Archivos de medicina veterinaria , 2003, DOI: 10.4067/S0301-732X2003000100007
Abstract: iodine (i) content of rations is a factor associated with the blood concentration of thyroxine (t4) and triiodothyronine (t3) in cattle. in herds from southern chile, low blood concentrations of t4 in grazing dairy cows have been reported. the objective was to obtain information about the i content in forage samples from dairy farms in the ixth and xth regions of chile. during 1999 forage samples were taken from 25 dairy farms located in both regions. the i concentration was analysed by a kinetic-colorimetric method. mean, standard deviation and ranges and the frequency of samples with values below 0.4 ppm on a dry matter basis (normal value) were obtained. the average of i concentration in the forage samples was 0.20±0.08 ppm. forage with normal concentrations were not found. these results suggest an i deficiency in forage from southern chile, and may be associated with low blood concentrations of t4 in grazing dairy cows
Concentraciones de inmunoglobulinas séricas y calostrales de vacas selenio-deficientes y en el suero sanguíneo de sus terneros
Leyan,V.; Wittwer,F.; Contreras,P.A.; Kruze,J.;
Archivos de medicina veterinaria , 2004, DOI: 10.4067/S0301-732X2004000200006
Abstract: the colostrum immunoglobulin concentrations of selenium-deficient cows and in the blood of their calves were studied in twelve friesian cows of 4-9 year old. the animals were 7 months pregnant at the beginning of the experience and it were fed with a selenium deficient diet consisted in hay and a commercial concentrate (diet 0.04 ppm dry matter) and kept under permanent housing condition with water ad libitum. the cows were allocated into two homogeneous groups of six animals each, selenium supplemented (se-s) and selenium deficient (se-d) and the animals of the se-s group were supplemented with barium selenate (1 mg/se/kg s. c.) ± 45 days before calving, whilst the se-d group received nothing. the balance of selenium was assessed by gsh-px activity in blood and the concentration of immunoglobulin in serum and colostrums by immunodiffusion radial method. selenium deficiency did not affect serum and colostrum total igg, igm and iga concentration in cows (p<0.05). however, the igg1 colostrum concentrations decreased in selenium supplemented cows (p<0.05). on the other hand, the nutritional deficiency of selenium did not affect total igg, igg1, igm and iga in calves serum concentrations until 6 days of age.
Efecto de una dieta con bajo aporte de selenio sobre la respuesta inmune a la vacuna Brucella abortus Cepa RB51 en vacas lecheras
Leyán,V; Wittwer,F; Contreras,P A; Schurig,G;
Archivos de medicina veterinaria , 2006, DOI: 10.4067/S0301-732X2006000200006
Abstract: the effect of a diet with a low selenium (se) content on the immune response to brucella abortus strain rb51 vaccine in dairy cows and in their serum inmunoglobulin concentrations was studied. twelve pregnant friesian cows (7 to 8 months) were randomly allocated into two homogeneous groups of six animals each. animals were maintained during 6 months in individual cubicles with water ad libitum and a diet based on grass hay with a low se content (0.02 ppm base on dry matter) and nutritionally balanced for other nutrients. one group was maintained only with the low se diet (se-d) and the other group (se-s) was treated with barium selenate (1 mg se/kg sc) 45 days before calving. all off the cows were immunized with brucella abortus rb51 vaccine during the fourth month of the experiment. blood samples were obtained before supplementation and thereafter every 15 days for determination of the gsh-px activity in erythrocytes. serum igg, igm and iga concentrations were determined by the inmunodiffusion radial method. anti brucella abortus antibodies were determined by an elisa technique. cellular immune response to brucella abortus antigen was evaluated by intradermic reaction test and histological analysis. erythrocyte gsp-px activity in the se-d group decreased to deficient values (<60 u/g hb) on day 150 of the experiment, while that in the se-s group increased and remained within adequate values (130 u/g hb) during the entire experimental period. serum concentrations of igg, igm and iga were similar in both groups of cows and also there were no differences (p0.05) in the humoral and cellular immune responses to rb51 vaccine. these results suggest that the use of a diet with a low se content does not affect the humoral and cellular response to rb51 vaccine.
Efecto del tipo de concentrado sobre indicadores sanguíneos del metabolismo de energía y de proteínas en vacas lecheras en pastoreo primaveral
Noro,M; Vargas,V; Pulido,R G; Wittwer,F;
Archivos de medicina veterinaria , 2006, DOI: 10.4067/S0301-732X2006000300005
Abstract: the objective of the study was to evaluate the effect of supplementation with starch or fibre-based concentrates on blood metabolites in dairy cows fed spring pasture. twenty seven lactating friesian cows producing 30.0 l/day were assigned to completely randomized design for 42 days. the treatments included: grazing alone (tg), grazing plus 6 kg/d of sugar beet pulp-based concentrate (ta) and grazing plus 6 kg/d of cereal-based concentrate (tf). the cows were supplemented twice a day and managed under a strip grazing system on pasture consisting mainly of perennial ryegrass. six coccigeal blood samples from each cow were obtained for seven consecutive days after the morning milking in vacuum tubes containing sodium heparin and sodium fluoride. plasma was separated after centrifugation, frozen at -25oc and analyzed for ?oh-butyrate, glucose, urea and albumin. the unsupplemented group had a lower glycaemia and a higher ?oh-butyrate concentrations than ta and tf (p < 0.05). it was observed a prevalence of 44% sub clinical ketosis in tp group, and no cases in ta or tf. the glycaemia were higher in ta (p < 0.05). the plasmatic urea concentrations were lower (p < 0.05) in ts and higher in tg (p < 0.05). among the treatments not differences were found for the plasmatic albumin concentrations (p>0.05). from the results it can be concluded that supplementation with starch concentrate advantage the energetic balance in lactating dairy cows at pasture. the supplementation with concentrate based on starch or fibre decreased the risk of sub clinical ketosis, and increase the utilization of pasture nitrogen reducing plasma urea concentrations.
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