Para estudiar el efecto de la suplementación con Mg en rebaños de carne hipomagnesémicos, sobre las concentraciones sanguíneas y urinarias de Mg y la prevención de la tetania hipomagnesémica, se realizaron 4 ensayos en rebaños Hereford (vacas pre y postparto) con casos clínicos y muertes por tetania hipomagnesémica e hipomagnesemia diagnosticada mediante un perfil metabólico. En el ensayo 1 se utilizaron 50 g/d/vaca de MgO (equivalente a 25 g de Mg) sobre ensilaje o heno por 44 días; en el ensayo 2 se uso el MgO + NaCl en mezcla con avena chancada (equivalente a 25 g de Mg) por 55 días. En el ensayo 3 se utilizó MgSO4 al 0.5% en el agua de bebida, durante 44 días, equivalente a 10 g/d de Mg. En el ensayo 4 se utilizó MgSO4 en el último mes de gestación y MgO después del parto, en iguales dosis a las señaladas para los otros ensayos, durante 55 días. En 10 vacas de cada ensayo se obtuvieron muestras de sangre y orina previo a la suplementación, durante la suplementación (cada 11&plusmn;2 días) y 1 semana después de finalizada. En las muestras se determinaron las concentraciones de Mg sérico (Mg-s), Mg urinario (Mg-u) y Mg-u corregido por creatinina (CUM). Las concentraciones de Mg-s sólo en el ensayo 3 aumentaron significativamente (p<0.05) desde 0.64 mmol/l previo a la suplementación hasta 0.86 mmol/l a los 44 días de suplementación, el Mg-u y el CUM también aumentaron significativamente (p<0.05) durante ese período. En el ensayo 1 no aumentaron significativamente las concentraciones de Mg-s pero sí lo hicieron significativamente (p<0.05) las concentraciones de Mg-u y CUM. En el ensayo 4 no aumentaron las concentraciones de Mg-s ni Mg-u, pero sí aumentó significativamente (p<0.05) el CUM desde 0.12 mmol/l previo a la suplementación hasta 0.52 mmol/l a los 55 días de suplementación. En el ensayo 2 no aumentó significativamente el Mg-s ni Mg-u y el CUM fue variable en el transcurso del ensayo para aumentar significativamente (p<0.05) desde 0.17 mmol/l hasta 0.36 mmol/l a los 55 días de suplementación. El CUM, si bien aumentó significativamente en los 4 ensayos, se mantuvo bajo el límite de referencia de 1 mmol/l. La incidencia de casos clínicos de tetania hipomagnesémica y muertes disminuyó significativamente (p<0.05) en el total de animales de los ensayos. Los resultados señalan que en rebaños de carne con hipomagnesemia la suplementación con MgO en el alimento o MgSO4 disuelto en el agua de bebida es efectiva para mantener o aumentar las concentraciones de Mg-s, Mg-u y CUM, permitiendo reducir la incidencia de casos clínicos o muertes por tetania hipomagnesémica | The effects of supplementation with magnesium (Mg) salts on blood and urine Mg concentrations and the prevention of grass tetany in hypomagnesaemic beef herds were examined. Two systems of supplementation were tested in 4 beef herds at grazing, between July and December 1993. The herds had an average of 100 cows and were between 7 months pregnant and 2 months after calving. The herds presented clinical cases of grass tetany, dead animals and hypomagnesaemia diagnosed by metabolic profile test. In two herds the cows were supplemented with MgO, (50 g/d/cow, mixed with silage, hay or grounded oats) for 44 to 55 days. In one trial the cows were supplemented with MgSO4 (0.5% in the drinking water) for 44 days. In the last herd the cows were supplemented with MgSO4 before calving and with MgO after calving in a similar way to the previous trials. Blood and urine samples were collected from 10 cows in each herd, starting 1 day before supplementation, and every 11&plusmn;2 days during the supplementation period and for one week after. The concentrations of serum magnesium (Mg-s), urinary magnesium (Mg-u) and creatinine corrected urinary magnesium (CUM) were determined in the samples. Of the two herds supplemented with MgO, only one presented a significant increase of Mg-s (p<0.05) during the supplementation period, reaching values of 0.71-0.78 mmol/l; whereas the Mg-u concentration of the same herd presented a significative increase (p<0.05), with values above the reference of <1.5 mmol/l. The herd supplemented with MgSO4 showed a significant increase of Mg-s (p<0.05) but the Mg-u did not increases during the supplementation period. In the last trial the Mg-s and Mg-u did not show any significant variation (p<0.05). The CUM presented a significant increase (p<0.05) in all the trials, but the values remained below the minimal reference value of 1 mmol/l. The proportion of animals with clinical hypomagnesaemic tetany decreased from 1.9% during the two months before supplementation to 0.3% and the mortality decreased from 1.2% to 0% in the same period. According to these results, in beef cows with hypomagnesaemia, supplementation with MgO given in food or MgSO4 in the drinking water is effective in maintaining or increasing the concentrations of Mg-s, Mg-u and CUM, and in reducing the incidence of clinical cases and deaths produced by grass tetany

Para estudiar el efecto de la suplementación con Mg en rebaños de carne hipomagnesémicos, sobre las concentraciones sanguíneas y urinarias de Mg y la prevención de la tetania hipomagnesémica, se realizaron 4 ensayos en rebaños Hereford (vacas pre y postparto) con casos clínicos y muertes por tetania hipomagnesémica e hipomagnesemia diagnosticada mediante un perfil metabólico. En el ensayo 1 se utilizaron 50 g/d/vaca de MgO (equivalente a 25 g de Mg) sobre ensilaje o heno por 44 días; en el ensayo 2 se uso el MgO + NaCl en mezcla con avena chancada (equivalente a 25 g de Mg) por 55 días. En el ensayo 3 se utilizó MgSO4 al 0.5% en el agua de bebida, durante 44 días, equivalente a 10 g/d de Mg. En el ensayo 4 se utilizó MgSO4 en el último mes de gestación y MgO después del parto, en iguales dosis a las señaladas para los otros ensayos, durante 55 días. En 10 vacas de cada ensayo se obtuvieron muestras de sangre y orina previo a la suplementación, durante la suplementación (cada 11&plusmn;2 días) y 1 semana después de finalizada. En las muestras se determinaron las concentraciones de Mg sérico (Mg-s), Mg urinario (Mg-u) y Mg-u corregido por creatinina (CUM). Las concentraciones de Mg-s sólo en el ensayo 3 aumentaron significativamente (p<0.05) desde 0.64 mmol/l previo a la suplementación hasta 0.86 mmol/l a los 44 días de suplementación, el Mg-u y el CUM también aumentaron significativamente (p<0.05) durante ese período. En el ensayo 1 no aumentaron significativamente las concentraciones de Mg-s pero sí lo hicieron significativamente (p<0.05) las concentraciones de Mg-u y CUM. En el ensayo 4 no aumentaron las concentraciones de Mg-s ni Mg-u, pero sí aumentó significativamente (p<0.05) el CUM desde 0.12 mmol/l previo a la suplementación hasta 0.52 mmol/l a los 55 días de suplementación. En el ensayo 2 no aumentó significativamente el Mg-s ni Mg-u y el CUM fue variable en el transcurso del ensayo para aumentar significativamente (p<0.05) desde 0.17 mmol/l hasta 0.36 mmol/l a los 55 días de suplementación. El CUM, si bien aumentó significativamente en los 4 ensayos, se mantuvo bajo el límite de referencia de 1 mmol/l. La incidencia de casos clínicos de tetania hipomagnesémica y muertes disminuyó significativamente (p<0.05) en el total de animales de los ensayos. Los resultados señalan que en rebaños de carne con hipomagnesemia la suplementación con MgO en el alimento o MgSO4 disuelto en el agua de bebida es efectiva para mantener o aumentar las concentraciones de Mg-s, Mg-u y CUM, permitiendo reducir la incidencia de casos clínicos o muertes por tetania hipomagnesémica | The effects of supplementation with magnesium (Mg) salts on blood and urine Mg concentrations and the prevention of grass tetany in hypomagnesaemic beef herds were examined. Two systems of supplementation were tested in 4 beef herds at grazing, between July and December 1993. The herds had an average of 100 cows and were between 7 months pregnant and 2 months after calving. The herds presented clinical cases of grass tetany, dead animals and hypomagnesaemia diagnosed by metabolic profile test. In two herds the cows were supplemented with MgO, (50 g/d/cow, mixed with silage, hay or grounded oats) for 44 to 55 days. In one trial the cows were supplemented with MgSO4 (0.5% in the drinking water) for 44 days. In the last herd the cows were supplemented with MgSO4 before calving and with MgO after calving in a similar way to the previous trials. Blood and urine samples were collected from 10 cows in each herd, starting 1 day before supplementation, and every 11&plusmn;2 days during the supplementation period and for one week after. The concentrations of serum magnesium (Mg-s), urinary magnesium (Mg-u) and creatinine corrected urinary magnesium (CUM) were determined in the samples. Of the two herds supplemented with MgO, only one presented a significant increase of Mg-s (p<0.05) during the supplementation period, reaching values of 0.71-0.78 mmol/l; whereas the Mg-u concentration of the same herd presented a significative increase (p<0.05), with values above the reference of <1.5 mmol/l. The herd supplemented with MgSO4 showed a significant increase of Mg-s (p<0.05) but the Mg-u did not increases during the supplementation period. In the last trial the Mg-s and Mg-u did not show any significant variation (p<0.05). The CUM presented a significant increase (p<0.05) in all the trials, but the values remained below the minimal reference value of 1 mmol/l. The proportion of animals with clinical hypomagnesaemic tetany decreased from 1.9% during the two months before supplementation to 0.3% and the mortality decreased from 1.2% to 0% in the same period. According to these results, in beef cows with hypomagnesaemia, supplementation with MgO given in food or MgSO4 in the drinking water is effective in maintaining or increasing the concentrations of Mg-s, Mg-u and CUM, and in reducing the incidence of clinical cases and deaths produced by grass tetany

The stability of food agglomerates is very important for keeping optimal instant properties as well as flow characteristics. Compression tests have been proven not only to be useful tools in char acterizing attrition, but also excellent descriptors for powder flowability. The purpose of this work was to study the effects of particle size and water activity (a w) on the compression characteristics of selected agglomerated food powders, and then to identify suitable mathematical models by using a non-linear regression program for predicting the compression characteristics of food agglomerates when partial attrition takes place. Three agglomerated food powders - non-fat milk, low fat milk and instant coffee - were classified by size into five or six fractions with a set of RX-29 sieve screens. Each fraction was conditioned at three a w levels, placed in a cylindrical compression cell, and compressed with a piston attached to the crosshead of a TA-XT2 texture analyser. The crosshead speed was 1 mm/s in all tests and the maximum force applied was 245 N. Particle size was found to play a significant role in compression tests in that the greater the particle size, the greater the volume reduction. It was easier to compress the low a w samples, but in all tests changing a w did not significantly affect compression characteristics. Sone's two- parameter model accurately described the combination of compaction and attrition when compres sion pressure did not exceed a certain level, while Peleg's double-exponential model with four parameters best fitted the compression data.

The suitability of a number of 'off-the-shelf' food items for use as secondary reference materials for incorporation into routine work batches to enhance quality assurance has been evaluated over a 5 month period. The commodities were canned ham (tested for cholesterol and fatty acids), wheat germ (tested for fatty acids, thiamine, riboflavin and niacin), two fish oils (tested for fatty acids) and powdered orange drink vitamin C supplement (tested for ascorbic acid). Foods were purchased locally and analysed using recognized methods. Seven replicate analyses were performed initially on each food to establish homogeneity, with subsequent analyses in triplicate. Overall mean results (+/-2 s.d.) for the 5 month study were as follows: cholesterol in canned ham, 65 +/- 7.2 mg/100 g; thiamine in wheatgerm, 1.97 +/- 0.26 mg/100 g; riboflavin in wheatgerm, 0.27 +/- 0.17 mg/100 g; niacin in wheatgerm, 7.1 +/- 0.9 mg/100 g; ascorbic acid in vitamin C supplement, 718 +/- 70 mg/100 g; C18:0, C18:1 and C18:2 in wheatgerm, 0.72 +/- 0.11, 15.2 +/- 0.5 and 57.7 +/- 1.4% total fatty acids respectively; C18:0, C18:1 and C18:3 in canned ham, 12.5 +/- 0.6, 44.7 +/- 1.4 and 0.57 +/- 0.12% total fatty acids respectively; C18:0, C20:5 and C22:6 in cod liver oil, 2.4 +/- 0.1, 12.6 +/- 1.2, and 5.6 +/- 0.8% total fatty acids respectively; C18:0, C20:5 and C22:6 in omega 3 fish oil, 3.7 +/- 0.2, 19.2 +/- 0.5, and 12.8 +/- 1.4% total fatty acids, respectively. Statistical data were obtained from the multiple analyses, and based on the data generated, the foods tested were shown to have satisfactory homogeneity and stability for use as secondary reference materials over an extended period.

Das in der semi-intensiven Milchfischproduktion genutzte Ergaenzungsfutter (30.1% Rohprotein, 9.2% Rohfett, 8.4% Rohasche, 7.9% Rohfaser u. 44.4% NfE) kompensierte die in der Naturnahrung auftretenden Defizite (Aminosaeuren, PE:UE-Verhaeltnis) nur unvollstaendig.

Se estudiaron 100 muestras de Pleurotus ostreatus procedentes de distintos establecimientos minoristas de alimentacion de la ciudad de Cordoba durante los anos 1995 y 1996, en las que se determino la humedad y se detecto en el 6 por ciento un posible fraude por adicion de agua.