Using sound to study bubble coalescence.

Frothers are surfactants used in flotation to aid generation of small bubbles, an effect attributed to coalescence prevention. Studying coalescence at the moment of bubble creation is a challenge because events occur over a time frame of milliseconds. This communication introduces a novel acoustic technique to study coalescence as bubbles are generated at a capillary. The sound signal was linked to bubble formation and coalescence events using high-speed cinematography. The technique has the resolution to detect events that occur within 1-2 ms. The results show that for common flotation frothers and n-alcohols (C(4)-C(8)) coalescence prevention is not simply related to surface activity. A total stress model is used to give a qualitative explanation to the action observed. Results for salt (sodium chloride) are included for comparison.

Effect of dehulling of rapeseed on feed value and nutrient digestibility of rape products in pigs.

In the presented study the influence of dehulling rapeseed on the composition of rapeseed meal (RM) and rapeseed cake (RC) and on its feed value for piglets and growing-finishing pigs was investigated. Before withdrawal of oil, rapeseed (variety Express) was dehulled applying a procedure developed by SKET GmbH Magdeburg and the Section Food-Technology of the University Essen. The steps of the dehulling procedure were described. For RM the oil was removed by the prepress-solvent procedure till a crude fat content of 2.1% in DM. RC was produced by pressing only resulting approximately 13% crude fat in DM. The RM and RC from not dehulled (ND) and dehulled (D) rapeseed were examined analytically. Crude nutrients, sugar and fibre substances, amino acids, some minerals and trace elements, fatty acids, glucosinolates and sinapine, and phytate were determined. By dehulling the seed the crude fibre content was decreased in RM and RC by approximately 40%. The ADF content declined by 35 and 39%, and the NDF content by 28% and 40% in RM and RC, respectively. The decrease in ADL content amounted to 50% and 65% for RM and RC, respectively. On the other hand, the CP content of RM and RC was increased by 7% and 13%, respectively, by dehulling the seed while the amino acid content of rape protein increased only slightly. The contents of glucosinolates and sinapine were also increased by dehulling, while the contents of phytate and phytate P were decreased. In digestibility and balance experiments with piglets and intact hybrid breeds of growing-finishing pigs, the digestibility of organic matter and of crude nutrients and the contents of digestible energy and metabolizable energy were estimated. Furthermore, the precaecal digestibility of crude nutrients and amino acids was determined with fistulated mini-pigs. By dehulling the seeds the digestibility of organic matter from RM and RC was improved in piglets and adult pigs by approximately 10%, and the ME contents increased by 13-15%. The precaecal digestibility of the sum of amino acids was increased by approximately 3 and 6 units in RM and RC, respectively. The precaecal digestibility of lysine in RM and RC reached that of soybean oil meal from not dehulled beans.

Effect of different technical treatments of rapeseed on the feed value for broilers and laying hens.

The effect of different technical treatments of rapeseed on its feed value for broilers and laying hens was the object of the study. The technical treatments comprised different grinding procedures (whole seed, roller mill--coarse and fine adjustment, flake mill) resulting in different average particle sizes of the ground seed and thermal treatments of flaked seed (hydrothermal treatment, micronizer, jet sploder). Each thermal treatment was carried out at two temperatures. A marked increase in the digestibility of organic matter and of the AMEN content was observed as the average particle size of the seed was decreased to < or = 0.56 mm and was much more pronounced for the broilers. AMEN contents of 21.1 to 22 and 22.6 to 23 MJ/kg DM were observed at this particle sizes for broilers and hens, respectively. Thermal treatment of rapeseed improved the apparent crude fat digestibility slightly whereas the apparent crude protein digestibility tended to decrease especially at the higher temperatures. This resulted in inconsistent changes in the apparent digestibility of the organic matter and the AMEN content. Only the treatment with hot air (jet sploder) seemed to have preferential effects on the feed value for both broilers and hens. For the thermal treatments AMEN contents ranged from 18.8 to 21.9 and 19.0 to 24.3 MJ/Kg DM for broilers and hens, respectively.

[Protein utilization of mixed feed rations in the lactating pig with reference to the essential amino acid content of the feed proteins. 1. Report. Description of the study methods for protein utilization in the use of peanut extraction residues and dry skim milk in the ration]. / Die Verwertung des Eiweisses gemischter Futterrationen beim laktierenden Schwein unter Berücksichtigung des Gehaltes der Rationsproteine an essentiellen Aminosäuren

A method is discussed which has been used to investigate protein utilization in lactating sows. Two N balance trials were carried out to establish the degree of protein utilization of mixed feed rations. The rations contained barley, oats and flaked potatoes. Extracted pea nut meal or, for comparison, dried skim milk, were added as protein sources. The average biological value achieved was 42% if extracted pea nut meal was fed and 59% if dried skim milk was added. The corresponding PPV data were 33% for the rations containing extracted pea nut meal and 49% for the dried skim milk rations. Balances made for the rate of dietary amino acid intake and amino acid excretion in the milk showed that lysine deficiency occurred when rations were fed containing the extracted pea nut meal.

[Protein utilization of mixed feed rations in lactating pigs with reference to the essential amino acid content of the feed proteins. 3. Report. Correlation between the protein metabolism data and the amino acid content of the dietary protein]. / Die Verwertung des Eiweisses gemischter Futterrationen beim laktierenden Schwein unter Berücksichtigung des Gehaltes der Rationsproteine an essentiellen Aminosäuren 3. Mitteilung Die Beziehungen zwischen den Eiweissstoffwechselkenndaten und dem Aminosäuregehalt des Futterproteins

Protein utilization data were established in N balance trials with lactating sows fed various dietary proteins. The data obtained were compared with the amino acid indices of the dietary proteins and regression equations were established for the relations existing between these data. Additionally, simple and multiple regressions were calculated for relationships between the levels of N balance and the levels of crude protein intake, digestible crude protein, lysine per kg of milk production or lysine and all the other essential amino acids per 10 g of milk N. A relation was found between the level of daily lysine intake and all the other essential amino acids and the level of productive N utilization.

[Protein utilization of mixed feed rations in lactating pigs with reference to the essential amino acid content of the feed proteins. 2. Report. Utilization of the feed proteins in the use of soy bean extraction residue, waste liquor yeast, horse bean meal fish meal and maize gluten for a basic ration]. / Die Verwertung des Eiwesses gemischter Futterrationen beim laktierenden Schwein unter Berücksichtigung des Gehaltes der Rationsproteine an essentiellen Aminosäuren 2. Mitteilung Untersuchungen zur Verwertung des Rationsproteins beim Einsatz von Sojaextraktionsschrot, Sulfitablaugenhefe, Ackerbohnenschrot, Fischmehl und Maiskleber als Eiweissfuttermittel zu einer Grundration

Nitrogen trials were performed on lactating pigs to investigate the utilization of protein from some feeding rations. The basal ration fed to the sows consisted of ground barley+oats+flaked potatoes or ground barley+sugar beet chips. The basal ration was supplemented with a protein source. The protein feeds used were extracted soya bean meal, horse bean meal, fish meal, maize gluten and waste liquor yeast. Data for the average biological value of the dietary proteins were as follows (in the given order of protein feeds): 61%, 59%, 54%, 58% and 37%. PPV data were: 44%, 43%, 39%, 44% and 28%. The proteins of nearly all rations were deficient in lysine when compared with the range of amino acids present in the proteins of sow milk.