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Ljøkjel, K., Sørensen, M., Storebakken, T. and Skrede, A. 2004. Digestibility of protein, amino acids and starch in mink (Mustela vison) fed diets processed by different extrusion conditions. Can. J. Anim. Sci. 84: 673-680. An experiment was carried out to evaluate the effect of different extrusion processes on digestibility of a fish-meal-based diet fed to mink. The feed was processed in a twin-screw extruder with the exit temperatures of the meal of 100, 125 or 150°C. Feed production was carried out three times, using different extrusion conditions to achieve the target temperatures. An untreated meal mixture was included as a control diet. True digestibilities of crude protein and total amino acids were lower for diets extruded at 125 and 150°C than for the control (P < 0.05). Digestibilities of crude protein, total amino acids, and the amino acids alanine, arginine, aspartic acid, cysteine, glutamic acid, histidine, isoleucine, leucine, lysine and valine decreased when increasing extrusion temperature from 100 to 125°C (P < 0.05), a further increase in temperature did not influence digestibility (P > 0.05). The highest reduction was seen for cysteine (6.8 percentage units). Starch digestibility was increased by extrusion, but there was no effect of temperature (P > 0.05). Digestibilities of crude protein, total amino acids, alanine, arginine, aspartic acid, glutamic acid, glycine, proline, histidine, lysine, tryptophan and valine were affected by the processing method (P < 0.05), which, by multivariate analysis, was revealed to be associated mainly with processing parameters: revolutions per minute, conditioner temperature, die temperature and feeding rate. Digestibility of starch was influenced mainly by the addition of water. L'aliment a été transformé au moyen d'une extrudeuse à vis double, la farine étant récupérée à une tempéra-ture de 100°C, de 125°C ou de 150°C à la sortie de la machine. La ration a été préparée à trois reprises, chaque fois dans des conditions différentes afin de parvenir à la température souhaitée. On s'est servi d'un mélange de farine non conditionnée comme ration témoin. Les protéines brutes et les acides aminés totaux des rations extrudées à 125°C et à 150°C ont une digestibilité réelle inférieure à celle relevée pour la ration témoin (P < 0,05). Quand la température d'extrusion passe de 100°C à 125°C, on remarque une diminution de la digestibilité des protéines brutes, des acides aminés totaux ainsi que de l'alanine, l'arginine, l'acide aspartique, la cystéine, l'acide glutamique, l'histidine, l'isoleucine, la leucine, la lysine et la valine (P < 0,05). Toutefois, une hausse supplémentaire de la température n'affecte pas la digestibilité (P > 0,05). La plus forte diminution de la digestibilité a été observée avec la cystéine (6,8 unités de pourcentage). L'extrusion accroît la digestibilité de l'amidon, mais celle-ci n'est pas affectée par la température (P > 0,05). La méthode de transformation modifie la digestibilité des protéines brutes, des acides aminés totaux ainsi que de l...

In situ digestion of protein and starch in barley, oats, wheat, wheat bran, maize, sorghum, peas, and soyabeans was evaluated in dairy cows after milling (untreated), pelleting (ca. 81 o C) and expander processing at two different temperatures (110 or 130 o C). Effective degradation of crude protein (EPD) and starch (ESD) in the rumen, as well as total tract indigested protein (IP) and starch (IS) fractions, were determined by in situ methods. Pelleting significantly decreased EPD of wheat and wheat bran by 14 and 10 percentage units, respectively, and increased ESD in maize by 10 percentage units. Expander treatment efficiently protected protein from rumen degradation in all feeds evaluated, except maize. The ESD of maize, sorghum, peas and oats increased with 31, 18, 22 and 5 percentage units, respectively, after expander treatment at 130 o C. The IP fraction of sorghum and peas increased after expander treatment. In maize, sorghum and peas the IS fraction decreased by heat treatment. It is concluded that protein and starch digestion of vegetable feeds in dairy cows can be modified by different heat treatment.

The concentration of omega-3 fatty acids and selenium (Se) is generally too low in the Western diet. But as the nutrient composition of pork meat and adipose tissue is influenced by the feed given to the animals, the product can be changed to support nutrient demands. Half (297/594) the pigs were given a feed concentrate based on low-glucosinolate rapeseed products (RS), while the other half was fed a traditional concentrate (Contr): The RS feed had an omega-6/omega-3 ratio of 3.6:1, and the Contr feed had a ratio of 8.9:1, and both feeds were supplemented with 0.4 mg Se/kg (organic Se: inorganic Se, 1:1). There was a small difference in growth rate, but no differences in feed conversion ratio, lean meat percentage, carcass value, and margin per pig for the two groups. There were no differences in meat quality between the two groups, but there were differences in technological fat quality. The RS pigs contained about 2 times more alpha-linolenic acid in the backfat and 41% more in the meat (M. longissimus dorsi) compared to the controls. The concentration of EPA, DPA, and DHA were 42% and 20% higher in backfat and meat of the RS pigs compared to the control pigs respectively. The ratio between omega-6/omega-3 fatty acids were 4.7 in the meat and 4.0 in the backfat in the RS pigs, and the corresponding values were 6.6 and 8.0 in the control pigs. The selenium content was 0.3 mg/kg meat in both groups. The study showed that a portion of the present pig meat (175 g) provided the daily recommended intake of Se for men and women and about 1/6 of proposed reference intake of omega-3 LCPUFA (250 mg/day) to reduce the risk of CVD thereby providing a meat that is somewhat healthier for the consumer.