Triennial Growth Symposium: effects of polymeric carbohydrates on growth and development in pigs

Polymeric carbohydrates, starch and nonstarch polysaccharides (NSP), quantitatively represent the largest portion of the diets for pigs and are, therefore, the largest energy contributor. The 2 types of polysaccharides, however, have different fates and functions in the gastrointestinal tract and lead to different metabolites upon digestion. Pancreatic and mucosal enzymes in the small intestine break down the majority of starch, whereas NSP primarily are degraded by the microflora in the large intestine. Starch degradation leads to the release of glucose, which is absorbed by an active absorption process that triggers the release of insulin from the pancreas, whereas the fermentation of NSP to short-chain fatty acids (SCFA; i.e., acetate, propionate, and butyrate) occurs at a slower and more constant rate and with SCFA being absorbed by passive diffusion. Type and amounts of polymeric carbohydrates influence growth and development through different mechanisms. First, the proportion of starch to NSP plays an important role for the content of available energy (i.e., DE, ME, and NE); available energy relative to protein is crucial for performance and carcass quality. Second, the proportion of starch to NSP will influence rate and type of metabolites (i.e., glucose vs. SCFA) deriving from carbohydrate assimilation. Third and finally, the type of starch (i.e., types A, B, and C) and soluble NSP will influence the release of insulin, the hormone that facilitates nutrient uptake by tissues, organs, and cells, and thus plays a critically essential role in protein synthesis and muscle growth, as well as lipid synthesis and adipose tissue growth. In conclusion, polymeric carbohydrates influence growth and development through events in the gut and direct and indirect effects of different metabolites deriving from carbohydrate assimilation.     

Effect of fermentation of cereals on the degradation of polysaccharides and other macronutrients in the gastrointestinal tract of growing pigs

The main objective of the present investigation was to study the impact of fermentation of cereals on the degradation of polysaccharides and other macronutrients in the small intestine and total tract of growing pigs. Eight pigs (initial BW, 34.5 ± 0.9 kg) were used in a replicated 4 × 4 Latin square design. Pigs were cannulated and housed individually in metabolism pens during sample collection. The 4 cereal-based diets were nonfermented liquid barley (NFLB), nonfermented liquid wheat (NFLW), fermented liquid barley (FLB), and fermented liquid wheat (FLW). The fermented feeds were prepared by storing the dietary cereals (barley and wheat) and water [1:2.75 (wt/wt)] in a closed tank at 25 °C for 2 d, after which 50% of the volume was removed and replaced with an equal amount of fresh cereals and water after each afternoon meal. At the time of feeding (0730 and 1430 h), the remaining dietary ingredients were added. Water was added to the dry nonfermented feeds [1:1 (wt/wt)] immediately before feeding. The fermentation process reduced the amount of DM in both cereals (P<0.001), whereas the amount of DM was similar (P=0.626) between the fermented cereals. There was an interaction of cereal and treatment for ileal flow of DM (P=0.014), OM (P=0.013), and protein (P=0.006), which were less in pigs fed the NFLB than the FLB diets, but unchanged in pigs fed the NFLW and FLW diets. Conversely, the ileal flow of protein was similar (P=0.605) in pigs fed the barley diets (average, 47.5 ± 1.7 g/kg of DMI) and increased with the FLW diet compared with the NFLW diet (43 vs. 35 g/kg of DMI, respectively). Ileal fat and CH(2)O digestibilities were 7.6 (P=0.002) and 8.9% (P<0.001) greater, respectively, when pigs were fed wheat compared with the barley-based diets, and the ileal digestibility of CH(2)O was greater when pigs were fed the fermented than nonfermented diets (86.5 vs. 84.5%, respectively; P<0.001). Fermentation reduced (P<0.0001) the fecal excretion of DM, OM, and protein in pigs fed the barley diet, but not when fed the wheat-based diet (P=0.305). Fermentation had no effect (P=0.243) on the fecal digestibility of nonstarch polysaccharides in either of the cereals but their digestibility was 10.0% greater (P<0.001) in pigs fed wheat than the barley-based diets. In conclusion, fermentation of cereal before feeding altered the dietary composition and influenced flow and composition of polysaccharides and other macronutrients at the ileum and in feces to a larger extent for barley than wheat.     

Influence of dietary fiber on luminal environment and morphology in the small and large intestine of sows

In this study, the effect of feeding different types and amounts of dietary fiber (DF) on luminal environment and morphology in the small and large intestine of sows was studied. Three diets, a low-fiber diet (LF) and 2 high-fiber diets (high fiber 1, HF1, and high fiber 2, HF2) were used. Diet LF (DF, 17%; soluble DF 4.6%) was based on wheat and barley, whereas the 2 high-fiber diets (HF1: DF, 43%; soluble DF, 11.0%; and HF2: DF, 45%; soluble DF, 7.6%) were based on wheat and barley supplemented with different coproducts from the vegetable food and agroindustry (HF1 and HF2: sugar beet pulp, potato pulp, and pectin residue; HF2: brewers spent grain, seed residue, and pea hull). The diets were fed for a 4-wk period to 12 sows (4 receiving each diet). Thereafter, the sows were killed 4 h postfeeding, and digesta and tissue samples were collected from various parts of the small and large intestine. The carbohydrates in the LF diet were well digested in the small intestine, resulting in less digesta in all segments of the intestinal tract. The fermentation of nonstarch polysaccharides in the large intestine was affected by the chemical composition and physicochemical properties. The digesta from pigs fed the LF diet provided low levels of fermentable carbohydrates that were depleted in proximal colon, whereas for pigs fed the 2 high-DF diets, the digesta was depleted of fermentable carbohydrates at more distal locations of the colon. The consequence was an increased retention time, greater DM percentage, decreased amount of material, and a decreased tissue weight after feeding the LF diet compared with the HF diets. The concentration of short-chain fatty acids was consistent with the fermentability of carbohydrates in the large intestine, but there was no effect of the dietary composition on the molar short-chain fatty acid proportions. It was further shown that feeding the diet providing the greatest amount of fermentable carbohydrates (diet HF1, which was high in soluble DF) resulted in significant morphological changes in the colon compared with the LF diet.     

Flowering in six clones of the Andean root crop arracacha (Arracacia xanthorrhiza Bancroft)

Summary

The effect of dehydration on arracacha (Arracacia xanthorrhiza Bancroft) cormels was investigated and found to have a positive effect on flowering for some accessions and a negative or negligible effect on others. The clear difference in flowering response between accessions is attributed to genetic variation and suboptimal growth conditions. The unclear results indicate that the treatments used were suboptimal and that factors other than drought stress are involved in flower induction. However, the dehydration treatments had a positive effect on the production of hermaphrodite flowers in all accessions, and dehydration is therefore considered an important factor in the flower-inducing treatment. The high temperatures and low humidity during the current experiment had a negative effect on pollen release and thus seed production, indicating that a moderate temperature is needed during the arracacha growth period. There are clear morphological differences between the accessions, with ABS 5516 as the most vigorous and with the highest measured values in all variables except percentage of hermaphrodite flowers.     

Dietary plasticity of Arctic charr (Salvelinus alpinus) facilitates coexistence with competitively superior European whitefish (Coregonus lavaretus)

Abstract – Habitat use and diet of Arctic charr (Salvelinus alpinus) coexisting with European whitefish (Coregonus lavaretus) and grayling (Thymallus thymallus) were studied in one deep and two relatively shallow subarctic lakes in northern Norway. Stomach content and stable isotope analyses revealed clear and temporally stable resource partitioning between the species in all three lakes. Arctic charr had a wide and flexible trophic niche and was the only piscivorous species. In contrast, whitefish and grayling had remarkably stable planktivorous and benthivorous niches, respectively. In the deepest lake, Arctic charr together with grayling mainly utilised littoral benthos, while piscivory was more prevalent in Arctic charr in the two shallower lakes. In one of the shallow lakes, whitefish was apparently relegated to the inferior profundal niche because of dominance of the littoral by grayling. Our results suggest that Arctic charr may not necessarily need an extensive profundal zone as a refuge, but can coexist with whitefish if a third competing fish species like grayling occurs in the littoral habitat or if profitable small prey fish are available. The study demonstrates that strong dietary plasticity of Arctic charr is instrumental in the observed coexistence with the commonly competitively superior whitefish.     

Are hybrids between Atlantic salmon and brown trout suitable long‐term hosts of Gyrodactylus salaris during winter?

The monogenean parasite Gyrodactylus salaris poses serious threats to many Atlantic salmon populations and presents many conservation and management questions/foci and challenges. It is therefore critical to identify potential vectors for infection. To test whether hybrids of native Atlantic salmon (Salmo salar) × brown trout (Salmo trutta) are suitable as reservoir hosts for G. salaris during winter, infected hybrid parr were released into a natural subarctic brook in the autumn. Six months later, 23.9% of the pit‐tagged fish were recaptured. During the experimental period, the hybrids had a sixfold increase in mean intensity of G. salaris, while the prevalence decreased from 81% to 35%. There was high interindividual hybrid variability in susceptibility to infections. The maximum infrapopulation growth rate (0.018 day^?1) of G. salaris throughout the winter was comparable to earlier laboratory experiments at similar temperatures. The results confirm that infrapopulations of G. salaris may reproduce on a hybrid population for several generations at low water temperatures (~1 °C). Wild salmon–trout hybrids are undoubtedly susceptible to G. salaris and represent an important reservoir host for the parasite independent of other co‐occurring susceptible hosts. Consequently, these hybrids may pose a serious risk for G. salaris transmission to nearby, uninfected rivers by migratory individuals.     

Effect of ripeness and postharvest storage on the phenolic profiles of Cherries (Prunus avium L.)

The phenolic compounds hydroxycinnamates, anthocyanins, flavonols, and flavan-3-ols of sweet cherry cultivars Burlat, Saco, Summit, and Van harvested in 2001 and 2002 were quantified by HPLC-DAD. Phenolics were analyzed at partially ripe and ripe stages and during storage at 15 +/- 5 degrees C (room temperature) and 1-2 degrees C (cool temperature). Neochlorogenic and p-coumaroylquinic acids were the main hydroxycinnamic acid derivatives, but chlorogenic acid was also identified in all cultivars. The 3-glucoside and 3-rutinoside of cyanidin were the major anthocyanins. Peonidin and pelargonidin 3-rutinosides were the minor anthocyanins, and peonidin 3-glucoside was also present in cvs. Burlat and Van. Epicatechin was the main monomeric flavan-3-ol with catechin present in smaller amounts in all cultivars. The flavonol rutin was also detected. Cultivar Saco contained the highest amounts of phenolics [227 mg/100 g of fresh weight (fw)] and cv. Van the lowest (124 mg/100 g of fw). Phenolic acid contents generally decreased with storage at 1-2 degrees C and increased with storage at 15 +/- 5 degrees C. Anthocyanin levels increased at both storage temperatures. In cv. Van the anthocyanins increased up to 5-fold during storage at 15 +/- 5 degrees C (from 47 to 230 mg/100 g of fw). Flavonol and flavan-3-ol contents remained quite constant. For all cultivars the levels of phenolic acids were higher in 2001 and the anthocyanin levels were higher in 2002, which suggest a significant influence of climatic conditions on these compounds.     

Effect of heat treatment on nutritional quality of germinated legume seeds

The effect of heat treatment of germinated soybean, lupin, and black bean on chemical composition and protein utilization in rats was evaluated. Heat treatment caused complete inactivation of trypsin inhibitors whereas it did not affect phytic acid levels. Proximate components, minerals, and amino acids did not change, but low molecular weight sugars were affected by heat treatment differently for each germinated legume. The sugar digestibility ratio (total digestible sugars/total nondigestible sugars) in germinated black beans doubled after heat treatment. True protein digestibility (TD) increased with heat treatment only in germinated soybean. Net protein utilization was markedly improved (20%) with heat treatment in germinated soybean and lupin. Utilizable protein of heat-treated germinated legumes was 289, 236, and 132 g/kg of legume dry weight for soybean, lupin, and black bean, respectively. Supplementation with methionine did not alter TD but improved all other indices of protein utilization in the germinated legumes, particularly in black bean. All three germinated legumes become equivalent in protein quality when heating and supplementation with methionine are combined with germination. The use of germinated heat-treated soybean, lupin, and black bean on their own and/or as food ingredients is nutritionally advantageous due to the low content of nondigestible oligosaccharides and the high protein utilization.     

Electrochemical principles for active control of liquids on submillimeter scales

Electrochemical methods were combined with redox-active surfactants to actively control the motions and positions of aqueous and organic liquids on millimeter and smaller scales. Surfactant species generated at one electrode and consumed at another were used to manipulate the magnitude and direction of spatial gradients in surface tension and guide droplets of organic liquids through simple fluidic networks. Solid microparticles could be transported across unconfined surfaces. Electrochemical control of the position of surface-active species within aqueous films of liquid supported on homogeneous surfaces was used to direct these films into periodic arrays of droplets with deterministic shapes and sizes.