Dietary xylose as an energy source for young pigs

Abstract

Summary Energy balances were compared in eight pigs (6–8 kg) fed 5% glucose or 10% D‐xylose added to a basal diet. In a carry‐over design, each pig received the glucose and 2 weeks later the xylose diet or vice versa. The basal diet consisted mainly of barley, corn, soya flour and skim milk powder. Pigs were fed 1.3 times the maintenance requirement for energy. Energy balances were measured after 4 days of adjustment to the diet and over a 7 day period. The rate of weight gain was similar between the treatments. The metabolizable energy of 10% D‐xylose was about equal to 5% glucose. The heat production was similar between treatments. This indicated that the absorbed and metabolized D‐xylose is probably utilized to the same extent as or somewhat less than glucose, with the potential of some xylose being fermented in the large intestine and absorbed as volatile fatty acids. This could contribute to the well‐being of the small pigs especially under situations of limited energy intakes. Zusammenfassung Xylose als Energiequelle in Rationen für Ferkel Zum Vergleich von Energiebilanzen erhielten acht Ferkel (6–8 kg Lebendgewicht 5% Glucose oder 10% D‐Xylose zu einer Basaldiät in einem Carry over Versuch zu einer Basaldiät. Jedes Ferkel erhielt die Glucose und zwei Wochen später Xylose vice versa. Die Basaldiät bestand hauptsächlich aus Gerste, Mais, Sojamehl und Magermilchpulver und deckte das l,3fache des Bedarfes an Energie für Erhaltung. Die Energiebilanzen wurden nach einer viertägigen Adaptationsphase an das Futter in einer siebentägigen Versuchsperiode ermittelt. Die Zunahmeraten lagen bei etwa allen Behandlungen gleich hoch. Die umsetzbare Energie von 10% D‐Xylose entsprach etwa der von 5% Glucose. Die Wärmeproduktion war bei allen Behandlungen gleich. Das deutet daraufhin, daß die absorbierte und umgesetzte D‐Xylose zum gleichen oder etwas geringerem Anteil wie Glucose genutzt werden kann, wobei ein gewisser Anteil an Xylose im Dickdarm fermentiert und als flüchtige Fettsäuren absorbiert wird. Die Verabreichung von Xylose könnte damit zum Wohlbefinden der Ferkel beitragen, vor allem bei limitierter Energieaufnahme.

Xylose metabolism in the pig

“…Contrary to the results of previous studies [ 9 , 43 ], dietary xylose concentration did not affect total tract digestibility of DM, GE, or CP in biologically relevant ways. Among all treatments and throughout the entire trial, the ATTD of DM ranged from 87.6–89.1% and diet DE was found to be slightly lower in the 2% treatment compared to the other three treatments.…”

“…This was the first indication that the efficiency of xylose utilization decreases proportionally as dietary xylose concentration increases. These value are comparable to previous studies in pigs which reported that 35–53% of absorbed xylose is excreted in the urine [ 9 , 43 , 44 ].…”

“…Unlike previous studies using dietary xylose concentrations of 10% [ 43 ] or 18.7 and 37.4% [ 51 ], a significant ADG or feed efficiency response due to dietary xylose inclusion was not detected in pigs on this experiment. This result may be partially explained due to the experimental design of this experiment, including limit feeding, as well as by the relatively small differences in diet ME value among treatments.…”

“…Xylanase releases a portion of the xylose from the xylan backbone [ 1 – 3 ]. This free xylose can then be absorbed in the small intestine [ 9 , 43 – 46 ] and potentially contribute energy to the pig. However, previous research indicates that xylose is poorly utilized [ 4 ], so it is unknown whether xylose would contribute more energy when absorbed as a monosaccharide or through fermentation of arabinoxylan in the hindgut.…”

“…Among all treatments and throughout the entire trial, the ATTD of DM ranged from 87.6–89.1% and diet DE was found to be slightly lower in the 2% treatment compared to the other three treatments. Based on previous research [ 9 , 43 , 44 ] and analysis of a subset of the colon digesta and fecal samples from pigs on this experiment, dietary xylose was assumed to be completely absorbed by the terminal ileum. Because possible microbial fermentation of xylose in the small intestine [ 9 , 44 ] was not evaluated, one potential drawback of this assumption is an overestimation of retained xylose.…”