Re‐examination of the metabolizable energy contents of various rations containing different types and levels of bacterially fermentable substrates in digestibility experiments with growing pigs

Abstract

Introduction Feedstuffs with elevated contents of bacterially fermentable substrates (BFS: GFE 1987) offered to pigs have intermediate metabolizable energy (ME) contents compared with feedstuffs mainly composed of starch or hardly fermentable fibre (H adorn et al. 1996a,b). Consequently, BFS‐elevated feeds could be used as major components enabling pig fattening rations to obtain the ME values required for feed calculation from tabulated values (DLG 1991) or equations based on nutrient composition (GFE 1996). The main field of application for BFS‐elevated feeds is, however, still the feeding of adult, non‐lactating sows, with the majority of investigations on fermentation characteristics also being conducted with sows. In fattening pigs a higher accuracy of estimated ME contents is required than in non‐lactating sows. Furthermore, the ME values of feeds with elevated BFS contents might be systematically different in sows and fattening pigs because a still incomplete evolution of the fermentative capacity of the hindgut of growing pigs cannot be totally excluded (J entsch et al. 1990). The efficiency of hindgut bacterial protein synthesis might also be different from that being assumed from sow data (e.g. K irchgessner et al. 1989, 1994). The objective of the present study was to determine the actual ME and BFS contents of rations varying widely in type and level of BFS in three experiments with growing pigs. By comparing these values with those calculated from equations or from tabulated values a re‐examination of the currently applied feed evaluation system should be carried out. Furthermore, interactions of BFS with dietary protein reduction were investigated, since in low‐protein rations fermentation efficiency might be limited by a lack of nitrogen in the hindgut (M osenthin 1987).

Fiber-related digestive processes in three different breeds of pigs12

“…The supplementation of SBP resulted in less digestibility of nonfiber and greater digestibility of fiber fractions, thus confirming the results of several other experiments where SBP was fed to pigs (Chabeauti et al, 1991;Kreuzer et al, 1999;Bindelle et al, 2009). A considerable proportion of SBP fiber is degraded in the small intestine of pigs, whereas the ileal digestibility of ash, protein, and fat was reduced at increased SBP intake (Graham et al, 1986;Dierick et al, 1989).…”

“…However, the absolute amount of BEDN increased with SBP as compared with the basal diet-fed pigs, indicating an elevated bacterial N fixation in the hindgut. The greater UDN excretion observed in SBP-fed pigs may have resulted from increased quantity of fiber-bound N, and the increased WSN excretions can be explained by the enhanced endogenous secretion of enzymes, reduced urea absorption at the end of the ileum, increased resecretion of urea through the hindgut wall, or lysis of bacteria before excretion (Kreuzer et al, 1999).…”

Effects of nutrition on digestion efficiency and gaseous emissions from slurry in growing pigs: II. Effect of protein source in practical diets

“…Consequently, differences in supply of soluble fibre among diets were great and led to a significant increase of DM and N intake. However, when citrus and beet pulp were added to diets with similar NDF levels, little effect of inclusion of soluble fibre on daily BEDN excretion was also reported (Kreuzer et al, 1999; experiment 1). In the same way, several works (Graham et al, 1986;Bach Knudsen et al, 1993;Glitso et al, 1998) have demonstrated that a significant proportion of the dietary soluble fibre (from 0.20 to 0.40) is fermented before the ileum, and so it would not be a direct substrate for hindgut microbial population.…”

“…However, in the current study, BEDN proportion in total faecal N tended to be lower when a higher proportion of highly fermentable fibre was given in OP diets. Previous works (Kreuzer et al, 1999;Heimendahl et al, 2010) measured faecal N fractions in pigs using the same methodology than in the current study. In these studies, a significant decrease of BEDN proportion in total faecal N was observed with soluble fibre supplementation, but daily faecal N and BEDN excretion increased, because highly fermentable sources of fibre (as citrus or sugar beet pulp) replaced starch in the experimental feeds, so that dietary NDF content increased in parallel to by-products inclusion.…”

Relationships among slurry characteristics and gaseous emissions at different types of commercial Spanish pig farms

“…In the same way, there is a general agreement in that inclusion of fermentable fibre, as sugar beet pulp or inuline, leads to a shift in the N excretion from faeces to urine (Aarnink & Verstegen, 2007), which is generally associated to an enhanced metabolic urea retention and excretion as microbial protein in the faeces (Kreuzer et al, 1999). This shift would imply in turn a decrease of ammonia emissions from the slurry with fibre supplementation but also a higher fermentation activity and methane losses, as observed by Montalvo et al (2013).…”