Preliminary evaluation of fenugreek (Trigonella foenum-graecum) seed gum as a potential prebiotic for growing rabbits in Tunisia: effects on in vivo faecal digestibility and in vitro fermentation

Abstract

<p>This study aims to determine the effect of dietary inclusion of fenugreek seed gum (FSG), rich in galactomannans, on nutrient apparent digestibility and caecal environment, as well as on <em>in vitro</em> caecal fermentation of Tunisian growing rabbits. Three experimental diets were formulated, including 0, 0.25 and 0.5% of FSG (FSG0, FSG0.25 and FSG0.5, respectively) for the <em>in vivo</em> trial and 0, 0.125, 0.25, 0.5 and 100% of FSG (FSG0, FSG0125, FSG0.25, FSG0.5 and FSG100, respectively) for the <em>in vitro</em> trial. In the <em>in vivo</em> trial, 45 weaned rabbits 31 d old (15 per treatment) were housed in individual cages until 94 d of age. Apparent digestibility coefficients were determined at two ages, from 38 to 41 and from 56 to 59 d old, and caecal traits were recorded after slaughtering. In the <em>in vitro</em> trial, the five experimental diets were incubated with a rabbit caecal inoculum. Gas production was measured and modelled until 72 h and the fermentation traits were measured. Apparent faecal digestibility coefficients of main nutrients and main caecal environment traits were not significantly affected by the dietary inclusion of FSG (<em>P</em>>0.05). However, animals fed with FSG showed lower caecal pH (–0.15; <em>P</em><0.05) values. Regarding the in vitro fermentation, FSG100 increased asymptotic gas production (+11.25, <em>P</em><0.001), sharpness of the switching characteristic of the profile (+1.98, <em>P</em><0.001) and the maximum substrate degradation rate (RM) (+0.188, <em>P</em><0.001), but decreasing the time after incubation at which half of the asymptotic amount of gas has been formed (–5.86, <em>P</em><0.001) and at which RM occurs (–4.53, <em>P</em><0.01). Likewise, FSG100 significantly decreased caecal pH (–1.035, <em>P</em><0.001), lactic acid (–9.51, <em>P</em><0.069) and N-NH<sub>3</sub> concentrations (–12.81, <em>P</em><0.001). Meanwhile, it increased the total volatile fatty acids (VFA) production (+43.15, <em>P</em><0.001). Gradual dietary inclusion of FSG from 0 to 0.5% only significantly increased total VFA production in the caecum (+100 mmol/L per percentage point of FSG inclusion; <em>P</em><0.05). In conclusion, FSG is highly and rapidly in vitro fermented by rabbit caecal bacteria. However, dietary inclusion of FSG up to 0.5%, might be insufficient to affect the apparent digestibility and fermentation profile of growing rabbits to a great extent.</p>

Comparison of In Vivo and In Vitro Digestibility in Rabbits

“…In our trial, with the inclusion of 5% of fenugreek in the diet, no effects were observed on apparent digestibility, but the inclusion of 10% showed the tendency of increasing the digestibility. Zemzmi et al [ 44 ] found that the dietary inclusion up to 0.5% of fenugreek seeds gum (a potential prebiotic extracted from seeds, containing a galactomannan resistant to acid and pancreatic digestion and highly fermentable) did not significantly affect the apparent digestibility of main nutrients and main cecal environment traits, but it lowered the cecal pH and it can be used by the fibrolytic microbiota of the rabbit’s caecum. Martinez-Vallespín et al [ 45 , 46 ] demonstrated that high fermentability of galactomannans in the cecum could promote the fibrolytic microbiota, influencing the use of the rest of the fibrous fractions.…”

Evaluation of Trigonella foenum-graecum L. Plant Food Safety after Lead Exposure: Phytochemical Processes

“…Fenugreek ( Trigonella foenum-graecum L.) is an annual leguminous herb that is extensively cultivated in India and North African countries [ 8 ]. In Tunisia, fenugreek is widely cultivated in the northwestern, northern and northeastern regions [ 9 ]. It has been investigated not only as a multipurpose medicinal herb through the extraction of phenolic compound to be used in pharmacological field [ 10 ], but also in phytoremediation programs [ 11 , 12 ].…”

In vitro and in vivo characterization of galactomannanes extracted from fenugreek seeds (Trigonella foenum-graecum) for young rabbit nutrition.

“…FSG seems to affect caecal microbiota in rabbits. In fact, in vitro enzymatic digestion of FSG reduced caecal pH, lactate and nitrogen ammonia (N-NH3) concentrations (Zemzmi et al, 2020a), and increased propionate, isobutyrate and isovalerate proportions and reduced that of caproate (Zemzmi et al, 2020b). In addition, FSG inclusion in rabbits diets seems to increase neutral detergent fibre (NDF) and acid detergent fibre (ADF) faecal digestion (Zemzmi et al, 2020a).…”

“…In fact, in vitro enzymatic digestion of FSG reduced caecal pH, lactate and nitrogen ammonia (N-NH3) concentrations (Zemzmi et al, 2020a), and increased propionate, isobutyrate and isovalerate proportions and reduced that of caproate (Zemzmi et al, 2020b). In addition, FSG inclusion in rabbits diets seems to increase neutral detergent fibre (NDF) and acid detergent fibre (ADF) faecal digestion (Zemzmi et al, 2020a). However, in vivo supplementation of FSG up to 5 g/kg in a commercial antibiotic-free diet only produced little relevant changes on health status and caecal activity in growing rabbits (Zemzmi et al, 2020a).…”

“…In addition, FSG inclusion in rabbits diets seems to increase neutral detergent fibre (NDF) and acid detergent fibre (ADF) faecal digestion (Zemzmi et al, 2020a). However, in vivo supplementation of FSG up to 5 g/kg in a commercial antibiotic-free diet only produced little relevant changes on health status and caecal activity in growing rabbits (Zemzmi et al, 2020a).…”