Vincent Niderkorn

Binding of Fusarium mycotoxins by fermentative bacteria in vitro.

Aims:  Fusarium toxins can occur in conserved forages impairing farm animal performances and health. On‐farm biological decontamination methods could be an alternative to traditional physico‐chemical methods. In this work, the ability to remove Fusarium toxins by fermentative bacteria was evaluated in vitro.

Cell wall component and mycotoxin moieties involved in the binding of fumonisin B1 and B2 by lactic acid bacteria

Aims:  The ability of lactic acid bacteria (LAB) to bind fumonisins B1 and B2 (FB1, FB2) in fermented foods and feeds and in the gastrointestinal tract could contribute to decrease their bioavailability and toxic effects on farm animals and humans. The aim of this work was to identify the bacterial cell wall component(s) and the functional group(s) of FB involved in the LAB–FB interaction.

Screening of fermentative bacteria for their ability to bind and biotransform deoxynivalenol, zearalenone and fumonisins in an in vitro simulated corn silage model

Fermentative bacteria can potentially be utilized to detoxify corn silage contaminated by Fusarium toxins. The objective of the present study was to test a large number of these bacteria for their ability to bind and/or biotransform deoxynivalenol (DON), zearalenone (ZEN) and fumonisins B1 and B2 (FB1, FB2) in conditions simulating corn silage. A total of 202 strains were screened in contaminated, pH 4, corn infusion inoculated with 5 × 108 CFU ml–1. Eight Lactobacilli and three Leuconostoc biotransformed ZEN into α-zearalenol, but no biotransformation was detected for DON and fumonisins. In contrast, most strains were capable of binding Fusarium toxins. The most effective genera were Streptococcus and Enterococcus, capable of binding up to 33, 49, 24 and 62% of DON, ZEN, FB1 and FB2, respectively. The ability to bind Fusarium toxins seems to be a common property of fermentative bacteria and could help to decrease their toxicity in animals.

Occurrence of associative effects between grasses and legumes in binary mixtures on in vitro rumen fermentation characteristics

When animals are fed a grass and legume mixture, digestive interactions can occur in the rumen between the substrates contained in the different plants, and the response of the animal to the combination of forages can differ from the balanced median values of their components considered individually. Our objective was to assess the associative effects between temperate forages in 8 grass-legume binary combinations on in vitro rumen fermentation characteristics to highlight synergies or antagonisms in terms of nutritional and environmental impacts. Two grasses (cocksfoot, CF; ryegrass, RG) and 4 legume species (alfalfa, A; white clover, WC; red clover, RC; sainfoin, SAN) were incubated alone and in grass-legume mixture (1:1, wt/wt) in batches containing buffered rumen fluid during 3.5 and 24 h. For each substrate and each incubation time, parameters describing the degradation of the energetic and nitrogenous compounds and their partition into fermentation end products were measured. Data were subjected to ANOVA using a mixed procedure to test quadratic contrasts. At 3.5 h of incubation, many quadratic effects were observed. The presence of A, WC, or RC in mixtures quadratically increased the NH(3)-N production (up to +28% when compared with the calculated value, P < 0.001), whereas the presence of condensed tannin (CT) activity in SAN considerably decreased it (up to -67%, quadratic effect, P < 0.001) and the N disappearance. To a lesser extent, the presence of SAN reduced the proportion of methane in the gas produced (up to 7%, quadratic effect, P = 0.018). Generally, the degradation of OM and NDF was not stimulated by mixing grass and legume, except for SAN. However, the presence of SAN severely impaired the NDF digestion at the early phase of fermentation. At 24 h of incubation, few associative effects were observed in comparison with those observed at 3.5 h of incubation, but the effect of CT of SAN on N metabolism was still clearly present. This study shows that, among the grass-legume mixtures tested in vitro, only the presence of SAN can interact with the grasses to reduce the degradation of proteins and the production of methane but with a transitory negative effect on fiber digestion.

Associative effects between orchardgrass and red clover silages on voluntary intake and digestion in sheep: Evidence of a synergy on digestible dry matter intake1

The aim of this study was to assess the associative effects between orchardgrass () and red clover () silages as a model of preserved grass-legume mixture on voluntary intake parameters and digestive efficiency in sheep. Ten sheep were assigned to a repeated 5 × 5 Latin square design, in which 5 proportions of orchardgrass and red clover silages were tested (0:100, 25:75, 50:50, 75:25, and 0:100, on a DM basis). Measurements were performed simultaneously on intake, feeding behavior (eating time and chewing activity), digestive parameters (nutrient digestibility and rumen parameters), nitrogen balance, and enteric methane (CH) emissions using the SF6 tracer technique. Positive associative effects were observed on daily voluntary DMI ( < 0.001), which was greater when sheep were fed with at least 50% red clover (1.56-1.59 kg/d) compared with those fed with 0 or 25% red clover (1.29 and 1.45 kg/d, respectively; < 0.001). This synergy between forages was not observed on nutrient digestibility, as these parameters linearly decreased with increasing proportions of red clover ( < 0.001). As a result, positive associative effects were observed on daily voluntary intake of digestible DM ( < 0.001). Taken together, the results indicate that the synergy on voluntary intake was due to a greater motivation of animals to eat mixtures (seen in increased intake rates) rather than a positive associative effect on digestive efficiency. Methane yield decreased linearly with increasing proportion of red clover ( < 0.001) and ranged from 20.0 g/kg DMI for sheep fed 100% orchardgrass to 16.1 g/kg DMI for sheep fed 100% red clover. Mixtures of orchardgrass and red clover quadratically ( = 0.03) decreased urinary nitrogen losses and tended ( = 0.099) to quadratically increase nitrogen retention. This synergy between orchardgrass and red clover silages could improve animal performances in addition to the known agronomic benefits of grass-legume mixtures.

Bioactive forage legumes as a strategy to improve silage quality and minimise nitrogenous losses

The use of forage legumes as a source of protein for ruminants is a sustainable strategy to reduce the use of inorganic-nitrogen fertiliser. In addition, some legumes species contain naturally bioactive secondary compounds, which could improve silage quality and digestive processes in ruminants. The aim of this study is to investigate the effects of bioactive legumes containing condensed tannins or polyphenol oxidase, ensiled alone or in mixture with a grass, on silage quality and conservation characteristics. Six mini-silos were prepared in triplicate as follows: 100% red clover (RC), 100% sainfoin (SF), 100% Timothy (T, control without bioactive compounds), binary mixtures 50% T + 50% RC, 50% T + 50% SF and ternary mixture 50% T + 25% RC + 25% SF. Condensed tannins remain unaltered during the silage-making process in terms of quantity and chemical structures, while polyphenol oxidase is activated during this process. All the silages that contained bioactive legumes were better conserved than the pure grass silo. In addition bioactive legumes were able to preserve protein from their degradation during the silage process. Inclusion of bioactive legumes can improve silage quality, and polyphenol oxidase may be more efficient than condensed tannins to improve the nitrogen value of silage.

Fatty acid composition of ruminal digesta and longissimus muscle from lambs fed silage mixtures including red clover, sainfoin, and timothy

This work investigated the effects of feeding silage mixtures of a plant containing polyphenol oxidase (PPO; red clover [; RC]), a plant containing tannins (sainfoin [; SF]), and a grass species not containing these compounds (timothy [; T]) on ruminal and intramuscular (i.m.) fatty acids of lambs. Forty 4-mo-old castrated male Romane lambs, divided into 5 groups, received 1 of the following silages: 1) T (100%), 2) a binary mixture of timothy and tannin-containing sainfoin ( cv. Perly; 50:50 [T-SF]), 3) a binary mixture of timothy and PPO-containing red clover ( cv. Mervius; 50:50 [T-RC]), 4) a ternary mixture of timothy, sainfoin, and red clover containing both tannins and PPO (50:25:25, respectively [T-SF-RC]), and 5) a binary mixture of tannin-containing sainfoin and PPO-containing red clover (50:50 [SF-RC]). In the rumen digesta, the partial or total replacement of T with forage legumes was associated with greater concentrations of PUFA ( < 0.001) and 1esser concentrations of MUFA ( < 0.001). The inclusion of forage legumes in the silage favored the accumulation of 18:3 -3 ( < 0.001), with the greatest concentrations being observed in SF-RC. This latter diet also led to the greatest percentage of 18:2 -6 ( < 0.001). Forage legumes decreased the -11 18:1 to 30% of T in rumen digesta ( < 0.001). Forage legumes decreased the total concentration of branched-chain fatty acids in the rumen digesta (on average, -28%; < 0.001), this effect being less marked (-17%; = 0.014) in T-RC in comparison with T. The dietary treatment tended to affect the proportion of MUFA ( = 0.081) and of PUFA ( = 0.079) in the i.m. fat of the LM, respectively, at the highest and lowest numerical value in the T group. The sum of -3 fatty acids was less in the T and T-SF groups compared with the mixture of legumes without T (SF-RC; < 0.001 and < 0.008, respectively). The latter group had also a lesser -6-to--3 ratio than the T-SF group ( = 0.01). -11 18:1 was greater ( < 0.03) in lambs given T as the sole silage in comparison with lambs given T-RC, T-SF-RC, and SF-RC. Rumenic acid (-9 -11 CLA) was detected at a greater percentage in the LM from the animals fed the T silage compared with animals fed the T-SF-RC treatment ( = 0.004). Contrarily, -9 -12 -15 18:3 was found at a greater concentration in the muscle from lambs in the SF-RC treatment compared with lambs in the other treatments ( < 0.001). Furthermore, the T-RC group showed a greater proportion of α-linolenic acid than the T group ( = 0.03). In conclusion, the effects of the 2 active compounds (PPO and tannins) appear to be similar and additive. Moreover, a silage composed of a mixture of RC and SF is an excellent forage for growing lambs in terms of i.m. fatty acid composition.

Sodium Hydroxide Enhances Extractability and Analysis of Proanthocyanidins in Ensiled Sainfoin (Onobrychis viciifolia).

Little information exists on the effects of ensiling on condensed tannins or proanthocyanidins. The acetone-butanol-HCl assay is suitable for measuring proanthocyanidin contents in a wide range of samples, silages included, but provides limited information on proanthocyanidin composition, which is of interest for deciphering the relationships between tannins and their bioactivities in terms of animal nutrition or health. Degradation with benzyl mercaptan (thiolysis) provides information on proanthocyanidin composition, but proanthocyanidins in several sainfoin silages have proved resistant to thiolysis. We now report that a pretreatment step with sodium hydroxide prior to thiolysis was needed to enable their analysis. This alkaline treatment increased their extractability from ensiled sainfoin and facilitated especially the release of larger proanthocyanidins. Ensiling reduced assayable proanthocyanidins by 29%, but the composition of the remaining proanthocyanidins in silage resembled that of the fresh plants.

Stability of the bacteria-bound zearalenone complex in ruminal fluid and in simulated gastrointestinal environment in vitro

Zearalenone (ZEA), an oestrogenic secondary metabolite of Fusarium, is a common feed contaminant. Lactic acid bacteria are capable to bind ZEA and this property could be used to limit its negative biological effects on farm animals. The aim of this work was to examine the stability of a lactic acid bacterium, Streptococcus thermophilus RAR1-ZEA complex in ruminal fluid and in conditions simulating compartments of the gastrointestinal tract. The lactic acid bacteria-ZEA complex was 70% stable in ruminal fluid incubations for up to 18 h, and about 50% of ZEA initially complexed still remained bound after incubation in pepsin, lysozyme, pancreatin and bile either alone or sequentially. However, the release of ZEA was predominantly caused by washing, except for bile which produced a partial dissociation of the complex (P<0.05). Addition of free ZEA to ruminal fluid resulted in instantaneous binding of about 70% of the toxin. ZEA bound to ruminal fluid was even more stable than lactic acid bacteria-ZEA in in v...

Associative effects between Arachis pintoi and dwarf elephantgrass hays on nutritional value in sheep

The aim of the present study was to evaluate the effect of including different levels of peanut (Arachis pintoi cv. Amarillo) hay (167 and 572 g/kg dry matter (DM) of crude protein and neutral detergent fibre respectively) on the nutritional value of diets based on dwarf elephantgrass (Pennisetum purpureum Shum, cv. Kurumi) hay (98 and 668 g/kg DM of crude protein and neutral detergent fibre respectively). Peanut hay was included in the proportions of 0.0, 0.33, 0.66 and 1.00 of total diet DM. Eight Texel × Suffolk crossbred wethers provided with duodenal cannula were assigned to the treatments in a replicated 4 × 4 Latin-square experiment. The organic matter (OM) intake increased linearly (P < 0.05) and the total apparent OM digestibility decreased linearly (P < 0.001) with an increasing inclusion of legume. The nitrogen (N) intake and N urinary excretion increased linearly (P < 0.05), whereas linear and quadratic responses were significant for digestible OM intake, N retention, and for the efficiency of rumen microbial protein synthesis. Cubic positive responses were significant (P < 0.05) for duodenal flow of total N, non-ammonia-N and rumen microbial-N. The inclusion of A. pintoi in dwarf elephantgrass-based diets improved the nutrient supply to sheep, but no additive effect was observed as a result of increasing the peanut proportion in the mixed diet.