In vitro ruminal fermentation characteristics and utilisable CP supply of sainfoin and birdsfoot trefoil silages and their mixtures with other legumes

Abstract

The extensive protein degradation occurring during ensiling decreases the nutritive value of silages, but this might be counteracted by tannins. Therefore, silages from two legume species containing condensed tannins (CT) – sainfoin (SF) and birdsfoot trefoil (two cultivars: birdsfoot trefoil, cv. Bull (BTB) and birdsfoot trefoil, cv. Polom) – were compared for their in vitro ruminal fermentation characteristics. The effect of combining them with two CT-free legume silages (lucerne (LU) and red clover (RC)) was also determined. The supply of duodenally utilisable CP (uCP) in the forages was emphasised. The legumes were each harvested from three field sites. After 24 h of wilting on the field, the legumes were ensiled in laboratory silos for 86 days. Proximate constituents, silage fermentation characteristics, CT content and CP fractions were determined. Subsequently, silage samples and 1 : 1 mixtures of the CT-containing and CT-free silages were incubated for 24 h in batch cultures using ruminal fluid and buffer (1 : 2, v/v). Each treatment was replicated six times in six runs. The effects on pH, ammonia and volatile fatty acid concentrations, protozoal counts, and total gas and methane production were determined. uCP content was calculated by considering the CP in the silage and the ammonia in the incubation fluid from treatments and blanks. Statistical evaluation compared data from single plants alone and together with that from the mixtures. Among treatments, SF silage contained the least CP and the most CT. The non-protein nitrogen content was lower, favouring neutral detergent soluble and insoluble protein fractions, in the SF and RC silages. Absolute uCP content was lowest in SF and SF mixtures, although the ratio to total CP was the highest. In comparison with LU, the ammonia concentration of the incubation fluid was lower for SF, RC and BTB and for the mixture of SF with LU. The total gas and methane production was similar among the treatments, and the total volatile fatty acid production was decreased with the CT-containing legumes. Protozoal count was increased with the mixtures containing LU and either SF or BTB compared with single LU. In conclusion, compared with the other legumes, SF and RC have similar advantages as they show limited proteolysis during ensiling. In addition, SF supplies more uCP relative to total CP. The CT-containing legumes also differed in their effect on ruminal fermentation and ammonia formation, probably because of their different CT contents. Thus, SF and its mixtures appear promising for improving the protein utilisation of ruminants.

Modification of the proportion of extractable and bound condensed tannins in birdsfoot trefoil (Lotus corniculatus) and sainfoin (Onobrychis viicifolia) during wilting, ensiling and pelleting processes

“…No mineral fertilizer was applied. To obtain three independent replicates (batches) per legume, fields were subdivided in three plots and sampling between two plots was performed at a distance of approximately 150 m (Grosse Brinkhaus et al 2016b).…”

“…The insoluble portion of CT is interesting from an animal nutrition perspective as it has been shown that protein-bound CT can dissociate in the small intestine of ruminants and makes protein available for digestion (Kariuki and Norton, 2008). In addition, the study of Grosse Brinkhaus et al (2016b) showed that an OvP silage, with 60% of protein-bound CT, supplied more duodenally utilisable crude protein relative to total crude protein than other legumes. The increase in protein-and fibre-bound CT fractions confirms results obtained on sainfoin by Scharenberget al (2007b) who compared hay and silage and by Terrill et al (2007) who showed that pellets of Sericea lespedeza contained mainly protein-bound CT.…”

Promising options for improving performance and proanthocyanidins of the forage legume sainfoin (Onobrychis viciifolia Scop.)

“…Sainfoin is 117 usually cut and used fresh or preserved as hay or pellets, while grazing is restricted to dry areas with 118 moderate irrigation (Wilman and Asiedu 1983). In addition, a large potential for silage production 119 has also been reported (Copani et al 2016;Grosse Brinkhaus et al 2016). Dry matter yields range 120 between 2 and 12 t ha -1 and are therefore considerably lower when compared to alfalfa or red clover 121 (Table 1; Frame et al 1998).…”

Benefits of Condensed Tannins in Forage Legumes Fed to Ruminants: Importance of Structure, Concentration, and Diet Composition

“…Hydrolyzable tannins are not considered here, although evidence is emerging that some may exert similarly useful bioactive effects Engström et al, 2016;Bee et al, 2017). Hydrolyzable tannins are not considered here, although evidence is emerging that some may exert similarly useful bioactive effects Engström et al, 2016;Bee et al, 2017).…”

“…Although plants synthesize many different tannin types, this review will focus on CTs, as these are of particular interest in forage legumes and several other pasture plants. Hydrolyzable tannins are not considered here, although evidence is emerging that some may exert similarly useful bioactive effects Engström et al, 2016;Bee et al, 2017).…”