Mixing sainfoin and lucerne to improve the feed value of legumes fed to sheep by the effect of condensed tannins

Abstract

The aim of this study was to investigate whether the use of sainfoin-based condensed tannins (CT) enhances feed value when given with tannin-free legumes (lucerne) to sheep. The experiments were conducted with fresh sainfoin and lucerne harvested at two stages (vegetative stage as compared with early flowering) in the first growth cycle. Fresh sainfoin and lucerne forages were combined in ratios of 100 : 0, 75 : 25, 25 : 75 and 0 : 100 (denoted S100, S75, S25 and S0, respectively). Voluntary intake, organic matter digestibility (OMD) and nitrogen (N) retention were measured in sheep fed the different sainfoin and lucerne mixtures. Loss of dry matter (DM) and N from polyester bags suspended in the rumen, abomasum and small intestine (SI) was also measured using rumen-fistulated sheep and intestinally fistulated sheep. The CT content in sainfoin (S100) decreased with increasing percentage of lucerne in the mixture (mean value from 58 g/kg DM for S100 to 18 g/kg DM for S25) and with growth stage (S100: 64 to 52 g/kg DM). OMD did not differ between different sainfoin/lucerne mixture ratios. Sainfoin and lucerne had an associative effect (significant quadratic contrast) on voluntary intake, N intake, total-tract N digestibility, N in faeces and urine (g/g N intake) and N retained (g/g N intake). Compared with lucerne mixtures (S0 and S25), high-sainfoin-content mixtures (S100 and S75) increased the in situ estimates of forage N escaping from the rumen (from 0.162, 0.188 for S0 and S25 to 0.257, 0.287 for S75 and S100) but decreased forage N intestinal digestibility (from 0.496, 0.446 for S0 and S25 to 0.469, 0.335 for S75 and S100). The amount of forage N disappearing from the bags in the SI (per g forage N) was the highest for high-sainfoin mixtures (from 0.082, 0.108 for S100 and S75 to 0.056, 0.058 for S25 and S0, P , 0.001). Rumen juice total N (tN) and ammonia N (NH3-N) values were the lowest in the high-sainfoin diet (mean tN 0.166 mg/g in S100 as compared with 0.514 mg/g in S0; mean NH3-N 0.104 mg/g in S100 as compared with 0.333 mg/g in S0, P , 0.001).Keywords: ruminants, in vivo, condensed tannins, sainfoin-lucerne mixtures. ImplicationsLucerne is favoured for its high yield and nutritional quality, but is seldom grazed in pure stands as it causes bloating. Condensed tannins (CT)-containing legumes do not cause bloating and form CT-protein complexes that are stable and insoluble at rumen pH. Several papers have focused on the effect of CT on the nutritive value of CT-containing forages. The aim of this study was to investigate whether the use of sainfoin CT enhances feed value when given with tannin-free legumes (lucerne). We tested the effects of different sainfoin/lucerne proportions on voluntary intake, in vivo digestibility and in situ ruminal and intestinal digestibility in sheep.

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

“…A number of studies with sainfoin and birdsfoot trefoil have also yielded contradictory results, often with lower or no production benefits measured when compared with CT-free controls (Thomson et al, 1971;Theodoridou et al, 2010;Aufrère et al, 2013;Azuhnwi et al, 2013b;Copani et al, 2016;Girard et al, 2016aGirard et al, , 2016b. In addition to the constraints mentioned above (dietary crude protein concentration, or whether other nutrients are limiting production), variations in CT traits within germplasms may also affect animal responses .…”

Sainfoin production in western Canada: A review of agronomic potential and environmental benefits

“…In fact, much of the ammonia in the atmosphere can be traced to livestock Sheppard and Bittman (2012). When there is a greater proportion of bypass protein in ruminant diets, there is less urea N in urine (Bouchard et al., ) and more N is excreted as non‐ammoniacal N in faecal matter (Aufrère, Dudilieu, Andueza, Poncet, & Baumont, ; Azuhnwi et al., ; Fraser, Fychan, & Jones, ; Thomson, Beever, Harrison, Hill, & Osbourn, ). This results in markedly lower release of ammonia to the atmosphere.…”

Nutritional evaluation of the legume Macrotyloma axillare using in vitro and in vivo bioassays in sheep

“…The increased production of NH 3 ‐N of animals fed MAC was likely a consequence of their higher CP intake. In the rumen, the protein‐binding ability of tannins usually leads to decreases in deamination reactions and consequently lessens NH 3 ‐N production (Aufrère, Dudilieu, Andueza, Poncet, & Baumont, ; Wang, Berg, Barbieri, Veira, & McAllister, ). As observed in our in vitro assay, tannins from macrotiloma apparently did not reduce ruminal degradation of proteins in our in vivo ATTD assay.…”