High Concentrations Of Condensed Tannins Research Articles

Supplementation of Oilseeds to an Herbage Diet High in Condensed Tannins Affects Methane Production with Minimal Impact on Ruminal Fermentation in Continuous Culture

Condensed tannins (CT) have been observed to reduce enteric CH4 production when added to ruminant diets. However, high concentrations of CT in forages such as sericea lespedeza (SL; Lespedeza cuneata (Dum. Cours.) G. Don) may depress nutrient digestibility. Oilseed crops, high in lipid concentration, also reduce enteric CH4 via toxicity to methanogenic bacteria with less depression of nutrient digestibility. However, it is unclear whether combining these two feeds would result in even greater decreases in CH4 without impairing ruminal fermentation. This study used an in vitro continuous culture fermentor system to determine if supplementation of ground oilseeds would further reduce enteric CH4 production while improving nutrient digestibility of high-CT forages. The experimental design was a 4 × 4 Latin square, with four diets containing (dry matter basis) 45% orchardgrass (OCH; Dactylis glomerata L.), 45% sericea lespedeza (SL; Lespedeza cuneata (Dum. Cours.) G. Don), and 10% oilseed supplements, using canola (CAN; Brassica napus L.), soybean (SOY; Glycine max L.), sunflower (SUN; Helianthus annuus L.), or a mix of all three species (MIX; in equal proportions). Fermentors were fed 82 g of dry matter/d in four equal feedings over four 10 d periods. Methane was recorded every 10 min, and effluent samples were analyzed for pH, volatile fatty acids, dry matter, organic matter, crude protein, neutral detergent fiber, and acid detergent fiber to determine apparent and true nutrient digestibilities. The CAN, SUN, and MIX diets had greater concentrations of crude fat (7–8 g/kg) than the SOY diet (5.7 g/kg), which contributed to the greater reduction in enteric CH4 production in those diets (13–27 mg/d) compared to the SOY diet (84 mg/d). Apparent and true nutrient digestibilities were not affected by the addition of ground oilseeds. While N intake increased concomitant with crude protein increases in the diets, there were no additional effects on N flows. While supplementing a high-CT diet with any of the three oilseeds (canola, soybean, sunflower, or a mixture of the three oilseeds) reduced total CH4 emission without depressing nutrient digestibility, canola and mixes containing canola were most effective. Further research is needed in vivo to evaluate whether these results translate to greater feed efficiency and animal production.

Yield, Morphological Characteristics, and Chemical Composition of European‐ and Mediterranean‐Derived Birdsfoot Trefoil Cultivars Grown in the Colder Continental United States

ABSTRACTNorth American birdsfoot trefoil (BFT, Lotus corniculatus L.) cultivars such as Norcen produce forage with low condensed tannin (CT) concentrations that may be insufficient for optimal livestock performance. Our objective was to identify European‐ and Mediterranean‐derived cultivars with higher CT concentrations that would be suitable for production in the colder continental United States. One alfalfa (Medicago sativa L.) and 14 BFT cultivars were established during 2005 in MI, UT, WI, and WV and harvested under a two‐ or three‐cut management to determine herbage chemical composition in 2006 and dry matter yield (DMY) in 2006 and 2007. During 2006, variances in crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin (ADL) were mainly influenced by location‐harvest environments, while CT was influenced by both cultivar and environment. Earlier‐maturing cultivars such as Bokor, AU Dewey, Rodeo, and Grasslands Goldie produced herbage with relatively high CT concentrations, but not undesirably low CP or high NDF, ADF, and ADL concentrations compared with Norcen BFT or alfalfa. By the second full production year in 2007, total DMY in UT exceeded WI by twofold and MI by ninefold, and total DMY of the moderate CT‐containing cultivar Lotar surpassed most other cultivars, suggesting it may be well suited for forage production in the United States. Yields of alfalfa in all environments exceeded BFT by about 1.5‐fold. Additional studies are needed to identify optimal CT concentrations in BFT for ruminants and to improve the compositional uniformity and yield of harvested BFT in various environments.

Condensed tannin concentrations found in vegetative and mature forage legumes grown in western Canada

Berard, N. C., Wang, Y., Wittenberg, K. M., Krause, D. O., Coulman, B. E., McAllister, T. A. and Ominski, K. H. 2011. Condensed tannin concentrations found in vegetative and mature forage legumes grown in western Canada. Can. J. Plant Sci. 91: 669–675. There has been limited effort to examine condensed tannin (CT) concentrations of forage legume species grown in western Canada. Using the butanol-HCl technique, extractable CT concentrations were measured in Trifolium hybridum L., T. ambiguum M. Bieb, T. pratense L., T. repens L., Dalea purpurea Vent., Onobrychis viciifolia Scop., Lotus corniculatus L., Medicago sativa L., and Astragalus cicer L. collected from research and variety trial plots across the Canadian prairies. Above ground plant biomass was harvested at the vegetative and mature physiological stages for two growing seasons. Dalea purpurea, a native legume, had the highest mean CT concentration of 68.6±22.6 g kg−1DM, with minimum and maximum values ranging from 37.9 to 92.9 g kg−1DM. Onobrychis viciifolia had the second highest mean CT concentration (46.0 g kg−1DM) with a range of 16.3 to 94.4 g kg−1DM. The third highest mean CT concentration of 15.1 g kg−1DM was found in L. corniculatus with a range of 0.0 to 25.7 g kg−1DM. Forage biomass had higher CT concentrations (P<0.05) when harvested at the mature stage for all species except O. viciifolia, which had higher CT concentrations in the vegetative state. The potential benefit of inclusion of these species in ruminant diets at the observed concentrations requires further exploration.

Early Onset of Poinsettia Bract Necrosis is Associated with Condensed Tannin Accumulation

The early onset of bract necrosis in poinsettia (Euphorbia pulcherrima Willd. ex. Klotzch) is characterized by small dark-stained spots that precede the development of enlarged necrotic lesions. Electron micrographs of adaxial epidermal and subepidermal tissues with early symptoms of necrosis revealed large, electron dense deposits in cell vacuoles. These spherical bodies resembled condensed tannins observed in the epidermal tissues of peach and apple fruit. Chemical analysis of bract tissues showed higher condensed tannin concentrations in bract samples with 2 mm diameter lesions than in samples with lesions less than 0.5 mm (equivalent to catechin concentrations of 59 and 13 mg·g–1 fresh mass, respectively). Tannin bodies were not observed in micrographs from parallel samples of healthy appearing bracts, and chemical analysis revealed only trace concentrations of condensed tannins in these tissues (0.2 mg·g–1 fresh mass). The evidence suggests that condensed tannins accumulate in affected cells at the earliest observable stages of bract necrosis.

Patch‐Size Effects on Plant Phenolics in Successional Openings of the Southern Appalachians

We examined the seasonal changes in plant chemical defenses of key tree species (Robinia pseudoacacia, Liriodendron tulipifera, Acer rubrum, and Cornus florida) regenerating during early succession in different patch sizes within Southern Appalachian forests. Trees of each species were sampled from five sizes of forest openings (0.016, 0.08, 0.4, 2.0, and 10 ha; two replicates each) and from the understory of surrounding forests. Leaves of rapidly growing, pioneer species (Robinia and Liriodendron) were slightly less tough and contained lower levels of hydrolyzable tannins and total phenolics, but higher condensed tannin concentrations than the slower growing, more shade—tolerant species (Acer and Cornus). These results generally support earlier findings indicating the evolutionary development of greater levels of constitutive phenolics in slow—growing than fast—growing species. The differential use of condensed and hydrolyzable tannins by slow— and fast—growing species may reflect adaptive trade—offs in the allocation of different types of phenolics. Regenerating trees often had tougher leaves and contained higher levels of phenolics in large than small openings by midsummer. The differences in phenolics were more pronounced for condensed tannins and when comparing the smallest canopy openings with larger patch sizes. Plant phenolics were also generally lower in understory trees than in conspecific sprouts in openings. These findings may reflect phenotypic carbon/nutrient adjustments as light availability changes across the patch—size gradient. The greater sunlight in large than small openings apparently promotes excess carbon production and a metabolic buildup of phenolic compounds. Independent measures of phenolic compounds peaked at different times during the growing season. Hydrolyzable tannins reached peak levels quite early whereas condensed tannins increased later in the growing season. Total phenolics peaked in midsummer. Herbivore damage was consistently high (5—9%) on Robinia sprouts in all openings. Insect herbivory on the remaining three species (1—5%) was significantly lower in large than small patch sizes. Tree species regenerating in the high sunlight of larger openings in Southern Appalachian forests thus tend to have tougher leaves, contain greater phenolics, and experience less herbivore damage than conspecifics in small openings.

Genotypic and Cultural Effects on Condensed Tannin Concentration of Cotton Leaves

Condensed tannins reportedly act as feeding deterrents to bollwonn [Helicoverpa zea (Boddie)], tobacco budworm [Heliothis virescens (F.)], and two spotted spider mite [Tetranychus urticae (Koch)] in cotton [Gossypium hirsutum L.]. This study was conducted to determine the effects of planting date, plant density, growth stage, and leaf age on the condensed tannin concentration of six cotton genotypes planted at College Station, TX, in 1988 and 1989. Planting commenced on 25 April in both years and consisted of three plantings at approximately 2‐wk intervals. The topmost unfolded leaf from the terminal and the fourth mainstem leaf from the terminal were sampled at five growth stages from plants spaced 8 and 30 cm, within rows spaced at 102 cm. Genotypes included two commercial checks and four high‐tannin breeding lines developed in a spider mite resistance program. Condensed tannin concentration, expressed as a percentage of fresh weight, was determined spectrophotometrically following extraction with HC1‐butanol. The younger leaf tissue had significantly higher levels of condensed tannins than the more mature leaf tissue. Condensed tannin concentration increased with plant age through the first‐bloom growth stage. The condensed tannin concentration of plants sown on Planting Dates 1, 2, and 3 did not differ in 1988, but in 1989, plants from Planting Date 2 had higher condensed tannin concentrations than those from Planting Dates 1 or 3. Plant density did not significantly affect condensed tannin concentration. Many interactions of other factors with genotypes suggest that breeding for high tannin levels would require close attention to leaf age, growth stage, and environment.