Morphology,tannin concentration and forage value of 15 Swiss accessions of sainfoin (Onobrychis viciifolia Scop.) as influenced by harvest time and cultivation site

Fifteen accessions of sainfoin (Onobrychis viciifolia Scop.) were characterized for morphological and phenological traits at Reckenholz in the Swiss lowlands (Experiment 1). The effects of accession, harvest time and site on dry‐matter yield, condensed tannin (CT) concentration and forage value (Experiment 2) were determined at three sites in Switzerland varying in altitude from 440 to 559 m. Three to four harvests were taken in the first year after establishment (second year of stand) with harvests 1 and 2 chemically analysed. From the characterization in Experiment 1, a clear grouping of single flowering (Communis) and multiple flowering (Bifera) accessions emerged. Additionally, within the Communis accessions, distinct groupings were identified (historical landraces and newly collected ecotypes) based on morphological characteristics. Experiment 2 showed that Communis and Bifera accessions had a similar chemical composition in the first harvest. In the second harvest, Communis accessions were higher in crude protein and CT and lower in neutral and acid detergent fibre concentrations than Bifera accessions. Total dry‐matter yields were higher for Bifera accessions. Among the Communis accessions, ecotypes had consistently higher CT concentrations than landraces. In vitro organic matter digestibility did not significantly differ among accessions. There were clear effects of harvest time and site for most variables, with clear harvest time × sainfoin group interaction but no site × sainfoin group interactions. The results clearly demonstrate that historical landraces and newly collected ecotypes expand the range of available genetic variation for sainfoin breeding.     

Influence of harvesting site on chemical composition and potential protein value of Acacia erioloba,A. nilotica and Ziziphus mucronata leaves for ruminants

This study was designed to evaluate the chemical composition, buffer N solubility, in vitro ruminal N degradation and in vitro ruminal biological activity of condensed tannins in Acacia erioloba, Acacia nilotica and Ziziphus mucronata leaves harvested from two sites (Masuthle communal grazing land and Molelwane private farm). Leaves were harvested, dried at 60 °C and milled. The highest crude protein (CP) content was found in leaves of Z. mucronata (177.7 g/kg DM). Leaves harvested from Masuthle had higher (p < 0.05) soluble phenolics (SPh) (44.6 g TAE/kg DM) compared to those harvested from Molelwane (29.8 g TAE/kg DM). In both Molelwane and Masuthle, leaves of A. nilotica had higher levels of condensed tannins (CT) (0.76 AU_550/200 mg and 0.52 AU_550/200 mg respectively) followed by A. erioloba and Z. mucronata, which did not differ (p > 0.05). Nitrogen degradability at 24 h was the same (p > 0.05) for all tree species but not at 12 and 36 h. No linear association (p > 0.05) was found between buffer‐soluble N and in vitro ruminal N degradability in leaves with high SPh content. The largest polyethylene glycol (PEG) effect was in leaves of A. nilotica (448%) harvested from Masuthle after 36 h of incubation. Ziziphus mucronata leaves harvested from Molelwane had the least PEG effect at 48 h. There was no linear association (p > 0.05) between PEG effect and SPh for all incubation periods, but a positive relationship was observed between PEG effect and condensed tannins content. There was no linear association between solubility index (SI) and in vitro ruminal N degradability for tannin‐rich leaves. It was concluded that higher browsing pressure in Masuthle communal rangeland resulted in leaves with higher levels of condensed tannins, which had higher in vitro ruminal biological activity, compared to those harvested from Molelwane.     

氮素对羽叶决明缩合单宁及相关酶活性的影响

缩合单宁对牧草品质的影响极大,适量的缩合单宁含量对于提高牧草的利用率和营养品质非常重要。研究以豆科牧草羽叶决明Cassia nictitoms为材料,分析了氮素梯度处理后茎和叶中缩合单宁的含量及其生物合成酶二氢黄酮醇还原酶(DFR)活性的变化特征。结果表明,羽叶决明叶片的缩合单宁含量高于茎,随氮素的增加,叶片中缩合单宁含量从14.78%下降到1.14%;茎中从4.62%开始降低,达到0.98%后趋于稳定;DFR活性表现出与缩合单宁相似的变化规律,二者在叶和茎中都呈显著(P0.01)的二次曲线关系。植株粗蛋白含量测定发现,随氮素的增加粗蛋白含量无显著增加(P0.05)。因此,适当增加氮素的使用量可以达到减少缩合单宁含量,从而提高羽叶决明的利用率和营养品质。     

Use of Fura 2 Fluorescent Dyes as Indicator for Studying Calcium Distribution in Several Plant Tissues

Calcium (Ca) is an essential plant nutrient and is important in determining quality of fruits in storage. The analytical method presently known to determine Ca concentration in vegetables measures total Ca, and there is a need to develop methods that can determine the distribution of Ca within vegetable tissues. The objective of this study was to determine the ability of fluorescent probes to visualize Ca location and distribution in vegetable tissues. We examined three protocols using fluorescent dyes developed to detect Ca. The first tested Fura 2 acetoximetil (AM) probe in fresh cuts from grapes at different combinations of temperatures and incubation times. The second protocol was developed with the aim of lowering the natural autofluorescense. In the third protocol, the Fura 2 probe was used in tissues previously fixed in formalin, acetic acid, and alcohol solution (FAA). Tissues were observed under an epifluorescence microscope and, to compare and complement the observations, under a scanning electron microscope (SEM). No sign of fluorescence was observed in fixed and fresh tissue using the Fura 2 AM. In fresh cuts, there was autofluorescent interference, provoked mainly by chlorophyll, but also from the vascular system and tannins. The Fura 2 probe was introduced to vegetable tissues by utilizing a pH of 4.5, and a more intense signal was observed in tissues with greater Ca concentration. This signal was also associated with Ca crystals, which might have had some degree of hydrolysis at low pH. Under a SEM microscope, Ca oxalate crystals were clearly observed in those tissues. Our results show that Fura 2 probe can be used to detect Ca and its distribution in vegetable tissues.     

Effects of heat on the removal of polyphenols and in vitro protein digestibility of cowpea (Vigna unguiculata (L.) Walp.)

Simple wet heat treatments like simple boiling (atmospheric pressure, 100 °C) and pressurized boiling (higher than 100 °C) reduced the polyphenol content of mature dark red seeds of cowpea (Vigna unguiculata (L.) Walp.) cultivar UPL Cp 3 by 61 to 80% and improved in vitro protein digestibility (IVPD) by 6 to 26%. Pressurized steaming (higher than 100 °C) removed 48 to 83% of the polyphenols but increased IVPD by only 1.1 to 4.2%. Dry heat as exemplified by roasting and microwave treatment inactivated 58 to 71% of the tannins but increased IVPD by only 1%. All the heat treatments were effective in removing/inactivating polyphenols though different responses were observed with the resulting in vitro protein digestibilities.     

Effects of soaking in aqueous acidic and alkali solutions on removal of polyphenols and in vitro digestibility of cowpea

Mature dark red seeds of cowpea (Vigna unguiculata (L.) Walp.) UPL Cp 3, were subjected to several soaking treatments to remove their polyphenols. Soaking in water at room temperature for 8 and 24 h resulted in 17% and 21% loss of assayable polyphenols, respectively. Dilute solutions of alkali (Na₂CO₃, NaHCO₃, NH₄OH and KOH) and acid (CH₃ COOH, HCl and H₂ SO₄) were more effective in removing polyphenols up to 88% than higher concentrations of alkali and acid solutions.Vinegar (0.005–0.65 M CH₃ COOH) decreased polyphenols from 55 to 62% with a 6 to 14% improvement in in vitro protein digestibility (IVPD). Commercial lime (65% CaO) removed polyphenols from seeds soaked for 8 to 24 h by 70% with 2 to 10% increase in in vitro protein digestibility. Ash removed 40 to 60% of the polyphenols after 8 and 24 h of soaking with an increase in IVPD of 7 to 13%. Total polyphenols were significantly correlated (+0.92**) with protein precipitable polyphenols (condensed tannins).     

黑荆树皮单宁不同级分对水解酶的抑制作用

通过对黑荆树皮单宁进行醇沉纯化和溶剂萃取分级,可得到分子量分布范围不同的单宁级分。各级分对5种水解酶均表现出不同程度的抑制作用,具有一定的选择性。其抑制能力与抑制剂常数Ki值有关,分子量大的单宁级分,Ki值小,对酶活性的抑制作用大,同时,证明了黑荆树皮单宁对纤维素酶的抑制作用属于非竞争性抑制。     

喀斯特山区特征灌木 白刺花的青贮效果

为合理开发利用贵州喀斯特山区资源,促进其生态畜牧业可持续发展,以该区域特征灌木白刺花(Sophora davidii)为研究对象,开展单独青贮与添加剂青贮(乳酸菌、纤维素酶、乳酸菌+纤维素酶、甲酸、蔗糖和乳酸菌+纤维素酶+甲酸+蔗糖)研究,以探讨其可青贮性与最优青贮技术,为贵州岩溶山区粗饲料资源的开拓及贮存提供可借鉴的方法与技术支持。结果表明,白刺花青贮饲料感官品质较好,pH值(3.97～4.73)和氨态氮/总氮(3.76%～12.23%)较低,纤维和单宁总体下降,酸性洗涤纤维(30.70%～42.16%)、中性洗涤纤维(48.37%～61.84%)和单宁(0.63%～0.89%)较低,蛋白质下降幅度不大或略有上升,含量(16.83%～20.10%)较高,品质较好;添加剂处理可改善其感官品质,降低pH值、氨态氮/总氮(降幅8.26%～69.26%)与酸性洗涤纤维含量(降幅7.78%～27.18%),提高青贮品质;其中蔗糖(3% FM)处理感官品质最好,pH值(3.97)和氨态氮/总氮(5.67%)较低,蛋白质(19.89%)较高,青贮品质最好,是白刺花青贮的最适添加剂。     

Intake and Selection of Goats Grazing Heterogeneous Vegetation: Effect of Gastrointestinal Nematodes and Condensed Tannins

Feeding behavior is a multifactorial process with pivotal relevance for the maintenance and survival of ruminants. This study evaluated the effect of gastrointestinal nematodes (GIN), condensed tannin (CT) content of plants, and their possible interaction on the intake and selection of feed resources by Criollo goats in a heterogeneous vegetation. An 8-wk field experiment was conducted in the tropical deciduous forest (TDF) during the rainy season with adult Criollo goats (35.1 ± 6.7 kg body weight [BW]). Goats were assigned to four groups (n = 6): 1) MOX: suppressive treatment with moxidectin (Cydectin 0.4 mg/kg BW subcutaneous every 4 wk), 2) INF: with natural GIN infection, 3) MOX + PEG: treated with moxidectin and dosed with a CT-neutralizing agent (50 g of polyethylene glycol [PEG] diluted in 50 mL of water, per os), and 4) INF + PEG: with natural GIN infection and PEG dosage. Intake was measured using a direct observation method in a 2.2-ha TDF plot. Plant availability was obtained from 30 exclusion quadrants (2 × 2 m). Selection was estimated with the Cheeson index using the ratio of consumed plants and their availability by grouping plant species as shrubs and herbs (with high CT [> 10%], medium CT [> 3% to < 10%], or low CT [< 3%]), vines, and grasses. Neither GIN infection nor CT neutralization influenced intake or selection of feed resources. All groups showed high selection toward grass species (P < 0.001), which may represent a strategy to reduce intake of crude protein and CT from shrubs and herbs. In conclusion, GIN infection and CT neutralization do not influence intake or selection of goats with browsing experience in the TDF. Selection toward grass suggested a trade-off between nutrient harvest optimization and the health risk of GIN infective larvae consumption. Thus, it is necessary to revalorize the TDF as a sustainable feed resource for goats.     

Dose–response effect of a pine bark extract on in vitro ruminal ammonia and methane formation kinetics

ABSTRACT

This study assessed the potential of a pine bark extract (PBE) to decrease methane (CH₄) and ammonia nitrogen (NH₃-N) production in vitro. Dietary substrates, mixed hay, soybean meal and corn grain, were supplemented 0, 2, 4 and 6% of PBE and incubated in an in vitro batch culture for 24-h. Incubations were run three times. Total gas production (GP) was determined at 6, 12 and 24-h and gas samples were analysed for CH₄. Samples were collected for volatile fatty acids (VFA) and NH₃-N analysis. Treatments were compared by polynomial contrasts for PBE concentration. Increasing PBE caused linear decreases in NH₃-N, microbial biomass production and digestibility, whereas the degradation rate was quadratically reduced. Total VFA were decreased but total GP and CH₄ production and kinetics were unaffected. The inclusion of 2% PBE in ruminant feed has the capability to reduce NH₃-N concentration by 50%, without affecting diet digestibility or CH₄ production.