饲料中抗营养因子--单宁的含量分析方法

针对近年来单宁在动物营养上的最新研究成果,本文重点阐述了饲料中缩合单宁、可水解单宁和总酚类化合物的分析方法。旨在为更好地利用含单宁饲料提供参考。     

Effect of wilting,silage additive,PEG treatment and tannin content on the distribution of N between different fractions after ensiling of three different sainfoin (Onobrychis viciifolia) varieties

Sainfoin (Onobrychis viciifolia) is a tanniniferous, leguminous plant that has potentially beneficial effects on protein utilization in ruminants. As ensiling causes protein breakdown and elevated levels of buffer soluble N (BSN), we studied the distribution of N before and after ensiling sainfoin. Three varieties of sainfoin were either direct‐cut and frozen directly or wilted and frozen before later ensiling in mini‐silos with and without acidification with Promyr (PM; an acidifying commercial mixture of propionic and formic acid) and with or without polyethylene glycol (PEG). Extractable tannins (ET) and protein‐bound tannins (PBT) were measured with an HCl/butanol method in an attempt to correlate tannin levels to N fractions. The sainfoin silages showed good ensiling characteristics and had relatively high concentrations of undegraded protein. The effect of wilting on BSN levels (g/kg N) was dependent on sainfoin variety (P < 0·001). PEG increased and PM decreased the level of BSN in the silages (P < 0·001). PM treatment also produced less non‐protein N and ammonia‐N (P < 0·05) as compared with no additive. Addition of PEG to the silage increased the BSN‐proportion 1·8‐ and 2·6‐fold for both DM stages. A strong tannin‐protein binding effect is, therefore, confirmed in sainfoin. However, correlations between tannin levels (ET and PBT) and BSN were poor in the (non‐PEG) silages, indicating either that the HCl/butanol method is unsuitable for measuring tannin in silages or that qualitative attributes of tannins are more relevant than quantitative. The HCl/butanol method seems therefore not to be useful to predict degradation of protein in sainfoin silages.     

单宁酸对猪卵母细胞体外成熟及胚胎发育能力的影响

研究旨在探讨单宁酸对猪卵母细胞体外成熟质量及其胚胎发育能力的影响。在猪卵丘卵母细胞复合体（COCs）体外成熟培养液中添加不同浓度（0、1、10、100 μg/mL）单宁酸培养42 h后,检测COCs的扩散程度和卵丘细胞扩散指数,统计COCs的体外成熟率,检测成熟卵母细胞内谷胱甘肽（glutathione,GSH）、活性氧（reactive oxygen species,ROS）和生长分化因子9（growth differentiation factor 9,GDF9）的水平,并统计孤雌激活及体外受精胚胎48和168 h的卵裂率、囊胚率及囊胚总细胞数。结果显示,与对照组相比,10 μg/mL单宁酸组卵丘细胞扩散指数显著提高（P<0.05）,100 μg/mL单宁酸组显著降低（P<0.05）;1和10 μg/mL单宁酸组卵母细胞成熟率差异不显著（P>0.05）,100 μg/mL单宁酸组卵母细胞成熟率显著降低（P<0.05）;1和10 μg/mL单宁酸组GSH和GDF9水平显著提高（P<0.05）,ROS水平显著降低（P<0.05）。孤雌胚胎和体外受精胚胎发育能力结果显示,与对照组相比,各单宁酸组卵裂率差异不显著（P>0.05）,10 μg/mL单宁酸组孤雌胚胎囊胚率及体外受精胚胎囊胚率显著提高（P<0.05）,100 μg/mL单宁酸组孤雌胚胎囊胚细胞数及体外受精胚胎囊胚细胞数均显著低于其他各组（P<0.05）。以上结果表明,10 μg/mL单宁酸可通过提高卵丘细胞扩散能力及GSH和GDF9水平、降低卵母细胞内ROS水平,改善猪卵母细胞成熟质量,提高孤雌胚胎及体外受精胚胎的发育能力。     

Impact of variation in structure of condensed tannins from sainfoin (Onobrychis viciifolia) on in vitro ruminal methane production and fermentation characteristics

Our study investigated the effects of condensed tannins (CT) on rumen in vitro methane (CH₄) production and fermentation characteristics by incubating lucerne in buffered rumen fluid in combination with different CT extracts at 0 (control), 40, 80 and 120 g CT/kg of substrate DM. Condensed tannins were extracted from four sainfoin accessions: Rees ‘A’, CPI63763, Cotswold Common and CPI63767. Gas production (GP) was measured using a fully automated GP apparatus with CH₄ measured at distinct time points. Condensed tannins differed substantially in terms of polymer size and varied from 13 (Rees ‘A’) to 73 (CPI63767) mean degree of polymerization, but had relatively similar characteristics in terms of CT content, procyanidin: prodelphinidin (PC: PD) and cis:trans ratios. Compared to control, addition of CT from CPI63767 and CPI63763 at 80 and 120 g CT/kg of substrate DM reduced CH₄ by 43% and 65%, and by 23% and 57%, respectively, after 24‐h incubation. Similarly, CT from Rees ‘A’ and Cotswold Common reduced CH₄ by 26% and 46%, and by 28% and 46% respectively. Addition of increasing level of CT linearly reduced the maximum rates of GP and CH₄ production, and the estimated in vitro organic matter digestibility. There was a negative linear and quadratic (p < 0.01) relation between CT concentration and total volatile fatty acid (VFA) production. Inclusion of 80 and 120 g CT/kg of substrate DM reduced (p < 0.001) branched‐chain VFA production and acetate: propionate ratio and was lowest for CPI63767. A decrease in proteolytic activity as indirectly shown by a change in VFA composition favouring a shift towards propionate and reduction in branched‐chain VFA production varied with type of CT and was highest for CPI63767. In conclusion, these results suggest that tannin polymer size is an important factor affecting in vitro CH₄ production which may be linked to the CT interaction with dietary substrate or microbial cells.     

高粱在畜禽日粮中的应用研究

高粱的抗旱性强，比玉米的生长环境条件更宽广。随着玉米、小麦等能量原料价格的高涨，为了降低成本，提高产品竞争力，很多大型饲料企业开始从国外进口高粱。然而，由于高粱中含有丹宁，与玉米相比，用高梁作为饲料原料降低了非反刍动物对能量和其它养分的消化利用率。文章就目前高粱在非反刍动物营养中的研究应用进行了总结。     

Effects of High-tannin Sorghum and Bentonite on the Performance of Laying Hens

The effects of feeding high-tannin sorghum (HTS) (5% catechin equivalents (CE)) on the performance of laying hens were examined in two experiments. In experiment 1, the effects of including varying levels of HTS in layer diets were investigated. Sixty-three Isabrown hens were randomly assigned to each of the seven diets over a period of 56 days. In experiment 2, the effects of bentonite on the utilization of HTS (3.74% CE) by laying hens were investigated. Forty-five Isabrown hens were randomly assigned to each of five diets over a period of 42 days. In both experiments, weekly measurements were made for feed intake (FI), percent hen-house production (% HHP), egg weight and egg specific gravity (ESG). The results of experiment 1 showed that the different sorghum inclusion levels had no effect (p>0.05) on HHP, egg weight and ESG, while those of experiment 2 showed that maize and LTS diets gave similar weight gain, FI and FE (p>0.05). However, HHP was higher (p<0.05) for the LTS diet than for the other diets. The addition of bentonite of 0.25% or 0.5% to the HTS diet did not improve (p>0.05) layer performance. When all the results were considered together, it was concluded that HTS can be used in layer diets without adverse effects on performance. The use of bentonite to deactivate sorghum tannins is not considered necessary.     

Growth and Apparent Absorption of Minerals in Broiler Chicks Fed Diets with Low or High Tannin Contents

Sorghum grains with low (0.28 per cent catechin equivalent (%CE) or high (1.36 %CE)) tannin contents were used to study the effect of tannin on growth and on the apparent absorption of Ca, P, Mg, Na, K, Fe and Co by chickens. High-tannin sorghum caused a highly significant (p0.01) reduction in the weight gain and feed intake of broiler chicks compared to low-tannin sorghum and increased the feed conversion ratio (p0.01). The amount of tannin did not affect mortality. The apparent absorption of Ca, P, Mg, Na, K, Fe and Co was reduced (p0.01) by feeding sorghum grains with a high tannin content.     

甘肃天祝高寒地区5种灌木中酚类物质含量的研究

对甘肃天祝金强河高寒地区5种灌木中的酚类物质含量进行了测定和比较分析。结果表明,不同的灌木品种其酚类物质的含量不同。藏沙棘总酚,单宁和缩合单宁的干物质含量均高于其他灌木,分别高达69.67,63.34和42.45 g/kg,而其简单酚的干物质含量最低,仅为4.27 g/kg。窄叶鲜卑木的酚类物质含量较低,与其他灌木相比差异极显著(P<0.01)。相关性分析表明,单宁和简单酚含量呈显著的正相关关系(r=0.94,P<0.01),与缩合单宁的相关系数为r=0.82(P<0.05),而简单酚与缩合单宁含量呈不显著的负相关关系。     

单宁对反刍动物养分利用的营养机制

植物饲料中适量的单宁含量对反刍动物养分利用有其积极作用。本文从分析单宁的理化性质入手,详细综述了植物饲料中单宁的营养作用机制、抗营养作用、去除措施以及研究展望,以期为有效利用含单宁的植物饲料提供理论参考。