ABSTRACT Diets excessive in crude protein (CP) are unfavourable in terms of metabolic and environmental load. Dietary phenols, often binding to dietary proteins, may alleviate these problems. In an experiment with 60 lambs (3.2 ± 1.6 months of age; 29.7 ± 5.1 kg body weight), kept in pairs, five diets were tested. A diet with 157 g CP/kg dry matter (DM) served as negative control. Four diets with on average 229 (225–233) g CP/kg DM remained either non-supplemented or were supplemented with 13 g/kg DM of Acacia mearnsii extract, grapeseed extract, or a combination of both (26 g extract/kg DM). The analysed concentrations of total extractable phenols were 7.1, 8.1, 14.3, 16.6 and 25.4 g/kg DM for low (CP‒) and high CP (CP+), and high CP with acacia (CP+A), grapeseed (CP+G) and acacia plus grapeseed (CP+AG), respectively. Diets were fed for 10 weeks, and for 6 d faeces and urine were collected and subsequently stored as complete manure for 8 weeks. In blood plasma, phenol concentrations and activities of enzymes indicating liver and kidney stress were analysed. The CP+ diet increased apparent digestibility of N and its removal with the urine, with the expected increase in gaseous N emissions from the manure (13.5 vs 6.5 g/lamb per day during 8 weeks) compared to CP‒. However, no clear signs of metabolic stress were detected. Supplementing the extracts did not impair intake, growth performance and digestibility. Only the supplementation with both extracts decreased urinary N proportion of manure N, and the concomitant weak decline in gaseous emission from the manure was not significant. At least part of the phenols of both extracts seem to be bioavailable as their supplementation elevated blood plasma phenol concentrations by 15% to 40% compared to CP+. A combination of both extracts did not result in a further increase. Further studies have to identify the minimally effective dosage for reducing N emissions, which, at the same time, does not cause adverse side effects in performance.

中文翻译：

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单独或联合补充金合欢和葡萄籽提取物是否能减轻喂食高粗蛋白饮食的羔羊的代谢氮负荷和粪便氮排放？

摘要 粗蛋白 (CP) 过多的饮食对代谢和环境负荷不利。膳食酚通常与膳食蛋白质结合，可以缓解这些问题。在 60 只羔羊（3.2 ± 1.6 个月大；体重 29.7 ± 5.1 kg）成对饲养的实验中，测试了五种饮食。含有 157 g CP/kg 干物质 (DM) 的饮食作为阴性对照。四种平均含 229 (225–233) g CP/kg DM 的日粮要么未添加，要么添加了 13 g/kg DM 的金合欢提取物、葡萄籽提取物或两者的组合（26 g 提取物/kg DM ）。低 (CP-) 和高 CP (CP+) 以及金合欢 (CP+A)、葡萄籽 (CP+G) 和高 CP 的总可提取酚的分析浓度为 7.1、8.1、14.3、16.6 和 25.4 g/kg DM ) 和金合欢加葡萄籽 (CP+AG)，分别。饮食被喂食了 10 周，收集粪便和尿液 6 天，然后作为完整的粪便储存 8 周。在血浆中，分析了苯酚浓度和指示肝脏和肾脏压力的酶的活性。CP+ 饮食增加了 N 的表观消化率及其随尿液的去除，与 CP- 相比，粪便中的气态 N 排放量预期增加（8 周内每天 13.5 对 6.5 克/羊）。然而，没有检测到明显的代谢压力迹象。补充提取物不会损害摄入量、生长性能和消化率。只有补充两种提取物才能降低粪便 N 中尿 N 的比例，同时粪便中气体排放的微弱下降不显着。两种提取物的至少部分酚类似乎是生物可利用的，因为与 CP+ 相比，它们的补充使血浆苯酚浓度提高了 15% 到 40%。两种提取物的组合不会导致进一步增加。进一步的研究必须确定减少氮排放的最低有效剂量，同时不会对性能产生不利的副作用。