蛋氨酸羟基异丙酯对母犊牛瘤胃发酵和微生物区系的影响

doi:10.3864/j.issn.0578-1752.2022.04.014

摘要/Abstract

摘要：

【目的】蛋氨酸羟基异丙酯（HMBi）作为饲料添加剂广泛用于补充反刍动物日粮中缺乏的蛋氨酸（Met）,尽管HMBi拥有过瘤胃特性,但仍有部分在瘤胃中降解。研究拟探究HMBi对犊牛瘤胃发酵和微生物区系的影响。【方法】选取36头体重在（101±10）kg的84日龄断奶后荷斯坦母犊牛并随机分为两个处理组,分别为对照组（PC,0.40%Met）和蛋氨酸扣除组（PCMet,0.28%Met）,通过减少PCMet组日粮中HMBi的添加使Met含量较PC组少30%。试验期97 d,其中预饲期7 d,正式试验期90 d。于试验0、90 d测定犊牛体重,正试期每天记录采食量,在试验90 d收集血清样品和瘤胃液样品用于发酵参数和微生物区系的测定。【结果】（1）与PC组相比,PCMet组犊牛生长性能无显著差异（P>0.05）,血清Met含量有降低的趋势（0.05<P<0.10）;（2）PCMet组瘤胃乙酸摩尔百分比和微生物蛋白浓度与PC组相比显著降低（P<0.05）,但两组间氨态氮和总挥发性脂肪酸浓度无显著差异（P>0.05）;（3）与PC组相比,PCMet组微生物菌群的Shannon指数显著降低（P<0.05）,PCoA和PREANOVA分析显示两组间显著分离（P<0.05）。PCMet组的后壁菌门（Firmicutes）相对丰度显著降低（P<0.05）,而拟杆菌门（Bacteroidetes）相对丰度显著升高（P<0.05）。属水平上,PCMet组莱克氏菌属（Olsenella）、瘤胃球菌属（[Ruminococcus] gauvreauii group）、聚乙酸菌属（Acetitomaculum）、真杆菌属（[Eubacterium] nodatum group）和粪球菌属（Coprococcus 1）的相对丰度显著降低。相关性分析揭示聚乙酸菌属和真杆菌属与乙酸摩尔百分比之间呈正相关关系,瘤胃球菌属与微生物蛋白浓度间呈正相关关系（P<0.05,r>0.7）。【结论】研究说明扣除日粮中HMBi后犊牛瘤胃微生物多样性降低,微生物蛋白合成减少,其中,产乙酸菌属对HMBi扣除敏感,降低了乙酸的产生。总之,HMBi尽管作为过瘤胃产品,瘤胃中被降解部分仍对瘤胃发酵有调控作用。

关键词: 蛋氨酸羟基异丙酯, 母犊牛, 微生物区系, 瘤胃发酵参数

Abstract:

【Objective】2-Hydroxy-4-(Methylthio)-Butanoic Acid (HMBi) is widely used to satisfy the absent of methionine (Met) in ruminal diet. Although the characteristic of HMBi is a rumen protected product, there is still an amount of HMBi degraded in rumen, which should be taken seriously. Hence, this study was conducted to evaluate the effects of HMBi on rumen fermentation and microbiota. 【Method】The experiment was conducted for 97 days with 36 Holstein female calves aged about 84 day-old with (101±10) kg body weight, and those calves were allocated to 2 groups, including PC group (0.40% Met) and PCMet group (0.28% Met). The treatment was achieved by deducting HMBi in diet of PCMet group and made Met level 30% lower than that of PC group. The first 7 d were an adaptation to the diets and the next 90 d for sampling. The body weight was measured at 0 d and 90 d, respectivley. The dry matter intake was recorded daily throughout the whole trial period. The serum and rumen fluid samples from five calves in each group were sampled on day 90 to determine rumen fermentation parameters and microbial communities. 【Result】(1) Compared with PC group, the growth performance of PCMet group was not changed (P>0.05). The Met in serum of PCMet group had trend to be significantly decreased when compared with PC group (0.05<P<0.1); (2) The molar proportion of acetate and microprotein concentration in PCMet group was significantly decreased by Met deduction (P<0.05). There were no significant differences on concentrations of total volatile fatty acid and ammonia nitrogen between two groups (P>0.05). (3) The Shannon index of microbiota in PCMet group was lower than that in PC group (P<0.05). The PCoA and PREANOVA analysis showed the significant distinction between microbiota in two groups (P<0.05). Furthermore, the relative abundance of Firmicutes in PCMet group was decreased and the relative abundance of Bacteroidetes was increased when compared with PC group (P<0.05). At genus level, the relative abundance of Olsenella, [Ruminococcus] gauvreauii group, Acetitomaculum, [Eubacterium] nodatum group, and Coprococcus 1 were decreased in PCMet group (P<0.05). The correlation analysis showed that [Eubacterium] nodatum group and Acetitomaculum were significantly correlated with acetate and [Ruminococcus] gauvreauii group was significantly correlated with MCP (P<0.05, r>0.7). 【Conclusion】 The ruminal microbiota was inhibited by HMBi deduction, which led to the decrease of MCP and Shannon index. Among them, the acetogen was sensitive with HMBi. In conclusion, although HMBi was a rumen protected product, the part of HMBi degraded in rumen still had the ability to regulate rumen fermentation.

Key words: HMBi, female calves, microbiota, rumen fermentation parameters

孔凡林,李媛,付彤,刁其玉,屠焰. 蛋氨酸羟基异丙酯对母犊牛瘤胃发酵和微生物区系的影响[J]. 中国农业科学, 2022, 55(4): 796-806.

KONG FanLin,LI Yuan,FU Tong,DIAO QiYu,TU Yan. Effects of 2-Hydroxy-4-(Methylthio)-Butanoic Acid on Rumen Fermentation and Microbiota in Holstein Female Calves[J]. Scientia Agricultura Sinica, 2022, 55(4): 796-806.

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日粮组成 Ingredient	含量Content (%)	营养成分Nutrient²⁾	营养水平Nutrient level
玉米 Corn	45.67	干物质 DM （风干物质基础 Air-dry basis）	90.53
苜蓿 Alfalfa	25.00	干物质 DM （风干物质基础 Air-dry basis）	90.53
小麦麸 Wheat bran	15.00	总能 GE（Mcal·kg^-1）	16.76
大豆粕 Soybean meal	11.97	代谢能 ME（Mcal·kg^-1）	12.71
细石粉 CaCO₃	1.06	有机物 OM	93.32
预混料1% Premix¹⁾	1.00	粗蛋白质 CP	19.22
食盐 NaCl	0.30	粗脂肪 EE	4.56
合计 Total	100.00	中性洗涤纤维 NDF	20.08
		酸性洗涤纤维 ADF	11.43
		钙 Ca	1.07
		磷 P	0.49
		赖氨酸 Lys	0.73
		蛋氨酸 Met	0.11
		苏氨酸 Thr	0.41

项目 Item	组别 Group
项目 Item	PC	PCMet
基础日粮蛋氨酸 Met in basal diet	0.11	0.11
基础日粮赖氨酸 Lys in basal diet	0.73	0.73
过瘤胃蛋氨酸添加量 Addition of HMBi¹⁾	1.32	0.77
过瘤胃赖氨酸添加量 Addition of rumen protected Lys²⁾	1.68	1.68
日粮蛋氨酸水平 Met level in test diet	0.40	0.28
日粮赖氨酸水平 Lys level in test diet	1.21	1.21

项目 Item	组别 Group		SEM	P值 P value
项目 Item	PC	PCMet	SEM	P值 P value
初始体重 Initial BW (kg)	101.75	101.25	1.790	0.89
结束体重 Final BW (kg)	180.62	176.92	2.207	0.41
日增重 ADG (g·d^-1)	876.31	840.78	18.109	0.34
干物质采食量 DMI (kg·d^-1)	3.20	3.25	0.029	0.42
饲料转化比 Feed effeiciency, gain/feed	0.28	0.26	0.007	0.21
血清蛋氨酸 Serum Met (μg·mL^-1)	4.19	3.44	0.212	0.07

KEGG 通路 KEGG Pathway	组别 Group		SEM	P值 P value
KEGG 通路 KEGG Pathway	PC	PCMet	SEM	P值 P value
前5通路 Top 5 pathway
转运蛋白 Transporters	7.01	5.96	0.277	0.06
一般功能基因 General function prediction only	3.63	3.60	0.035	0.76
ABC转运蛋白 ABC transporters	3.42	2.94	0.136	0.08
DNA修复和重组蛋白DNA repair and recombination proteins	2.89	2.99	0.043	0.28
核糖体 Ribosome	2.50	2.56	0.040	0.46
蛋氨酸代谢相关通路 Methionine metabolism pathway
氨酰-tRNA生物合成 Aminoacyl-tRNA biosynthesis	1.27	1.26	0.013	0.63
半胱氨酸和蛋氨酸代谢 Cysteine and methionine metabolism	0.97	0.99	0.011	0.37
甘氨酸、丝氨酸和苏氨酸代谢Glycine, serine and threonine metabolism	0.82	0.87	0.015	0.08
氮代谢 Nitrogen metabolism	0.66	0.69	0.008	0.13
谷胱甘肽代谢 Glutathione metabolism	0.18	0.20	0.008	0.28
牛磺酸和亚牛磺酸代谢 Taurine and hypotaurine metabolism	0.10	0.11	0.004	0.78