研究论文

裂壶藻粉对阿尔巴斯白绒山羊体外瘤胃发酵特性和脂肪酸组成的影响

  • 刘锦涛 ,
  • 玛克塔拉 ,
  • 陈玉亮 ,
  • 赵雨薇 ,
  • 赵艳丽 ,
  • 郭晓宇 ,
  • 郭咏梅 ,
  • 张清月 ,
  • 闫素梅 , *
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  • 内蒙古农业大学动物科学学院,内蒙古自治区高校动物营养与饲料科学重点实验室,呼和浩特 010018
* 闫素梅,教授,博士生导师,E-mail:

刘锦涛(1996—),男,内蒙古呼和浩特人,博士研究生,从事动物营养与饲料领域研究。E-mail:

Office editor: 陈燕

收稿日期: 2025-07-22

  网络出版日期: 2026-02-12

基金资助

内蒙古自治区自然科学基金重点项目(2024ZD16)

内蒙古自治区直属高校基本科研业务(BR251030)

Effects of Schizochytrium Powder on in Vitro Rumen Fermentation Characteristics and Fatty Acid Composition in Albas White Cashmere Goats

  • LIU Jintao ,
  • MAKETALA ,
  • CHEN Yuliang ,
  • ZHAO Yuwei ,
  • ZHAO Yanli ,
  • GUO Xiaoyu ,
  • GUO Yongmei ,
  • ZHANG Qingyue ,
  • YAN Sumei , *
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  • Key Laboratory of Animal Nutrition and Feed Science at Universities of Inner Mongolia Autonomous Region, College of Animal Science, Inner Mongolia Agricultural University, Hohhot 010018, China
* professor, E-mail:

Received date: 2025-07-22

  Online published: 2026-02-12

摘要

本试验旨在探究发酵底物中添加不同水平裂壶藻粉对阿尔巴斯白绒山羊体外瘤胃发酵特性和脂肪酸(FA)组成的影响。选择阿尔巴斯白绒山羊羯羊作为瘤胃液供体进行体外瘤胃发酵试验,采用单因素完全随机试验设计,根据发酵底物中裂壶藻粉的添加水平将试验分为对照组(无添加,CON组)、0.5%添加组(SCM1组)、1.0%添加组(SCM2组)、1.5%添加组(SCM3组)和2.0%添加组(SCM4组)5个组,每组设8个重复,每重复1个发酵瓶,体外培养24 h后测定各项指标。结果表明:1)与CON组相比,SCM3组和SCM4组体外瘤胃发酵液pH和氨态氮(NH3-N)浓度显著降低(P<0.05),菌体蛋白(BCP)浓度显著升高(P<0.05);SCM4组原虫数量显著降低(P<0.05)。2)与CON组相比,SCM3组和SCM4组体外瘤胃发酵液中乙丙比显著降低(P<0.05),丙酸、异丁酸、异戊酸和总挥发性脂肪酸(TVFA)浓度显著升高(P<0.05)。3)与CON组相比,SCM2组、SCM3组和SCM4组C20∶3n3、C20∶5n3、C22∶6n3(DHA)、不饱和脂肪酸(UFA)、单不饱和脂肪酸(MUFA)浓度和不饱和脂肪酸/饱和脂肪酸(U/S)显著升高(P<0.05),C16∶0浓度和n-6多不饱和脂肪酸/n-3多不饱和脂肪酸(n-6 PUFA/n-3 PUFA)显著降低(P<0.05);SCM3组和SCM4组C18∶3n3浓度显著升高(P<0.05),C18∶0和C24∶0浓度显著降低(P<0.05);SCM4组C18∶2n6c、C18∶3n6和多不饱和脂肪酸(PUFA)浓度显著升高(P<0.05);SCM3组C18∶1n9t和C18∶1n9c浓度显著升高(P<0.05)。4)发酵底物中添加不同水平裂壶藻粉均能提高多项组合效应指数(MFAEI),尤以SCM3组值最高,其次依次为SCM4组、SCM2组、SCM1组和CON组。综上所述,发酵底物中添加1.5%~2.0%的裂壶藻粉可以促进绒山羊体外瘤胃发酵,优化体外瘤胃发酵液的FA组成,提高C18∶3n3、C20∶5n3和DHA等n-3 PUFA浓度,降低C16∶0、C18∶0等饱和脂肪酸(SFA)浓度和n-6 PUFA/n-3 PUFA。

本文引用格式

刘锦涛 , 玛克塔拉 , 陈玉亮 , 赵雨薇 , 赵艳丽 , 郭晓宇 , 郭咏梅 , 张清月 , 闫素梅 . 裂壶藻粉对阿尔巴斯白绒山羊体外瘤胃发酵特性和脂肪酸组成的影响[J]. 动物营养学报, 2026 , 38(2) : 1459 -1468 . DOI: 10.12418/CJAN2026.115

Abstract

This experiment was conducted to investigate the effects of fermentation substrate supplemented with different levels of Schizochytrium powder on the in vitro rumen fermentation characteristics and fatty acid (FA) composition in Albas white cashmere goats. Using rumen fluid from Albas white cashmere castrated male goats as donors, a single-factor completely randomized design was adopted. The experiment was divided into 5 groups based on the supplemental level of Schizochytrium powder in the fermentation substrate: control group (no addition, CON group), 0.5% supplemental group (SCM1 group), 1.0% supplemental group (SCM2 group), 1.5% supplemental group (SCM3 group) and 2.0% supplemental group (SCM4 group). There were 8 replicates per group, with one fermentation bottle per replicate. Various parameters were measured after 24 h of in vitro incubation. The results showed that: 1) compared with CON group, the SCM3 and SCM4 groups exhibited significantly lower pH and ammonia nitrogen (NH3-N) concentration (P<0.05) of rumen fermentation broth, while the bacterial crude protein (BCP) concentration was significantly increased (P<0.05). The protozoal number was significantly reduced in the SCM4 group (P<0.05). 2) Compared with CON group, SCM3 and SCM4 groups showed a significantly decreased acetate-to-propionate ratio (P<0.05), and significantly increased concentrations of propionate, isobutyrate, isovalerate, and total volatile fatty acids (TVFA) (P<0.05). 3) Compared with CON group, concentrations of C20∶3n-3, C20∶5n-3, C22∶6n-3 (DHA), unsaturated fatty acids (UFA), monounsaturated fatty acids (MUFA) and UFA to saturated fatty acids (SFA) ratio (U/S) were significantly increased (P<0.05), while the C16∶0 concentration and the n-6/n-3 long-chain polyunsaturated fatty acid ratio (n-6 PUFA/n-3 PUFA) were significantly decreased (P<0.05) in SCM2, SCM3 and SCM4 groups compared to the CON group. Compared with CON group, the SCM3 and SCM4 groups had a significantly higher C18∶3n-3 concentration (P<0.05) and significantly lower C18∶0 and C24∶0 concentrations (P<0.05). Compared with CON group, the SCM4 group demonstrated significantly increased concentrations of C18∶2n-6c, C18∶3n-6 and polyunsaturated fatty acids (PUFA) (P<0.05). Compared with CON group, the concentrations of C18∶1n-9t and C18∶1n-9c were significantly elevated in SCM3 group (P<0.05). 4) The fermentation substrate supplemented with different levels of Schizochytrium powder improved the multiple-factors associative effects index (MFAEI), with the highest value observed in SCM3 group, followed by SCM4, SCM2, SCM1 and CON groups. In conclusion, supplemented with 1.5% to 2.0% Schizochytrium powder in the fermentation substrate can enhance in vitro rumen fermentation, optimize the FA composition in vitro of rumen fermentation broth, increase the concentrations of n-3 PUFAs such as C18∶3n-3, C20∶5n-3 and DHA, and reduce the concentrations of SFAs like C16∶0 and C18∶0, as well as n-6 PUFA/n-3 PUFA.

阿尔巴斯白绒山羊作为优秀的绒肉兼用品种,在我国西部和北部地区广泛分布,其肉质鲜美,营养价值高,在高端羊肉市场广受青睐[1]。由于天然牧草中营养的季节性不平衡及草场生态环境恶化等因素,舍饲育肥已然成为绒山羊主要的育肥方式之一[2]。羊肉的脂肪酸(fatty acid,FA)组成会影响其感官特性和健康价值。而多不饱和脂肪酸(polyunsaturated fatty acid,PUFA)在人类膳食中的重要性日益凸显,n-3多不饱和脂肪酸(n-3 PUFA)是人体必需脂肪酸,可防治心血管疾病、促进大脑发育[3]。C22∶6n3(docosahexaenoic acid,DHA)是n-3 PUFA家族重要成员,对胎儿神经和视觉发育、免疫调节至关重要[4]。课题组前期研究表明,与放牧绒山羊相比,舍饲羊肉中α亚麻酸、DHA、n-3 PUFA浓度明显减少,羊肉营养价值下降[1]。营养干预是改善羊肉FA组成,生产健康、高品质羊肉的主要措施之一。国内外研究发现,在动物饲粮中添加n-3 PUFA能够调控反刍动物瘤胃发酵模式和瘤胃液FA组成,进而促进DHA等n-3 PUFA在畜产品中沉积[5]。人体获得DHA最主要的方式是通过摄食海鲜或服用鱼油和藻油,但在许多国家海鲜并不属常规食物[6];且据联合国粮食及农业组织(FAO)统计,由于过度捕捞和全球气候变暖,导致富含DHA的深海鱼类数量下降,未来几十年全球10%~19%的人口可能面临DHA摄入量不足的问题[7]。因此,通过拓宽DHA来源来弥合人类未来的供需缺口已经迫在眉睫。裂壶藻(Schizochytrium)是一种海洋藻类,是植物性食物中含有DHA的较好来源之一。研究表明,裂壶藻粉对反刍动物瘤胃菌群结构、营养物质消化、瘤胃液及畜产品FA组成均有较好的改善效果[8-9]。Lv等[8]研究表明,海洋藻类降低了山羊瘤胃液中C18不饱和脂肪酸(unsaturated fatty acid,UFA)的生物氢化(biohydrogenation,BH),增加了c9t11-共轭亚油酸(cis-9,trans-11 conjugated linoleic acid,c9t11-CLA)比例,抑制了瘤胃氢化菌活性,降低氨态氮(NH3-N)和乙酸浓度。Pajor等[9]研究发现,在高山奶山羊饲粮中补充5 g裂壶藻,可显著提高瘤胃液中c9t11-CLA和羊奶中DHA浓度,降低n-6 PUFA/n-3 PUFA。目前利用裂壶藻粉调控反刍动物瘤胃发酵及瘤胃液中FA组成的研究多集中在乳畜上,鲜有关于肉羊的报道。鉴于此,本试验通过体外瘤胃发酵技术,探究饲粮中添加不同水平裂壶藻粉对绒山羊体外瘤胃发酵特性和FA组成的影响,筛选适宜的裂壶藻粉添加水平,为在集约化肉羊生产中合理使用裂壶藻粉调控绒山羊生产性能和羊肉营养价值提供理论依据,也为人类寻找更加广泛、健康的DHA饮食提供新视角。

1 材料与方法

1.1 试验材料

本试验所用的裂壶藻粉营养成分如下:粗蛋白质(CP)含量为25.8%,粗脂肪(EE)含量为36.8%,水分含量为2.7%,DHA含量为15.5%。

1.2 试验设计与发酵底物组成

本试验获得内蒙古农业大学实验动物福利与伦理委员会的许可(NND2023122)。选取3只体况相近、体重为(45±1) kg的健康阿尔巴斯白绒山羊羯羊为瘤胃液供体,通过口腔采集瘤胃液。采用单因素完全随机试验设计,根据发酵底物中裂壶藻粉的添加水平将试验分为对照组(无添加,CON组)、0.5%添加组(SCM1组)、1.0%添加组(SCM2组)、1.5%添加组(SCM3组)和2.0%添加组(SCM4组)5个组,每组设8个重复,每重复1个发酵瓶,进行体外瘤胃发酵试验。参考《肉羊营养需要量》(NY/T 816—2021)中体重为45 kg的肉用山羊营养需要量,基于等能等氮原则配制发酵底物,精粗比为5∶5,发酵底物组成及营养水平见表1
表1 发酵底物组成及营养水平(风干基础)

Table 1 Composition and nutrient levels of fermentation substrates (air-dry basis) %

项目
Items
CON组
CON group
SCM1组
SCM1 group
SCM2组
SCM2 group
SCM3组
SCM3 group
SCM4组
SCM4 group
原料Ingredients
苜蓿干草Alfalfa hay 15 15 15 15 15
玉米秸秆Corn stover 35 35 35 35 35
玉米Corn 18.87 19.05 19.3 19.4 19.02
大豆粕Soybean meal 8.7 8.9 8.92 8.5 8.78
麸皮Bran 8 8.5 8.27 5.3 4.6
玉米胚芽粕Corn germ meal 7.6 7.06 7.15 9.9 11.8
玉米干酒糟及其可溶物Corn DDGS 3.5 2.8 2.3 2.4 0.8
大豆油Soybean oil 0.33 0.19 0.06 0 0
裂壶藻粉Schizochytrium powder 0.5 1 1.5 2
石粉Limestone 0.6 0.6 0.6 0.6 0.6
磷酸氢钙CaHPO4 1.1 1.1 1.1 1.1 1.1
食盐NaCl 0.3 0.3 0.3 0.3 0.3
预混料Premix1) 0.5 0.5 0.5 0.5 0.5
小苏打NaHCO3 0.5 0.5 0.5 0.5 0.5
合计Total 100 100 100 100 100
营养水平Nutrient levels2)
代谢能ME/(MJ/kg) 9.25 9.27 9.21 9.26 9.31
粗蛋白质CP 13.38 13.14 13.24 13.39 12.83
粗脂肪EE 3.27 3.09 3.14 3.07 2.97
中性洗涤纤维NDF 32.65 32.84 33.01 32.83 31.94
酸性洗涤纤维ADF 22.44 21.7 22.46 21.65 22.73
钙Ca 0.8 0.8 0.8 0.79 0.79
磷P 0.47 0.47 0.46 0.44 0.43

1)预混料为每千克发酵底物提供 Premix provided the following per kg of fermentation substrates:VA 5 000 IU,VD3 800 IU,VE 9 mg,烟酰胺 nicotinamide 7.1 mg,Fe 50 mg,Cu 5 mg,Zn 45 mg,Mn 40 mg,I 1 mg,Se 0.2 mg,Co 0.4 mg。

2)代谢能参考NY/T 816—2021计算,其余均为实测值。ME was calculated with reference to NY/T 816—2021, while the others were measured values.

1.3 体外瘤胃发酵

参考Menke等[10]的方法配制缓冲液,将采集好的瘤胃液经4层纱布过滤,与缓冲液按1∶2的比例混合后,按照60 mL的培养液体系,分别加入提前盛有1.00 g不同发酵底物的100 mL玻璃培养瓶中,发酵环境温度为39 ℃,全程持续通入二氧化碳(CO2)。用胶塞将发酵瓶密封后,与全自动产气记录仪(ANKOM AGRS,ANKOM科技公司,美国)孔道气针连接,发酵24 h后,迅速冰浴停止发酵,将发酵液取样,待测瘤胃发酵特性指标和FA组成。

1.4 测定指标与方法

1.4.1 常规营养成分测定

分别参考《饲料中粗蛋白的测定 凯氏定氮法》(GB/T 6432—2018)、《饲料中粗脂肪的测定》(GB/T 6433—2006)、《饲料中钙的测定》(GB/T 6436—2018)和《饲料中总磷的测定 分光光度法》(GB/T 6437—2018)测定发酵底物中的粗蛋白质、粗脂肪、钙和磷含量;然后参照Van Soest等[11]的方法,使用纤维分析仪(200i,ANKOM科技公司,美国)测定发酵底物中的中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)含量。

1.4.2 瘤胃发酵参数测定

发酵液pH通过手持便携式pH计(CT-6022,深圳市柯迪达电子有限公司)测定;总产气量通过全自动产气记录仪测定24 h内的实时产气量得到;菌体蛋白(bacterial crude protein,BCP)浓度的测定采用考马斯亮兰法[12];原虫数量参考王加启[13]的方法计数;NH3-N浓度的测定采用比色法[14]

1.4.3 发酵液中挥发性脂肪酸(VFA)浓度测定

VFA浓度的测定采用气相色谱法[15],通过使用气相色谱仪(岛津GC-2014,株式会社岛津制作所,日本)测定,以二乙基丁酸作为内标,测定乙酸、丙酸、异丁酸、丁酸、异戊酸和戊酸浓度,计算乙丙比和总挥发性脂肪酸(total volatile fatty acid,TVFA)浓度。

1.4.4 发酵液中的FA组成测定

参照闫素梅等[16]的方法,使用气相色谱仪(7890B,Agilent科技有限公司,美国)测定发酵液中37种单一FA:C4∶0、C6∶0、C8∶0、C10∶0、C11∶0、C12∶0、C13∶0、C14∶0、、C15∶0、C16∶0、C17∶0、C18∶0、C20∶0、C21∶0、C22∶0、C23∶0、C24∶0、C14∶1、C15∶1、C16∶1、C17∶1、C18∶1n9t、C18∶1n9c、C20∶1、C22∶1、C24∶1、C18∶2n6t、C18∶2n6c、C18∶3n6、C20∶2n6、C20∶3n6、C20∶4n6、C22∶2n6、C18∶3n3、C20∶3n3、C20∶5n3和DHA浓度,计算饱和脂肪酸(saturated fatty acid,SFA)、UFA、单不饱和脂肪酸(monounsaturated fatty acid,MUFA)、PUFA、n-3 PUFA、n-6 PUFA、n-3长链多不饱和脂肪酸(n-3 long-chain polyunsaturated fatty acid,n-3 LCPUFA)、n-6长链多不饱和脂肪酸(n-6 LCPUFA)浓度以及n-6 PUFA/n-3 PUFA、不饱和脂肪酸/饱和脂肪酸(U/S)和多不饱和脂肪酸/饱和脂肪酸(P/S)。色谱柱型号为SP-2560(100 m×0.25 mm×0.20 μm),37种脂肪酸甲酯化标准品购自西格玛奥德里奇(上海)贸易有限公司。

1.4.5 单项组合效应指数(SFAEI)与多项组合效应指数(MFAEI)

SFAEI是用于量化评估2种或多种饲料组合后在某一特定发酵指标上产生的相互作用(组合效应)强度的参数,MFAEI是多项不同处理的SFAEI之和。计算公式如下:
SFAEI= n m = 1 ( A 2 m - A 1 m ) / n A 2 m;
MFAEI=∑SFAEI。
式中:m为各培养时间点;n为培养时间点的个数(n=1);A1m为CON组各单一指标不同培养时间点的数值;A2m为试验组各单一指标不同培养时间点的数值。

1.5 数据统计分析

试验数据采用Excel 2021进行初步整理,然后采用SAS 9.2软件进行单因素方差分析(one-way ANOVA),差异显著时用Duncan氏法进行多重比较。结果通过平均值和均值标准误(SEM)表示,以P<0.05表示差异显著。

2 结果

2.1 不同添加水平裂壶藻粉对体外瘤胃发酵参数的影响

表2可知,裂壶藻粉的添加显著降低了体外瘤胃发酵液pH和NH3-N浓度(P<0.05),显著提高了BCP浓度(P<0.05),对总产气量无显著影响(P>0.05)。与CON组相比,4个试验组体外瘤胃发酵液pH显著降低(P<0.05);SCM3组和SCM4组体外瘤胃发酵液中BCP浓度显著高于CON组(P<0.05),且SCM3组显著高于其他4组(P<0.05);SCM4组体外瘤胃发酵液中原虫数量显著低于CON组和SCM1组(P<0.05);SCM3组和SCM4组体外瘤胃发酵液中NH3-N浓度显著低于CON组和SCM1组(P<0.05)。
表2 不同添加水平裂壶藻粉对体外瘤胃发酵参数的影响

Table 2 Effects of different supplemental levels of Schizochytrium powder on rumen fermentation parameters in vitro

项目
Items
CON组
CON
group
SCM1组
SCM1
group
SCM2组
SCM2
group
SCM3组
SCM3
group
SCM4组
SCM4
group
均值
标准误
SEM
P
P-value
pH 6.50a 6.43b 6.40bc 6.39bc 6.36c 0.021 0.001
总产气量Total gas production/mL 67.03 67.75 72.49 69.60 71.54 2.003 0.261
菌体蛋白BCP/(mg/dL) 18.83c 22.10bc 23.36bc 31.92a 25.69b 1.593 <0.001
原虫Protozoa/(×105个/mL) 1.95ab 2.00a 1.75bc 1.77bc 1.68c 0.049 0.024
氨态氮NH3-N/(mg/dL) 12.72a 12.50a 11.48ab 10.31b 10.09b 0.688 0.023

同行数据肩标无字母或有相同字母表示差异不显著(P>0.05),不同小写字母表示差异显著(P<0.05)。下表同。

In the same row, values with no letter or the same letter superscripts mean no significant difference (P>0.05), while with different small letter superscripts mean significant difference (P<0.05). The same as below.

2.2 不同添加水平裂壶藻粉对体外瘤胃发酵液中VFA浓度的影响

表3可知,裂壶藻粉的添加对体外瘤胃发酵液中丙酸、异丁酸、丁酸、异戊酸、戊酸和TVFA浓度以及乙丙比均有显著影响(P<0.05),对乙酸浓度无显著影响(P>0.05)。SCM3组和SCM4组体外瘤胃发酵液中丙酸浓度显著高于CON组和SCM1组(P<0.05),SCM3组和SCM4组间差异不显著(P>0.05);SCM2组、SCM3组和SCM4组体外瘤胃发酵液中异丁酸、异戊酸浓度均显著高于CON组和SCM1组(P<0.05),TVFA浓度显著高于CON组(P<0.05);SCM1组体外瘤胃发酵液中丁酸和戊酸浓度显著低于其他组(P<0.05);SCM3组和SCM4组体外瘤胃发酵液中乙丙比均显著低于其他3组(P<0.05)。
表3 不同添加水平裂壶藻粉对体外瘤胃发酵液中VFA浓度的影响

Table 3 Effects of different supplemental levels of Schizochytrium powder on VFA concentrations of rumen fermentation broth in vitro

项目
Items
CON组
CON
group
SCM1组
SCM1
group
SCM2组
SCM2
group
SCM3组
SCM3
group
SCM4组
SCM4
group
均值
标准误
SEM
P
P-value
乙酸Acetate/(mmol/L) 30.33 30.06 30.35 29.83 29.88 0.341 0.730
丙酸Propionate/(mmol/L) 11.13c 11.13c 11.38bc 11.78ab 12.24a 0.183 <0.001
异丁酸Isobutyrate/(mmol/L) 0.29b 0.27b 0.35a 0.34a 0.35a 0.012 <0.001
丁酸Butyrate/(mmol/L) 4.12a 3.81b 4.21a 4.29a 4.16a 0.082 0.003
异戊酸Isovalerate/(mmol/L) 0.41c 0.41c 0.47b 0.53a 0.52a 0.014 <0.001
戊酸Valerate/(mmol/L) 0.44a 0.41b 0.44a 0.44a 0.45a 0.007 0.005
乙丙比Acetate-to-propionate ratio 2.66a 2.70a 2.66a 2.53b 2.44b 0.042 <0.001
总挥发性脂肪酸TVFA/(mmol/L) 46.23b 46.52ab 47.51a 47.54a 47.62a 0.373 0.028

2.3 不同添加水平裂壶藻粉对体外瘤胃发酵液中FA组成的影响

表4可知,所有试验组体外瘤胃发酵液中C8∶0、C10∶0、C13∶0、C24∶1、C18∶2n6t、C20∶3n6和DHA浓度均显著高于CON组(P<0.05),C16∶0、C20∶0浓度均显著低于CON组(P<0.05),其中SCM3组和SCM4组DHA浓度显著高于其他3组(P<0.05);SCM2组、SCM3组和SCM4组体外瘤胃发酵液中C20∶3n3和C20∶5n3浓度均显著高于CON组(P<0.05),C11∶0、C15∶1、C17∶1浓度均显著低于CON组(P<0.05);SCM3组和SCM4组体外瘤胃发酵液中C18∶0和C24∶0浓度均显著低于CON组(P<0.05),C18∶3n3浓度显著高于CON组(P<0.05),SCM3和SCM4组间无显著差异(P>0.05);SCM1组体外瘤胃发酵液中C12∶0、C17∶0、C21∶0、C16∶1和C20∶4n6浓度均显著高于CON组(P<0.05);SCM1组、SCM2组和SCM3组体外瘤胃发酵液中C6∶0和C22∶0浓度均显著低于CON组(P<0.05);SCM3组体外瘤胃发酵液中C18∶1n9t和C18∶1n9c浓度均显著高于CON组(P<0.05);SCM4组体外瘤胃发酵液中C18∶2n6c和C18∶3n6浓度均显著高于CON组(P<0.05);SCM2组和SCM3组体外瘤胃发酵液中C20∶2n6显著高于CON组(P<0.05);SCM2组体外瘤胃发酵液中C22∶2n6显著高于CON组(P<0.05);SCM3组体外瘤胃发酵液中C23∶0浓度显著高于SCM2组(P<0.05),但是各试验组C23∶0浓度均与CON组差异不显著(P>0.05)。
表4 不同添加水平裂壶藻粉对体外瘤胃发酵液中脂肪酸组成的影响

Table 4 Effects of different supplemental levels of Schizochytrium powder on FA composition of rumen fermentation broth in vitro %

项目
Items
CON组
CON
group
SCM1组
SCM1
group
SCM2组
SCM2
group
SCM3组
SCM3
group
SCM4组
SCM4
group
均值
标准误
SEM
P
P-value
C4∶0 0.75 0.77 0.71 0.66 0.68 0.036 0.186
C6∶0 0.45a 0.38b 0.39b 0.40b 0.47a 0.015 <0.001
C8∶0 0.12b 0.21a 0.18a 0.18a 0.19a 0.011 <0.001
C10∶0 0.07c 0.07b 0.12a 0.11a 0.12a 0.004 <0.001
C11∶0 0.05a 0.05a 0.04b 0.03b 0.04b 0.003 <0.001
C12∶0 0.21b 0.32a 0.22b 0.19b 0.26ab 0.028 0.017
C13∶0 0.06b 0.12a 0.13a 0.11a 0.12a 0.007 <0.001
C13∶0 0.06b 0.12a 0.13a 0.11a 0.12a 0.007 <0.001
C14∶0 0.56 0.60 0.65 0.57 0.56 0.038 0.246
C15∶0 0.26 0.31 0.30 0.34 0.36 0.025 0.092
C16∶0 24.49a 22.84b 21.67bc 21.15bc 20.61c 0.572 <0.001
C17∶0 0.24bc 0.31a 0.20cd 0.19d 0.27ab 0.015 <0.001
C18∶0 13.13a 13.58a 12.92a 11.20b 11.46b 0.494 0.004
C20∶0 0.05a 0.04b 0.04b 0.03b 0.03b 0.002 0.003
C21∶0 0.11b 0.18a 0.08b 0.06b 0.10b 0.021 0.005
C22∶0 0.84a 0.71b 0.68b 0.66b 0.75ab 0.038 0.017
C23∶0 0.40abc 0.36bc 0.44a 0.35c 0.43ab 0.024 0.029
C24∶0 0.77ab 0.81a 0.70b 0.57c 0.57c 0.032 <0.001
C14∶1 0.08 0.08 0.09 0.08 0.09 0.004 0.243
C15∶1 0.13a 0.12a 0.10b 0.08b 0.09b 0.004 <0.001
C16∶1 0.08bc 0.12a 0.08bc 0.07c 0.10ab 0.011 0.019
C17∶1 0.09a 0.08ab 0.07b 0.06b 0.06b 0.006 0.014
C18∶1n9t 22.05b 22.08b 23.03ab 24.51a 24.26ab 0.714 0.048
C18∶1n9c 22.67b 23.09ab 23.98ab 24.21a 22.49b 0.479 <0.001
C20∶1 0.72 0.67 0.55 0.63 0.67 0.047 0.149
C22∶1 0.28 0.31 0.29 0.29 0.33 0.024 0.548
C24∶1 0.27b 0.53a 0.51a 0.58a 0.52a 0.040 <0.001
C18∶2n6t 0.09b 0.13a 0.13a 0.14a 0.16a 0.009 <0.001
C18∶2n6c 9.66b 9.15b 9.31b 10.19b 12.41a 0.660 0.008
C18∶3n6 0.09b 0.12ab 0.11b 0.11b 0.14a 0.010 0.014
C20∶2n6 0.15c 0.20bc 0.29a 0.25ab 0.20bc 0.018 <0.001
C20∶3n6 0.08b 0.16a 0.15a 0.18a 0.19a 0.016 <0.001
C20∶4n6 0.15b 0.22a 0.13b 0.12b 0.15b 0.017 0.002
C22∶2n6 0.06b 0.05b 0.08a 0.05b 0.06b 0.005 0.021
C18∶3n3 0.16c 0.21bc 0.24abc 0.25ab 0.31a 0.025 0.004
C20∶3n3 0.10b 0.11b 0.16a 0.19a 0.19a 0.015 <0.001
C20∶5n3 0.14c 0.16bc 0.21ab 0.26a 0.21ab 0.017 <0.001
C22∶6n3
(二十二碳六烯酸DHA)
0.11d 0.55c 0.89b 1.09a 1.23a 0.063 <0.001
表5可知,所有试验组体外瘤胃发酵液中n-3 PUFA、n-3 LCPUFA和n-6 LCPUFA浓度均显著高于CON组(P<0.05),n-6 PUFA/n-3 PUFA显著低于CON组(P<0.05);SCM2组、SCM3组和SCM4组体外瘤胃发酵液中SFA浓度显著低于CON组和SCM1组(P<0.05),UFA浓度和U/S均显著高于CON组和SCM1组(P<0.05),MUFA浓度显著高于CON组(P<0.05);SCM4组体外瘤胃发酵液中PUFA浓度显著高于其他4组(P<0.05),其他4组间差异不显著(P>0.05);SCM3和SCM4组体外瘤胃发酵液P/S显著高于CON组和SCM1组(P<0.05)。裂壶藻粉的添加对体外瘤胃发酵液中n-6 PUFA浓度无显著影响(P>0.05)。
表5 不同添加水平裂壶藻粉对体外瘤胃发酵液中SFA、UFA、MUFA和PUFA浓度的影响

Table 5 Effects of different supplemental levels of Schizochytrium powder on concentrations of SFA, UFA, MUFA and PUFA of rumen fermentation broth in vitro

项目
Items
CON组
CON
group
SCM1组
SCM1
group
SCM2组
SCM2
group
SCM3组
SCM3
group
SCM4组
SCM4
group
均值
标准误
SEM
P
P-value
饱和脂肪酸SFA/% 42.67a 41.71a 39.47b 36.84c 36.98c 0.706 <0.001
不饱和脂肪酸UFA/% 57.32c 58.28c 60.52b 63.15a 63.01a 0.706 <0.001
单不饱和脂肪酸MUFA/% 46.25c 46.98bc 48.63ab 50.46a 48.55ab 0.718 0.002
多不饱和脂肪酸PUFA/% 10.41b 11.11b 11.74b 12.55b 14.70a 0.689 0.001
n-3多不饱和脂肪酸n-3 PUFA/% 0.56d 1.05c 1.52b 1.81a 1.95a 0.074 <0.001
n-6多不饱和脂肪酸n-6 PUFA/% 10.31 10.05 10.22 10.74 12.08 0.648 0.193
n-3长链多不饱和脂肪酸
n-3 LCPUFA/%
0.39d 0.84c 1.27b 1.55a 1.64a 0.065 <0.001
n-6长链多不饱和脂肪酸
n-6 LCPUFA/%
0.45b 0.64a 0.66a 0.61a 0.62a 0.038 0.004
n-3多不饱和脂肪酸/
n-6多不饱和脂肪酸
n-6 PUFA/n-3 PUFA
15.40a 9.59b 6.75c 6.00c 6.68c 0.727 <0.001
不饱和脂肪酸/饱和脂肪酸U/S 1.35c 1.40c 1.53b 1.71a 1.73a 0.045 <0.001
多不饱和脂肪酸/饱和脂肪酸P/S 0.25c 0.26c 0.29bc 0.34b 0.40a 0.022 <0.001

2.4 不同添加水平裂壶藻粉对体外瘤胃发酵SFAEI与MFAEI的影响

表6可知,所有试验组的SFAEI与MFAEI均高于CON组,均大于0;总产气量的SFAEI以SCM2组最高,BCP浓度的SFAEI以SCM3组最高,TVFA浓度的SFAEI以SCM4组最高;MFAEI以SCM3组最高,其次依次为SCM4组、SCM2组、SCM1组和CON组。
表6 不同添加水平裂壶藻粉对体外瘤胃发酵SFAEI和MFAEI的影响

Table 6 Effects of different supplemental levels of Schizochytrium powder on SFAEI and MFAEI of rumen fermentation in vitro

项目
Items
CON组
CON group
SCM1组
SCM1 group
SCM2组
SCM2 group
SCM3组
SCM3 group
SCM4组
SCM4 group
单项组合效应指数SFAEI
总产气量Total gas production/mL 0.000 0.011 0.081 0.038 0.067
菌体蛋白BCP/(mg/dL) 0.000 0.174 0.241 0.695 0.364
总挥发性脂肪酸TVFA/(mmol/L) 0.000 0.006 0.028 0.028 0.030
多项组合效应指数MFAEI 0.000 0.191 0.350 0.762 0.462

3 讨论

瘤胃NH3-N浓度是评估瘤胃内氮代谢效率与蛋白质利用状况的核心指标。NH3-N是瘤胃微生物生长和BCP合成的重要氮源[17],通常NH3-N浓度降低表明细菌合成BCP的能力增强[18]。瘤胃的原虫是NH3-N的净生产者,去除原虫会导致瘤胃NH3-N浓度降低[19];适当降低瘤胃的原虫数量,可提高瘤胃的细菌数量,提高BCP合成效率[20]。沈奔等[21]研究表明,泡叶藻能够降低湖羊体外瘤胃液中NH3-N浓度,提高BCP浓度。本试验发现,与CON组相比,发酵底物中添加1.5%和2.0%裂壶藻粉的体外瘤胃发酵液NH3-N浓度显著降低,BCP浓度显著提高;发酵底物中添加2.0%裂壶藻粉的原虫数量显著降低,本试验结果说明,裂壶藻粉可以增加细菌对饲粮氮的利用效率,促进BCP的合成,这与其降低瘤胃中原虫数量、提高细菌数量有关。
反刍动物具有复杂的瘤胃微生物群落,瘤胃内碳水化合物经微生物发酵后生成的VFA是反刍动物主要的能量来源。高昌鹏[22]研究表明,在滩羊饲粮中添加2%的裂殖壶藻能显著提高滩羊瘤胃液中TVFA浓度,且丙酸浓度有升高趋势。Boeckaert等[23]研究发现,在奶牛饲粮中添加43 g/kg DMI的裂壶藻粉,显著提高了瘤胃中异戊酸浓度、降低了丁酸浓度。本试验结果表明,与CON组相比,发酵底物中添加1.5%和2.0%的裂壶藻粉显著提高了体外瘤胃发酵液中丙酸、异丁酸、异戊酸和TVFA浓度,显著降低乙丙比,而且体外瘤胃发酵液pH随着丙酸等有机酸浓度上升而显著下降,说明发酵底物中添加适宜水平的裂壶藻粉可以促进绒山羊体外瘤胃发酵,为机体代谢和生产提供更多的能量来源。MFAEI可以通过量化评估多种饲料添加剂或组合对瘤胃发酵的协同/拮抗效应,反映其对瘤胃发酵效率的综合调控能力。本试验结果表明,发酵底物中不同添加水平的裂壶藻粉均能提高MFAEI,尤以添加水平为1.5%时MFAEI最高,说明该添加水平对体外瘤胃发酵促进效果最好。
通过增加饮食中C18∶3n3、DHA等n-3 PUFA浓度,同时降低C18∶0浓度,能够有效提高机体健康水平,降低脑血栓、动脉粥样硬化的发病风险[3]。增加饲粮n-3 PUFA浓度供给是提高反刍动物过瘤胃和血液中n-3 PUFA浓度,进而提高乳、肉产品中n-3 PUFA浓度,实现优化产品品质的主要措施[1]。因此,优化瘤胃液的FA组成对改善畜产品FA品质具有重要意义。瘤胃生物氢化过程会产生大量的FA异构体,其主要成分包括C18∶2、C18∶3和C18∶1,FA异构体经过进一步转化,最终变为C18∶0[24]。研究表明,通过饲喂富含n-3 LCPUFA的补充剂可抑制山羊瘤胃中生物氢化至C18∶0的最后一步,使得C18∶1和C18∶2异构体积累[8],而反刍动物体内的c9t11-CLA是从C18∶2转化而来的[25]。本试验结果表明,与CON组相比,发酵底物中添加1.5%的裂壶藻粉显著提高了体外瘤胃发酵液中C18∶1n9t和C18∶1n9c浓度,添加2.0%的裂壶藻粉显著提高了体外瘤胃发酵液中C18∶2n6c浓度,添加1.5%和2.0%的裂壶藻粉显著降低了C18∶0浓度。这与前人研究结果相似,说明添加1.5%和2.0%的富含DHA的裂壶藻粉可能通过降低绒山羊瘤胃微生物的生物氢化过程,抑制了瘤胃中生物氢化至C18∶0的最后一步,使得C18∶1和C18∶2异构体积累,C18∶0浓度下降,有助于提高机体健康水平。Pajor等[9]研究发现,在高山奶山羊饲粮中补充5 g裂壶藻,显著提高了瘤胃液中c9t11-CLA浓度和羊奶中DHA浓度,降低了n-6 PUFA/n-3 PUFA。本试验结果表明,与CON组相比,发酵底物中添加裂壶藻粉对体外瘤胃发酵液中FA组成的影响呈剂量依赖性,其中以添加水平为1.5%和2.0%时效果较好,可以显著增加C18∶3n3、C20∶5n3和DHA等n-3 PUFA浓度,降低C16∶0、C18∶0等SFA浓度和n-6 PUFA/n-3 PUFA。
综上可知,发酵底物中添加裂壶藻粉可以促进绒山羊体外瘤胃发酵,同时可优化体外瘤胃发酵液的FA组成。由此推测,饲粮中添加裂壶藻粉将有助于改善绒山羊后肠道食糜和血液、肌肉的FA组成,提高畜产品营养价值,本试验结果为在绒山羊生产中通过营养干预增加肉产品的FA品质提供了新思路。

4 结论

发酵底物中添加1.5%~2.0%的裂壶藻粉可以促进绒山羊体外瘤胃发酵,优化体外瘤胃发酵液的FA组成,提高C18∶3n3、C20∶5n3和DHA等n-3 PUFA浓度,降低C16∶0、C18∶0等SFA浓度和n-6 PUFA/n-3 PUFA。
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