畜牧兽医学报  2019, Vol. 50 Issue (6): 1208-1218. DOI: 10.11843/j.issn.0366-6964.2019.06.011    PDF    
牛至精油对甘肃高山细毛羊肌肉脂肪酸组成及共轭亚油酸含量的影响
梁婷玉1, 刘婷1, 宫旭胤2, 吴建平1,2, 张瑞1, 高良霜1     
1. 甘肃农业大学动物科学技术学院, 兰州 730070;
2. 甘肃省农业科学院畜草与绿色农业研究所, 兰州 730070
摘要:旨在研究饲粮中添加牛至精油对甘肃高山细毛羊肌肉脂肪酸组成的影响。本试验筛选30只健康状况良好、体况相近的60日龄甘肃高山细毛羊,随机分为3组,每组10只,分别为对照组,添加2和4 g·d-1牛至精油组(Ⅰ组和Ⅱ组)。饲喂3个月后每组随机屠宰6只,屠宰后取背最长肌和半腱肌测定脂肪酸组成和共轭亚油酸(CLA)含量。结果表明:1)Ⅰ组母羊和Ⅱ组公羊血液高密度脂蛋白胆固醇(HDL-C)浓度显著低于对照组母羊(P < 0.05),其他血液生化参数无显著性差异。2)各部位肌肉脂肪酸以油酸(C18:1n9c)和棕榈酸(C16:0)为主;背最长肌中,对照组母羊MUFA、UFA含量显著高于该组公羊(P < 0.05),而n-6PUFA含量显著低于该组公羊(P < 0.05),Ⅰ组公羊SFA含量显著高于Ⅱ组公羊(P < 0.05);Ⅱ组公羊MUFA含量显著高于该组母羊及对照组、Ⅰ组公羊(P < 0.05),Ⅱ组母羊PUFA含量显著高于该组公羊及对照组、Ⅰ组母羊(P < 0.05),Ⅰ组公羊UFA含量显著低于Ⅱ组公羊(P < 0.05);半腱肌中,对照组公羊PUFA、n-6PUFA及n-3PUFA含量显著高于该组母羊(P < 0.05),Ⅱ组公羊MUFA含量显著高于对照组及Ⅰ组公羊(P < 0.05),Ⅰ组公羊n-6/n-3含量显著高于该组母羊(P < 0.05)。3)各部位肌肉c9t11-CLA含量均为母羊高于公羊,且Ⅰ组母羊c9t11-CLA含量显著高于该组公羊(P < 0.05);Ⅱ组公羊和母羊背最长肌c9t11-CLA含量分别显著高于对照组公羊和母羊(P < 0.05),与Ⅰ组无显著性差异(P>0.05)。综上所述,甘肃高山细毛羊肌肉脂肪酸组成因动物性别、组织部位、添加剂添加量不同而存在差异;日粮中添加牛至精油可提高其肌肉CLA含量,且4 g·d-1添加量效果优于2 g·d-1
关键词牛至精油    甘肃高山细毛羊    脂肪酸    共轭亚油酸    
Effects of Oregano Essential Oil on Fatty Acid Composition and Conjugated Linoleic Acid Content in Muscle of Gansu Alpine Fine-wool Sheep
LIANG Tingyü1, LIU Ting1, GONG Xuyin2, WU Jianping1,2, ZHANG Rui1, GAO Liangshuang1     
1. College of Animal Science and Technology, Gansu Agricultural University, Lanzhou 730070, China;
2. Animal Husbandry, Pasture and Green Agriculture Institute, Gansu Academy of Agricultural Sciences, Lanzhou 730070, China
Abstract: The purpose of this experiment was to study the effects of oregano essential oil on the fatty acid composition in muscles of Gansu Alpine Fine-wool sheep. Thirty 60-day-old healthy Gansu Alpine Fine-wool sheep with the similar body condition were selected and randomly divided into 3 groups:control group, adding 2 and 4 g·d-1 oregano essential oil groups (group Ⅰ and group Ⅱ). There were 10 sheep per group. Six sheep in each group were slaughtered randomly after 3 month, the samples of longissimus dorsi (LD) muscle and semitendinosus (SE) muscle were collected, and the fatty acid composition and conjugated linoleic acid (CLA) content were measured. The results showed that:1) The concentration of blood HDL-C of ewes in group Ⅰ and rams in group Ⅱ was significantly lower than that of ewes in control group (P < 0.05), and there was no significant difference in other blood biochemical parameters (P>0.05) among the 3 groups. 2) Oleic acid (C18:1n9c) and palmitic acid (C16:0) were the main fatty acids in muscle of different parts. In LD muscle, the content of MUFA and UFA of the ewes in control group were significantly higher than that of rams in control group(P < 0.05), while the content of n-6PUFA of ewes in control group was significantly lower than that of rams in control group (P < 0.05), the SFA content of rams in group Ⅰ was significantly higher than that of rams in group Ⅱ(P < 0.05); The content of MUFA of rams in group Ⅱ was significantly higher than that of ewes in groupⅡ, the rams in control group and group Ⅰ(P < 0.05); The content of PUFA of ewes in group Ⅱ was significantly higher than that of rams in group Ⅱ, ewes in control group and group Ⅰ(P < 0.05), the UFA content of rams in group Ⅰ was significantly lower than that of rams in group Ⅱ(P < 0.05). In SE muscle, the contents of PUFA, n-6PUFA and n-3PUFA of rams in control group were significantly higher than that of ewes in control group (P < 0.05), the MUFA content of rams in group Ⅱ was significantly higher than that of rams in control group and group Ⅰ(P < 0.05), n-6/n-3 content of rams in group Ⅰ was significantly higher than that of ewes in group Ⅰ (P < 0.05). 3) The content of c9t11-CLA in muscles of ewes was higher than that of rams in the 3 groups, and the content of c9t11-CLA of ewes in group Ⅰ was significantly higher than that of rams in group Ⅰ (P < 0.05); The c9t11-CLA content in LD muscle of rams and ewes in group Ⅱ was significantly higher than that in control group (P < 0.05), and there was no significant difference between group Ⅰ and group Ⅱ (P>0.05). In summary, the fatty acids composition in muscle of Gansu Alpine Fine-wool sheep are different with animal sex, tissue location and additive dosage, adding oregano essential oil in diet can increase CLA content in muscle, and the supplementation effect of 4 g·d-1is better than 2 g·d-1.
Key words: oregano oil     Gansu Alpine Fine-wool sheep     fatty acid     conjugated linoleic acid    

牛至精油是从天然植物牛至中提取所得的一种挥发性植物精油,其主要成分是挥发性酚类化合物,具有强烈的抗氧化、杀菌消炎作用,可提高机体免疫力[1]。且因其具有挥发性芳香味,无化学毒性,不具有耐药性,逐渐成为抗生素的替代品,在畜禽生产和兽药临床研究中扮演重要角色[2]。近年来,国内外学者对牛至精油在畜牧业中进行了大量研究。有研究发现,在全混合日粮中添加牛至精油可显著抑制霉菌、细菌和大肠杆菌活性,从而起到保鲜作用[3]。牛至精油也可改变动物胃肠道微生物,尤其是调节反刍动物瘤胃微生物发酵,并进一步改善营养物质的吸收利用[4]。研究表明,日粮中添加牛至精油可提高仔猪饲料利用率,促进生长,提高日增重[5]。陈昊等[6-7]研究发现,饲喂牛至精油可降低荷斯坦奶牛乳房炎和腹泻发病率,促进犊牛生长发育、提高采食量及免疫力。此外,牛至精油对动物产品品质也有重要作用。研究发现,日粮中添加牛至精油不仅可以提高奶牛产奶量,也可提高牛奶脂肪含量[8]。刘立山等[9]研究发现,日粮中添加牛至精油可显著降低牛肉中饱和脂肪酸含量,显著提高不饱和脂肪酸含量。陈立华等[10]研究发现,牛至精油可改变肉鸡胴体品质。由于牛至精油的经济成本较高,因此筛选出适宜的添加量才可产生最大经济效益。徐善金和朱永兴[11]研究发现,日粮中添加20 mg·kg-1牛至精油对肉鸭的促生长效果最佳。王娟等[12]研究了0、4、7 g·d-1牛至精油添加量对绵羊瘤胃发酵特征及青贮、黄贮玉米秸秆瘤胃降解率的影响,结果表明,添加量为4 g·d-1时瘤胃发酵及青贮饲料利用率最佳。

甘肃高山细毛羊是20世纪80年代初经杂交改良培育的毛肉兼用型地方品种,是高海拔牧区的优势家畜品种[13]。近年来,为了增强市场竞争力,提高牧民收入,促进地区经济快速发展,实现即可生产优质细毛又可生产高档羊肉的目标,提高甘肃高山细毛羊产肉性能、改善其肉品质势在必行。通过营养调控手段可在保护好品种资源的前提下提高动物产肉性能,且快速有效。研究发现,饲粮中添加20%苜蓿草粉可提高猪肉品质和营养价值[14]。绵羊饲粮中添加桑树叶可提高其背最长肌中不饱和脂肪酸(UFA)含量,降低饱和脂肪酸(SFA)含量,从而提高绵羊肉品质[15]。肌肉中脂肪酸组成及含量会影响肉的营养价值和风味,对人体健康也有重要意义,且反刍动物肌肉中的共轭亚油酸具有抗癌、增强免疫力、抗动脉粥样硬化等生物学功能,已成为目前药物、食品及动物营养等领域的研究热点,反刍动物乳脂及肉制品中的CLA是主要的天然来源。

本研究以甘肃高山细毛羊为研究对象,在完全舍饲状态下,通过在日粮中添加0、2、4 g·d-1牛至精油,研究对其肌肉脂肪酸组成及共轭亚油酸含量的影响,以期为牛至精油在甘肃高山细毛羊肉品质改善中的应用提供理论依据。

1 材料与方法 1.1 试验动物及饲养管理

本试验在甘肃省张掖市甘州区平山湖绒山羊育肥基地进行。选取健康状况良好、体况相近的30只平均体重为(20.13±0.02)kg的60日龄甘肃高山细毛羊(公母各15只),随机分为3组,每组10只羊(公母各5只),单栏饲喂。其中对照组只饲喂基础日粮,试验组分别添加2(Ⅰ组)和4 g·d-1(Ⅱ组)牛至精油,每只羊每天早上准确量取相应量的牛至精油与少量精料混匀饲喂。自由采食及饮水,试验期为3个月。试验日粮组成及营养水平见表 1

表 1 基础饲粮组成及营养成分(风干基础) Table 1 Composition and nutrient levels of the basal diet (air-dry basis)
1.2 样品采集

饲养试验最后1 d所有试验动物禁食24 h后称重(各组平均体重为34~39 kg),颈静脉采血,离心分离血清用于血液生化指标测定。再每组随机选公母各3只进行屠宰,屠宰后取左侧胴体背最长肌和半腱肌各50 g左右,真空包装,于-80 ℃保存,用于脂肪酸和共轭亚油酸检测分析。

1.3 测定指标及方法 1.3.1 血液生化指标检测

将分离的血清送往湖南锋锐生物科技有限公司,检测甘油三酯(TG)、总胆固醇(TC)、高密度脂蛋白胆固醇(HDL-C)和低密度脂蛋白胆固醇(LDL-C)浓度。

1.3.2 肌肉脂肪酸和共轭亚油酸测定 1.3.2.1 样品前处理

肉样脂肪酸甲酯化处理参考O’Fallon等[16]的方法进行。将真空包装袋中的肉样在室温下解冻4 h,解开包装,削去表层肌肉取中间部分,剔除肌肉表面脂肪,放入研钵用液氮研磨,称取1 g研磨后的样品于10 mL有塞试管中,添加0.7 mL 10 mol·L-1的KOH溶液和5.3 mL无水甲醇,摇匀后在55 ℃下恒温水浴1.5 h,期间每20 min振摇试管5 s,水浴结束后取出试管用自来水冲洗冷却至室温,再加入0.58 mL 12 mol·L-1的H2SO4,55 ℃水浴1.5 h进行游离脂肪酸甲酯化,期间每20 min振摇5 s,水浴结束后取出试管用自来水冲洗冷却至室温,加入3 mL正己烷摇匀后转移至10 mL离心管,3 000 r·min-1离心5 min,取出上清液,并用有机相过滤膜将其过滤到样品瓶中,-20 ℃保存待气相色谱(Gas chromatography,GC)分析。

1.3.2.2 GC分析

用GC-2010气相色谱仪(日本岛津)对制备好的脂肪酸甲酯进行GC分析。毛细柱为100 m×0.25 mm×0.2 μm(SP-2560,Sigma)。升温程序为:初始温度150 ℃,保持4 min,以3 ℃·min-1升至225 ℃,保持4 min,以0.5 ℃·min-1升至230 ℃,保持4 min,再以3 ℃·min-1升至240 ℃,保持6 min。进样口和检测器(FID)温度分别为250和260 ℃;分流进样,分流比为80:1;氮气(载气)流速为1.5 mL·min-1,进样量1 μL。37种脂肪酸甲基酯混合标样和共轭亚油酸c9t11(c9t11-CLA)甲基酯标样均购于Sigma公司。

1.4 数据统计与分析

采用SPSS 21.0统计分析软件对试验数据进行单因素方差分析(one-way ANOVA),用Duncan氏法进行多重比较,当P < 0.05认为差异显著,结果以“平均值±标准误(mean±SE)”表示。

2 结果 2.1 牛至精油不同添加量对甘肃高山细毛羊血液生化指标的影响

表 2可知,对照组母羊血液HDL-C浓度显著高于Ⅰ组母羊和Ⅱ组公羊(P < 0.05),与Ⅱ组母羊血液HDL-C浓度无显著性差异(P>0.05),Ⅰ、Ⅱ组公羊HDL-C浓度与对照组公羊无显著性差异(P>0.05);血液生化参数TG、TC和LDL-C在各处理组及不同性别间均无显著性差异(P>0.05)。

表 2 牛至精油对甘肃高山细毛羊血清生化参数的影响 Table 2 Effects of oregano essential oil on serum biochemical parameters of Gansu Alpine Fine-wool sheep
2.2 牛至精油不同添加量对甘肃高山细毛羊背最长肌脂肪酸组成的影响

表 3可知,甘肃高山细毛羊背最长肌中共检测到26种脂肪酸,含量高于1%的有肉豆蔻酸(C14:0)、十五烷酸(C15:0)、棕榈酸(C16:0)、棕榈烯酸(C16:1)、十七烷酸(C17:0)、十七碳烯酸(C17:1)、硬脂酸(C18:0)、反油酸(C18:1n9t)、油酸(C18:1n9c)、亚油酸(C18:2n6c)和二十三烷酸(C23:0)11种脂肪酸,其中油酸(C18:1n9c)占总脂肪酸的相对百分比最高,约37.45%~40.51%,其次是棕榈酸(C16:0),约占总脂肪酸的23.67%~26.21%,硬脂酸(C18:0)次之,占总脂肪酸10%以上。由对照组可知,公羊背最长肌丁酸(C4:0)、十五烷烯酸(C15:1)、亚油酸(C18:2n6c)、二十碳三烯酸(C20:3n6)、二十三烷酸(C23:0)和n-6 PUFA含量显著高于母羊(P < 0.05);母羊油酸(C18:1n9c)、MUFA和UFA含量显著高于公羊(P < 0.05)。对照组公羊十五烷酸(C15:0)、十五烷烯酸(C15:1)、二十碳三烯酸(C20:3n6)、二十三烷酸(C23:0)含量显著高于Ⅰ组公羊(P < 0.05),对照组和Ⅱ组公羊二十碳五烯酸(C20:5n3)含量显著高于Ⅰ组公羊(P < 0.05),对照组公羊十七碳烯酸(C17:1)含量显著低于Ⅰ组和Ⅱ组公羊(P < 0.05),Ⅱ组母羊十七烷酸(C17:0)和十七碳烯酸(C17:1)含量显著高于Ⅰ组母羊(P < 0.05),Ⅰ组公羊反油酸(C18:1n9t)含量显著高于对照组和Ⅱ组公羊,而Ⅱ组母羊反油酸(C18:1n9t)含量显著高于对照组和Ⅰ组母羊(P < 0.05),Ⅰ组母羊反亚油酸(C18:2n6t)含量显著高于Ⅱ组母羊(P < 0.05),对照组母羊神经酸(C24:1)含量显著高于Ⅰ组母羊(P < 0.05)。Ⅰ组公羊SFA含量显著高于Ⅰ组母羊及Ⅱ组公羊(P < 0.05);对照组母羊MUFA含量显著高于对照组公羊及Ⅰ、Ⅱ组母羊(P < 0.05),且Ⅱ组公羊MUFA含量显著高于该组母羊及对照组、Ⅰ组公羊(P < 0.05);对照组公羊PUFA含量显著高于Ⅰ组公羊(P < 0.05),Ⅱ组母羊PUFA含量显著高于该组公羊及对照组、Ⅰ组母羊(P < 0.05);对照组母羊UFA含量显著高于该组公羊及Ⅰ组母羊(P < 0.05),且Ⅰ组公羊UFA含量显著低于Ⅱ组公羊(P < 0.05);对照组和Ⅰ组母羊n-6PUFA含量显著低于本组公羊(P < 0.05),且Ⅰ组母羊n-6/n-3含量显著低于该组公羊(P < 0.05)。

表 3 牛至精油对甘肃高山细毛羊背最长肌脂肪酸组成的影响 Table 3 Effects of oregano essential oil on fatty acid composition in longissimus dorsi muscle of Gansu Alpine Fine-wool sheep
2.3 牛至精油不同添加量对甘肃高山细毛羊半腱肌脂肪酸组成的影响

表 4可知,甘肃高山细毛羊半腱肌中共检测出26种脂肪酸,其中含量高于1%的有肉豆蔻酸(C14:0)、十五烷酸(C15:0)、棕榈酸(C16:0)、棕榈烯酸(C16:1)、十七烷酸(C17:0)、十七碳烯酸(C17:1)、硬脂酸(C18:0)、反油酸(C18:1n9t)、油酸(C18:1n9c)、亚油酸(C18:2n6c)、α亚麻酸(C18:3n3)和二十三烷酸(C23:0)12种脂肪酸,其中油酸(C18:1n9c)含量最高,占总脂肪酸的34.71%~40.35%,其次是棕榈酸(C16:0),占总脂肪酸的22.32%~24.71%,硬脂酸(C18:0)次之,占总脂肪酸的10.50%~12.78%。对照组公羊丁酸(C4:0)、亚油酸(C18:2n6c)、榆树酸(C22:0)、二十碳三烯酸(C20:3n6)、二十三烷酸(C23:0)、二十碳五烯酸(C20:5n3)含量显著高于对照组母羊(P < 0.05),而对照组母羊月桂酸(C12:0)、肉豆蔻酸(C14:0)、油酸(C18:1n9c)含量显著高于对照组公羊(P < 0.05)。Ⅱ组公羊月桂酸(C12:0)、十七碳烯酸(C17:1)、油酸(C18:1n9c)、二十碳二烯酸(C20:2)含量显著高于对照组公羊,Ⅱ组公羊二十碳烯酸(C20:1)和榆树酸(C22:0)含量显著低于对照组公羊(P < 0.05);Ⅰ组母羊硬脂酸(C18:0)和反亚油酸(C18:2n6t)含量显著高于Ⅱ组和对照组母羊(P < 0.05)。对照组公羊PUFA、n-6PUFA及n-3PUFA含量显著高于该组母羊(P < 0.05),且对照组公羊PUFA含量显著高于Ⅱ组公羊(P < 0.05);Ⅱ组公羊MUFA含量显著高于对照组及Ⅰ组公羊(P < 0.05);对照组、Ⅰ组n-6PUFA含量公羊显著高于该组母羊(P < 0.05);Ⅰ组公羊n-6/n-3含量显著高于该组母羊(P < 0.05)。

表 4 牛至精油对甘肃高山细毛羊半腱肌脂肪酸组成的影响 Table 4 Effects of oregano essential oil on fatty acid composition in Semitendinosus muscle of Gansu Alpine Fine-wool sheep
2.4 牛至精油不同添加量对甘肃高山细毛羊共轭亚油酸c9t11含量的影响

表 5可知,除公羊半腱肌外,肌肉中c9t11-CLA含量均随牛至精油添加量的增加而增大;各处理组母羊背最长肌及半腱肌c9t11-CLA含量均高于公羊,且处理Ⅰ组母羊两部位c9t11-CLA含量均显著高于其公羊(P < 0.05);Ⅱ组公羊及母羊背最长肌c9t11-CLA含量分别显著高于对照组公羊和母羊(P < 0.05),与Ⅰ组无显著性差异(P>0.05),其余各组间差异不显著(P>0.05)。

表 5 牛至精油对甘肃高山细毛羊背最长肌和半腱肌中c9t11-CLA的影响 Table 5 Effects of oregano essential oil on c9t11-CLA in longissimus dorsi muscle and Semitendinosus muscle of Gansu Alpine Fine-wool sheep
3 讨论 3.1 牛至精油不同添加量对甘肃高山细毛羊血液生化指标的影响

血液中TG含量反映脂质沉积能力,TC含量反映脂质吸收代谢能力,HDL-C主要促进机体胆固醇代谢、降低胆固醇浓度,而LDL-C的主要作用是由肝向肝外组织输送胆固醇[17]。有研究报道,牛至精油可通过抑菌杀菌改变动物胃肠道微生物,提高反刍动物瘤胃中乳酸菌和双歧杆菌等有益菌的数量,进一步促进胆汁酸的合成,胆汁酸可调控脂质的消化吸收和胆固醇代谢,降低血液中TG和TC浓度[18]。本研究发现,添加牛至精油可降低血清中TC、TG和HDL-C浓度,且对母羊的影响大于公羊,表明牛至精油对血液生理指标的影响可能与性别相关。

3.2 牛至精油不同添加量对甘肃高山细毛羊肌肉脂肪酸组成的影响

反刍动物肌肉脂肪含量和脂肪酸组成直接影响其嫩度、风味等食用品质和贮藏性能[19]。脂肪中脂肪酸的组成与人类健康密切相关[20]。研究表明,SFA可在一定程度上提高血液脂蛋白中胆固醇的含量,其中豆蔻酸(C14:0)、棕榈酸(C16:0)含量与血液中胆固醇水平呈显著正相关,但硬脂酸(C18:0)和短链脂肪酸不能升高血液中胆固醇含量[21-22]。油酸(C18:1n9c)能够降低血脂、胆固醇及LDL-C含量,是良性MUFA之一[23]。UFA是肉品香味的前体物,也是人体重要的营养物质。高含量的UFA,尤其是PUFA有助于防治心脑血管疾病,PUFA能够降低血脂,抑制血小板聚集和抗自身免疫反应,并可促进机体的生长发育[24]。营养调控是快速改变动物肌肉脂肪酸组成的有效方法。有研究表明,通过控制日粮脂肪酸可以使长链PUFA在动物体组织的储存最大化[24]。鸡饲粮中同时添加共轭亚油酸和鱼油可显著提高鸡胸肌和腿肌中n-3PUFA含量[25]。饲料中添加一定比例的龙须菜,可提高草鱼肌肉功能性脂肪酸和PUFA的含量[26]。刘立山等[9]研究发现,饲粮中添加牛至精油可显著降低牛肉SFA含量,显著升高UFA含量。本研究发现,牛至精油对不同性别及不同部位肌肉脂肪酸含量的影响不同,2 g·d-1牛至精油添加量提高了背最长肌中SFA含量,降低了MUFA及UFA含量,对半腱肌中SFA和PUFA含量影响不显著,而4 g·d-1添加量显著提高了公羊背最长肌和半腱肌中MUFA含量,以及母羊背最长肌中PUFA含量。结合血清生化参数测定结果推测,该结果可能是牛至精油通过调节血液中与脂肪形成相关的TG和HDL-C等血清生化参数来完成的;另外,由于肌肉脂肪酸的组成与瘤胃微生物组成相关,该结果也可能由不同牛至精油添加量对瘤胃微生物的影响不同所致,韩旭[27]在鸡日粮中分别添加50、100和150 mg·kg-1牛至精油后发现,100 mg·kg-1组鸡肠道中可促进脂质消化吸收和胆固醇代谢的乳酸菌及双歧杆菌数量最高。牛至精油对肌肉脂肪酸组成的影响还处于探索阶段,其具体作用机理还有待进一步研究。从营养价值来看,4 g·d-1牛至精油添加量有利于甘肃高山细毛羊肌肉品质的改善,2 g·d-1添加量不利于甘肃高山细毛羊脂肪酸组成的改善,但从肉品贮存保鲜来看,UFA的氧化降解是肉质腐败变质的重要原因之一,当肌肉中SFA含量高时肌肉的抗氧化能力可能会有提高的趋势,有利于肉类食品的长期储存。研究发现,牛至精油能够抑制油脂氧化,其抗氧化性在肉糜、水果等食物保鲜及延长货架期中也得到了广泛应用[28-29]。郑宗林等[30]研究发现,牛至精油可明显抑制红罗非鱼片肌肉过氧化进程,对红罗非鱼肉冷藏期肉质保鲜有一定帮助,Alarcón-Rojo等[31]也发现,饲粮添加1 g·kg-1牛至精油可显著提高猪肉脂质抗氧化能力。因此,关于牛至精油对甘肃高山细毛羊肌肉的抗氧化性作用还有待进一步研究。

3.3 牛至精油不同添加量对甘肃高山细毛羊肌肉共轭亚油酸含量的影响

共轭亚油酸(conjugated linoleic acid,CLA)是最初在反刍动物瘤胃中分离所得的一种不饱和脂肪酸,由于其主要来源于瘤胃,因此又被命名为瘤胃酸,有多种异构体,反刍动物产品中主要的CLA异构体是c9t11-CLA,约占总CLA的80%~90%[32]。植物组织及海产品中CLA含量很少,天然来源的CLA主要存在于牛、羊的乳脂及肉制品中,而羊肉中CLA的含量比牛肉及乳制品中含量均高,故羊肉中共轭亚油酸的含量也可间接反映其营养价值[33-34]。CLA具有特异性生物保健功能,可促进机体生长发育、提高免疫力、抗动脉硬化等,其中最引人关注的功能是抗癌作用。CLA可抑制皮肤癌、乳腺癌等细胞的癌变和扩散[35]。有研究报道,日粮中添加植物油或鱼油能显著提高泌乳母牛乳脂中CLA的含量,同时也会导致乳脂率降低[36]。本研究发现,甘肃高山细毛羊母羊肌肉中CLA含量高于公羊,另外随着牛至精油添加量的增加,甘肃高山细毛羊背最长肌和半腱肌中c9t11-CLA含量呈递增趋势,其中4 g·d-1添加量使公羊和母羊背最长肌c9t11-CLA含量均显著提高,其肉制品更加符合目前消费者对健康、保健食品的要求。反刍动物肌肉和乳脂共轭亚油酸含量取决于瘤胃中CLA和总挥发性脂肪酸的产量[37],牛至精油可通过改变反刍动物瘤胃微生态,调控瘤胃发酵产物的生成,从而改善其产品中CLA含量。

4 结论

本研究表明,甘肃高山细毛羊母羊肌肉中CLA含量高于公羊,饲粮中添加牛至精油可提高甘肃高山细毛羊肌肉中CLA含量,在本试验条件下4 g·d-1牛至精油添加量效果最佳。

参考文献
[1] 王秋梅. 牛至油对肉仔鸡生长性能和细胞免疫功能的影响[J]. 饲料与畜牧, 2008(7): 48–50.
WANG Q M. Effects of oregano oil on growth performance and cellular immune function of broilers[J]. Food and Husbandry, 2008(7): 48–50. DOI: 10.3969/j.issn.1006-6314-B.2008.07.014 (in Chinese)
[2] 牛彪, 梁剑平, 刘宇. 牛至精油在兽药基础研究中的进展[J]. 动物医学进展, 2018, 39(4): 92–96.
NIU B, LIANG J P, LIU Y. Progress on oregano essential oil in basic veterinary drug research[J]. Progress in Veterinary Medicine, 2018, 39(4): 92–96. DOI: 10.3969/j.issn.1007-5038.2018.04.019 (in Chinese)
[3] 杨昭, 刘婷, 吴建平, 等. TMR中添加牛至精油抑菌作用的研究[J]. 中国农学通报, 2015, 31(14): 8–13.
YANG Z, LIU T, WU J P, et al. Bacteriostatic action of oregano essential off adding to TMR[J]. Chinese Agricultural Science Bulletin, 2015, 31(14): 8–13. DOI: 10.11924/j.issn.1000-6850.casb15010026 (in Chinese)
[4] 徐方华.牛至油及主要成分对瘤胃发酵特性和甲烷产量影响的研究[D].延吉: 延边大学, 2014.
XU F H.Research on the effect of oregano oil and main components on rumen fermentation characteristics and methane production[D].Yanji: Yanbian University, 2014. (in Chinese) http://cdmd.cnki.com.cn/Article/CDMD-10184-1014359780.htm
[5] 汪莉, 李军. 牛至油与安来霉素对仔猪生产性能的影响[J]. 畜禽业, 2006(5): 14–15.
WANG L, LI J. Effect of oregano oil and Amithromycin on piglet performance[J]. Livestock and Poultry Industry, 2006(5): 14–15. DOI: 10.3969/j.issn.1008-0414.2006.05.004 (in Chinese)
[6] 陈昊, 刘婷, 姚喜喜, 等. 牛至精油对荷斯坦奶牛乳房炎和腹泻发病率的影响[J]. 中国草食动物科学, 2015, 35(2): 39–41.
CHEN H, LIU T, YAO X X, et al. Effect of oregano essential oil on the mastitis and diarrhea of Holstein cows[J]. China Herbivore Science, 2015, 35(2): 39–41. DOI: 10.3969/j.issn.2095-3887.2015.02.012 (in Chinese)
[7] 陈昊, 刘婷, 吴建平, 等. 牛至精油对新生犊牛生长发育和血液免疫的影响[J]. 草业科学, 2017, 34(10): 2141–2148.
CHEN H, LIU T, WU J P, et al. Effects of oregano essential oil on growth and hematogenic immunity of newborn calves[J]. Pratacultural Science, 2017, 34(10): 2141–2148. DOI: 10.11829/j.issn.1001-0629.2016-0559 (in Chinese)
[8] NOWERS N.The effect of an oregano oil extract in a lactating dairy cow diet on production responses of Holstein cows[D].Stellenbosch: Stellenbosch University, 2016: 13-17.
[9] 刘立山, 刘婷, 周瑞, 等. 饲粮中添加牛至精油对牛肉脂肪酸含量及氧化稳定性的影响[J]. 甘肃农业大学学报, 2017, 52(4): 23–29.
LIU L S, LIU T, ZHOU R, et al. Effects of adding oregano oil to ration on beef fatty acid content and oxidative stability of the beef[J]. Journal of Gansu Agricultural University, 2017, 52(4): 23–29. (in Chinese)
[10] 陈立华, 袁缨, 王秋梅. 不同水平牛至油对肉仔鸡生产性能和胴体品质的影响[J]. 今日畜牧兽医, 2006(12): 3–5.
CHEN L H, YUAN Y, WANG Q M. Effects of different levels of oregano oil on growth performance and carcass quality of broilers[J]. Today Animal Husbandry and Veterinary Medicine, 2006(12): 3–5. (in Chinese)
[11] 徐善金, 朱永兴. 牛至油对肉鸭生长及屠宰性能影响的研究[J]. 现代畜牧兽医, 2013(11): 20–23.
XU S J, ZHU Y X. Effects of oregano oil addictive on production performance and carcass traits of ducks[J]. Modern Journal of Animal Husbandry and Veterinary Medicine, 2013(11): 20–23. DOI: 10.3969/j.issn.1672-9692.2013.11.004 (in Chinese)
[12] 王娟, 吴建平, 焦婷, 等. 添加牛至精油对绵羊瘤胃发酵特征及青贮、黄贮玉米秸秆瘤胃降解率的影响[J]. 甘肃农业大学学报, 2018, 53(4): 8–14.
WANG J, WU J P, JIAO T, et al. Effects of oregano essential oil adding on sheep rumen fermentation and degradation of corn silage and corn straw silage[J]. Journal of Gansu Agricultural University, 2018, 53(4): 8–14. DOI: 10.3969/j.issn.1003-4315.2018.04.002 (in Chinese)
[13] 保国俊, 何茂昌, 王珂, 等. 甘肃高山细毛羊种质资源保护方案[J]. 畜牧兽医杂志, 2016, 35(5): 51–54.
BAO G J, HE M C, WANG K, et al. Genetic resources conservation plan of Gansu Alpine Fine-wool sheep[J]. Journal of Animal Science and Veterinary Medicine, 2016, 35(5): 51–54. (in Chinese)
[14] 朱晓艳, 吕先召, 邱晓东, 等. 苜蓿草粉对育肥猪肉品质、肌肉氨基酸和脂肪酸含量的影响[J]. 动物营养学报, 2018, 30(9): 3473–3482.
ZHU X Y, LV X Z, QIU X D, et al. Effects of alfalfa meal on meat quality, muscle amino acids and fatty acids contents of finishing pigs[J]. Chinese Journal of Animal Nutrition, 2018, 30(9): 3473–3482. DOI: 10.3969/j.issn.1006-267x.2018.09.017 (in Chinese)
[15] 罗阳.桑树叶与羊草的组合效应及其对绵羊瘤胃发酵、生长性能、脂肪沉积和肉品质的影响[D].扬州: 扬州大学, 2018.
LUO Y.Associative effects of mulberry leave with leymus chinensis and affects on rumen fermentation, growth performance, fat deposition in sheep fed with the combined forage diet[D].Yangzhou: Yangzhou University, 2018. (in Chinese)
[16] O'FALLON J V, BUSBOOM J R, NELSON M L, et al. A direct method for fatty acid methyl ester synthesis:Application to wet meat tissues, oils, and feedstuffs[J]. J Anim Sci, 2007, 85(6): 1511–1521. DOI: 10.2527/jas.2006-491
[17] 祝倩, 姬玉娇, 李华伟, 等. 高、低营养水平饲粮对妊娠环江香猪繁殖性能、体成分和血浆生化参数的影响[J]. 动物营养学报, 2016, 28(5): 1534–1540.
ZHU Q, JI Y J, LI H W, et al. High-or low-nutrient level diets affect reproductive performance, body composition and plasma biochemical parameters of pregnant Huanjiang mini-pigs[J]. Chinese Journal of Animal Nutrition, 2016, 28(5): 1534–1540. DOI: 10.3969/j.issn.1006-267X.2016.05.030 (in Chinese)
[18] 韩丽, 潘杰, 张婷, 等. 低聚木糖对生长肥育猪血浆生化参数和肌肉脂肪酸组成的影响[J]. 动物营养学报, 2017, 29(9): 3316–3324.
HAN L, PAN J, ZHANG T, et al. Effects of Xylo-oligosaccharide on plasma biochemical parameters and fatty acid composition of muscle in growing-finishing pigs[J]. Chinese Journal of Animal Nutrition, 2017, 29(9): 3316–3324. DOI: 10.3969/j.issn.1006-267x.2017.09.036 (in Chinese)
[19] ARSHAD M S, SOHAIB M, AHMAD R S, et al. Ruminant meat flavor influenced by different factors with special reference to fatty acids[J]. Lipids Health Dis, 2018, 17: 223. DOI: 10.1186/s12944-018-0860-z
[20] 双金, 敖力格日玛, 敖长金. 苏尼特羊体脂脂肪酸组成的研究[J]. 畜牧兽医学报, 2015, 46(8): 1363–1374.
SHUANG J, AO L G R M, AO C J. Study on composition of Sunit sheep body fatty acid[J]. Acta Veterinaria et Zootechnica Sinica, 2015, 46(8): 1363–1374. (in Chinese)
[21] 陈银基.不同影响因素条件下牛肉脂肪酸组成变化研究[D].南京: 南京农业大学, 2007.
CHEN Y J.Study on changes of fatty acids profiles of beef under different factors[D].Nanjing: Nanjing Agricultural University, 2007. (in Chinese) http://cdmd.cnki.com.cn/Article/CDMD-10307-2008031557.htm
[22] COLOMBO S M, PARRISH C C, WIJEKOON M P A. Optimizing long chain-polyunsaturated fatty acid synthesis in salmonids by balancing dietary inputs[J]. PLoS One, 2018, 13(10): e0205347. DOI: 10.1371/journal.pone.0205347
[23] 祝仁铸.野莱F1猪肉品质及肌内脂肪沉积机理的研究[D].泰安: 山东农业大学, 2013.
ZHU R Z.Study on the meat qualities and the sedimentary mechanism of intramuscular fat in YL F1 pigs[D].Tai'an: Shandong Agricultural University, 2013. (in Chinese) http://cdmd.cnki.com.cn/Article/CDMD-10434-1014156646.htm
[24] CARLSON S J, O'LOUGHLIN A A, ANEZ-BUSTILLOS L, et al. A diet with docosahexaenoic and arachidonic acids as the sole source of polyunsaturated fatty acids is sufficient to support visual, cognitive, motor, and social development in mice[J]. Front Neurosci, 2019, 13: 72. DOI: 10.3389/fnins.2019.00072
[25] 刘永祥, 刘艳丽, 姜东风, 等. 共轭亚油酸和鱼油组合对雄性肉鸡屠体性状、肌肉脂肪酸组成和脂质过氧化状态的影响[J]. 动物营养学报, 2015, 27(8): 2517–1526.
LIU Y X, LIU Y L, JIANG D F, et al. Combination effects of conjugated linoleic acid and fish oil on carcass traits, fatty acid composition and lipid peroxidation status of muscles of male broiler chickens[J]. Chinese Journal of Animal Nutrition, 2015, 27(8): 2517–1526. DOI: 10.3969/j.issn.1006-267x.2015.08.025 (in Chinese)
[26] 陈明, 刘永坚, 李雅婷, 等. 饲料中添加龙须菜对草鱼生长性能、血清生化指标及肌肉脂肪酸组成的影响[J]. 动物营养学报, 2016, 28(4): 1257–1266.
CHEN M, LIU Y J, LI Y T, et al. Effects of dietary gracilaria lemaneiformis on growth performance, serum biochemical indices and muscle fatty acid composition of grass carp (Ctenopharyngodon idellus)[J]. Chinese Journal of Animal Nutrition, 2016, 28(4): 1257–1266. DOI: 10.3969/j.issn.1006-267x.2016.04.038 (in Chinese)
[27] 韩旭.牛至油对蛋鸡肠道消化吸收功能影响的研究[D].大庆: 黑龙江八一农垦大学, 2013.
HAN X.The effects of oregano oil on intestinal digestion and absorptive function in layinghens[D].Daqing: Heilongjiang Bayi Agricultural University, 2013. (in Chinese) http://cdmd.cnki.com.cn/Article/CDMD-10223-1013207867.htm
[28] DOLEA D, RIZO A, FUENTES A, et al. Effect of thyme and oregano essential oils on the shelf life of salmon and seaweed burgers[J]. Food Sci Technol Int, 2018, 24(5): 394–403. DOI: 10.1177/1082013218759364
[29] KINTZIOS S, PAPAGEORGIOU K, YIAKOUMETTIS I, et al. Evaluation of the antioxidants activities of four Slovene medicinal plant species by traditional and novel biosensory assays[J]. J Pharm Biomed Anal, 2010, 53(3): 773–776. DOI: 10.1016/j.jpba.2010.05.013
[30] 郑宗林, 朱成科, GATLINⅢ D M. 饲料中添加牛至精油对红罗非鱼货架期的影响[J]. 食品科学, 2015, 36(22): 203–209.
ZHENG Z L, ZHU C K, GATLINⅢ D M. Evaluation of the dose of oregano essential oil in the feed to prolong the shelf life of Oreochromis niloticus×O. mossambicus[J]. Food Science, 2015, 36(22): 203–209. DOI: 10.7506/spkx1002-6630-201522039 (in Chinese)
[31] ALARCÓN-ROJO A D, PEÑA-GONZÁLEZ E, JANACUA-VIDALES H, et al. Meat quality and lipid oxidation of pork after dietary supplementation with oregano essential oil[J]. World Appl Sci J, 2013, 21(5): 665–673.
[32] 王小静.调控反刍动物消化代谢提高乳脂中共轭亚油酸含量及其机理的研究[D].南京: 南京农业大学, 2007.
WANG X J.Study on manipulation of ruminant digestion and metabolism to enhance conjugated linoleic acid content in milk fat and its involved mechanism[D].Nanjing: Nanjing Agricultural Univesity, 2007. (in Chinese) http://cdmd.cnki.com.cn/Article/CDMD-10307-2008031408.htm
[33] 吴风亮, 陈卫涛, 张若鸿, 等. 共轭亚油酸的生理功效及其在乳品中的强化途径[J]. 中国乳品工业, 2004, 32(11): 24–30.
WU F L, CHEN W T, ZHANG R H, et al. Physiological benifits and fortifications of conjugated linoleic acids in dairy products[J]. China Dairy Industry, 2004, 32(11): 24–30. DOI: 10.3969/j.issn.1001-2230.2004.11.007 (in Chinese)
[34] 杨晶.不同月龄不同部位羊肉中共轭亚油酸的含量及脂肪酸成分的分析[D].呼和浩特: 内蒙古农业大学, 2014.
YANG J.Analysis of the conjugated linoleic acid content and fatty acid composition in fat from different months and different parts of sheep[D].Hohhot: Inner Mongolia Agricultural University, 2014. (in Chinese) http://cdmd.cnki.com.cn/Article/CDMD-10129-1014374174.htm
[35] HA Y L, GRIMM N K, PARIZA M W. Anticarcinogens from fried ground beef:heat-altered derivatives of linoleic acid[J]. Carcinogenesis, 1987, 8(12): 1881–1887. DOI: 10.1093/carcin/8.12.1881
[36] SHINGFIELD K J, AHVENJÄRVI S, TOIVONEN V, et al. Effect of incremental levels of sunflower-seed oil in the diet on ruminal lipid metabolism in lactating cows[J]. Br J Nutr, 2008, 99(5): 971–983. DOI: 10.1017/S0007114507853323
[37] LOCK A L, BAUMAN D E, GARNSWORTHY P C. Short communication:effect of production variables on the Cis-9, Trans-11 conjugated linoleic acid content of cows' milk[J]. J Dairy Sci, 2005, 88(8): 2714–2717. DOI: 10.3168/jds.S0022-0302(05)72950-7