兰州大学机构库 >草地农业科技学院
植物精油对羔羊生长性能和瘤胃微生物代谢的影响
Alternative TitleEffects of Essential Oil on Growth Performance and Rumen Microbial Metabolism of Lambs
孟亚蓉
Subtype硕士
Thesis Advisor王静
2023-05-27
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name农学硕士
Degree Discipline畜牧学
Keyword植物精油,羔羊,生长性能,脂肪酸组成,瘤胃微生物 essential oil lamb growth performance fatty acid composition rumen microbial
Abstract

植物精油(Essential Oil,EO)是植物次级代谢物,因其具有强抗氧化性和广谱抗菌性而被人们作为天然绿色饲料添加剂在反刍动物生产中应用,用以提高动物生产性能和维护机体健康。肉桂油源于肉桂,其化学成分是肉桂醛,能影响细菌群落,促进瘤胃发酵模式向丙酸型发酵;牛至油源于牛至,其化学成分是香芹酚,能清除动物氧化应激时产生的自由基,提高动物的抗氧化能力。研究发现,与单一EO相比,复合EO的作用效果更好。因此,本研究拟评估富含肉桂醛和香芹酚的复合EO对湖羊羔羊生长性能、营养物质消化率、长链脂肪酸(Long chain fatty acid,LCFA)的瘤胃生物氢化和多不饱和脂肪酸(Polyunsaturated fatty acid,PUFA)在背最长肌中沉积的影响,确定其在反刍动物生产中的应用效果,明确作用机理,以期为EO在肉羊生产中科学、合理的应用提供数据支撑和理论依据。

1、植物精油对羔羊生长性能、养分消化、瘤胃发酵及抗氧化性能的影响

本研究采用单因素随机试验设计,将64只湖羊公羔随机分配到4个添加0、30、60和120 mg/kg EO的处理组中,通过70 d动物饲养试验探究EO对羔羊生长性能、养分消化、瘤胃发酵及抗氧化性能的影响。

(1)随EO添加量的增加,羔羊末体重(FBW)呈线性增加(P < 0.05)和先降低后提高的二次变化趋势(P = 0.06),平均日增重(ADG)呈线性增加和先降低后提高的二次变化(P < 0.05),饲料转化效率呈先降低后提高的二次变化(P < 0.05),并有线性增加趋势(P = 0.07)。

(2)随EO添加量的增加,干物质(DM)、有机物(OM)、粗蛋白(CP)和能量的表观消化率呈线性下降和二次变化(P < 0.05),中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)和半纤维素表观消化率呈线性下降(P < 0.05)。

(3)添加EO线性降低羔羊瘤胃总挥发性脂肪酸(TVFA)浓度和乙丙比(P < 0.05)。随EO添加量的增加,乙酸摩尔比例呈线性降低和二次变化(P < 0.05),但丁酸摩尔比例呈线性增加和二次变化(P < 0.05)。

(4)随EO添加量的增加,血清超氧化物歧化酶(SOD)活性呈线性增加和二次变化(P < 0.05),谷胱甘肽过氧化物酶(GSH-Px)活性和总抗氧化能力(T-AOC)呈线性增加(P < 0.05)。

2、植物精油对羔羊背最长肌脂肪酸组成和瘤胃生物氢化的影响

由于EO线性影响湖羊公羔的瘤胃发酵模式和饲粮养分表观消化率,因此本试验随机选取饲喂0 mg/kg和120 mg/kg EO的各7只羔羊屠宰取样,分析其屠宰性能、背最长肌脂肪酸组成、瘤胃生物氢化和细菌群落。

(1)饲粮中添加120 mg/kg EO能提高羔羊宰前活重和胴体重(P < 0.05)。

(2)饲粮中添加120 mg/kg EO分别提高背最长肌中的ΣPUFA和Σn-6 FA比例(P ≤ 0.05),降低Σn-3 FA/Σn-6 FA(P < 0.05),并有降低ΣSFA/ΣPUFA的趋势(P = 0.06),C18:2n6c、C20:3n6和C20:5n3的比例分别增加25.0%、78.8%和100%(P ≤ 0.05)。

(3)饲粮中添加120 mg/kg EO对羔羊瘤胃内容物中ΣSFA、ΣMUFA、ΣPUFA、Σn-3 FA、Σn-6 FA、ΣSFA/ΣPUFA和Σn-3 FA/Σn-6 FA无影响(P > 0.05)。

(4)饲粮中添加120 mg/kg EO增加羔羊瘤胃细菌PD指数和观察到的ZOTU指数(P ≤ 0.05)。瘤胃内容物门、纲、目、科和属水平共获得38个差异显著的细菌,0 mg/kg处理组的羔羊瘤胃中共发现24个差异显著的细菌,其中门水平上是Actinobacteriota和Firmicutes;120 mg/kg EO的羔羊瘤胃中共发现14个差异显著的细菌,其中门水平上是Bacteroidota和Verrucomicrobiota。

(5)饲粮中添加120 mg/kg EO后预测得到的代谢基因相对丰度提高2.5%(P < 0.05),上调中枢碳水化合物代谢(Central carbohydrate metabolism)途径中的半磷酸化Entner-Doudoroff途径(Semi-phosphorylative Entner-Doudoroff pathway),下调非氧化磷酸戊糖途径(Pentose phosphate pathway, non-oxidative phase)(P < 0.05)。

(6)基因预测表明Firmicutes、Spirochaetota和Bacteroidota成员具有瘤胃生物氢化功能。在至少拥有一个瘤胃生物氢化基因的前100个ZOTU中,受EO影响的基因有16个,其中Firmicutes中的基因减少10个,增加5个,而Spirochaetota中的基因仅增加1个(P < 0.05)。

综上所述,添加120 mg/kg EO不仅能提高饲料转化效率节约成本,还能减少羔羊氧化应激和增加肌肉中PUFA的沉积,故在本研究评估的剂量范围内综合EO的作用效果,最适添加剂量为120 mg/kg。

Other Abstract

Essential oil (EO) is secondary metabolites of plants. It has strong antioxidant and broad-spectrum antibacterial properties. Thus, the EO is used to improve animal production performance and maintain animal health, as natural feed additive in ruminant production. The chemical composition of cinnamon oil originated from cinnamon is cinnamaldehyde. Cinnamaldehyde affects bacterial community and promote the rumen fermentation tended to propionate. Carvacrol is the main chemical component of oregano oil originated from oregano. It eliminates free radicals generated during oxidative stress in animals and improve their antioxidant capacity. The study indicated that the effect of compound EO is better than EO. In order to determine the application effect of EO rich in cinnamaldehyde and carvacrol in ruminant production, clarify the mechanism, the present study evaluated the effects of EO on growth performance, nutrient digestibility, rumen biohydrogenation of long chain fatty acid (LCFA), and polyunsaturated fatty acid (PUFA) deposition in longissimus dorsi of lambs, so as to provide data support and theoretical basis for scientific and reasonable application of EO in mutton sheep production.

1. Effects of essential oil on growth performance, nutrient digestibility, rumen fermentation and antioxidant performance of lamb

Under a single factor design, 64 Hu lambs were randomly assigned to four dietary treatments of EO supplemented at 0, 30, 60, and 120 mg/kg in this study. The effects of an EO on growth performance, nutrient digestibility, rumen fermentation and antioxidant performance were studied by animal feeding experiments during 70 d.

(1) FBW responded linearly (P < 0.05) and tended to firstly decrease and then increase in a quadratic manner (P = 0.06) to EO. ADG was linearly increased and firstly decreased and then increased in a quadratic manner with increasing supplementation of EO (P < 0.05). The feed conversion rate was firstly decreased and then increased in a quadratic manner (P < 0.05) with increasing supplementation of EO, and tended to be linearly increased (P = 0.07) by increasing supplementation of EO.

(2) The apparent digestibilities of DM, OM, CP, and energy linearly decreased and quadratically respond (P < 0.05) with increasing supplementation of EO. The apparent digestibilities of NDF, ADF and hemicellulose linearly (P < 0.05) decreased with EO supplementation.

(3) Supplementation with EO linearly decreased total VFA concentration (P < 0.05) and the acetate to propionate ratio (P < 0.05). The molar percentage of acetate was linearly decreased and quadratically respond (P < 0.05), but linearly increased and quadratically respond the molar percentage of butyrate in rumen of lambs with increasing supplementation of EO (P < 0.05).

(4) The activity of SOD linearly increased and quadratically respond (P < 0.05) with increasing supplementation of EO. Supplementation with EO linearly increased the activity of GSH-Px and T-AOC (P < 0.05).

2. Effects of essential oil on fatty acid composition of longissimus dorsi and rumen biohydrogenation of lamb

As the effects of EO supplementation dosage on rumen fermentation pattern and the apparent digestibility of the diet of Hu lambs were linear, subsequent analysis of EO supplementation effects on slaughter performance, fatty acid composition of longissimus dorsi, rumen biohydrogenation and rumen bacterial community, were conducted by comparing the highest supplementation dose of 120 mg/kg and the control group. Seven lambs from each treatment were randomly selected to slaughter sampling.

(1) Supplementation with 120 mg/kg of EO in diet increased pre-slaughter weight and carcass weight of lambs (P < 0.05).

(2) Supplementation with 120 mg/kg of EO in diet increased the proportions of ΣPUFA and Σn-6 FA (P ≤ 0.05), decreased the ratio Σn-3 FA/Σn-6 FA (P < 0.05), and tended to decrease ΣSFA/ΣPUFA in longissimus dorsi (P = 0.06), but increased by 25.0%, 78.8%, and 100% the proportions of C18:2n6c, C20:3n6 and C20:5n3, respectively (P ≤ 0.05).

(3) Supplementation with 120 mg/kg of EO in diet did not affect the proportions of ΣSFA, ΣMUFA, ΣPUFA, Σn-3 FA, Σn-6 FA, ΣSFA/ΣPUFA, and Σn-3 FA/Σn-6 FA in the rumen contents of lambs (P > 0.05).

(4) Supplementation with 120 mg/kg of EO in diet increased the PD index, Observed ZOTU (P ≤ 0.05). A total of 38 bacteria with significant differences were obtained at the levels of phyla, class, order, family, and genus in the rumen content. Twenty four taxonomic groups were enriched in the rumen of lambs fed the control diet: phyla Actinobacteriota and Firmicutes. Specifically. Fourteen clades were enriched in the rumen of lambs fed 120 mg/kg of EO: phyla Bacteroidota and Verrucomicrobiota.

(5) The relative abundance of genes predicted to be involved in metabolism was 2.5% higher in rumen of lambs fed diet with 120 mg/kg of EO than in the rumen of lambs fed the control diet (P < 0.05). There were two modules involved in central carbohydrate metabolism affected by 120 mg/kg of EO supplementation, with the semi-phosphorylative Entner-Doudoroff pathway being increased and the pentose phosphate pathway (non-oxidative phase) decreased (P < 0.05).

(6) The gene prediction indicated that Firmicutes, Spirochaetota, and Bacteroidota had the function of rumen biohydrogenation. Among the top 100 ZOTU with at least one rumen biohydrogenation genomes, there were sixteen predicted genomes in major contributors to biohydrogenation affected by supplementation of EO (P ≤ 0.05), with ten predicted genomes in the phylum Firmicutes being decreased (P ≤ 0.05), and five genomes in the phylum Firmicutes and one genome in the phylum Spirochaetota being increased (P < 0.05).

In conclusion, supplementation 120 mg/kg of EO to the diet not only improved feed conversion rate and save costs, but also reduced oxidative stress and increased the deposition of PUFA in muscle of lambs. Considering comprehensive effects of EO, supplementation the EO at 120 mg/kg was optimal within the doses evaluated in this study.

MOST Discipline Catalogue农学 - 畜牧学 - 动物营养与饲料科学
URL查看原文
Language中文
Other Code262010_220200901330
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/539182
Collection草地农业科技学院
Affiliation
兰州大学草地农业科技学院
Recommended Citation
GB/T 7714
孟亚蓉. 植物精油对羔羊生长性能和瘤胃微生物代谢的影响[D]. 兰州. 兰州大学,2023.
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