Effect of Different Levels of Oregano Essential Oil on Some Rumen Parameters in Lambs#

Aylin ÜNAL BARUH1, Neşe KOCABAĞLI2*


1Tilia Veterinary Clinic, Teşvikiye Mah. Nişantaşı Ihlamur yolu sok. No:86/B Şişli, Istanbul, TURKEY

2Istanbul University, Faculty of Veterinary Medicine, Department of Animal Nutrition and Nutritional Diseases, TR-34320 Istanbul, TURKEY


*Sorumlu Yazar / Corresponding Author:

Neşe Kocabağlı

e-mail: kbagli@istanbul.edu.tr

Geliş Tarihi / Received:

21 November 2016

Kabul Tarihi / Accepted:

17 January 2017

Anahtar Kelimeler:

Amonyak nitrojeni, kekik uçucu yağı,

kuzu, pH, rumen, uçucu yağ asitleri

Key Words:

Ammonia-nitrogen, oregano essential oil, lamb, pH, rumen, volatile fatty acids

Abstract

This study was conducted to determine the effects of different levels of oregano (Origanum vulgare) essential oil (OEO) on ruminal fermentation in lambs. Thirty-six weaned male Kivircik lambs were used as trial materials. Lambs were divided into one control and two treatment groups. For the two treatment groups, OEO was added into grower feed at a level of 250 and 500 ppm, respectively. Treatment period lasted for 9 weeks, including adaptation period. Feed and water was supplied ad libitum during the trial. Rumen fluid samples were collected from 9 lambs of each group, before the morning feeding and 3 and 6 hours after the feeding. From the ruminal fluid, pH, total volatile fatty acids (VFA), acetic acid, propionic acid, butyric acid and ammonia-nitrogen concentrations were determined. There were no effects of OEO on ruminal pH and concentrations of ammonia. In some of the rumen parameters (pH and total VFA), the results were statistically different periodically between groups and it was established that the time of measurement had an important role on the results of the rumen parameters. Furthermore, the quantitative increase of the total volatile fatty acid concentrations in the treatment groups according to the control was directly proportional to the increase of the oregano levels, in the periods except for the beginning. This situation makes us think that the oregano essential oil could have positive effects on digestion in lambs.


Özet

Yeme Farklı Düzeylerde Katılan Kekik Yağının Kuzularda Bazı Rumen Parametreleri Üzerine Etkisi

Bu çalışma, kuzularda, rasyona farklı düzeylerde katılan kekik (Origanum vulgare) uçucu yağının rumen fermantasyon parametreleri üzerine etkilerini saptamak amacı ile yürütülmüştür. Bu amaçla 36 baş sütten kesilmiş, erkek Kıvırcık ırkı kuzu deneme materyali olarak kullanılmıştır. Kuzular, biri kontrol, ikisi deneme grubu olmak üzere üç gruba ayrılmıştır. Deneme gruplarından birinin kuzu büyütme yemine 250 ppm, diğerine ise 500 ppm kekik uçucu yağı (OEO) eklenmiştir. Deneme, ilk haftası adaptasyon dönemi olmak üzere, toplam 9 hafta sürdürülmüş; deneme süresince büyütme yemi, kuru ot ve su ad libitum olarak verilmiştir. Yemlemeden önce ve yemlemeden sonraki 3. ve 6. saatlerde, her gruptan 9 adet kuzudan rumen sıvısı örnekleri alınmıştır. Rumen sıvılarında; pH, toplam uçucu yağ asitleri (UYA), asetik asit, propiyonik asit, bütirik asit ve amonyak azotu düzeyleri belirlenmiştir. Rumen parametrelerinden bazılarında (pH ve toplam UYA) ve dönemsel olarak gruplar arasında istatistiksel önemde farklılıkların olduğu ve ölçüm zamanının da bu parametrelerin üzerinde önemli bir etkiye sahip olduğu belirlenmiştir. Bunun yanı sıra, başlangıç dönemi dışındaki diğer dönemlerde, kekik esansiyel yağının dozunun artması ile orantılı olarak deneme gruplarının toplam uçucu yağ asidi düzeylerinin kontrole göre her zaman için sayısal bir artış içinde olması, kekik esansiyel yağının sindirim üzerinde olumlu bir etki meydana getirdiğini düşündürmektedir.


Introduction

For the past few decades, phytogenic feed additives such as plant extracts have received increased attention as potential alternatives to growth promoters for animal production (Benchaar et al., 2008). The use of essential

oils (EO) in animal nutrition is growing in Turkey, as well as all over the world, because their consumption by humans and animals is recognized as safe (OJEU of 10/18/2003), and they have many beneficial effects (Ünal and Kocabağlı, 2014a).


image

#This study was summarized from the doctoral thesis (supported by the Istanbul University Research Fund, Project number:T-2418). Presented

at International VETistanbul Group Congress (poster presentation), 7-9 April 2015, Saint Petersburg- Russia.

Ünal Baruh and Kocabağlı, J. Fac. Vet. Med. Istanbul Univ., 43 (2), 116-122, 2017 117


There are numerous studies showing beneficial effects of herbs and plant extracts on feed intake, immune functions and health, rumen fermentation and productivity of calves, dairy cows, heifers and also beef cattle (Cardozo et al., 2006; Devant et al., 2007; Fandiño et al., 2008; Greathead, 2003; Vakili et al., 2013; Yang et al,. 2007). Moreover, EO have been evaluated for their antimicrobial activity and they are being investigated as rumen modifiers in ruminants (Wallace, 2004). The chemical composition and dosage rate of EO may also affect the manner in which they alter ruminal N metabolism (Castillejos et al., 2006). However, most experiments conducted on EO have been laboratory based (in vitro) and of short-term nature (Busquet et al., 2006; Hristov et al., 2008). There are very limited in vivo studies that have evaluated the effectiveness of EO on rumen parameters of ruminants, especially in lambs.

The objective of the present study was to investigate the effects of oregano essential oil (OEO), which is produced in Turkey and added in different levels into the feed, on ruminal fermentation characteristics of growing lambs.

Materials and Methods Animals, feeding, and feed analyses

This experiment, conducted with the principles of ethical committee, was approved by Istanbul University Local Ethical Committee on the Care and Use of Experimental Animals (No: 05). In this study, 36 weaned male Kivircik lambs with an initial live weight of 22.71 ±

0.71 kg obtained from the research farm of Istanbul University were used. The study lasted for 9 weeks including one-week adaptation period. At the end of adaptation period, live weights of the lambs were recorded and they were randomized in three groups, two treatment groups and one control group each of which consisted of 12 lambs.

During the study, hay was used as forage and lamb grower feed was used as concentrate pellets. Concentrate feed was specially produced (oregano essential oil sprayed on to pellets) on a monthly basis in a factory, in order to prevent the spoiling of oregano essential oil (OEO) while it was stored. The oregano oil was added into lamb grower feed of two treatment groups, for the first treatment group 250 ppm, and 500 ppm for the second treatment group. The oregano oil used in the study, was provided from a commercial company (Türer Tarım ve Orman Ürünleri A.Ş., İzmir) in Turkey and analyzed in BIBAM Laboratory of Anadolu University and it was reported that analyzed material contained 65.0% carvacrol and 0.3% thymol.


Feed ingredients were formulated by regarding maintenance and performance rate for weaned lambs and in accordance with nutrient and energy requirements specified by NRC (1985). In the study, group feeding method was used and a diet consisting of 60% concentrate pellets + 40% hay (metabolizable energy (ME) = 2.65 Mcal/kg) and ad libitum water were offered. Dry matter, crude ash, crude protein, crude fat (ether extracts) and crude cellulose contents of lamb grower feed and hay were analyzed according to AOAC (1995) procedures, colorimetric calcium level analysis and spectrophotometric phosphorus level analysis were performed in the laboratory of Animal Nutrition and Nutritional Diseases department (Veterinary Faculty, Istanbul University). The neutral detergent fiber (NDF) and acid detergent fiber (ADF) analyses were carried out as described by Van Soest et al. (1991) and Goering and Van Soest (1970), respectively (Table 1).

Rumen samples collection and analyses

On day 1, 28, and 56 of the experiment, samples of whole ruminal contents were collected from 9 lambs of each group, before the morning feeding and 3 and 6 hours after feeding. The ruminal pH was measured immediately with a portable pH meter (Hanna Instruments pH 211 microprocessor pH meter, Romania).

Ruminal fluid was strained through 4 layers of cheesecloth, and 2 sub-samples of the filtrate were acidified to pH 2 with 50% H2 SO4 and frozen at -20°C for later determination volatile fatty acids, and ammonia nitrogen (NH3 -N) analyses. Ammonia nitrogen and total VFA concentrations of ruminal fluid were measured according to steam distillation method described by Markham (1942). Samples for VFA analysis were prepared as described by Erwin et al. (1961) and analyzed by GLC (Sigma-Aldrich, USA) using a polyethylene glycol nitroterephthalic acid-treated capillary column (Column 80/120 Carbopack B-DA / 4% Carbowax 20M, USA) at 200°C in the injector and 1.2 mL/min gas flow rate (24 mL /sec gas velocity). Ammonia N concentration was analyzed by spectrophotometry (Chebios UV-VIS, Italy).

Statistical Analysis

For the statistical analysis of ruminal fermentation characteristics (pH, VFA, and NH3 -N), sampling time and sampling time × treatment were added to the model and analyzed using repeated measures variance analysis method. In the statistical model; group was indicated as “between subject factor”, and measurement time was indicated as “within subject factor”. For statistical calculations, SPSS 10.0 software was used (SPSS, 1999).

118 Ünal Baruh and Kocabağlı, J. Fac. Vet. Med. Istanbul Univ., 43 (2), 116-122, 2017


Table 1. Ingredient and nutrient composition of the basal diet fed to lambs (Dry Matter, %)

Tablo 1. Kuzulara verilen temel rasyonun içeriği ve besin maddeleri kompozisyonu (%, KM’de)


Ingredient (%)

Basal diet

Barley

Corn

Corn Gluten Wheat Bran Soybean Meal Sunflower Meal Limestone Molasses

Salt

Mineral Premiks1 Vitamin Premiks2


19.40

11.30

8.50

31.80

6.50

13.90

2.85

5.10

0.54

0.10

0.01

Total

100.00

Nutrient composition (%)

Basal diet

Hay

Dry Matter Crude Protein Crude Fat Crude Cellulose Crude Ash

NDF ADF

Calcium Phosphorus

87.30

17.86

3.55

5.13

6.15

19.56

7.83

1.05

0.54

93.40

8.89

0.95

40.32

7.79

60.95

43.04

1.31

0.20

11 kg premix contained 10.000 mg Cu, 50.000 mg Fe, 50.000 mg Mn, 50.000 mg Zn, 50 mg Co, 800 mg I, 150 mg Se, 340.000 mg Ca.

21 kg premix contained 66.700.000 IU Vitamin A, 16.700.000 IU Vitamin D3 , 167.000 IU α-tocopherol acetate, 42000 mg Vitamin B1 ,

25.000 mg Vitamin B2 , 125 mg Vitamin B12 , 12,500 mg Niacin


Differences in P values less than 0.05 were considered to be significant.

Results

Chemical compositions of the diets and formulation of grain diet have shown in Table 1. The effect of different levels of OEO on performance and some blood parameters in lambs were previously published elsewhere (Ünal and Kocabağlı, 2014b). Results of different dosages OEO on fermentation parameters at the 28th and at the 56th days of the experimental period in the rumen of sheep are presented in Table 2 and in Table 3, respectively. No difference was observed in rumen pH, acetate, propionate and ammonia nitrogen concentration among treatments during the study, except ruminal pH (sampling time: before feeding) at the 56th days of the experimental period. Total VFA concentration increased in 500 ppm OEO (P<0.05) group at 28th days of the experiment (sampling time: 3h after feeding) and also 56th days of the experiment (sampling time: 6h after feeding). Butyrate proportions were influenced by addition of OEO (Table 2, Table 3). It was

established that the time of measurement had an important role on the results of the rumen parameters. Furthermore, the quantitative increase of the total volatile fatty acid concentrations in the treatment groups according to the control, were directly proportional with the increase of the oregano doses at the 56th days of the experiment, except beginning.

Discussion

Various studies have been conducted to determine the effects of EO and their components on rumen microbial fermentation in ruminants (Newbold et al., 2004; Biricik et al., 2016; Busquet et al., 2006; Cardozo et al., 2006; Castillejos et al., 2006). These studies used a wide range of EO and EO compounds, dosages, diets and, not surprisingly, results have been inconsistent. The varied response among EO products evidently reflects differences in chemical structure, which influences their effects on microbial activity. In this study, different levels of OEO, which has been produced in Turkey, were examined.

Ünal Baruh and Kocabağlı, J. Fac. Vet. Med. Istanbul Univ., 43 (2), 116-122, 2017 119

Table 2. Effect of Oregano essential oil (OEO) on fermentation parameters at 28th days of the experimental period in the rumen of lambs

Tablo 2. Kekik uçucu yağının denemenin 28. gününde kuzuların rumen parametreleri üzerine etkisi

Variables of ruminal fluid

Sampling times (hours)

Treatments

Control

250 ppm OEO

500 ppm OEO

Sx

Significance

01

6.89x

6.77x

6.77x

0.09

NS

Ruminal pH

32

5.86y

5.83y

5.88y

0.09

NS

62

6.09y

5.90y

5.91y

0.10

NS

Time effect

***

***

***

Acetate, Mmol/l

01

50.14y

54.04z

52.34y

4.81

NS

32

60.11xy

67.06y

78.62x

4.35

NS

62

68.11x

83.46x

66.95xy

5.01

NS

Time effect

*

***

**

Propionate, Mmol/l

01

15.99y

16.71y

15.81z

1.52

NS

32

34.30x

28.78x

37.48x

3.31

NS

62

30.01x

29.29x

27.91y

3.41

NS

Time effect

***

**

***

Butirate, Mmol/l

01

8.86y

9.54y

9.25z

0.94

NS

32

15.99b,x

18.63ab,x

22.0a,x

1.31

*

62

16.48x

17.81x

18.01y

1.30

NS

Time effect

***

***

***

Total volatile fatty acids, Mmol/l

01

77.10y

82.18z

79.40y

6.61

NS

32

114.44b,x

117.16b,y

142.32a,x

7.00

*

62

117.91x

133.32x

116.57x

7.40

NS

Time effect

**

***

***

Ammonia N mg/dl

01

14.43y

14.59y

14.29y

0.25

NS

32

17.86x

18.09x

17.84x

0.41

NS

62

12.19z

12.10z

12.05z

0.26

NS

Time effect

***

***

***

1 Before feeding; 2 After feeding

a-b Values with different superscripts in a row differ significantly (P<0.05).

x-z Values with different superscripts in a column for each variables differ significantly (P<0.05).


No difference was observed in rumen pH and ammonia nitrogen concentration among treatments during this study (Table 2 and 3). Newbold et al. (2004) reported that, the addition of EO (Crina Ruminants, UK) to the diet had no effect (P>0.05) on ruminal pH or ammonia concentrations. Thus, results presented here are consistent with Newbold et al. (2004). The findings of the present study for ruminal pH were also in line with the results of previous studies in lambs (Chaves et al., 2008), calves (Vakili et al., 2013), dairy cows (Yang et al., 2007), and beef cattle (Cardozo et al., 2006; Fandiño et al., 2008, Yang et al., 2010) which showed that EO has no effect on ruminal pH. In contrast to these findings, Castillejos et al. (2006) reported an increase in pH in in vitro systems and Benchaar et al. (2006) found that an increase in ruminal pH when dairy cows received EO. Biricik et al. (2016) observed that lambs had higher rumen pH, NH3 -N, and total volatile fatty acid (VFA) compared to those in the control group when they were

fed high concentrate diet with calvacrol and/or thymol. Canbolat et al. (2010) reported that, the inclusion of oregano oil in different doses (0, 50, 100, 200, 400, 600 and 800 mg/L) decreased the total volatile fatty acids (VFA), acetic acid, propionic acid, butyric acid, acetic acid/propionic acid ratio and ammonia level whereas it increased the ruminal pH. They used rams and fed the animals 40:60 (DM) concentrate: forage mix. In our study, animals were fed a diet consisting of 60:40 (DM) concentrate: hay mixture. The results of Canbolat et al. (2010) study opposed to the results of our study, which can be partially explained by the type of diets used; because different diets cause different proteolytic activities in microbial communities with different predominant species of proteolytic bacteria (Wallace et al., 1987).

The total VFA concentration increased significantly in the 500 ppm OEO (P<0.05) group compared to the control group on the 28th (sampling time: 3h after

120 Ünal Baruh and Kocabağlı, J. Fac. Vet. Med. Istanbul Univ., 43 (2), 116-122, 2017


Table 3. Effect of Oregano essential oil (OEO) on fermentation parameters at 56th days of the experimental period in the rumen of lambs

Tablo 3. Kekik uçucu yağının denemenin 56. gününde kuzuların rumen parametreleri üzerine etkisi

Variables of ruminal fluid

Sampling times

(hours)

Treatments

Control

250 ppm OEO

500 ppm OEO

Sx

Significance

01

6.79a,x

6.54b,x

6.94a,x

0.07

**

Ruminal pH

32

5.52z

5.76y

5.60z

0.12

NS

62

6.44y

6.46x

6.18y

0.15

NS

Time effect

***

***

***

Acetate, Mmol/l

01

34.96y

43.13y

39.06y

4.04

NS

32

55.68x

58.68x

65.63x

4.45

NS

62

50.18x

45.17y

61.70x

4.69

NS

Time effect

***

**

**

Propionate, Mmol/l

01

14.04z

16.40y

13.69y

1.09

NS

32

37.25x

34.58x

38.92x

6.47

NS

62

21.83y

27.16x

31.07x

3.38

NS

Time effect

***

*

**

Butirate, Mmol/l

01

5.22b,z

10.67a,z

7.90ab,y

1.12

**

32

14.03x

19.13x

21.06x

2.14

NS

62

11.26y

15.04y

17.83x

1.81

NS

Time effect

***

***

***

Total volatile fatty acids, Mmol/l

01

55.89z

72.77z

63.54y

5.44

NS

32

111.47x

118.22x

130.95x

11.89

NS

62

85.90b,y

91.78ab,y

115.39a,x

8.36

*

Time effect

***

**

***

Ammonia N mg/dl

01

15.29y

15.79y

15.40y

0.21

NS

32

18.97x

18.96x

18.68x

0.21

NS

62

12.81z

13.02z

11.94z

0.34

NS

Time effect

***

***

***

1 Before feeding; 2 After feeding

a-b Values with different superscripts in a row differ significantly (P<0.05).

x-z Values with different superscripts in a column for each variables differ significantly (P<0.05).


feeding) and the 56th (sampling time: 6h after feeding) days of the experiment (Table 2-3). Wang et al. (2009) also reported a higher VFA concentration in sheep that were fed a hay/concentrate-based diet supplemented with oregano oil. In contrast to this, Castillejos et al. (2006) found that the antimicrobial activity of tyhmol used at a dose of 500 mg/L led to an increased pH, depression in total VFA concentration and a reduction in diet fermentability. However, in another study, Castillejos et al. (2008) reported a decrease in pH, associated with an increase in total VFA concentration at all doses (5, 50 and 500 mg/L) of thymol in the batch culture fermentation. According to these different results, it can be concluded that the optimum and toxic amounts in tyhmol are close and identifying the optimum dose is difficult. The different pH results obtained by using essential oils in in vitro and in vivo studies can be considered as the different responses of the rumen microorganisms to these additives (Benchaar and Greathead, 2011).

Besides their effects on VFA and pH concentrations, essential oils have also various influences on ruminal NH3 -N concentrations. Reduction of protein and starch degradation and inhibition of amino acid degradation are the main effects of EO in the rumen (Hart et al., 2008). Some studies show that the NH3 -N concentrations are dose dependent, while other studies state that the experimental method and length of the study also have an effect on the concentrations. When long-term in vivo studies and short-term in vitro studies are compared, the lack of effects of EO on nitrogen metabolism in long-term studies can be related to the longer exposure of rumen microorganisms to EO. Longer exposure time may cause an adaptation of rumen microorganisms to the EO, which may lead to a degradation of these compounds by ruminal bacteria (Busquet et al., 2005; Cardozo et al., 2004). An in vitro study, evaluating the effects of thymol and eugenol at different doses (0, 5, 50, 500 and 5.000 mg/L) on rumen fermentation, shows that only the highest dose of these

Ünal Baruh and Kocabağlı, J. Fac. Vet. Med. Istanbul Univ., 43 (2), 116-122, 2017 121


compounds decreased the ruminal concentrations of NH3 -N (Castillejos et al., 2006), whereas in another study by the same authors demonstrated that all doses of thymol decreased the NH3 -N concentrations (Castillejos et al., 2008). As seen in most in vivo studies (Benchaar et al., 2007; Devant et al., 2007; Yang et al., 2007), our study also showed that EO mostly does not affect ruminal NH3 -N concentrations.

The results of this study indicate that OEO, which is produced in Turkey, has a potential to improve rumen fermentation by increasing total VFA and that it might be useful as ruminal fermentation modifier in lambs. However, additional research is required to establish the optimal level of OEO considering the potential adaptation of microbial populations, and to demonstrate the effect of OEO on improvement in animal performance.

REFERENCES

AOAC, 1995. Association of Official Analytical Chemists: Official Methods of Analysis, Vol I, 16th Ed. AOAC, Arlington, VA.

Benchaar, C., Calsamiglia, S., Chaves, A.V., Fraser, G.R., Colombatto, D., McAllister, T.A., Beauchemin, K.A., 2008. A review of plant-derived essential oils in ruminant nutrition and production. Animal Feed Science and Technology, 145, 209–228.

Benchaar, C., Greathead, H., 2011. Essential oils and opportunities to mitigate enteric methane emissions from ruminants. Animal Feed Science and Technology, 166–167, 338–355.

Benchaar, C., Petit, H.V., Berthiaume, R., Ouellet, D.R., Chiquette, J., Chouinard, P.Y., 2007. Effects of essential oils on digestion, ruminal fermentation, rumen microbial populations, milk production, and milk composition in dairy cows fed alfalfa silage or corn silage. Journal of Dairy Science, 90, 886–897.

Benchaar, C., Petit, H.V., Berthiaume, R., Whyte, T.D., Chouinard, P.Y., 2006. Effects of addition of essential oils and monensin premix on digestion, ruminal fermentation, milk production, and milk composition in dairy cows. Journal of Dairy Science, 89, 4352–4364.

Biricik, H., Hanoğlu Oral, H., Taluğ, A.M., Cengiz, Ş.Ş., Koyuncu, M., Dikmen, S., 2016. The effects of carvacrol and/or thymol on the performance, blood and rumen parameters, and carcass traits of Merino sheep. Turkish Journal of Veterinary and Animal Science, 40,651-659.

Busquet, M., Calsamiglia, S., Ferret, A., Cardozo, P.W., Kamel, C., 2005. Effects of cinnamaldehyde and garlic oil on rumen microbial fermentation in a dual flow continuous culture. Journal of Dairy Science, 88, 2508– 2516.


Busquet, M., Calsamiglia, S., Ferret, A., Kamel, C., 2006. Plant extracts affect in vitro rumen microbial fermentation. Journal of Dairy Science, 89, 761–771.

Canbolat, Ö., Karaman, Ş., Filya, İ., 2010. Farklı kekik yağı dozlarının mısır silajının sindirimi ve rumen fermantasyonu üzerine etkileri. Kafkas Üniversitesi Veteriner Fakültesi Dergisi, 16, 933-939.

Cardozo, P.W., Calsamiglia, S., Ferret, A., Kamel, C., 2006. Effects of alfalfa extract, anise, capsicum, and a mixture of cinnamaldehyde and eugenol on ruminal fermentation and protein degradation in beef heifers fed a high-concentrate diet. Journal of Animal Science, 84, 2801–2808.

Cardozo, P.W., Calsamiglia, S., Ferret, A., Kamel, C., 2004. Effects of natural plant extracts on ruminal protein degradation and fermentation profiles in continuous culture. Journal of Animal Science, 82, 3230–3236.

Castillejos, L., Calsamiglia, S., Ferret, A., 2006. Effect of essential oils active compounds on rumen microbial fermentation and nutrient flow in in vitro systems. Journal of Dairy Science, 89, 2649–2658.

Castillejos, L., Calsamiglia, S., Martín-Tereso, J., Ter Wijlen, H., 2008. In vitro evaluation of effects of ten essential oils at three doses on ruminal fermentation of high concentrate feedlot-type diets. Animal Feed Science and Technology, 145, 259–270.

Chaves, A.V., Stanford K., Gibson, L.L., McAllister, T.A., Benchaar, C., 2008. Effects of carvacrol and cinnamaldehyde on intake, rumen fermentation, growth performance, and carcass characteristics of growing lambs. Animal Feed Science and Technology, 145, 396–408.

Devant, M., Anglada, A., Bach, A., 2007. Effects of plant extract supplementation on rumen fermentation and metabolism in young Holstein bulls consuming high levels of concentrate. Animal Feed Science and Technology, 137, 46–57.

Erwin, E.S., Marco, G.J., Emery, E.M., 1961. Volatile Fatty Acid Analyses of Blood Rumen Fluid by Gas Chromatography. Journal of Dairy Science, 44(9), 1768- 1771.

Fandiño, I., Calsamiglia, S., Ferret, A., Blanch, M., 2008. Anise and capsicum as alternatives to monensin to modify rumen fermentation in beef heifers fed a high concentrate diet. Animal Feed Science and Technology, 145, 409–417.

Goering, H.K., Van Soest, P.J., 1970. Forage Fiber Analyses. Agriculture Handbook No: 379. Washington, DC, USA: ARS-USDA.

Greathead, H., 2003. Plants and plants extracts for improving animal productivity. Proceedings of the Nutrition Society, 62, 279–290.

Hart, K.J., Yanez-Ruiz, D.R., Duval, S.M., McEwan, N.R., Newbold, C.J., 2008. Plant extracts to manipulate rumen fermentation. Animal Feed Science and Technology, 147, 8–35.

122 Ünal Baruh and Kocabağlı, J. Fac. Vet. Med. Istanbul Univ., 43 (2), 116-122, 2017


Hristov, A.N., Ropp, J.K., Zaman, S., Melgar, A., 2008. Effects of essential oils on in vitro ruminal fermentation and ammonia release. Animal Feed Science and Technology, 144, 55–64.

Markham R., 1942. A steam distillation apparatus suitable for

micro-Kjeldahl analysis. Biochemical Journal, 36, 790-

791.

NRC, 1985. National Research Council: Nutrient Requirements of Sheep. Washington, DC: National Academy Press.

Newbold, C.J., McIntosh, F.M., Williams, P., Losa, R., Wallace, R.J., 2004. Effects of a specific blend of essential oil compounds on rumen fermentation. Animal Feed Science and Technology, 114, 105–112.

OJEU, 2003. Official Journal of the European Union: Regulation (EC) No 1831/2003 of the European Parliament and of the Council of 22 September 2003 on additives for use in Animal Nutrition. L268/29-L268/43 in OJEU of 10/18/2003.

SPSS, 1999. Statistical Package for the Social Sciences, Release

10.0. SPSS Inc. IL, Chicago, USA.

Ünal, A., Kocabağlı, N., 2014a. The use of oregano essential oil in ruminant nutrition. Journal of the Faculty of Veterinary Medicine Istanbul University, 40, 121-130.

Ünal, A., Kocabağlı, N., 2014b. Effect of different dosages of oregano oil on performance and some blood parameters in lambs. Veterinary Journal of Ankara University, 61, 199-204.

Vakili, A.R., Khorrami, B., Danesh Mesgaran, M., Parand, E., 2013. The effects of Thyme and Cinnamon essential oils on performance, rumen fermentation and blood

metabolites in Holstein calves consuming high concentrate diet. Asian-Australasian Journal of Animal Sciences, 26, 935–944.

Van Soest, P.J., Robertson, J.B., Lewis, B.A., 1991. Methods for dietary fiber, neutral detergent fiber, and nonstarch polysaccharides in relation to animal nutrition. Journal of Dairy Science, 74, 3583-3597.

Wallace, R.J., Broderick, G.A., Brammall, M.L., 1987. Protein degradation by ruminal microorganisms from sheep fed dietary supplements of urea, casein or albumin. Applied and Environmental Microbiology, 53, 751–753.

Wallace, R.J., 2004. Symposium: Plants as animal foods: A case of catch 22? Antimicrobial properties of plant secondary metabolites. Proc Nutr Soc, 63, 621–629.

Wang ,C.J., Wang, S.P., Zhou, H., 2009. Influences of flavomycin, ropadiar and saponin on nutrient digestibility, rumen fermentation and methane emission from sheep. Animal Feed Science and Technology, 148, 157-166.

Yang, W.Z., Benchaar, C., Ametaj, B.N., Chaves, A.V., He, M.L., McAllister, T.A., 2007. Effects of garlic and juniper berry essential oils on ruminal fermentation and on the site and extent of digestion in lactating cows. Journal of Dairy Science, 90, 5671–5681.

Yang, W.Z., Benchaar, C., Ametaj, B.N., Beauchemin, K.A., 2010. Dose response to eugenol supplementation in growing beef cattle: ruminal fermentation and intestinal digestion. Animal Feed Science and Technology, 158, 57–64.