Citation of this paper

Effect of Oregano oil on growth performance, rumen fermentation parameters and blood metabolites of growing lambs

O Canbolat, I Filya and A Kamalak¹

Uludag University, Faculty of Agriculture, Department of Animal Nutrition, Bursa, Turkey
akamalak@ksu.edu.tr
¹ Kahramanmaras Sutcu, Imam University, Faculty of Agriculture, Department of Animal Science, 46100 Kahramanmaras, Turkey

Abstract

Increasing dietary concentrations of oregano oil (from zero to 1200 mg/kg diet DM) in a low-fibre fattening diet fed to growing lambs (n = 40; initial weight 22.2 ± 0.05 kg) did not affect feed intake but had negative effects on live weight gain and feed conversion. The depressed growth performance appeared to be due to the direct effect of the oil depressing the rumen fermentation and the consequent supply of essential nutrients - glucose and amino acids - needed for efficient growth and feed conversion.

Key words: essential oils, feed conversion, feed intake, live weight gain

Introduction

The prohibition of antibiotic use in livestock feed, due to increased public concern in most parts of world, has led to substantial interest in evaluating plant extracts, which are secure for human health and can be used to manipulate ruminal microbial fermentation (Busquet et al 2006).

Essential oils obtained from plants through distillation have many uses (Dorman and Deans 2000) associated with their odor and color, and extent of antimicrobial activity. Most experiments to evaluate their anti-microbial activities have been done in vitro, as this is an effective and cheap method to evaluate the range of essential oils from different plant sources. On the other hand the antimicrobial effect recorded in in vitro experiments may not be reflected in in vivo experiments due to the time needed for adaptation of the micro-organisms (Cardozo et al 2004).

The current experiment aimed to verify the impact of Oregano essential oil on growth performance, rumen fermentation and blood parameters in growing lambs.

Materials and Methods

Experimental design

Forty Kivrcik male lambs with initial weight 22.2 ± 0.05 kg were assigned to diets with 4 levels of Oregano oil (0, 400, 800 and 1200 mg/kg diet DM) in a completely randomized design over a 9-week trial. The Oregano oil from Sigma-Aldrich (catalog no: W28281-2) was included in a low fiber fattening diet (Table 1) given ad libitum.

Measurements

Feed intake was recorded and the lambs weighed weekly, before the morning feeding. Rumen fluid was collected from 8 lambs in each group by stomach tube 2h after the morning feed during the last week of the experiment. Blood was taken from the jugular vein before taking the rumen samples.

Chemical analysis

Proximate composition of the diets was determined by methods of AOAC (1990). Neutral detergent fibre (NDF) and acid detergent fiber (ADF) was according to Van Soest et al (1991).

Rumen NH₃ concentration was determined following the method described by Weinberg et al (2001). Volatile fatty acids in rumen fluid were determined as described by Wiedmeier et al (1987) using a gas chromatograph (Stabilwax-DA, 30 m, 0.25 mm ID, 0.25 um df. Max. temp: 260°C). Glucose, urea, protein and triglycerides were measured in an Abbott Architect analyzer. Level of insulin was determined using the Electro-Chemi-Luminiscent Immuno-assay) on the Cobas e411 equipment.

Table 1. Ingredients and chemical composition of the diets (g/kg DM)
	Oregano oil, mg/kg diet DM
	0	400	800	1200

Barley	385.7	385.3	384.9	384.5
Wheat	200.0	200.0	200.0	200.0
Wheat bran	50.0	50.0	50.0	50.0
Cottonseed meal	240.0	240.0	240.0	240.0
Wheat straw	100.0	100.0	100.0	100.0
DCP	15.0	15.0	15.0	15.0
NaCl	8.0	8.0	8.0	8.0
Vit-Min complex	1.3	1.3	1.3	1.3
Oregano oil	0.0	0.4	0.8	1.2
Chemical composition #
Crude protein	17.1	17.1	17.1	17.1
Crude ash	6.37	6.37	6.37	6.37
NDF	36.9	36.90	36.89	36.88
ADF	20.7	20.7	20.7	20.7
# Contained (mg/kg): ZnSO₄7H₂ O (150), MnSO₄ (80), MgO (200), CoSO ₄7H₂O (5), KIO₃(1), vitamin A (5000), vitamin D (1000), vitamin E (20),

Statistical analysis

Data were analyzed by one-way analysis of variance (ANOVA); sources of variation were diets and error.

Results and discussion

Addition of oregano oil did not affect feed intake but had negative effects on live weight gain and feed conversion (Table 2; Figures 1 and 2).

Table 2. Mean values for feed intake, live weight change and feed conversion in lambs fed increasing levels of oregano oil
	Oregano oil, mg/kg DM diet				SEM	p
	0	400	800	1200	SEM	p

Initial weight, kg	22.3	22.1	22.2	22.2	0.847	1.00
Final weight, kg	38.8	38.1	37.3	36.7	0.849	0.328
Daily gain, g	296^a	284^b	270^c	258^d	0.519	<0.001
DM intake, kg/d	1.39	1.39	1.39	1.38	0.047	0.999
DM conversion	4.70	4.89	5.17	5.39	0.199	0.096
^abcd Row means with common superscript do not differ at P<0.05),


Figure 1. Live weight gain was decreased by supplementation with oregano oil	Figure 2. Feed conversion nwas negatively affected by supplementation with oregao oil

All rumen fermentation parameters were negatively affected by supplementation with oregano oil (Table 3. Figures 3-6). These findings are similar to those reported by Canbolat et al (2010).

Table 3. Mean values for rumen fermentation parameters in lambs fed increasing proportions of oregano oil
		Oregano oil, mg/kg DM diet				SEM	p
		0	400	800	1200	SEM	p

	pH	6.04^c	6.39^b	6.54^ab	68^a	0.050	<0.0001
	NH₃, mg/100 ml	34.6^a	31.3^b	25.5^c	18.9^d	0.752	<0.0001
	VFA, mmol/liter
	Total	137^a	124^b	108^c	88.9^d	1.375	<0.0001
	Acetate	68.4^a	62.4^b	51.4^c	41.7^d	0.818	<0.0001
	Propionate	43.1^a	38.5^b	35.3^b	29.3^c	0.551	<0.0001
	Butyrate	16.7^a	15.28^a	4.39^a	11.45^b	0.388	<0.0001
	Iso-butyrate	2.95^a	2.47^ab	2.31^ab	2.21^b	0.098	<0.0001
	Valerate	2.75^a	2.86^a	2.08^b	2.01^b	0.122	<0.0001
	Iso-valerate	2.82^a	2.54^ab	2.46^ab	2.25^b	0.088	<0.0001
^abc Row means with common superscript do not differ (P<0.05),


Figure 3. Oregano oil increased the rumen pH	Figure 4. Oregano oil decreased rumen ammonia

Figure 5. Oregano oil decreased total VFA production	Figure 6. Oregano oil decreased the acetate: propionate ratio

The negative relationships between oregano oil supplementation and concentrations of glucose, urea and protein at levels of metabolism (Table 4), reflect the patterns of rumen fermentation (Table 3; Figures 3-6), all of which indicate a decreased supply of nutrients for protein and glucose metabolism due to supplementation with oregano oil.

Table 4. Mean values of selected blood metabolites in lambs fed increasing proportions of oregano oil
	Oregano oil, mg/kg DM diet				SEM	p
	0	400	800	1200	SEM	p

Glucose, mg/100 ml	84.0^a	80.3^ab	77.5^bc	73.5^c	0.906	<0.0001
Urea, mg/100 ml	44.5^a	41.3^ab	36.8^b	38.4^ab	1.306	<0.000
Protein, g/100 ml	8.78^a	7.77^b	7.09^c	6.54^d	0.212	<0.000
Triglyceride, g/100 ml	26.4^a	26.8^a	25.1^a	25.0^a	0.935	0.442
Insulin, μu/ml	23.5^a	23.4^a	22.1^a	20.8^a	0.918	0.143
^abc Row means with common superscript do not differ at P<0.05

Conclusions

Increasing dietary concentrations of oregano oil (from zero to 1200 mg/kg diet DM) in a low-fibre fattening diet fed to sheep did not affect feed intake but had negative effects on live weight gain and feed conversion.
The reduced growth performance appeared to be due to the direct effect of the oil depressing the rumen fermentation and the consequent supply of essential nutrients - glucose and amino acids - needed for efficient growth and feed conversion.

References

AOAC 1990 Official methods of analysis. 15th ed. AOAC, Washington, DC

Busquet M, Calsamiglia S, Ferret A and Kamel C 2006 Plant extracts affect in vitro rumen microbial fermentation. Journal of Dairy Science, 89, 761-771. http://www.dzumenvis.nic.in/Microbes%20and%20Plants%20Growth/pdf/Plant%20Extracts%20Affect%20In%20Vitro%20Rumen.pdf

Canbolat O, Karaman S and Filya I 2010 The effect of different doses of oregano oil on corn silage digestive and rumen fermentation. Kafkas Univeritesi Veteriner Fakultesi Dergisi, 16(6), 933-939. http://vetdergi.kafkas.edu.tr/extdocs/2010_6/933_939.pdf

Cardozo P W, Calsamiglia S, Ferret A and Kamel C 2004 Effects of natural plant extract on protein degradation and fermentation profiles in continuous culture. Journal of Animal Science, 82, 3230-3236. https://www.researchgate.net/publication/8185439_Effects_of_natural_plant_extracts_on_ruminal_protein_degradation_and_fermentation_profiles_in_continuous_culture1

Dorman H J D and Deans S G 2000 Antimicrobial agents from plants: Antibacterial activity of plant volatile oils. Journal of Applied Microbiology, 88, 308-316. http://onlinelibrary.wiley.com/doi/10.1046/j.1365-2672.2000.00969.x/epdf

Van Soest P J, Robertson J B and Lewis B A 1991 Methods for dietary fibre, neutral detergent fibre and non-starch polysaccharides in relation to animal nutrition. J Dairy Science 74, 3583–3597.

Wiedmeier R D, Arambel M J and Walters J L 1987 Effect of yeast culture and Aspergillus oryzae fermentation extract on ruminal characteristics and nutrient digestibility. Journal of Dairy Science 70, 2063-2068. http://www.journalofdairyscience.org/article/S0022-0302(87)80254-0/pdf 70, 2063-2068.

Weinberg Z G, Szakacs G, Ashell G and Hen Y 2001 The effect of temperature on the ensiling process of corn and wheat. Journal of Applied Microbiology 90,561-566 http://onlinelibrary.wiley.com/doi/10.1046/j.1365-2672.2001.01276.x/epdf

Received 7 October 2017; Accepted 9 March 2018; Published 1 April 2018

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