Effect of Oregano Essential Oil and Black Wattle Tanniniferous Extract in the Diet of Feedlot Lambs on Meat Fatty Acid Composition

The objective of the present study was to evaluate the effect of oregano essential oil and black wattle tanniniferous extract in the diet of feedlot lambs on meat fatty acid composition. At the beginning of the trial, 36 intact male lambs (Dorper x Santa Inês x Texel), at approximately 90 days of age and initial body weight of 26 kg, were housed in individual stalls. The lambs were allocated into three treatments (n = 12) in a randomized block design, using initial body weight as blocking criteria, and fed for 60 days. The experimental treatments evaluated were: 1) Control; 2) Control diet with inclusion of oregano essential oil (1 ml/kg of concentrate) and 3) Control diet with inclusion of black wattle tanniniferous extract (5% of diet; DM basis), with dietary forage: concentrate ratio of 30:70. The samples were taken on deboned of animals, 96 hours after slaughter. Meat samples were collected and ground for fatty acid profile, and lipids were extracted as described by Folch et al. (1957), from 2 g of ground steak, which the fatty acids were quantified by gas chromatography. Data were analyzed using the MIXED procedure of SAS software (2001). The inclusion of oregano essential oil and black wattle tanniniferous extract in the diet of feedlot lambs increased the meat fat concentration of Omega-3 (P = 0.01). Additionally, lambs fed diets with supplements had a trend of increased meat concentration of vaccenic (P = 0.07) and Omega-6 (P = 0.09) fatty acids. However, the inclusion of oregano essential oil and black wattle tanniniferous extract reduced the oleic fatty acid concentration (P = 0.01), and had no effect on Omega-6/Omega-3 ratio (P = 0.44) and on cis-9 trans-11 CLA (P= 0.55). There was no difference between oregano essential oil and black wattle tanniniferous extract on meat fatty acid composition (table 1). Thus, we conclude that dietary inclusion of oregano essential oil and black wattle tanniniferous extract may change the meat fat composition, increasing the Omega-3 fatty acids content.

Table 1. Lambs meat fatty acid composition.

ITEM	TREATMENTS			SEM	P-value
	Control	Oregano essential oil	Black wattle tanniniferous extract
Omega-3	0.70b	0.85a	0.90a	0.03	0.01
Omega-6	9.74	10.53	11.15	0.30	0.09
Omega 6/3 ratio	13.26	12.23	12.30	0.36	0.44
CLA (cis-9 trans-11)	0.25	0.28	0.31	0.02	0.55
Vaccenic	0.471	0.492	0.604	0.03	0.07
Oleic	36.08a	33.89b	32.68b	0.55	0.01