Document Type : Original Article
Authors
1
Animal and Poultry Nutrition Department, Desert Research Center, El-Matarya, Cairo, Egypt
2
Department of Animal and Fish Production, Faculty of Desert and Environmental Agriculture, Matrouh University,51744 Matrouh, Egypt
Abstract
Recently, some plants essential oils (EO) are used as natural feed additives for ruminants because their major bioactive compounds have antimicrobial properties that can be effective against undesirable rumen microbes. In addition, EO have not an adverse effect either on animal or human health and environment. This work was carried out to evaluate the effect of natural additives as essential oils addition on animal performance, feed intake, apparent digestibility, carcass characteristics, chemical composition and fatty acids profile of longissimus lumborum muscle of Barki lambs. Twenty weaned male Barki lambs ( 19.72 ± 2.09) kg BW, 3 months old were randomly assigned in one of four diet groups, 5 animals each , were received the same basal diet,(50% berseem hay, BH, and 50% concentrate feed mixture). All experimental animals were kept in individual pens for 195 days for fattening trial and 15 days for digestibility trial. At the end of the experiment all lambs were slaughtered for carcass characteristics evaluation and meat fatty acids (FAs) profile determination. The control lambs were fed their basal diet without EO supply. The other three groups were orally given, by syringe, one of the three tested EO before morning feeding as follow: the basal diet plus 2 ml/day/lamb of anise EO (Anise group), 2 ml/day /lamb clove EO (Clove group) or 2 ml/day/lamb thyme EO (Thyme group). According to the results, the experimental EO had no significant effects on nutrients intake, lamb's performance (final body weight, average daily gain and feed conversion ratio) (P> 0.05). Clove EO improved dry matter (DM), organic matter (OM), crude protein (CP), ether extract (EE), acid detergent fiber (ADF) digestibility (P<0.05) and nitrogen balance% of intake (P<0.05). Ruminal parameters showed higher ruminal ammonia with thyme EO supply (P<0.05). Most of carcass characteristics were not affected by EO addition but lambs of clove group showed a significant increase in weight of feet (P<0.05), full (P<0.01) and empty (P<0.05) digestive tract, tail fat (P<0.01) and liver (P<0.05) compared with control lambs. Some blood plasma metabolites were affected by EO where plasma createnine and low-density lipoprotein (LDL) were increased (P <0.05) in thyme group however, total lipids and cholesterol increased in clove group. Fatty acids content of longissimus lumborum muscle was slightly affected by addition of EO where palmitoleic (C16:1n-7) was increased and arachidonic acids (C20:4n-6) was decreased (P<0.05) in meat of lambs fed clove. Also, clove inclusion in lambs diet increased monounsaturated fatty acids (MUFA) deposition in their meat (P<0.05). Overall, addition of anise, clove or thyme EO to lambs' diets may not have the potential to improve animal growth performance, blood metabolites and meat chemical composition. Clove EO has a considerable positive effect on nutrients digestibility and improve carcass characteristics, meat FA profile. Further research are needed with higher concentrations of EO for longer duration of supply.
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