Blend of Essential Oils Supplemented Alone or Combined with Exogenous Amylase Compared with Virginiamycin Supplementation on Finishing Lambs: Performance, Dietary Energetics, Carcass Traits, and Nutrient Digestion

Abstract

Two experiments were conducted to compare a supplemental blend of essential oils alone (EO) or combined with enzymes (EO + ENZ) versus virginiamycin (VM), on characteristics of growth performance (Exp. 1) and digestion (Exp. 2) in finishing lambs. Lambs were fed a high-energy finishing diet supplemented with: (1) no supplement (control); (2) 150 mg supplemental EO; (3) 150 mg supplemental EO plus 560 mg alpha-amylase (EO + ENZ); and 4) 25 mg VM. Compared with the control, growth performance response to EO and VM were similar, enhancing (5.7%, p < 0.05) feed efficiency and observed dietary net energy. Compared with control, supplementation with EO + ENZ tended (p = 0.09) to increase dry matter intake (6.8%), improving (p < 0.05) weight gain and feed efficiency (10.4 and 4.4%, respectively). Dietary energy utilization was greater (2.7%, p < 0.05) for EO and VM than EO + ENZ. Treatment effects on the carcass and visceral mass were small, but additive supplementation decreased (p ≤ 0.03) the relative weight of the intestines. There were no treatment effects on measures of digestion nor digestible energy of the diet. Supplemental EO may be an effective alternative to VM in high-energy finishing diets for feedlot lambs. Combination EO + ENZ may further enhance dry matter intake, promoting increased weight gain.

Effects of a Polyherbal Dietary Additive on Performance, Dietary Energetics, Carcass Traits, and Blood Metabolites of Finishing Lambs

“…Except for the stomach complex and liver, in this study, supplementation of increasing doses of PA did not affect the weight of internal and external organs of finishing lambs. Similar results were previously reported by Orzuna-Orzuna et al [ 6 ] in lambs supplemented with increasing doses of PA (0, 1, 2, and 3 g kg −1 DM for 56 days) based on Acacia concinna , Balanites roxburghii, and Saccharum officinarum and by Estrada-Angulo et al [ 18 ] in lambs fed on high-concentrate diets and supplemented with 150 mg d −1 of essential oils (mixture of eugenol, thymol, limonene, and vanillin).…”

“…However, in cattle fed on a high-concentrate diet, Rivera-Méndez et al [ 24 ] observed that dietary supplementation of hydrolyzable tannins (6 g kg −1 DM for 84 days) increased ObsNEm and ObsNEg by 2 and 3%, respectively. Similarly, Estrada-Angulo et al [ 18 ] observed that, compared to CON, dietary supplementation with 150 mg d −1 of a mixture of essential oils (eugenol, thymol, vanillin, and limonene) increased ObsNEm and ObsNEg in lambs by 5 and 6%, respectively. Tannins, flavonoids, and essential oils were reported to reduce enteric methane production and increase ruminal propionate concentration in sheep and cattle [ 9 , 15 , 25 ], which would explain the positive effects of the PA used in the present study on ObsNEm and ObsNEg.…”

“…It was previously reported that the observed dietary net energy (NE) to expected dietary NE ratio of 1.0 indicates that ADG was consistent with the measured DMI value and with the estimated dietary NE value with tabular values [ 26 ]. Furthermore, the observed to expected dietary NE ratio greater than 1.0 suggests higher dietary energy utilization, whereas a ratio less than 1.0 indicates lower energy utilization [ 18 , 27 ]. In this study, the values recorded for the ratio between observed and expected dietary NE for maintenance and gain suggest that, compared to the CON, lambs in the PA1 treatment had higher efficiency of dietary energy utilization.…”

“…According to Estrada-Angulo et al [ 18 , 27 ], in productive performance trials with finishing lambs, the relationship between observed and expected net energy (NE) and the relationship between observed and expected DMI can be used to evaluate the efficiency of dietary energy utilization. Based on the observed average for ADG and SBW, and with the NE values of the diet ( Table 1 ), expected DMI was estimated using the equation: expected DMI, kg d −1 = (ME/NEm) + (EG/NEg), in which ME (energy required for maintenance, expressed in Mcal d −1 ) = 0.056 × SBW 0.75 and EG (represents energy gain, expressed in Mcal d −1 ) = ADG × 0.276 × SBW 0.75 .…”

“…Similarly, some essential oils improve the composition and function of the rumen microbiome, increase the production of volatile fatty acids in the rumen, and improve the development of the papillae of the rumen epithelium in cattle [ 17 ]. On the other hand, some essential oil mixtures increase the energy intake of diets for finishing sheep and cattle [ 18 , 19 ], while other essential oils improve the immune response [ 20 ] and increase the abundance of fiber-degrading microorganisms in the rumen and the digestibility of dry matter in sheep [ 21 ].…”