-The objective of this research was to evaluate the inclusion of two qualities of Mexican oregano oil (MOO) in broiler diets on broiler weight, feed intake, feed efficiency, average daily gain, and water intake. The qualities were MOO 1 (4% thymol, 60% carvacrol) and MOO 2 (40% thymol, 20% carvacrol). Nine treatments were prepared by the combinations of MOO 1 + MOO 2 (0, 400, and 800 mg kg −1 ; added per kg of feed) respectively: 0+0, 0+400, 0+800, 400+0, 400+400, 400+800, 800+0, 800+400, and 800+800. Eighteen chicks per treatment were divided in a completely randomized design into nine cages. Broiler weights were altered by the treatments at 21 d, when 400+400 had the highest weight, and on day 39, when the greatest weight was seen in broilers on treatments 800+0 and 800+400. Feed intake was affected by treatment on day 39, with broilers on 800+0 exhibiting the highest values. Water intake was influenced by the treatments on days 14, 21, 35, and 39, when 0+0 represented the lowest. Feed efficiency was altered by the treatments on days 14, 28, 35, and 39, whereas average daily gain was affected from days 14 to 39. Supplementation of Mexican oregano oil has beneficial effects on broiler weight, feed efficiency, average daily gain, and feed and water intakes. Combinations of thymol and carvacrol levels have varying effects on these parameters. The higher relative body weights of groups 400+0, 800+0, and 800+400 suggest positive market value effects of these combinations of Mexican oregano oil.

-The objective of the current study was to evaluate performance, blood parameters, and carcass yield of broilers supplemented with Mexican oregano oil. A total of 162 one-day-old broilers were randomly distributed into three dietary treatments: control diet (without oregano oil or antibiotic); control diet + 0.25 g kg -1 of oxytetracycline; and control diet + 0.4 g kg -1 of Mexican oregano oil. Treatment with organ oil had positive effects on body weight at 35 and 42 days. Feed intake was significantly different at 21 and at 1-42 days; control treatment presented the highest feed intake at 28 and 35 days, while treatment with oxytetracycline had the lowest feed intake from 21 to 42 days. Weekly body weight gain was different at 42 days, in which treatment with oregano oil was the highest and control the lowest. Feed efficiency rate was significantly different at 42 and at 1-42 days; treatment with oxytetracycline and treatment with oregano oil had the best values over control treatment. Blood parameters were found different among treatments, in which treatment with oregano oil was the highest in cholesterol and high-density lipoprotein at 42 days. Carcass and blood biometric variables were not different among treatments. The amount of 0.4 g kg -1 of Mexican oregano oil in diets improves high-density lipoprotein, body weight, and feed efficiency rate of broiler chickens.

Resumen Se evaluó el efecto de la inclusión de aceite esencial de orégano (AEO) en el agua de bebida sobre la microbiología intestinal, características fisicoquímicas y rendimiento en canal y carne de 440 pollos de engorda de 1 d de edad no sexados (42.59 ± 1.63 g de peso) y alimentados durante 42 d. Las aves fueron asignadas al azar en cuatro tratamientos con 11 repeticiones de 10 aves con 0, 100, 200 y 400 p.p.m. de AEO en el agua de bebida. Se aplicó a los datos un análisis de varianza (ANDEVA) y un análisis multivariado (MANDEVA). No se encontraron diferencias significativas (P>0.05) en las variables microbiológicas, fisicoquímicas ni rendimiento en canal. Se concluye que el AEO en las concentraciones utilizadas no redujo significativamente los conteos de Salmonella spp. y Campylobacter spp. en ciego, no afectó las propiedades fisicoquímicas de la carne ni de rendimiento de canal.