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An experiment was conducted to determine the effects of Ralco’s Microfused Essential Oils (MEO) on growth, jejunal histology, and meat quality of coccidiosis-challenged broilers. Day old broilers (
Consumer pressure for antibiotic-free meat products has led to increased research in the area of antibiotic alternatives, including essential oils. Essential oils have a wide variety of effects including antimicrobial, antioxidant, and digestive stimulant activities (
Microfused Essential Oils is a blend of oils, but is comprised mainly of oregano. The oils undergo a patented microfusion process that creates a surface area of oil droplets that is 20 times greater than other commercially available oils, increasing the stability and effectiveness of the oils. Due to its oregano content, MEO has a high antioxidant activity, which is attributed to its 2 main phenols, carvacrol and thymol (
The objective of this experiment was to determine the effects of Ralco’s Microfused Essential Oils (MEO) on growth performance, jejunal histology, and meat quality of coccidiosis-challenged broilers.
Day old broiler cockerels (
Composition and formulated nutrients of basal broiler diets for starter, grower, finisher, and withdrawal phases
Ingredient/Nutrient % | Starter | Grower | Finisher | Withdrawal |
Corn | 59.0 | 65.1 | 68.8 | 70.2 |
Soybean Meal, 46% | 36.6 | 30.3 | 25.4 | 24.6 |
Limestone | 1.25 | 1.28 | 1.30 | 1.30 |
Soy Oil | 0.50 | 1.00 | 1.25 | 1.75 |
Monocal. Phosphate | 1.35 | 1.18 | 1.10 | 1.13 |
Sodium Bicarbonate | 0.30 | 0.30 | 0.29 | 0.29 |
DL-Methionine | 0.28 | 0.26 | 0.27 | 0.21 |
Salt | 0.24 | 0.23 | 0.24 | 0.24 |
L-Lysine | 0.17 | 0.17 | 0.16 | 0.14 |
Choline 60 (dry) | 0.08 | 0.07 | 0.06 | 0.06 |
L-Threonine | 0.04 | 0.03 | 0.05 | 0.05 |
VTM Premix | 0.20 | 0.17 | 0.14 | 0.14 |
Phytase | 0.01 | 0.01 | 0.01 | 0.01 |
Total | 100 | 100 | 100 | 100 |
Crude Protein | 21.3 | 18.8 | 16.9 | 16.5 |
Net Energy (Kcal/kg) | 2222 | 2317 | 2383 | 2410 |
Lysine | 1.352 | 1.182 | 1.044 | 1.004 |
Calcium | 0.90 | 0.85 | 0.83 | 0.83 |
Total Phosphorus | 0.69 | 0.63 | 0.59 | 0.59 |
Broilers were fed starter from d 0 to 16, grower from d 17 to 27, finisher from d 28 to 34, and withdrawal from d 35 to 41.
Vitamin/trace mineral premix was formulated to contain the following: 42,047 KIU/kg vitamin A; 8,190 KIU/kg vitamin D; 275, 579 IU/kg vitamin E; 24, 683 mg/kg vitamin K; 10,441 mg/kg biotin; 7,976 mg/kg folic acid; 195,778 mg/kg niacin; 130,827 mg/kg
The broilers (
A coccidiosis challenge was induced to stimulate the conditions of a disease stress. Broilers, including replacements on d 3, were offered a commercial coccidiosis vaccine containing viable oocysts of
Individual bird weights were taken on d 0, 15, 26, 35, and 41 and a pen mean was calculated for statistical analysis. Pen feed disappearance was measured on d 15, 26, 35, and 42 at the end of each feeding phase. All feeders were emptied on the previously mentioned days and the new diet phase was added. Pens were checked daily for mortality or those needing to be euthanized due to leg or health problems. Any broilers that showed signs of disease and did not maintain or improve health over time were euthanized.
On d 14, a randomly selected broiler from each pen was removed and euthanized using a CO2 chamber. A 5 cm section of the jejunum, beginning 5 cm proximal to Meckel’s diverticulum, was collected and placed into 10% formalin for histological assessment. Slides were prepared and stained with hematoxylin and eosin at a commercial pathology diagnostics lab (Animal Disease Research and Diagnostic Laboratory, Brookings, SD). Villus height and crypt depth was measured using a Nikon microscope (Tokyo, Japan) equipped with a DS2MV Nikon camera (Tokyo, Japan) and NIS Elements software (Tokyo, Japan). Due to an unexpected amount of damaged villi, measurements were taken on all viable villus and the crypt associated with each villi. The villus height:crypt depth ratio was calculated.
On d 41, two broilers were randomly selected from each pen, leg banded, and transported to a small harvest facility in Pipestone, MN for harvest the following morning. Seventeen hours after removal from pens, broilers were stunned, butchered, eviscerated, and chilled in water. Individually bagged whole chickens were transported to the meat laboratory at South Dakota State University, Brookings, SD in a refrigerated trailer. The carcasses were placed in a cooler (1 to 3°C) overnight and fabricated the following morning. Breasts were removed, deskinned, deboned, and placed on a foam tray and overwrapped. Thigh meat was deskinned, deboned, and ground twice with a 3.18 mm die. Two pens (four carcasses) were pooled and utilized as one replication for color analysis and shelf life of thigh meat. The grinder was rinsed between replications. Each replication was split into four 113.4 g patties, placed on a black polystyrene foam tray, overwrapped with oxygen permeable polyvinyl chloride (15,500 – 16,275 cm3/m2/24 h oxygen transmission rate), and labeled as d 1, 3, 5, or 7. Following tray overwrapping, both breasts and thighs were placed with one sample of each treatment per column on tables in an illuminated cooler using dual fluorescent lighting (2,950 lumens/bulb, at 4,100 K, and 40 inches from the samples) at 4°C and rotated from front to back daily. Measurement of color using a Minolta colorimeter (CR-410; Minolta Corp., Ramsey, NJ; equipped with a 50 mm diameter measuring space, D65 illuminant, 0° viewing angle, and 2° observer) was taken on both breasts and thighs on d 0, 1, 2, 3, 4, 5, 6, and 7.
Rancidity compounds were measured using 2-thiobarbituric reactive substances (TBARS) on 2 broilers per pen on whole breasts at d 7 postmortem, and on ground thigh meat on d 0, 3, 5, and 7 postmortem. Thighs were removed from the refrigerator, vacuum sealed, and frozen (–80°C) as labeled on d 1, 3, 5, or 7. Breasts were removed, vacuum sealed, and frozen (–80°C) on d 7. To create a homogenous sample, breasts and thighs were powdered by placing small cubes of meat into liquid nitrogen. Once frozen, the cubes were placed into a chilled Waring blender and blended until it was powdered. The powder was then placed into a Whirl-Pak bag, vacuum sealed, and stored at –80°C. All samples for TBARS were run in duplicate and one spiked sample using TEP (97% 1,1,3,3, tetraethoxypropane, Sigma-Aldrich T9889) was used per plate to determine percent recovery. For each sample, 1 mL of 0.2 mg/mL butylated hydroxyl toluene (BHT; MP Biomedicals, LLC, cat# 101162) and 45.5 mL 10% trichloroacetic acid (TCA) were added to 5 g of sample. TCA was prepared using 96.26 g of o-phosphoric acid (Acros Organics, 389025000) and 400 g of trichloroacetic acid (Fischer Scientific, A322–500) into a total volume of 4,000 mL with double distilled water. The spiked sample was prepared by weighing 5 g of sample, adding 1 mL BHT, 35.5 mL TCA, and 10 mL of 10 µM TEP. Each sample was homogenized using an IKA T25 Digital Ultra-Turrax (IKA Works, Inc., Wilmington, NC) for 1 min and filtered through Whatman No1 filter paper into a 100 mL glass sample bottle. A clean culture tube was then used to mix 5 mL of filtrate with 5 mL of 0.02 M thiobarbituric acid (TBA; 2-thiobarbituric acid, Sigma Aldrich T5500). A standard curve was also prepared using 25 µM TEP, TCA, and TBA. The tubes were inverted 5 times and placed in a shaker at room temperature for 15 to 20 h and then plated (250 μL) in duplicate and read using a plate reader (Molecular Devices SpectraMax 190, Molecular Devices, Sunnyvale, CA) at 530 nm (
Two frozen, powdered, homogenous breast samples from each pen were used to determine pH. A volume of 90 mL of distilled water was added to 10 g of sample. The solution was then homogenized and read for pH, where pH 7 solution (Fischer Scientific, SB107–500) was used for a standard. The pH values were obtained using a Thermo Scientific Orion 370 Advanced PerpHecT LogR Meter (Chelmsford, MA). Samples were averaged for each pen and pen was considered the experimental unit.
All statistical analysis was performed using the PROC MIXED procedure of SAS (Version 9.3, SAS Inst. Inc., Cary, NC). A completely randomized design was used with pen as the experimental unit for the performance and meat quality and bird was used as the experimental unit for histology. The control treatment had 12 replications for all results, except
In-feed antimicrobials were intended to be included at manufacturers recommended levels; however, due to a mixing error, the levels of both antimicrobials in the ANTI diet in the starter phase were approximately 10% of the levels indicated in the materials and methods. During transport to the harvest facility, one broiler fed the CON diet died, so no meat quality data was collected from that broiler.
Growth performance results were divided by phases as follows: starter, grower, finisher, withdrawal, and overall. The ANTI and MEO250 supplemented broilers were heavier than CON at d 17, 28, and 35, respectively (
Broiler performance during the starter, grower, finisher, and withdrawal phases
Item | CON | ANTI | MEOD | MEO500 | MEO250 | Pooled SEM | |
Weight (g) | |||||||
Day 0 | 38.4 | 38.3 | 38.3 | 38.2 | 38.2 | 0.30 | 0.99 |
Day 17 | 494b | 543a | 525a,b | 521a,b | 545a | 8.40 | 0.0003 |
Day 28 | 1400b | 1486a | 1441a,b | 1440a,b | 1476a | 18.74 | 0.001 |
Day 35 | 1966b | 2071a | 2023a,b | 2011a,b | 2055a | 19.75 | 0.003 |
Day 41 | 2552y | 2617x,y | 2591x,y | 2572x,y | 2646x | 26.05 | 0.08 |
Starter | |||||||
ADG | 26.8b | 29.7a | 28.6a,b | 28.4a,b | 29.8a | 0.50 | 0.0003 |
ADFI | 38.3 | 38.7 | 39.3 | 38.2 | 39.5 | 0.69 | 0.34 |
G:F | 0.71c | 0.77a | 0.73b,c | 0.75 a,b | 0.77a,b | 0.01 | 0.0002 |
Grower | |||||||
ADG (g) | 82.0b | 85.4a | 83.0a,b | 83.2a,b | 84.3a,b | 0.99 | 0.04 |
ADFI (g) | 120y | 124x,y | 123x,y | 123x,y | 125x | 1.65 | 0.09 |
G:F | 0.68a,b | 0.69a | 0.67a,b | 0.67a,b | 0.67b | 0.005 | 0.01 |
Finisher | |||||||
ADG (g) | 82.0 | 84.8 | 84.3 | 82.8 | 83.9 | 1.81 | 0.66 |
ADFI (g) | 165 | 170 | 174 | 169 | 178 | 3.86 | 0.14 |
G:F | 0.50 | 0.50 | 0.49 | 0.49 | 0.47 | 0.01 | 0.33 |
Withdrawal | |||||||
ADG (g) | 96.7 | 90.4 | 94.9 | 93.4 | 97.3 | 2.41 | 0.20 |
ADFI (g) | 179 | 180 | 179 | 183 | 183 | 2.87 | 0.74 |
G:F | 0.54 | 0.51 | 0.54 | 0.51 | 0.54 | 0.009 | 0.02 |
a,bValues with different superscripts indicate a significant difference within rows (
x,yValues with different superscripts indicate a tendency to be significantly different within rows (
Experimental diets were fed in the starter phase as follows: corn-soybean meal basal diet (CON), CON diet with BMD50/Coban90 added at 55/121 mg/kg (ANTI), CON+MEO added at 375 mg/kg (MEOD), CON+MEO added at 500 mg/kg (MEO500), and CON+MEO added at 250 mg/kg (MEO250). MEO = Microfused Essential Oils (Ralco Nutrition, Inc, Marshall, MN). Broilers were fed starter from d 0 to 16, grower from d 17 to 27, finisher from d 28 to 34, and withdrawal from d 35 to 41.
ADG = Average daily gain.
ADFI = Average daily feed intake.
G:F = Gain to feed.
Broiler growth performance for the entire experimental feeding period (d 0 to 41)
Item | CON | ANTI | MEOD | MEO500 | MEO250 | Pooled SEM | P-value |
ADG | 61.3y | 62.9x,y | 62.2x,y | 61.8x,y | 63.6x | 0.63 | 0.08 |
ADFI | 98.9 | 102 | 102 | 101 | 103 | 1.33 | 0.13 |
G:F | 0.62 | 0.62 | 0.61 | 0.61 | 0.61 | 0.007 | 0.67 |
x,yValues with different superscripts indicate a tendency to be significantly different within rows (
Experimental diets were fed in the starter phase as follows: corn-soybean meal basal diet (CON), CON diet with BMD50/Coban90 added at 55/121 mg/kg (ANTI), CON+MEO added at 375 mg/kg (MEOD), CON+MEO added at 500 mg/kg (MEO500), and CON+MEO added at 250 mg/kg (MEO250). MEO = Microfused Essential Oils (Ralco Nutrition, Inc, Marshall, MN). Broilers were fed starter from d 0 to 16, grower from d 17 to 27, finisher from d 28 to 34, and withdrawal from d 35 to 41.
ADG = Average daily gain.
ADFI = Average daily feed intake.
G:F = Gain to feed.
Jejunal collections were performed on Day 14 and peak infection appeared to have occurred on d 15 according to both the pooled oocyst counts and visual signs of lethargy, fever, and weakness. Pooled fecal oocyst counts were 0; 14,053; 13,467; 1052,533; 5227; 1734; 133; 0 and 0 on d 6, 8, 13, 15, 20, 22, 28, 34, and 36, respectively. The MEOD-fed broilers had a tendency for higher villus height than MEO500 (
Measurements of villus height, crypt depth, and VH:CD
Item | CON | ANTI | MEOD | MEO500 | MEO250 | Pooled SEM | |
Villus Height (µm) | 774.4x,y | 752.1x,y | 806.6x | 716.4y | 800.6x,y | 27.7 | 0.09 |
Crypt Depth (µm) | 103.0 | 100.7 | 111.8 | 108.7 | 103.4 | 4.9 | 0.42 |
VH:CD | 8.01 | 7.93 | 7.95 | 7.07 | 8.27 | 0.36 | 0.12 |
x,yValues with different superscripts indicate a tendency to be significantly different within rows (
Experimental diets were fed in the starter phase as follows: corn-soybean meal basal diet (CON), CON diet with BMD®50/Coban®90 added at 55/121 mg/kg (ANTI), CON+MEO added at 375 mg/kg (MEOD), CON+MEO added at 500 mg/kg (MEO500), and CON+MEO added at 250 mg/kg (MEO250). MEO = Microfused Essential Oils (Ralco Nutrition, Inc, Marshall, MN).
VH = villus height; CD = crypt depth.
To determine meat quality from broilers, pH, color, and lipid oxidation were measured. There were no differences in pH among treatments for breasts at d 7 of retail display (
pH, L*, a*, and b* color values of raw whole chicken breasts during retail display for 7 d
Item | CON | ANTI | MEOD | MEO500 | MEO250 | Pooled SEM | P-value |
pH | 6.08 | 6.04 | 6.04 | 6.07 | 6.08 | 0.027 | 0.54 |
L* | 60.17c | 61.97a | 59.96c | 61.32b | 61.72a,b | 0.12 | < 0.0001 |
a* | 9.97b,c | 9.19d | 10.44a | 10.09c | 9.67b | 0.079 | < 0.0001 |
b* | 12.60a | 11.82c,d | 12.23b | 12.10c,b | 11.74d | 0.094 | < 0.0001 |
a–dValues with different superscripts indicate a significant difference within rows (
Experimental diets were fed in the starter phase as follows: corn-soybean meal basal diet (CON), CON diet with BMD50/Coban90 added at 55/121 mg/kg (ANTI), CON+MEO added at 375 mg/kg (MEOD), CON+MEO added at 500 mg/kg (MEO500), and CON+MEO added at 250 mg/kg (MEO250). MEO = Microfused Essential Oils (Ralco Nutrition, Inc, Marshall, MN). Broilers were fed starter from d 0 to 16, grower from d 17 to 27, finisher from d 28 to 34, and withdrawal from d 35 to 41.
L* color value of raw whole chicken breast during a 7 d retail display for broilers fed corn-soybean meal basal diet (CON), CON diet with BMD50/Coban90 added at 55/121 mg/kg (ANTI), CON+MEO added at 375 mg/kg (MEOD), CON+MEO added at 500 mg/kg (MEO500), and CON+MEO added at 250 mg/kg (MEO250). MEO = Microfused Essential Oils (Ralco Nutrition, Inc, Marshall, MN). Broilers were fed starter from d 0 to 16, grower from d 17 to 27, finisher from d 28 to 34, and withdrawal from d 35 to 41.a–c Values with different superscripts indicate a significant difference (
a*color values of raw whole chicken breasts during a 7 d retail display for broilers fed corn-soybean meal basal diet (CON), CON diet with BMD50/Coban90 added at 55/121 mg/kg (ANTI), CON+MEO added at 375 mg/kg (MEOD), CON+MEO added at 500 mg/kg (MEO500), and CON+MEO added at 250 mg/kg (MEO250). MEO = Microfused Essential Oils (Ralco Nutrition, Inc, Marshall, MN). Broilers were fed starter from d 0 to 16, grower from d 17 to 27, finisher from d 28 to 34, and withdrawal from d 35 to 41.a–f Values with different superscripts indicate a significant difference (
b* color values of raw whole chicken breasts during a 7 d retail display for broilers fed corn-soybean meal basal diet (CON), CON diet with BMD50/Coban90 added at 55/121 mg/kg (ANTI), CON+MEO added at 375 mg/kg (MEOD), CON+MEO added at 500 mg/kg (MEO500), and CON+MEO added at 250 mg/kg (MEO250). MEO = Microfused Essential Oils (Ralco Nutrition, Inc, Marshall, MN). Broilers were fed starter from d 0 to 16, grower from d 17 to 27, finisher from d 28 to 34, and withdrawal from d 35 to 41. a–f Values with different superscripts indicate a significant difference (
For thigh color, there was an interaction of treatment*day for L*, a*, and b*. The 2 treatments that did not change in L* value over time were MEOD and MEO250. The CON and ANTI treatments performed similarly in their L* values over time. Both treatments did not change from d 0 to 1, increased from d 1 to 3, and plateaued from d 3 to 7 (
L* color values of raw ground chicken thighs during a 7 d retail display for broilers fed corn-soybean meal basal diet (CON), CON diet with BMD50/Coban90 added at 55/121 mg/kg (ANTI), CON+MEO added at 375 mg/kg (MEOD), CON+MEO added at 500 mg/kg (MEO500), and CON+MEO added at 250 mg/kg (MEO250). MEO = Microfused Essential Oils (Ralco Nutrition, Inc, Marshall, MN). Broilers were fed starter from d 0 to 16, grower from d 17 to 27, finisher from d 28 to 34, and withdrawal from d 35 to 41. (SEM = 0.52; Treatment × d
a* color values of raw ground chicken thighs during a 7 d retail display for broilers fed corn-soybean meal basal diet (CON), CON diet with BMD50/Coban90 added at 55/121 mg/kg (ANTI), CON+MEO added at 375 mg/kg (MEOD), CON+MEO added at 500 mg/kg (MEO500), and CON+MEO added at 250 mg/kg (MEO250). MEO = Microfused Essential Oils (Ralco Nutrition, Inc, Marshall, MN). Broilers were fed starter from d 0 to 16, grower from d 17 to 27, finisher from d 28 to 34, and withdrawal from d 35 to 41. (SEM = 0.29; Treatment × d
b* color values of raw ground chicken thighs during a 7 d retail display for broilers fed corn-soybean meal basal diet (CON), CON diet with BMD50/Coban90 added at 55/121 mg/kg (ANTI), CON+MEO added at 375 mg/kg (MEOD), CON+MEO added at 500 mg/kg (MEO500), and CON+MEO added at 250 mg/kg (MEO250). MEO = Microfused Essential Oils (Ralco Nutrition, Inc, Marshall, MN). Broilers were fed starter from d 0 to 16, grower from d 17 to 27, finisher from d 28 to 34, and withdrawal from d 35 to 41. (SEM = 0.29; Treatment × d
Differences among treatments were also noted for TBARS of thighs, but not breasts (
Malondialdehyde levels (MDA) per kg of wet tissue of raw chicken breasts (A; SEM = 0.08,
The objective of this experiment was to determine the effects of MEO on growth performance, jejunal histology, and meat quality of coccidiosis-challenged broilers. Furthermore, it was of interest to determine if MEO could be a suitable replacement for antimicrobials in commercial poultry facilities. If the antimicrobials would have been included at the appropriate inclusion rate in the starter, it would have been expected for the ANTI-fed broilers to have better performance than what was observed.
Based on performance measures, it is evident that MEO fed at a constant 250 mg/kg was the most effective method of combatting the negative effects of the coccidiosis challenge. One reason for these results could be that MEO at 500 mg/kg is too high, especially in the starter phase. Once the normal microbiota composition is altered, pathogens may be able to proliferate in the small intestine (
While there were positive effects on growth performance of MEO250-fed broilers, there was no effect of this treatment on jejunal histology. However, MEOD had a tendency for increased villus height over MEO500. Increased villus height can serve as an indicator of increased surface area for nutrient absorption (
The beneficial effects of MEO fed at 250 mg/kg were also shown in the meat quality data. There were no differences among treatments for pH of breasts, which suggests that no treatment has an impact on this meat quality measure. This is consistent with research performed by
The objectives of the experiment were met and effects of MEO were quantified. Overall, MEOD- and MEO500-fed broilers performed intermediate to CON- and ANTI-fed broilers and MEO250-fed broilers performed similarly to ANTI-fed broilers. Based on this study, it appears that MEO250 is the optimal level to feed MEO. Microfused Essential Oils fed at 250 mg/kg has the potential to improve growth performance when broilers are experiencing a coccidiosis disease challenge and decrease lipid oxidation of ground thigh meat during illuminated storage.
The authors would like to acknowledge Ralco Nutrition (Marshall, MN) for use of their facilities for the live animal research and partial funding of this trial.