Source: Ministry of Agriculture, Food and Rural Affairs
Introduction
An alternative approach to feeding cattle with antibiotics is to replace antibiotics with other feed ingredients that have antimicrobial properties. Essential oils and organic acids are two feed ingredients that have antimicrobial properties and warrant investigation.
Essential oils are plant-based compounds that can mirror the mode of action of antibiotics. Organic acids can suppress fungal activity and maintain an acidic environment in the rumen to prevent diseases. Previous research studies have evaluated the effects of essential oils on beef cattle growth performance and carcass characteristics, yet organic acids have not been studied before. In both cases meat quality and sensory have not been determined. Therefore, the objective of this study is to understand the effects of feeding essential oils and/or an organic acid to finishing cattle on growth performance, carcass characteristics, meat quality, and sensory of the longissimus thoracis (ribeye) muscle.
What We Did
Sixty-eight crossbred steers (BW = 1188 ± 79 lb) were fed at the University of Guelph Elora Beef Research Centre. Steers were grouped by weight and randomly assigned to 5 different treatments:
- a negative control where no additives were included (CON)
- a positive control with supplementation of monensin/tylosin (M/T), where monensin was supplemented at 33 mg/kg (Rumensin; Elanco Animal Health, Greenfield, IN, USA), and tylosin was supplemented at 11 mg/kg (Tylan; Elanco Animal Health) on a dry matter basis
- a proprietary blend of essential oils (EO) supplemented at 1 g/steer/day (Victus Liv, DSM Nutritional Products, Parsippany, NJ, USA)
- benzoic acid (BA) provided at 0.5% dietary inclusion on a DM basis (VevoVitall; DSM Nutritional Products)
- a combination of a proprietary blend of essential oils and benzoic acid (COMBO). Steers were fed the assigned diets for 98 days leading up to slaughter
Growth performance data (weights, feed intake, and conversion rates) were measured/calculated at the beginning and the end of the finishing study. Grading data (carcass weight, ribeye muscle area, backfat thickness, marbling, and liver abscesses) were collected following slaughter. Meat quality evaluation included pH, instrumental color (Minolta handheld spectrophotometer), proximate composition, instrumental tenderness (Warner-Bratzler shear force), and cooking loss. Trained sensory panels were used to assess tenderness, chewiness, juiciness, and flavor of ribeye steaks.
Figure 1. Left to right: Minolta handheld spectrophotometer, pH meter, and Soxhlet extraction apparatus used for determination of extractable intramuscular fat
What We Found
Dietary treatment did not affect finishing weight, average daily gain, or feed intake (Table 1). A tendency for gain to feed ratio was observed; specifically, monensin/tylosin steers tended to have greater feed efficiency compared with CON (no additives), essential oils, and COMBO (blend of essential oils and benzoic acid) steers (Table 1). Dietary treatment did not affect carcass characteristics and most meat quality attributes (Table 2 and Table 3). Dietary treatment did affect lipid content in ribeye steaks, and the following trained sensory attributes: tenderness, chewiness, juiciness, and beef flavor (Table 3 and Table 4). Specifically, ribeye steaks from CON steers had less lipid content while ribeye steaks from CON and COMBO steers were tougher, chewier, and less juicy compared with other treatments (Table 3 and Table 4). Overall, results from this study suggest that growth performance was similar for steers supplemented with essential oils and(or) benzoic acid versus CON steers, and beef quality from alternative treatments was generally not compromised.
Table 1. Effects of replacing monensin and tylosin in beef finishing diets with alternative feed ingredients on steer growth performance.
| Item | Dietary Treatment | ||||||
|---|---|---|---|---|---|---|---|
| CON | M/T | EO | BA | COMBO | SEM | P-value | |
| Steers, number | 14 | 14 | 13 | 13 | 14 | – | – |
| Starting weight, lb | 1178 | 1199 | 1183 | 1182 | 1201 | 46 | 0.62 |
| Final weight, lb | 1606 | 1669 | 1600 | 1604 | 1621 | 49 | 0.21 |
| Total weight gain, lb | 428 | 470 | 417 | 422 | 420 | 16 | 0.15 |
| Average daily gain, lb/day | 4.39 | 4.78 | 4.30 | 4.30 | 4.25 | 0.15 | 0.15 |
| Dry matter intake, lb/day | 27.54 | 26.94 | 27.31 | 26.08 | 27.45 | 1.06 | 0.80 |
| Gain to feed ratio (G:F) | 0.161 | 0.178 | 0.158 | 0.167 | 0.156 | 0.007 | 0.07 |
a,b Least square means lacking a common superscript letter within a row are different (P < 0.05).
Table 2. Effects of replacing monensin and tylosin in beef finishing diets with alternative feed ingredients on steer carcass characteristics.
| Item | Dietary Treatment | ||||||
|---|---|---|---|---|---|---|---|
| CON | M/T | EO | BA | COMBO | SEM | P-value | |
| Steers, number | 14 | 14 | 13 | 13 | 14 | – | – |
| Hot carcass weight, lb | 943 | 980 | 934 | 937 | 959 | 32 | 0.18 |
| Ribeye muscle area, in2 | 14.8 | 15.4 | 14.4 | 15.1 | 15.3 | 0.4 | 0.27 |
| Backfat thickness, in | 0.76 | 0.72 | 0.76 | 0.81 | 0.72 | 0.06 | 0.78 |
| Marbling score1 | Sm58 | Mt24 | Mt40 | Mt46 | Mt07 | 25 | 0.12 |
| Liver Scores2 | 0.70 | 0.00 | 0.50 | 0.00 | 0.20 | – | – |
| No liver abscesses | 10 | 13 | 11 | 13 | 13 | – | – |
| 1-2 small abscesses | 1 | 0 | 0 | 0 | 0 | – | – |
| 2-4 large abscesses or multiple small abscesses | 0 | 0 | 0 | 0 | 0 | – | – |
| Liver adhered to gastrointestinal tract | 3 | 0 | 2 | 0 | 3 | – | – |
a,bLeast square means lacking a common superscript letter within a row are different (P < 0.05).
1 Marbling score: Sm00 = Small00; Mt00 = Modest00.
2 Liver scores were reported as observational data.
Table 3. Effects of replacing monensin and tylosin in beef finishing diets with alternative feed ingredients on meat quality evaluation of longissimus thoracis (ribeye).
| Item | Dietary Treatment | ||||||
|---|---|---|---|---|---|---|---|
| CON | M/T | EO | BA | COMBO | SEM | P-value | |
| Steers, number | 13 | 13 | 11 | 12 | 14 | – | – |
| pH | 5.52 | 5.49 | 5.49 | 5.49 | 5.48 | 0.01 | 0.22 |
| Minolta L* (lightness) | 37.66 | 39.21 | 39.01 | 39.01 | 39.02 | 0.66 | 0.36 |
| Minolta a* (redness) | 21.33 | 21.33 | 21.45 | 21.83 | 21.67 | 0.58 | 0.91 |
| Minolta b* (yellowness) | 8.17 | 8.70 | 8.60 | 9.00 | 8.92 | 0.39 | 0.30 |
| Moisture content, % | 71.86a | 70.48b | 70.15b | 70.84ab | 70.35b | 0.44 | 0.04 |
| Lipid content, % | 4.24b | 6.20a | 6.41a | 5.94a | 6.07a | 0.58 | 0.05 |
| 7 d aged, WBSF1, kg | 4.16 | 3.63 | 3.33 | 3.54 | 3.73 | 0.31 | 0.37 |
| 7 d aged, cooking loss, % | 19.05 | 19.38 | 18.17 | 19.15 | 19.57 | 0.82 | 0.58 |
| 14 d aged, WBSF1, kg | 3.36 | 3.04 | 2.77 | 3.25 | 3.04 | 0.18 | 0.18 |
| 14 d aged, cooking loss, % | 21.32 | 19.63 | 21.18 | 21.44 | 19.32 | 0.91 | 0.25 |
a,bLeast square means lacking a common superscript letter within a row are different (P < 0.05).
1 WBSF = Warner-Bratzler shear force.
Table 4. Effects of replacing monensin and tylosin in beef finishing diets with alternative feed ingredients on sensory evaluation1 of longissimus thoracis (ribeye).
| Item | Dietary Treatment | ||||||
|---|---|---|---|---|---|---|---|
| CON | M/T | EO | BA | COMBO | SEM | P-value | |
| Steaks, number | 13 | 13 | 11 | 12 | 14 | – | – |
| Tenderness | 8.72b | 10.36a | 10.42a | 10.50a | 9.42b | 0.72 | <0.0001 |
| Chewiness | 6.24a | 4.56b | 4.36b | 4.45b | 5.52a | 0.73 | <0.001 |
| Juiciness | 8.12c | 8.90ab | 9.68a | 9.44a | 8.58bc | 0.79 | 0.0005 |
| Beef flavor intensity | 9.20bc | 9.27abc | 9.79ab | 9.90a | 8.92c | 0.52 | 0.01 |
a,b,cLeast square means lacking a common superscript letter within a row are different (P < 0.05).
1 Traits were measured on a 15-cm line scale which included the following: tenderness: 0 = extremely tough to 15 = extremely tender; chewiness: 0 = not chewy to 15 = extremely chewy; juiciness: 0 = very little juiciness to 15 = very high juiciness; beef flavor intensity: 0 = very weak beef flavor detected to 15 = very intense beef flavor.
Acknowledgements
The authors would like to thank the OMAFRA-U of G Research Program, Beef Farmers of Ontario, and Weston Seeding Food Innovation for funding this project. Additionally, the support and assistance of the University of Guelph Elora Beef Research Centre and the University of Guelph Meat Science Laboratory is always very much appreciated.
Author: Lydia Wang (M.SC.), and Dr. Ben Bohrer, Assistant Professor, University of Guelph
