Evaluation of Three Initial Implants and Two Terminal Implants...

...on the Performance, Carcass Grading, and Animal Health of Feedlot Steer Calves in Western Canada

G. Kee Jim, D.V.M., Calvin W. Booker, D.V.M., M.Vet.Sc.,
P. Timothy Guichon, D.V.M., Oliver C. Schunicht, D.V.M., B.Sc.,
B.K. Wildman, D.V.M., B.E. Thorlakson B.Sc.,
Rick L. Sibbel, D.V.M.

Abstract

A trial was conducted in a commercial research feedlot in western Canada to compare three initial implants and two terminal implants on the performance, carcass grading, and animal health of beef calves. Seven hundred and twenty recently weaned, auction market-derived, exotic crossbred steer calves weighing between 545 pounds and 679 pounds were ranked by weight and randomly allocated to one of six experimental groups as follows:

  1. Ral/Rev, which received a 36-mg zeranol implant (Ralgro®, Intervet/Schering-Plough Animal Health, Union, New Jersey) on day 0 followed by an estradiol-17ß/trenbolone acetate implant (Revalor®-S, Hoechst Canada Inc., Regina, Saskatchewan ) on day 70;

  2. Ral/Plus, which received a 36-mg zeranol implant (Ralgro) on day 0 followed by an estradiol benzoate/trenbolone acetate implant (Synovex Plus®, Ayerst Veterinary Laboratories, Guelph, Ontario) on day 70;

  3. FE72/Rev, which received a 72-mg zeranol implant (Ralgro® FE72) on day 0 followed by an estradiol 17ß/trenbolone acetate implant (Revalor-S) on day 105;

  4. FE72/Plus, which received a 72-mg zeranol implant (Ralgro® FE72) on day 0 followed by an estradiol benzoate/trenbolone acetate implant (Synovex Plus) on day 105;

  5. Syn S/Rev, which received an estradiol benzoate implant (Synovex® S) on day 0 followed by an estradiol 17ß/trenbolone acetate implant (Revalor-S) on day 60; or

  6. Syn S/Plus, which received an estradiol benzoate implant (Synovex S) on day 0 followed by an estradiol benzoate/trenbolone acetate implant (Synovex Plus) on day 60.

The animals in each experimental group in a weight block were housed in separate pens. Each pen of twelve animals was an experimental unit, and each group of six pens (one from each experimental group) constituted a weight block.

The outcome parameters that were measured included daily dry matter intake (DDMI), average daily gain (ADG), the dry matter intake-to-gain ratio (DM:G), yield grade (YG), quality grade (QG), morbidity, and mortality.

The DDMI of the FE72/Plus group was significantly (p<0.05) higher than the Ral/Rev and Ral/Plus groups from day 60 to day 69. There were no significant (p>0.05) differences in DDMI between the experimental groups from day 0 to day 59, day 70 to day 104, day 105 to slaughter, day 0 to 69, day 0 to day 104, or day 0 to slaughter.

The most relevant ADG parameters are cumulative ADG from day 0 to slaughter (live and carcass weight basis). On a live weight basis, the ADG of the Syn S/Plus group was significantly (p<0.05) higher than the Ral/Rev, FE72/Rev, and Syn S/Rev groups. On a carcass weight basis, the ADG of the Syn S/Plus group was significantly (p<0.05) higher than the Ral/Rev, Ral/Plus, FE72/Rev, and Syn S/Rev groups. In addition, the ADG of the FE72/Plus group was significantly (p<0.05) higher than the Ral/Rev group.

Terminal implant contrasts demonstrated that the ADG (live and carcass weight basis) of animals receiving Synovex Plus was significantly (p<0.05) higher than animals receiving Revalor-S.

Initial implant contrasts demonstrated that the ADG (carcass weight basis) of animals receiving Synovex S was significantly (p<0.05) higher than animals receiving Ralgro® implants; however, this difference was not significant (p>0.05) on a live weight basis. There were no significant (p>0.05) differences in ADG (live or carcass weight basis) between animals receiving Ralgro implants FE72 as compared to Ralgro® or Synovex S.

The most relevant DM:G parameters are cumulative DM:G from day 0 to slaughter (live and carcass weight basis). On a live weight basis, the DM:G of the Syn S/Plus group was significantly (p<0.05) lower than the Ral/Rev, FE72/Rev, and Syn S/Rev groups. In addition, the DM:G of the Ral/Plus group was significantly (p<0.05) lower than the Ral/Rev group. On a carcass weight basis, the DM:G of the Syn S/Plus group was significantly (p<0.05) lower than the Ral/Rev and FE72/Rev groups.

Terminal implant contrasts demonstrated that the DM:G (live and carcass weight basis) of animals receiving Synovex Plus was significantly (p<0.05) lower than animals receiving Revalor-S.

Initial implant contrasts demonstrated that there were no significant (p<0.05) differences in DM:G (live or carcass weight basis) between animals receiving Ralgro® implants, Ralgro® FE72, or Synovex S.

The carcass grading data are summarized in Table 10. The proportion of animals grading YG A3 in the Syn S/Rev group was significantly (p<0.05) higher than in all other experimental groups. There were no significant (p>0.05) differences in the proportion of animals grading YG A1, YG A2, YG B1, YG B4, QG A, QG AA, or QG AAA between the experimental groups.

Terminal implant contrasts demonstrated that there were no significant (p>0.05) differences in the proportion of animals grading YG A3, YG B4, or QG AAA between animals receiving Synovex Plus versus Revalor-S.

Initial implant contrasts demonstrated that the proportion of animals grading YG A3 was significantly (p<0.05) higher in animals implanted with Synovex S versus Ralgro® implants. There was no significant (p0.05) difference in the proportion of animals grading YG B4 or QG AAA in animals implanted with Synovex S versus Ralgro implants. There were no significant (p>0.05) differences in the proportion of animals grading YG A3, YG B4, or QG AAA between animals receiving Ralgro® FE72 as compared to Ralgro/Synovex S.

There were few animal health events recorded during the study. There were no significant (p<0.05) differences in BRD treatment or overall mortality rates between the experimental groups. There were no rider treatments, rectal prolapse treatments, or aggressive behavior observations in any of the experimental groups.

Introduction

Numerous studies have been conducted to determine the relative efficacy of various estrogenic and androgenic implant strategies on the feedlot performance and carcass characteristics of yearling steers1-8. However, there are limited available data that compare various estrogenic and androgenic implant strategies in beef feedlot steer calves arriving at the feedlot weighing between 500 pounds and 700 pounds that are subsequently fed for 180 to 200 days. The purpose of the investigation reported herein was to compare three initial implants and two terminal implants on the performance, carcass grading, and animal health of feedlot steer calves in western Canada.

Materials and methods

Trial facilities

The trial was conducted in a research feedlot near Airdrie, Alberta, which has a capacity of 1,200 animals. The animals were housed in open air, dirt floor pens which are arranged side by side with 20% porosity wood fence wind breaks. The dimensions of each pen are 7.6 m x 30.5 m. Twelve animals were housed per pen, and there was 0.6 m of bunk space available for each animal.

A centrally located facility was utilized for allocation, weighing, implanting, and treatment of the study animals. This facility has cattle handling equipment, an individual animal scale (Model DF 2000S, Cell Builders Inc., Calgary, Alberta), a chute-side computer for the recording of animal health data, and sorting pens to facilitate the return of animals to designated research pens.

Trial animals

The animals utilized in the study were recently weaned, exotic crossbred beef steer calves purchased from auction markets throughout western Canada. The animals selected for the study were approximately five to 10 months of age and weighed between 545 and 679 pounds. Upon arrival at the feedlot, the animals were moved through a hydraulic chute for a group of procedures known collectively as processing. All animals were eartagged (to provide unique, individual animal identification) and vaccinated against infectious bovine rhinotracheitis (IBR) and parainfluenza-3 (PI3) viruses (Bovishield® IBR-PI3, Pfizer Animal Health, London, Ontario). In addition, each animal received a multivalent clostridial and Haemophilus somnus vaccine (Fermicon™ 7-Somnugen, Boehringer Ingelheim {Canada} Ltd., Burlington, Ontario), and a Pasteurella haemolytica bacterial extract (Presponse®, Ayerst Veterinary Laboratories, Guelph, Ontario). Also, the animals received topical ivermectin (0.5%) at the rate of 1.0 mL per 10 kg body weight (BW) (Invomec® Pour On, Merial, Baie d'Urfe, Quebec) and subcutaneous tilmicosin (Micotil®, Provel, Division of Eli Lilly Canada, Inc., Guelph, Ontario) at a rate of 10 mg per kg BW.

One thousand five hundred and fifty animals, which arrived at the feedlot from September 18, 1996, to September 26, 1996, were candidates for the study. Animals that were deemed unsuitable for the study because of breed type, sex, lack of appropriate ear, temperament, an existing growth implant, or morbidity were removed as candidates.

Experimental design

Using variance estimates for average daily gain (ADG) and the dry matter intake-to-gain ratio (DM:G) from trials previously conducted at Animal Research International by Jim, Guichon, Booker, Schunicht, and Wildman, it was calculated that approximately 10 pens per experimental group would be required to have a 90% chance of detecting differences in ADG or DM:G of 2% to 3% or larger (ß=0.10), and to be 95% certain that these differences are not due to chance (?=0.05).

Animals that fulfilled the criteria described in the trial animals section were weighed on two consecutive days (day -2 and day -1). The animals were ranked by average weight, and animals weighing between 545 and 679 pounds were selected as the final candidates for allocation to the study.

Ten weight blocks were established, and within each weight block animals were randomly assigned to one of six experimental groups as follows: Ral/Rev, which received a 36-mg zeranol implant (Ralgro) on day 0 followed by an estradiol 17ß/trenbolone acetate implant (Revalor-S) on day 70; Ral/Plus, which received a 36-mg zeranol implant (Ralgro) on day 0 followed by an estradiol benzoate/trenbolone acetate implant (Synovex Plus) on day 70; FE72/Rev, which received a 72-mg zeranol implant (Ralgro® FE72) on day 0 followed by an estradiol benzoate/trenbolone acetate implant (Synovex Plus) on day 105; Syn S/Rev, which received an estradiol benzoate implant (Synovex S) on day 0 followed by an estradiol 17ß/trenbolone acetate implant (Revalor-S) on day 60; or Syn S/Plus, which received an estradiol benzoate implant (Synovex S) on day 0 followed by an estradiol benzoate/trenbolone acetate implant (Synovex Plus) on day 60.

Animals were allocated to the study in two groups. The first five weight blocks were allocated on October 7, 1996, and the last five weight blocks were allocated on October 10, 1996. The animals in each experimental group in a weight block were housed in separate pens. Each pen of 12 animals was an experimental unit, and each group of six pens (one from each experimental group) constituted a weight block. A total of 720 animals were allocated to the study.

Feeding program

A standard mixed complete feedlot diet, formulated to meet or exceed the nutritional requirements of feedlot cattle (Nutritional Requirements of Beef Cattle, National Research Council, 1996) was offered ad libitum. The experimental diets were blended by combining dry-rolled barley, barley silage, and pelleted supplement in a truck-mounted mixer box (Model 490-14, Roto-Mix, Inc., Dodge City, Kansas) equipped with electronic load cells. The supplement was manufactured by a commercial feed mill (Masterfeeds, Calgary, Alberta). The diets were delivered to the pens once or twice daily. Daily feed allowances to each pen were recorded. Water was provided ad libitum from wells at the feedlot.

The composition of the diet supplement is shown in Table 1. The supplement was manufactured by a commercial feed mill (Masterfeeds,™ Calgary, Alberta)

Table 1. Calculated composition (100% dry matter basis) of the supplement.
Ingredient Unit Inclusion Rate
Crude protein % 32.00
Calcium % 9.00
Sodium % 2.40
Potassium % 1.65
Phosphorus % 0.40
Sulfur % 0.36
Magnesium % 0.15
Zinc ppm 1,025
Manganese ppm 825
Copper ppm 325
Iron ppm 200
Iodine ppm 20
Selenium ppm 6
Cobalt ppm 4
Vitamin A IU/kg 100,000
Vitamin D3 IU/kg 10,000
Vitamin E IU/kg 100
Monensin Sodium ppm 456
Tylosin Phosphate ppm 198


The animals were adapted to a finisher diet over a six-week period by increasing the proportion of dry-rolled barley and decreasing the proportion of barley silage at approximately one-week intervals. The composition of the diets fed is presented in Table 2.

Table 2. Proportional composition (100% dry matter basis) of the mixed complete diets.
Diets
Ingredient
1
2 3 4 5 6 7
Rolled Barley 28.87 40.22 50.61 60.30 68.98 76.65 83.37
Barley Silage 63.71 52.44 42.30 32.73 24.17 16.52 9.92
Canola Meal 2.35 2.33 2.15 1.98 1.83 1.81 1.69
Supplement 5.07 5.01 4.94 4.99 5.02 5.02 5.02


The mixed complete diets were sampled on days 0, 30, 60, 90, 120, and 150 of the study. These samples were analyzed for crude protein, acid detergent fibre (ADF), calcium (Ca), phosphorus (P), potassium (K), magnesium (Mg), sodium (Na), and salt (NaCl) (Northwest Labs, Lethbridge, Alberta).

Animal health

The cattle were observed once or twice daily by experimental pencheckers. Cattle exhibiting symptoms of illness were moved to the hospital facility, diagnosed, and treated as per written treatment protocols provided by the consulting veterinarians. The treatment events, including the treatment date, presumptive diagnosis, drug(s) administered, and dosage used were recorded on the chute-side computer system.

All animals deemed to be "chronics" by the attending feedlot veterinarians were weighed and removed from the study.

All animals that died during the study were weighed by feedlot personnel and necropsied by the attending feedlot veterinarian. If the cause of death could not be ascertained by gross post-mortem examination, tissues were submitted to a veterinary diagnostic laboratory to aid in determining the cause of death.

Marketing

All animals were slaughtered on day 182 of the study at the same packing plant (Lakeside Packers, Subsidiary of IBP, Brooks, Alberta).

Data collection and management

At the time of allocation (day 0), the frame size of each animal was measured (a scale of 0-9), and the average frame size for each pen was calculated. All animals on the study were individually weighed on days -2, -1, 60, 70, 105, 180, and 181 of the study. In addition, the carcass weight of each animal was converted to a live weight using a fixed carcass yield of 59.0%. Also, all animals that died and those that were removed from the study were weighed. These data were subsequently entered into a spreadsheet program (Quattro Pro for Windows, Version 5.00, Borland International Inc., Scotts Valley, California) and verified. Average pen weights were calculated at days 0 (average of day -1 and -2), 60, 70, 105, slaughter live weight basis (average of days 180 and 181), and slaughter carcass weight basis (calculated as the hot carcass weight converted to a live weight using a fixed yield of 59.0%). Pen-based DDMI, ADG, and DM:G were calculated for the intervals day 0 to day 59, day 60 to day 69, day 70 to day 104, day 105 to slaughter (live and carcass weight basis), day 0 to day 59, day 0 to day 69, day 0 to day 104, and day 0 to slaughter (live and carcass weight basis).

The outcome variables used to assess feedlot performance were calculated on a pen basis as follows:

DDMI= (total dry matter delivered in the interval minus total dry matter removed in the interval) divided by the number of head days in the interval

ADG= (·weight at the end of the interval minus · weight at the beginning of the interval) divided by the number of head days in the interval

DM:G= DDMI divided by ADG

Grading data on all carcasses were obtained at slaughter using an electronic identification system (E.I.D. Tags, Allflex, Dallas, Texas) to track the carcasses through the packing plant. The proportion of animals grading Canadian yield grade (YG) A1, YG A2, YG A3, YG B1, YG B4, Canadian quality grade (QG) A, QG AA, QG AAA was calculated for each pen.

The computerized animal health data were summarized for each pen. From these data, the bovine respiratory disease (BRD) treatment, rider treatment, rectal prolapse treatment, aggressive behavior observation, and overall mortality (mortality due to all causes) rates were calculated for each experimental group.

Statistical Analysis

The data were analyzed using an analytic software program (The SAS™ System for Windows, Release 6.11, SAS Institute Inc., Cary, North Carolina).

The chemical analyses of the mixed complete diets were compared between the experimental groups using least squares analysis of variance11.

Frame size, DDMI, ADG, DM:G, and the yield and quality grade parameters were compared between the experimental groups using least squares analysis of variance for block and treatment effects11. Frame size was tested as a covariate of DDMI, ADG, and DM:G. Those covariates with significant (p<0.05) effects were included in the final model used for comparison of each parameter between the experimental groups12. Pairwise comparisons between experimental groups were performed when significant (p<0.05) treatment effects were detected in the analysis of variance. Also, initial and terminal implant contrasts were performed for the following parameters: DDMI day 0 to slaughter, ADG day 0 to slaughter (live and carcass weight basis), DM:G day 0 to slaughter (live and carcass weight basis), YG A3, YG B4, and QG AAA.

The animal health parameters were compared between the experimental groups using linear logistic regression techniques to adjust for the clustering of animal health events within pens.13, 14, 15

Results

The chemical analysis of the mixed complete diets is presented in Table 3. Chemical analysis performed by Norwest Labs, Lethbridge, Alberta. There were no significant (p>0.05) differences in the levels of crude protein, ADF, Ca, P, K, Mg, Na, or NaCl between the experimental groups.

 

Experimental Group

a (100% dry matter basis) of the mixed complete diets by experimental group."
Table 3. Chemical analysisa(100% dry matter basis) of the mixed complete diets by experimental group.
Nutrient Ral/Rev Ral/Plus FE72/Rev FE72/Plus Syn S/Rev Syn S/Plus Standard Error
Crude Protein 13.20 13.40 13.25 13.38 13.23 13.23 ±0.11
A.D.F. 9.09 8.81 9.62 9.09 8.69 8.49 ±0.59
Calcium 0.64 0.56 0.57 0.62 0.55 0.59 ±0.04
Phosphorus 0.40 0.40 0.40 0.39 0.40 0.39 ±0.00
Potassium 0.90 0.86 0.87 0.87 0.86 0.89 ±0.04
Magnesium 0.18 0.18 0.18 0.18 0.18 0.18 ±0.00
Sodium 0.14 0.12 0.14 0.14 0.13 0.13 ±0.01
Salt 0.37 0.32 0.36 0.37 0.33 0.34 ±0.03


The average initial weight of animals in each of the experimental groups was 615 pounds. There was no significant (p<0.05) difference in frame size between the experimental groups. The average slaughter weight of animals in the Ral/Rev, Ral/Plus, FE72/Rev, FE72/Plus, Syn S/Rev, and Syn S/Plus groups was 1198, 1216, 1198, 1214, 1202, and 1234 pounds, respectively. The average carcass weight of animals in the Ral/Rev, Ral/Plus, FE72/Rev, FE72/Plus, Syn S/Rev, and Syn S/Plus groups was 716, 727, 718, 728, 721, and 739 pounds, respectively.

The interval and cumulative DDMI data are summarized in Tables 4 and 5, respectively. The DDMI of the FE72/Plus group was significantly (p<0.05) higher than the Ral/Rev and Ral/Plus groups from day 60 to day 69. There were no significant (p>0.05) differences in DDMI between the experimental groups from day 0 to day 59, day 70 to day 104, day 105 to slaughter, day 0 to 69, day 0 to day 104, or day 0 to slaughter.

Experimental Group

Table 4. Summary of the interval daily dry matter intake by experimental group
Interval Ral/Rev Ral/Plus FE72/ Rev FE72/ Plus Syn S/Rev Syn S/Plus Standard Error
Day 0 to Day 59 19.47 19.37 19.60 19.70 19.12 19.63 ±0.17
Day 60 to Day 69 20.46a 20.51a 20.95ab 21.20b 20.71ab 20.73ab ±0.18
Day 70 to Day 104 20.80 20.70 20.63 20.90 21.09 20.94 ±0.24
Day 105 to Slaughter 20.94 21.18 21.07 21.24 21.00 21.67 ±0.19


1. Means in the same row with different superscripts are significantly (p<0.05) different.

Experimental Group

Table 5. Summary of the cumulative daily dry matter intake by experimental group.
Interval Ral/Rev Ral/Plus FE72/
Rev
FE72/
Plus
Syn S/
Rev
Syn S/
Plus
Standard Error
Day 0 to Day 59 19.47 19.37 19.60 19.70 19.12 19.63 ±0.17
Day 0 to Day 69 19.61 19.53 19.80 19.91 19.35 19.78 ±0.16
Day 0 to Day 104 20.00 19.91 20.07 20.24 19.92 20.17 ±0.17
Day 0 to Slaughter 20.39 20.44 20.49 20.66 20.37 20.79 ±0.16


1.Contrasts for Day 0 to Slaughter: Revalor-S versus Synovex Plus, p=0.1002; Ralgro® implants versus FE72, p=0.3255; Ralgro® implants versus Synovex S, p=0.3103; and FE72 versus Synovex S, p=0.9746.

The interval and cumulative ADG are summarized in Tables 6 and 7, respectively. The most relevant ADG parameters are cumulative ADG from day 0 to slaughter (live and carcass weight basis). On a live basis, the ADG of the Syn S/Plus group was significantly (p<0.05) higher than the Ral/Rev, FE72/Rev, and Syn S/Rev groups. On a carcass weight basis, the ADG of the Syn S/Plus group was significantly (p<0.05) higher than the Ral/Rev, Ral/Plus, FE72/Rev, and Syn S/Rev groups. In addition, The ADG of the FE72/Plus group was significantly (p<0.05) higher than the Ral/Rev group.

Terminal implant contrasts demonstrated that the ADG (live and carcass weight basis) of animals receiving Synovex Plus was significantly (p<0.05) higher than animals receiving Revalor-S.

Initial implant contrasts demonstrated that the ADG (carcass weight basis) of animals receiving Synovex S was significantly (p<0.05) higher than animals receiving Ralgro® implants; however, this difference was not significant (p>0.05) on a live weight basis. There were no significant (p>0.05) differences in ADG (live or carcass weight basis) between animals receiving Ralgro implants FE72 as compared to Ralgro® or Synovex S.

Experimental Group

Table 6. Summary of the interval average daily gain by experimental group.
Interval Ral/Rev Ral/Plus FE72/ Rev FE72/ Plus Syn S/Rev Syn S/Plus Standard Error
Day 0 to Day 59 3.33 3.39 3.43 3.47 3.33 3.51 ±0.06
Day 60 to Day 69 4.30ab 4.01a 4.21ab 4.38ab 4.53bc 4.87c ±0.14
Day 70 to Day 104 3.46b 3.89c 3.13a 3.08a 3.49b 3.62b ±0.08
Day 105 to Slaughter              
Live Weight 2.78a 2.81ac 2.91ab 3.07b 2.80ac 2.98bc ±0.07
Carcass Weight 2.98a 3.01a 3.14ab 3.34b 3.06ac 3.22bc ±0.07


1. Means in the same row with different superscripts are significantly (p<0.05) different.

Experimental Group

Table 7. Summary of the cumulative average daily gain by experimental group.
Interval Ral/Rev Ral/Plus FE72/Rev FE72/Plus Syn S/Rev SynS/Plus Standard Error
Day 0 to Day 59 3.33 3.39 3.43 3.47 3.33 3.51 ±0.06
Day 0 to Day 69 3.47a 3.48a 3.55a 3.60ab 3.50a 3.70b ±0.05
Day 0 to Day 104 3.47a 3.61bc 3.41a 3.42a 3.50ab 3.67c ±0.04
Day 0 to Slaughter              
Live Weight 3.18a 3.27ab 3.20a 3.28ab 3.21a 3.38b ±0.04
Carcass Weight 3.26a 3.36ac 3.29ac 3.39bc 3.31ac 3.48b ±0.04


1. Means in the same row with different superscripts are significantly (p<0.05) different.

Contrast for Day 0 to Slaughter Live Weight: Revalor-S versus Synovex Plus, p=0.0006; Ralgro® versus FE72, p=0.8155; Ralgro® versus Synovex S, p=0.0766; and FE72 versus Synovex S, p=0.1217.

Contrast for Day 0 to Slaughter Carcass Weight: Revalor-S versus Synovex Plus, p=0.0005; Ralgro® versus FE72, p=0.4212; Ralgro® versus Synovex S, p=0.0274; and FE72 versus Synovex S, p=0.1488.

The interval and cumulative DM:G are summarized in Tables 8 and 9, respectively. The most relevant DM:G parameters are cumulative DM:G from day 0 to slaughter (live and carcass weight basis). On a live weight basis, the DM:G of the Syn S/Plus group was significantly (p<0.05) lower than the Ral/Rev, FE72/Rev, and Syn S/Rev groups. In addition, the DM:G of the Ral/Plus group was significantly (p<0.05) lower than the Ral/Rev group. On a carcass weight basis, the DM:G of the Syn S/Plus group was significantly (p<0.05) lower than the Ral/Rev and FE72/Rev groups.

Terminal implant contrasts demonstrated that the DM:G (live and carcass weight basis) of animals receiving Synovex Plus was significantly (p<0.05) lower than animals receiving Revalor-S.

Initial implant contrasts demonstrated that there were no significant (p<0.05) differences in DM:G (live or carcass weight basis) between animals receiving Ralgro® implants, Ralgro® FE72, or Synovex S.

Experimental Group

Table 8. Summary of the interval dry matter intake to gain ratio by experimental group
Interval Ral/Rev Ral/Plus FE72/ Rev FE72/Plus Syn S/ Rev Syn S/ Plus Standard Error
Day 0 to Day 59 5.85 5.74 5.72 5.69 5.74 5.62 ±0.08
Day 60 to Day 69 4.92ac 5.38a 5.15ab 5.00ab 4.70bc 4.35c ±0.20
Day 70 to Day 104 6.06b 5.35c 6.63a 6.84a 6.06b 5.82b ±0.13
Day 105 to Slaughter:              
Live Weight 7.59 7.63 7.28 7.02 7.56 7.29 ±0.17
Carcass Weight 7.11 7.13 6.75 6.45 6.93 6.78 ±0.17


1. Means in the same row with different superscripts are significantly (p<0.05) different.

Experimental Group

Table 9. Summary of the cumulative dry matter intake to gain ratio by experimental group
Interval Ral/Rev Ral/Plus FE72/Rev FE72/ Plus Syn S/ Rev Syn S/ Plus Standard Error
Day 0 to Day 59 5.85 5.74 5.72 5.69 5.74 5.62 ±0.08
Day 0 to Day 69 5.67a 5.64a 5.60a 5.56a 5.53a 5.36b ±0.06
Day 0 to Day 104 5.78ab 5.52c 5.90a 5.92a 5.70b 5.50c ±0.05
Day 0 to Slaughter:              
Live Weight/td> 6.43c 6.25ab 6.42ac 6.32bc 6.36ac 6.15b ±0.06
Carcass Weight 6.27a 6.10ab 6.23a 6.11ab 6.16ab 5.98b ±0.06


1. Means in the same row with different superscripts are significantly (p<0.05) different.

Contrast for Day 0 to Slaughter Live Weight: Revalor-S versus Synovex Plus, p=0.0026; Ralgro® implants versus Synovex S, p=0.2009; and FE72 versus Synovex S, p=0.0753.

Contrast for Day 0 to Slaughter Carcass Weight: Revalor-S versus Synovex Plus, p=0.0058; Ralgro® implants versus FE72, p=0.9237; Ralgro® implants versus Synovex S, p=0.1030; and FE72 versus Synovex S, p=0.1239.

The carcass grading data are summarized in Table 10. The proportion of animals grading YG A3 in the Syn S/Rev group was significantly (p<0.05) higher than in all other experimental groups. There were no significant (p>0.05) differences in the proportion of animals grading YG A1, YG A2, YG B4, QG A, QG AA, or QG AAA between the experimental groups.

 

Experimental Group

Table 10. Summary of the carcass grading data by experimental group.
Grading Parameter Ral/Rev Ral/Plus FE72/Rev FE72/Rev Syn S/Rev SynS/Plus Standard Error
Yield Grade              
A1 76.93 72.76 67.00 78.24 71.29 69.86 ±3.66
A2 21.33 22.67 30.50 17.52 19.57 25.65 ±3.46
A3 1.74a 1.00a 2.50a 3.41a 8.23b 2.74a ±1.36
B1 0.00 0.00 0.00 0.00 0.00 0.83 ±0.34
B4 0.00 3.58 0.00 0.83 0.91 0.91 ±0.95
Quality Grade              
A 4.17 7.24 6.50 6.14 5.30 9.89 ±2.55
AA 58.74 56.41 54.17 65.50 63.21 60.54 ±4.35
AAA 37.09 36.35 39.33 28.36 31.48 29.56 ±3.54


1. Means in the same row with different superscripts are significantly (p<0.05) different.

Contrast of Yield Grade A3: Revalor-S versus Synovex Plus, p=0.1175; Ralgro® versus FE72, p=0.2512; Ralgro® implants versus Synovex S, p=0.0041; and FE72 versus Synovex S, p=0.0693.

Contrast of Yield Grade B4: Revalor-S versus Synovex Plus, p=0.0658; Ralgro® implants versus FE72, p=0.1577; Ralgro® implants versus Synovex S, p=0.3620; and FE72 versus Synovex S, p=0.6084.

Contrast of Quality Grade AAA: Revalor-S versus Synovex Plus, p=0.1228; Ralgro® implants versus FE72, p=0.4212; Ralgro® implants versus Synovex S, p=0.0867; and FE72 versus Synovex S, p=0.3524.

Terminal implant contrasts demonstrated that there were no significant (p<0.05) differences in the proportion of animals grading YG A3, YG B4, or QG AAA between animals receiving Synovex Plus versus Revalor-S.

Initial implant contrasts demonstrated that the proportion of animals grading YG A3 was significantly (p<0.05) higher in animals implanted with Synovex S versus Ralgro® implants. There was no significant (p>0.05) difference in the proportion of animals grading YG B4 or QG AAA in animals implanted with Synovex S versus Ralgro® implants. There were no significant (p>0.05) differences in the proportion of animals grading YG A3, YG B4, or QG AAA between animals receiving Ralgro® FE72 as compared to Ralgro® implants or Synovex S.

There were few animals health events recorded during the study (Table 11). There were no significant (p<0.05) differences in BRD treatment or overall mortality rates between the experimental groups. There were no rider treatments, rectal prolapse treatments, or aggressive behavior observations in any of the experimental groups. Three animals died during the study. Two animals died due to musculoskeletal injuries and one animal died of peritonitis. Thirty-two animals were deemed to be "chronics" and were removed from the study.

Experimental Group

Table 11. Animal health summary by experimental group.
Animal Health Parameter Ral/Rev Ral/Plus FE72/Rev FE72/Plus Syn S/Rev Sys S/Plus Standard Error
BRD Treatment 9.17 6.67 4.17 5.00 4.17 3.33 ±1.88
Overall Mortality 0.00 0.83 0.00 0.00 1.67 0.00 ±0.58


Acknowledgments

This project was wholly supported by a research grant from Mallinckrodt Veterinary Inc., Mundelein, Illinois. We thank the management and staff of Animal Research International, Airdrie, Alberta for their assistance and cooperation in conducting this study.

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Revalor is a registered trademark of Intervet International BV. Ralgro is a registered trademark of Intervet Inc. Synovex and Synovex Plus are registered trademarks of Zoetis W LLC. Bovishield is a registered trademark of Zoetis LLC. Presponse is a registered trademark and Fermicon is a trademark of Boehringer Ingelheim Vetmedica. Ivomec is a registered trademark of Merial LLC. Micotil is a registered trademark of Eli Lilly and company.