Effects of a tylosin tartrate pellet added to cattle growth implants on the incidence of implant site abscesses

Professional Animal Scientist, Sep 2002 by Zollers, W G Jr, Cook, D L, Janes, T H, Barton, W E

Abstract

The antibacterial effects of tylosin tartrate, added to a cattle growth implant, were evaluated in terms of prevention of implant site abscess formation. An implant site abscess induction model was developed to create implant site abscesses reliably in test animals. This model was then used to test the ability of tylosin tartrate, added as a separate compressed pellet to Component(R) brand implants (Ivy Animal Health, Overland Park, KS), to reduce implant site abscess incidence in animals expected to develop an ear abscess. Abscesses were induced in all cattle at implanting (d 0). Implant sites were observed on d 6, 10, 16, 21, 28, and 35 post-implantation to determine the presence and severity of an abscess. Three steer implant formulations and two heifer implant formulations, each with and without the tylosin tartrate pellet, were tested. The overall implant site abscess rate was 94.1 % in animals that did not receive a tylosin tartrate pellet and 4.2% in animals that received a tylosin tartrate pellet. For each implant at each implant site observation, abscess rate was significantly less (P

with the tylosin tartrate pellet. Results show that a significantly lesser percentage of ear implant site abscesses are induced if a tylosin tartrate pellet is added to the implant.

(Key Words: Implant Site Abscess, Tylosin Tartrate, Cattle, Growth Implant.)

Introduction

Implanting growth promotants in the middle one-third of the ear of feedlot cattle "breaks the skin" in a highly contaminated area, which can lead to infection of the implant site and result in abscess formation. The implant site abscess rate generally averages 5 to 8% within a feedyard, but often exceeds 15% in a single pen of cattle (2). In a 1987 survey involving seven feedlots, the ears of 2,573 cattle previously implanted with a growth-promoting implant were palpated to determine abnormalities. Implant defects were defined as abnormalities that could result in an altered rate of absorption of the active ingredients from the implant. Defects observed during the survey included abscess formation, bunching of pellets, crushing of pellets, missing implants, partially missing implants, extensive fibrosis around the implant, and implant placement in the cartilage rather than subcutaneously. Abscess formation was the most frequent implant site defect, occurring at a rate of 22.2% (4). Several large databases within the industry show evidence of the implant defect rate. Fort Dodge Animal Health reported a 6.0% defect rate of 109,388 implants checked in feedyards during 1996 and 1997 (6). Hoechst Roussel Agri-Vet observed a defect of 1 of 8 implants checked; the implant site abscess rate was 6.8% (3). The VetLife database contains Implant Quality Assurance data from nearly 200,000 head of feedlot cattle. The data suggested that implant defects occurred at a rate of 6.0%. The implant defect rate was >15% in 8.1% of the pens evaluated (156 of 1,891 pens); abscessed and missing implants attributable to abscess accounted for 90% of implant defects (2).

Abscesses result in unrealized gains totaling millions of dollars in loss for the cattle industry. Industry estimates are that a 6.0% defect rate results in a loss of $1.37 per head (2). Although programs to promote cleanliness during the implanting process reduce the rate of abscess formation, ear abscesses are not completely eliminated. In a study by Spire et al., where abscesses were induced by methods of poor sanitation, ADG and feed efficiency were reduced 8.9% (1.33 vs 1.45 kg; P

Several studies were conducted by Parrott et al. (5) to evaluate methods for reducing the loss of silicone rubber estradiol-17P implants (Compudose(R); Elanco Animal Health, Indianapolis, IN) from the ears of cattle. Application of cattle feces to the ears before implanting resulted in a 30.6% loss of implants, primarily from abscess formation, compared with 8.6% loss from dry, clean ears. Coating the Compudose(R) implants with 0.5 to 2 mg oxytetracycline hydrochloride reduced (P

The objective of this research was to determine whether the addition of an antibacterial agent, as a separate pellet in a cattle growth promotant implant, reduces abscess incidence.

Materials and Methods

Abscess Induction Model. A model was developed to create implant site abscesses and to test the ability of an antibiotic pellet added to the growth implant to prevent abscess formation. As implanted cattle were evaluated at a standard implant check in commercial feedyards, exudate was collected on sterile culture swabs from ear implant site abscesses for culture. Culture swabs were transported to CAVL, Inc. (Amarillo, TX) for bacterial isolation and culture. Actinomyces pyogenes was the most common of several identified bacteria isolated from culture swabs. Isolates were frozen at approximately -70 deg C and stored.

From a pool of 29 bacteria isolates obtained from the field, 10 were randomly selected. The three isolates with the most consistent growth pattern were selected for preparation of the inoculum in Difco brain-heartinfusion broth (BHI; Becton Dickinson; Sparks, MD) (CAVL, Inc. Standard Operating Procedure No. 004.045). Bacterial isolates were thawed and added to 200 mL BHI. The culture was incubated at 37 deg C, 10% CO^sub 2^, 90% air, with moderate sparging. The culture was harvested at 0.2 to 0.3 absorbance (620 nm) and rapidly chilled; a purity check was performed. Total viable counts were determined and ranged from 2.0 x 10^sup -6^ to 4.8 x 10^sup -6^ across studies. The high abscess rate induced in control animals (>80%) indicated that these levels of bacteria were appropriate in our test system. The inoculum was aliquoted into sterile, 8-mL, screw-cap glass vials. Inoculum aliquots were transported from the CAVL, Inc. laboratory to the cattle facilities in a small cooler with two ice packs.

During the implanting process at the cattle facility, the Component(R) OneGun (Ivy Animal Health, Inc.) implanter needle (8 ga) was dipped into a vial of the bacteria inoculum just prior to implantation. The implant was placed under the skin in the middle one-third of the ear within 10 s of removing the implanter needle from the culture vial. The animal's ear was not cleaned prior to the implantation (induction) procedure. Implant sites were evaluated at selected time points following the implantation (induction) procedure for abscess formation. A licensed veterinarian observed all study cattle at least once each week to determine whether any adverse reactions occurred in cattle because of the abscess induction process. No adverse reactions were reported during the course of the study.

Study Design. The challenge model was used to test the ability of a separate tylsoin tartrate (Tylan(R)) pellet (Ivy Animal Health, Inc.) added to three steer growth implant formulations and two heifer growth implant formulations to reduce the incidence of abscess formation. Cattle were implanted with or without a tylosin tartrate pellet added to the growth implant; however, all animals were induced to form an abscess using the induction model described previously. The Tylan(R) pellet included 29 mg tylosin tartrate and various excipients manufactured by compression on a rotary tablet press. The Good Manufacturing Practices (GMP) manufacturing process was similar to that of steroid growth promotant implants. Cattle were implanted (induced) with or without a tylosin tartrate pellet added to the growth implant.