Nuflor® vs. Naxcel®: Feedyard Trial

Bovine respiratory disease (BRD) causes great economic loss to the cattle industry. Each year hundreds of millions of dollars are lost through death, reduced performance, and costs of medicine and labor. Although the benefits of good genetics are well known and proper management procedures generally utilized, cattle still become sick and need to be treated for BRD.

NUFLOR (florfenicol) is an antibiotic with superior efficacy against the major bacterial pathogens that cause BRD. The sustained-release formulation of florfenicol makes it convenient and labor-saving, with a single subcutaneous dose or two doses 48 hours apart providing four days of therapy.


The purpose of this study was to compare the efficacy of NUFLOR to that of Naxcel in naturally occurring BRD in a commercial feedyard in western Kansas. The animals involved in the study ranged in weight from 600 to 800 pounds and included both steers and heifers from multiple origins. When presented with clinical signs of BRD and a temperature of at least 104°F, animals were allocated to treatment groups by computer randomization.

Prior to initiation of the trial, treatment was allocated for each animal as it came through the chute. Sequentially numbered ear tags were used to identify each animal. In addition to the antibiotic, every animal treated also received a label dose of an antihistamine, which was part of the normal regimen for the feedyard. Because of labor considerations, the cowboys who rode pens also did some of the doctoring. Bias on repulls was unlikely, however, because it would have required memory of individual animal identification and associated treatment allocation.

Naxcel was dosed at 1 cc per 100 lbs IM, once daily for 3 days, and NUFLOR was dosed at 3 cc per 100 lbs IM, 2 doses 48 hours apart. The records of four animals could not be retrieved at the end of the study because they had been deleted from the computer after they and their penmates were shipped for slaughter. Three of those had been treated with NUFLOR and the other with Naxcel. Data was obtained and analyzed 30 days after the last animal had been treated.


Results are presented in Table 1. First treatment response rates were significantly better (p=0.014) in the NUFLOR group. The numbers of deads and chronics in the two groups were not statistically different.


Table 1 shows two different ways of analyzing the data obtained from the trial. Since the number of deads and chronics are not statistically different, only the repull numbers are included in the cost analysis. In Analysis #1, the cost of a second treatment and the cost of lost gain is calculated according to a formula1 which figures 0.25 pounds per day in reduced gain. (Another study2, however, has shown that figure to be as high as 0.34 pounds per day.) The value of lost gain is calculated at a conservative 50 cents per pound.

In Analysis #2, a given figure3 is used for repull cost which takes into account additional medicine, labor, and lost gain. In both analyses, a charge was added for the additional trips that Naxcel-treated animals had to make through the chute. A trip through the chute generally costs at least $5. While some feedyards charge a set figure, others estimate the cost based on labor, stress, disturbance of feed intake, potential injury (e.g., broken legs, lameness), and equipment wear. Both methods of charging show an economic advantage for NUFLOR.

The cost of antibiotic per treatment is an average determined by dividing the total treatment costs of all animals by the total number of treatments given. Of the 27 animals retreated with Naxcel, eight were retreated a second time, for a total of 35 retreatments. When added to the original 105 treatments and divided into the total treatment costs, the figure of $15.78 per treatment is obtained. The cost of NUFLOR was calculated in the same manner. Therapy of re-treated cattle in both groups was according to the normal regimen of the yard and generally consisted of combinations of antibiotics, particularly spectinomycin and tylosin.

Another economic factor affected by sickness is carcass quality. Data4 has shown that steers that got sick had lower carcass quality grades at slaughter when compared to steers that did not require treatment in the feedyard. It is logical to assume that the longer an animal remains sick, the more significant will be the impact on the final carcass quality and subsequent economic return.


Although the initial average cost of treatment per animal is slightly higher with NUFLOR, consideration must be given to all the factors involved in determining the overall cost-effectiveness of the antibiotic. In this study, a significantly lower number of cattle treated with NUFLOR had to be retreated for relapse of BRD, a circumstance which was economically beneficial.

While the actual values placed on each factor will vary from one operation to the next, repulls, chute trips, performance loss, and death loss all add to overall cost of treatment.


  1. Smith RA: Therapeutic Strategies for Managing Bovine Respiratory Disease: Optimal Health Management for Enhanced Calf Value, Veterinary Learning Systems, Trenton, NJ. 1997, p 58.
  2. Morck DW, Merrill JK, Thorlakson BE, et al: Prophylactic efficacy of tilmicosin for bovine respiratory tract disease. JAVMA 202:273-277, 1993.
  3. Stokka GL, Kansas State University Research and Extension: Personal communications, 1997.
  4. 1995-1996 Texas A&M Ranch to Rail North/South Summary Report. Texas Agricultural Extension Service, College Station, TX.

Nuflor is a registered trademark of Intervet Inc.

Naxcel is a registered trademark of Pharmacia & Upjohn.

© 1997, Intervet Inc. All rights reserved.