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U.S. Department of Health and Human Services

Animal & Veterinary

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NADA 038-233 RALGRO ® - supplemental approval (March 30, 1994)


Sponsor:Pitman-Moore, Inc.
421 E. Hawley Street
Mundelein, Illinois 60060
Generic Name:zeranol
Trade Name:RALGRO ®
Marketing Status:Over the Counter (OTC)
Effect of Supplement:This supplement provides for the deletion of the caution statement in the labeling against the use of RALGRO ; in heifer (suckling beef) calves intended for reproduction.



For increase rate of weight gain and improved feed conversion.



A.DOSAGE FORM:implantation
B.ROUTE OF ADMINISTRATION:The subcutaneous implantation on the posterior aspect of the ear by means of an implant gun.The implant must not be placed closer to the head than the edge of the auricular cartilage ring farthest from the head. The recommended dosage is one implant containing 36 mg of zeranol.
C.RECOMMENDED DOSAGES:Each implant is made up of three pellets with each pellet containing 12 mg of zeranol. Each implant is contained in a separate chamber of a multiple dose cartndge.



This supplement for the deletion of the caution statement against the use of RALGRO® in heifer calves intended for reproduction does not affect the efficacy information contained in the current NADA.



A target animal safety study was conducted by Drs. P.F. Arthur and M.F. Liu at the University of Alberta, Alberta, Canada. The purpose of the study was to evaluate the effect of RALGRO® implants administered to suckling heifer calves on their subsequent reproductive performance. Suckling heifer calves, between one and three months of age were randomly allotted to three dose groups, 50 animals per group. Heifers were either implanted with a single dose of RALGRO® on Day 0 (RALGRO® 1X Group), implanted with two doses of RALGRO®, one on Day 0 and a second at weaning (RALGRO® 2X Group), or were not implanted (Control Group). At approximately 15 months of age, the heifers were placed in pastures with bulls for a 60-day breeding season. The pregnant heifers calved the following spring and were re-bred and checked for pregnancy following the second breeding season.

The calving rate (number of live calves born per number of animals allotted to a dose group) for each of the three groups of heifers was 70% (Control Group), 77% (RALGRO® 1X Group), and 74% (RALGRO® 2X Group). One-sided lower 90% confidence bounds on the difference in calving rates between the control and the two treated groups demonstrate no significant adverse effect of the RALGRO® treatment on calving rate in the first breeding season. No adverse treatment effects were found for calving difficulty (P= 0.42), birth weight (P= 0.85), and the pregnancy rate in the second breeding season (P= 0.84). The weaning weights of calves born to heifers treated with RALGRO® had similar weaning weights (P= 0.87) to calves born to untreated heifers.



This supplement for the deletion of the caution statement against the use of RALGRO® in heifer calves intended for reproduction does not affect the human safety information contained in the current NADA.



Adequate data were provided to demonstrate that RALGRO® had no adverse effect on subsequent reproduction when administered to heifer (suckling beef) calves after 30 days of age. Under the Center's supplement approval policy (21 CFR



Copies of applicable labels may be obtained by writing to the:

Food and Drug Administration
Freedom of Information Staff (HFI-35)
5600 Fishers Lane
Rockville, MD 20857

Or requests may be sent via fax to: (301) 443-1726. If there are problems sending a fax, call (301) 443-2414.