Merck Animal Health Wednesday announced progress in its five-step plan to assess the feed additive Zilmax.
Zilmax was pulled from the market in August, 2013, on claims that the product was causing lameness and mobility issues. Zilmax was used in cattle to put on more muscle and less fat late in the feeding period.
In response to the claims, Merck later that month introduced a five-step approach to audit and recertify handlers and users of the product.
Review and dosing
As part of the five-step process, Merck assessed and analyzed existing, as well as new product data. Additionally, Merck Animal Health obtained the input of industry experts, business partners and customers about the product and its use.
According to the review, Zilmax was found to be safe when used according to the product label and in conjunction with sound animal husbandry practices, Merck reports.
The research results and industry data showed that cattle weights, and thus feed consumption rates, have been steadily increasing over time, Merck says, creating the possibility that certain cattle could consume feed quantities that result in ingestion of Zilmax in an amount that exceeds the approved dose.
The review also noted that enhanced label language – coupled with the implementation of certification requirements and a thorough best practices program – will ensure that usage of Zilmax remains compliant with the label.
An updated Zilmax label, to include Component Feeding, which is an alternative method of administering Zilmax using a targeted lower dose, was submitted to and approved by the U.S. Food and Drug Administration. Component Feeding provides cattle feeders with an alternative option to deliver the appropriate dose of Zilmax to cattle every day.
The new feed delivery method allows cattle feeders to mix Zilmax in feed to deliver a lower targeted dose of 60 mg/head/day of zilpaterol.
In addition, to help ensure that use of Zilmax is appropriate and consistent with best practices, Merck Animal Health said it has taken the following steps:
Certification: Every feedyard team member, distributor, feed manufacturer, nutritionist and veterinarian who uses Zilmax or provides consultative services on feeding Zilmax to cattle, must complete the Zilmax training program, as well as annual retraining, addressing the proper use of the product.
Best management practices: These practices include best regimens for the feeding of Zilmax, as well as a number of factors that are critical to animal well-being, including animal handling, proper nutrition/feeding protocols, environmental risk factors, transportation, and cattle management and selection.
Planned in-field use studies: For the studies, Merck will seek the participation of industry partners. Given the addition of Component Feeding to the label, the planned In-Field Use Study design and protocols will be reviewed before the studies commence. Studies will observe cattle before and after receiving Zilmax; observe the mobility of cattle by trained third-party experts; and review potential compounding factors that could impact mobility.
For the duration of the studies, Zilmax will be made available only to cattle feeders that can meet and maintain all conditions of the Best Management Practices initiative and the Certification Program, as well as fully comply with all protocols of the In-Field Use Studies, Merck says.
Additional label modifications: In addition to Component Feeding, the FDA has approved a revision to the existing Complete Feed indication in the label. The current Complete Feed label dose for zilpaterol is 6.8 grams/ton to provide 60 to 90 mg/head/day.
The label will now include an updated caution statement that notes cattle should not be fed Zilmax in excess of 90 mg/head/day. If pen consumption of complete feed exceeds 26.5 lb/head/day (90% on a dry matter basis), zilpaterol should not be fed in complete feed.
This additional language will further ensure that Zilmax use remains compliant with the label, regardless of the delivery feed method chosen, Merck says.
Source: Merck Animal Health