Implant Basics

Whether used in pre-weaned calves or feedlot cattle, growth implants do what their manufacturers claim - they improve rate of gain. Producers should, however, make some management adjustments to fully benefit from their use of implant technology, and some producers, particularly in the cow-calf sector, sacrifice economic opportunities by not using implants at all.

Implants extend the growth curve in cattle, essentially making them physiologically younger relative to their actual age, says Zoetis technical services nutritionist Gary Sides, PhD. One result of that delay in physiological maturity is a delay in deposition of body fat. Sides says many studies, which have shown a reduction in marbling and USDA Quality Grade in implanted cattle, have compared treated and control groups at the same age or weight endpoints.

Implanted cattle typically can reach Quality Grades similar to non-implanted cattle, but they need some extra time on feed. That results in heavier cattle and possibly higher USDA Yield Grades. Producers sometimes are concerned about heavyweight or Yield Grade discounts on longer-fed cattle, but for most cattle marketed on a carcass basis, heavier carcass weights and higher dressing percentages will more than compensate for any packer discounts for heavyweight carcasses or Yield Grade 4s and 5s. For more on the economics of weight gains late in the feeding period, read "Live Versus Carcass Gains" on

Sides says cattle generally need to reach around 28.5% "empty body fat" (EBF) to achieve their genetic potential for marbling. The formula for estimating EBF is: (Average Yield Grade + 1.7)/.152 = % EBF. So, at Yield Grade 3, cattle will average about 31% EBF. Implanted cattle generally need to reach heavier body weights compared with non-implanted cattle to achieve the goal of 28.5% EBF, Sides says.

Sides also challenges the assumption that implanting calves reduces the potential for feedlot gains or the benefits of additional implants during the feeding period. That assumption sometimes has led to lower sale prices for implanted calves, and reluctance to use implants in grass cattle.

Calf implants consistently produce heavier weaning weights, Sides says. And that weight advantage persists right up to slaughter - non-implanted calves just never catch up. Implanted calves that weigh 30 pounds more at weaning will average 30 pounds heavier at slaughter, meaning the cow-calf producer and the cattle feeder can benefit from calf implants. On average, he says, implants add 20 pounds of weaning weight to calves from heifer dams and up to 40 pounds to calves from mature cows.

Currently, some natural, organic or non-hormone-treated-cattle marketing programs offer premiums for non-implanted cattle, but Sides says these account for only about 2% of the total market, meaning there is no economic incentive for most producers to avoid implants.

Today's wide selection of implants with varying strength, hormone ratios and duration of activity offer producers options to fit nearly any management system or production goal for calves, stockers or feedlot cattle.

As for implant safety, Sides describes the process his company experienced in bringing its Synovex One Grass and Synovex Choice products to market. The implants originally were scheduled for approval in 2010, but Zoetis spent nearly another five years conducting environmental studies to meet EPA concerns over the possibility of trenbolone acetate (TBA) released into the environment, particularly in pastures or non-confined feeding facilities. Five years of studies, at a cost of around $5 million, showed the implant's contribution to hormones released into the environment was less than 1% of the total, with the remainder coming from natural sources. The implants were determined to have no significant environmental impact and were approved in 2014.