Evaluating implants with different payout lengths for growing beef cattle
Does length influences cattle performance on short duration tallgrass grazing systems?
By Jason M. Warner
Growth promoting implants have been widely researched and used for decades by the industry to increase weight gain of growing cattle. In general, the magnitude of response by administering an implant increases in direct proportion to the age and growth rate of the animal and energy level of the diet. In recent years, modern implant products have been introduced that have an extended payout period or length of time in which hormone is released to the blood stream, allowing for performance to be maintained or increased for a longer duration.
For producers to maximize the economic benefits by implanting, the amount of time the implant actively releases hormone should ideally match the length of the feeding or growing period. In the tallgrass area of Kansas, it is common for stocker cattle to graze for 90 days early in the growing season in an intensive double stocked system. In such a short duration grazing period, response to an implant may be different and data evaluating this are limited.
To research how length of an implant payout period influences cattle performance on short duration tallgrass grazing systems, a trial was conducted by the Department of Animal Sciences and Industry at Kansas State University (Farney and Corrigan, 2019; Evaluation of Two Implants for Steers on Early-Intensively Grazed Tallgrass Native Range (newprairiepress.org))[1]. The researchers hypothesis was that a faster release of hormone would result in greater early season gains, without differences in season-long gains.
For this trial, predominantly black weaned yearling steers (n = 281) weighing approximately 550 lb were received for summer grazing at the Bressner Research Range Unit near Yates Center in southeast Kansas. Steers were allotted to pastures and assigned to receive either a Revalor-G or Synovex One Grass implant with an equal number of calves representing each implant within the pasture. When compared to Revalor-G, Synovex One Grass has a longer payout period (approximately 200 d), thus a potentially slower initial release of hormone. Pastures were burned in early April and steers subsequently grazed eight individual pastures from late April to late July.
By design, initial steer body weight was not different between treatments (Table 1.). Both mid-point and final body weights were also not different between steers receiving a Revalor-G® or Synovex One Grass® implant. Therefore, body weight gain was not different between treatments when expressed as either total gain or average daily gain.
Likewise, incremental daily gain from trial initiation to mid-point, and from mid-point of the grazing season to trial conclusion was not different between implant treatments. Steers overall performed well in this trial, averaging approximately a 2.5 lb daily gain per head.
These data support that while performance of yearling stocker cattle grazing native Flint Hills tallgrass forage for a short duration period may be similar between these two implant regimens, there also is little benefit for producers in administering an extended release implant unless cattle are retained long enough for the additional gain later in the period to offset the cost of the implant.
Reference[1] Farney, J. K. and Corrigan, M. E. (2019) “Evaluation of Two Implants for Steers on Early-Intensively Grazed Tallgrass Native Range,” Kansas Agricultural Experiment Station Research Reports: Vol. 5: Iss. 1.
Warner is an Extension cow-calf specialist in the Department of Animal Sciences and Industry at Kansas State University.
