Two Kansas studies recently showed high-risk calves can be implanted on arrival in feedlots without increasing their risk of disease or harming performance.
The question is often asked whether implanting at the time of arrival has consequences related to the stress newly arrived cattle face, says Britt Hicks, Oklahoma State University animal scientist.
These stressors can negatively affect the immune system at a time when the animal is more likely to be exposed to infectious agents within the bovine respiratory disease complex.
Feedyards commonly implant newly received cattle shortly after arrival to improve performance and economic returns. Ultimately, the question is often raised whether stress during the receiving period may result in nutrients being shunted toward the immune system, which might result in implants being less effective during this period, Hicks says.
Kansas State University researchers evaluated whether delaying the initial feedlot implant might reduce post-transit stress and improve carcass quality of feedlot cattle.
In one study on 1,601 beef calves with a 604-pound initial weight in at a commercial feedlot in central Kansas, half the calves were implanted with Revalor XS at initial processing and the rest of the calves received that same implant on day 45, post-processing.
The authors reported that cattle performance and carcass characteristics were not affected by delaying the initial implant by 45 days. In addition, there was no difference in morbidity, case fatality rate, or death loss due to BRD for cattle that received their implant on arrival compared with delayed-implant cattle.
In another K-State feedlot study, timing of initial implant on 408 crossbred heifers with a 440-pound initial weight were evaluated for overall performance, carcass characteristics and health.
The heifers were divided into three treatments:
1. not implanted
2. implanted at initial processing
3. implanted 21 days after initial processing
Those given an initial implant got Revalor-H and all heifers received a terminal Revalor-200 implant on day 126 of the 222-day feeding period.
As would be expected, during the first 21 days of the trial, heifers that were implanted at initial processing gained significantly faster and more efficiently than the other two groups, Hicks says.
From day 22 to 42, gains were greater heifers implanted at day 21 with 3.64 pounds/day) and those implanted at processing with 3.16 pounds/day, compared with the non-implanted heifers at 2.48 pounds/day.
Over the last half of the finishing period, from day 127 to day 222, feed intake was higher for the 21-day implanted heifers than for the initially unimplanted heifers by 17.1 pounds/day and higher for the initially implanted heifers, which gained 17.6 pounds/day. Yet gains and efficiency were not affected by treatment.
Over the entire 222-day trial, gain was higher 21-day implanted heifers at 3.08 pounds/day than for the initially unimplanted heifers at 2.97 pounds/day and it was intermediate for the initially-implanted group of heifers.
Efficiency again was not affected but heifer carcass weight was greater: The 21-day implanted heifers had 711-pound carcasses, the unimplanted heifers had 69-pound carcasses, and the initially implanted heifers had 701-pound carcasses.
No other carcass characteristics were affected by treatment. The incidences of morbidity and mortality were also unaffected by treatment.
These researchers concluded that delaying the initial implant by 21 days did not negatively affect overall feedlot performance. However, the greater carcass weight with delayed implanting may have economic implications dependent upon how the cattle are marketed.
In summary, both of these studies suggest feedlot calves can be implanted upon feedlot arrival without increasing the risk of disease or harming performance.