Implants and performance of stocker calves

Many of the best and most up-to-date cattle producers in Arkansas are involved with raising stocker cattle. Producers who have no problem with investing $10 to $15 per calf for the  latest antibiotic to reduce mortality losses forgo the $1 to $2 per calf investment in growth-promoting implants for theircattle. One reason for this may be that producers can easily track sick pulls and death losses associated with respiratory disease but may not be able to see the 10 to 15 percent increase in performance gained from use of implants. Another possible reason may be the belief that use of implants prior to the finishing phase will either decrease performance during finishing, reduce carcass quality or both. Over the last three years, we have conducted research studies determining the benefits of implants pre-finishing and tracking the effects of pre-finishing implants through finishing and slaughter.
In one study, steers were placed on wheat pasture at the University of Arkansas Livestock and Forestry Branch Station at Batesville either after receiving an implant or were not implanted. Also, cattle in separate pastures were offered a non-medicated mineral, a mineral medicated with Rumensin or pressed protein blocks medicated with Rumensin. Steers fed the non-medicated mineral that did not receive an implant gained over 2.3 pounds per day, which is excellent performance for grazing steers. But the implanted steers fed the non-medicated mineral gained 2.7 pounds per day, an increase of 0.4 pound per day! While implanted steers fed the medicated mineral and blocks gained 0.55 pound more per day than steers fed the non-medicated mineral that did not receive an implant. Over a 100-day grazing period, supplying an ionophore and an implant would increase body weight gains by 55 pounds.
In another study conducted at both the University of Arkansas Livestock and Forestry Branch Station at Batesville and Southwest Research and Extension Center at Hope, steers were implanted upon arrival at the receiving pens, following delays of 14 and 28 days, or were not implanted. Implanting during the receiving period did not affect animal performance or animal health during the receiving period, but implants did increase gains while steers grazed cool-season annual pastures (wheat pasture at LFRS and rye or oat pasture at SWREC). Implanting increased overall average daily gain by 0.3 pound per day, but during the last 28-day grazing period, steers implanted on arrival gained less than steers implanted either on day 14 or 28 of receiving. During-receiving energy is likely being used by steers to combat stress and enhance immune function, as opposed to increasing performance in response to implants. While grazing steers were able to respond to implants by increasing weight gain, early implants were playing out before the end of the grazing season.
In the last study, sponsored by the Arkansas Beef Council and the Noble Foundation, steers and heifers from the SWREC cow herd were implanted (or not implanted) prior to finishing as calves (shipped to feedlot at 10 months of age) or as yearlings (shipped to feedlot at 15 months of age) after a stocker period with restricted gains (< 1 pound of gain per day) or unrestricted gains (> 2 pounds of gain per day). Implants increased pre-finishing gains of all cattle whether they were calf-fed, restricted gain yearlings or unrestricted gain yearlings. Interestingly, performance during finishing was not affected by implants pre-finishing. Carcass quality and tenderness were not affected by implant pre-finishing in calf-fed or unrestricted yearlings, but carcass quality grade of restricted gain yearlings was decreased and toughness was increased with implanting of restricted growth yearlings.
Growth promoting implants are a valuable tool for stocker producers with the potential to increase returns by up to $50 per calf. With judicious use of this technology, there is no detrimental effect on carcass quality or eating satisfaction of beef.
Source: Paul Beck, Professor


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