Weighing the pros & cons

Weight gain with growth promotant implants is a known issue in the feedlot trade but definitely not a major concern.


Implanted cattle must be taken to a higher weight to achieve the same quality grade as an animal without an implant. Put another way, to reach AAA, the final carcass weight of an implanted animal must be 15 to 40 kilograms higher than an animal fed without a growth promotant.


However, that reality isn’t top of mind for most folks in the feedlot sector.


“The industry standard is to use an implant, so that just gets factored in,” said Sandi Parr, professional services production consultant, team lead with Feedlot Health Management Services in Okotoks, Alta.


In 2013, Parr hosted a webinar looking at the impact of growth promotants on carcass quality. In it, she said non-implanted cattle typically reach an AAA grade at a lighter weight than implanted animals.


The obvious question is why.


Parr, a vet trained at Texas Tech University, said it’s related to nutrition priorities during growth.


For most animals, including cattle, the body’s first priority is to use calories for bone development. The second priority is for muscle growth.


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“Then at the very end, kind of the lowest priority, is fat deposition,” she said. 


“(But) when you give an implant, you’re increasing your bone growth and increasing your protein deposition, so more of the calorie pool is going to be shifted over there.”


The Beef Cattle Research Council, which funds beef research in Canada, has a slightly different explanation on its website.


It said adding fat requires more than twice the amount of feed energy than adding protein, or muscle. As well, muscle tissue contains around 70 percent water while fat tissue has less than 25 percent water.


“This means that for every ten pounds of muscle gained, about three lb. comes from dry feed and seven lb. comes from water,” the website said. 


This ratio is reversed for fat growth (roughly seven lb. from dry feed and three lb. from water).


Because implants discourage fat deposition, more days on feed are needed to add the necessary fat to increase marbling and improve grade.


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If implanted cattle must be taken to a higher weight to reach a higher grade, it does increase the amount of feed and number of days on feed.


Nonetheless, the economics clearly show that implants are worth the extra cost at the tail end of feeding, Parr said.


“The advantage that you gain by utilizing an implant, in terms of gain and improvements in feed conversion, would way more than compensate,” she said, adding that feedlot operators focus on feeding margins rather than additional days on feed.


“My cost of gain is a $1 and my live price is a $1.16, so I’m making 16 cents for every pound of weight I’m putting on that animal.”


The BCRC said “aggressive” implant regimes can be detrimental to carcass quality, especially if used on certain breeds of cattle.


Parr said breed is part of the story but there’s not enough research or data showing how breed and implants, in combination, affects beef quality.


“Breed is just kind of the unknown,” she said.


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“(But) you can counter-balance that (breed) by taking cattle heavier.”