There’s a reason why the practice of implanting feedlot cattle is almost ubiquitous in Canada — it works. Growth-promoting implants substantially improve cattle feed efficiency and muscle deposition. Their economic effects are hugely positive, with savings ranging from $40 to $100 per head. There is even a case for using them as a tool to reduce the carbon footprint of beef production. As beneficial as growth-promoting implants are to cattle feeders, inappropriate use of them is a waste of money and can even have negative effects on production. You may have preferred implant protocols, but are they tailored to your groups as well as they could be?
The key to maximizing an implant protocol’s benefits is often to keep the protocol simple. While there are aspects of implant protocols that will vary on individual operations, the main concepts remain constant no matter what your goals are or what type of cattle you are implanting. In this article, we will review the main components of effective implant programs in five steps and go through the fundamentals.
Step 1. Know your days on feed
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If you are finishing cattle, know the approximate slaughter date and work backwards. If you are background- ing cattle, know the move-out date and the desired size at that time. This way, you can work out which implants will pay out during that time frame. Shipping cattle before an implant payout is a waste of money and the labour to put in the implant. On the other hand, letting implants run long reduces the efficiency of the weight the animals gained from the initial implant. Stacking implants, or re- implanting before the previous implant has been depleted, has negative behavioural and health consequences associated with cattle riding each other.
Step 2. Start at the end
Terminal implants, the implants of highest potency used at the end of the feeding period, are the most important to time correctly. By working backwards, you ensure the terminal implant pays out. If you can’t work out the timing perfectly, you are far better off delaying implantation initially or letting the first implant run out to ensure that the terminal implant is used for the recommended payout duration when weight gain cost is highest. If you are backgrounding cattle, you won’t be using a terminal implant. However, the same principle applies — pick the last implant you would use and work backwards based on the suggested payout.
Step 3. Set carcass quality goals
Are you selling based on live weight? Hot carcass weight? On a grid? To a premium market? An aggressive implant strategy will be better if you’re selling based on weight, but not necessarily if you are being paid premiums for grade. Since implants maximize lean tissue deposition, they also limit marbling. This will vary even more depending on the breed. Continental cattle being sold on a grid might benefit more from a moderate implant protocol than Angus cattle sold on hot carcass weight. The sex of the cattle is important, too. Estrogen and progesterone levels differ between implants designed for heifers and steers. Make sure you are using an implant that is designated for that sex of animal to capture the most efficient gains and minimize the negative effects.
Step 4. Choose pre-terminal implant
The use of one or more implants before the terminal implant will depend on the days on feed and how aggressively the cattle need to gain weight. Each implant has a suggested implant payout and a maximum duration. An implant’s effects on weight gain and feed conversion will be greatest at the beginning stages of the implant payout. Extending the payout of an implant to its maximum duration reduces the average weight gain over the lifetime of the implant but limits the number of times an animal needs to be run through the chute to be re-implanted.
Implants will differ in their suggested re-implantation window. A wide re-implantation window allows for more flexibility in labour co-ordination without the risk of the implant running out. To see continued gain benefits, cattle should be re-implanted with a product of equal or greater strength than the previous one. When working backwards to develop a protocol, this means that the implants used before the terminal implant should have the same or less hormonal content than the terminal implant.
Step 5. Implanting ears
Implants are only as effective as the technique used to insert them. Implants placed incorrectly or into dirty ears are more likely to fail or cause unwanted behaviour. If ear-cleaning protocols are poor or absent, an abscess is more likely to form at the site of the implant. The purulent material of the abscess impedes the implant’s performance and can cause it to be walled off or to release too quickly. Placing implants incorrectly, such as too close to the head or into the cartilage, can impede their release or result in crushing, which releases the hormone all at once instead of over an extended period. Implant crushing can cause riding and dark cutting at slaughter.
A few recommendations for cleaning ears for implanting are as follows:
- Brush off the ears with a dry brush if the ears are slightly dirty but dry.
- Brush the ears with a brush soaked in a hibitane solution (teat dip is a good option) if the ears are wet; repeat with a second dip of the brush into a clean “final prep” hibitane solution.
- Wipe the needle of the implant gun on the surface of a sponge soaked in hibitane solution between each animal.
- Stay one finger away from ear tags or old implants.
What’s in an implant?
Growth-promoting implants are hormones that can be broken down into two main categories: estrogen and androgens. Estrogens can be natural, such as estradiol and progesterone; or synthetic, such as zeranol. Androgens can be natural, such as testosterone, but are more commonly available in the synthetic form, trenbolone acetate (TBA).
Estrogen drives feed intake and increases growth hormone release, which indirectly influences muscle deposition. Testosterone increases efficiency and directly increases muscle fibre diameter and length. Implants approved for heifers will have less estrogen in them compared to implants approved for steers only, as heifers will naturally have more circulating estrogen levels. For most feedlot cattle, the most efficient ratio of TBA to estrogen is 10:1.
Long vs. short acting
How beneficial are long-acting implants on your yard? Long-acting implants can replace a traditional two-implant program by providing the same amount of hormone but released over an extended period. The stress associated with running cattle through the chute, the cost and limits of labour availability make the benefits of a long acting- implant appealing. Although long-acting implants themselves are more costly than short-acting, most feedlots will save more in processing costs.
Long-acting implants are coated to delay the release of hormones and are formulated in two different ways. The hormone pellets will either all be coated equally to limit hormone release and then maintain a steady dissolution of the implant, or it will contain a mix of uncoated pellets that begin releasing immediately after implantation and coated pellets that are delayed-release. Implants with equally coated pellets will have a continuous release of hormone while implants with coated and uncoated pellets will result in an initial peak in hormone levels that slowly decline followed by a second, often larger peak later in the feeding period, to match the effect of using a weaker initial implant followed by a terminal implant.
– Dr. Lexie Reed is a food animal veterinarian at Sunny South Veterinary Services in Lethbridge, Alberta.
