A290
Growth Implants

All currently marketed implants contain some form of slow release estrogens, androgens, or progestins. To ensure that the products are safe and effective, they are regulated by the FDA and must go through the new animal drug approval process before marketing.

How They Work: Implants accelerate growth rates. Growth is largely controlled by the pituitary gland and its secretions of growth (somatotrophic) hormone. Implants act on the pituitary to produce increased levels of growth hormone, and at the cellular level to increase insulin production. The effect of these elevated hormone levels is an increase in the synthesis of muscle tissue and a reduction in the deposition of body fat. Because muscle tissue is more dense than fat, the increase in lean to fat production results in an increased rate of gain and more gain per pound of feed consumed. Table 1 summarizes the expected average improvements in daily gain and feed conversion from implanting cattle.

Together, these increased efficiencies can reduce the cost of feedlot gain by $2 to $6 per cwt. This can result in an overall decrease in the cost of beef production of up to 7%. Using a $1 implant to yield a gain of 20 lbs. more than non-implanted cattle nets a 20:1 return on investment when calves are worth $1 per pound.

Recent studies indicate that aggressive implanting strategies can have a negative impact on carcass quality. Yield grades do not appear to be affected, but the percent of cattle grading choice can decrease 10 to 25% depending on the implant strategy used. For this reason, it is important to use an implant strategy that maximizes gain and meat quality. This is done by matching the animal to be implanted with the correct product.

Products: Only Ralgro, Synovex C, Component EC, and Implus C are approved for use in young calves. These products have a lower effectiveness and are safe for this stage of growth and nutrition. As the animal ages and the level of nutrition advances, the effectiveness of the implant should increase to match the growth characteristics of the animal. Within 120 days of harvest, hormone combinations, including trenbolone acetate, can be used. These are the most effective products and can be used during the periods of fastest weight gain with minimal impact on carcass quality grades. The following table lists some of the currently available implants, their principal ingredients, and the animals and stage of growth for which they are indicated:

Implants used for backgrounding and feedlot cattle are more potent than calf implants and require a higher nutritional plane for optimum performance. Implants containing trenbolone acetate are the most potent and should be considered terminal implants (ones given to older animals just prior to being harvested). Terminal implants should be given 100-120 days prior to harvest to minimize negative effects on carcass quality.

Using proper procedures for placing implants is important. Being clean and precise in location will improve implant performance. Use the following guidelines for proper administration:

1. Properly restrain the animal in a way that allows good access to the ear.
2. Clean and disinfect the back side of the ear. Infected implants will not perform well.
3. Deposit the implant between the skin and the cartilage of the ear, just below the horizontal midline. The implant must not be placed too close to the head. Most implants should be placed in the middle third of the ear (Fig. #2).
4. The insertion site of the needle will be towards the outer tip of the ear, one needle length from the desired "middle-third" position.
5. Avoid placing the implant in the site of an old implant or in an area that will be used for an ear tag.
6. Do not crush implants.
7. Avoid injuring the major blood vessels of the ear.
8. Disinfect the implant needle between applications.