Implants

OVERVIEW Implants widely used in the U.S. cattle “feeding” Improve average daily gain by 5% to 15% and improve feed efficiency by 5% to 10%. (Implanting generates a $5-10 return for every $1 invested.) Cattle not implanted must sell for a premium price to generate the same net profit as implanted cattle.

MECHANISM OF ACTION Estrogenic implants: – Increase circulating levels of somatotropin (ST) – Increase Insulin-like growth factor-1 (IGF-1). Androgenic -trenbolone acetate (TBA) – Increase circulating levels of IGF-1 Decreases loss of muscle tissue in sedentary animals.

Estrogenic implants: – Suckling calves - increase weaning weights 3-5%. – Stocker cattle (grass) similar as long as base gain is above 1.5 pounds per day. - Feeder cattle - increase feed efficiency & gain 5-15% Implants which “include” TBA can provide additional 3-5 %improvement in feed efficiency & gain.

Estrogens –Estradiol 17  (Compudose) –Estradiol Benzoate (71% E17  ) - Synovex –Zeranol (mold) Ralgro Androgens –Testosterone Propionate (Component) –Trenbolone Acetate (TBA) Finaplix

Progesterones –Progesterone (Component) –Melengesterol Acetate (MGA) Combination implants Estradiol & TBARevS Estradiol benzoate & TBA SynovexPlus

IMPLANT RESPONSE DIFFERENCES Sex: Steers>Heifers>Bulls – Implants are not cleared for use with bulls Maturity: Growing>Finishing>Suckling Gain: Greatest response when ADG is greater than 1 lb. per day. Not recommended or approved for use in breeding cattle or calves less than 45 days of age as hormone production in these animals has not yet started.

Implant Strategies Start LOW => Finish HIGH – Re-implant during “Pay-Out Window” Must be eating … – implants require fuel Effects on tenderness … – YES (aggressive implant programs) Effects on Reproduction … YES – Maybe use on heifers born late in calving season? – Don’t use on bulls

Implants No withdraw time

A study in seven feedlots of 14 groups of cattle representing 2,573 head showed that many (33.7 percent) of the implants were improperly placed. Improperly Administered Implants: Problem Percent Abscess 22.2 Bunched 0.7 Crushed 0.6 Missing 7.5 Pellets missing 0.6 Fibrosis (scars) 1.2 In cartilage 0.4 Improper site 0.5 Total 33.7 Unpublished data from the University of Nebraska Great Plains Veterinary Educational Center during the summer of 1996 suggest abnormal implants are associated with 0.17 pound reduction in carcass gain in cattle fed 150 days

Take the ear of the animal firmly with the free hand Then insert the needle into the subcutaneous tissue at the point indicated After inserting the needle to its full extent squeeze the trigger gradually. Allow the pellets of the implant to be deposited in a single row. Withdraw the implanter.

Develop a “light touch” and “slightly rotate” the needle is best defense against cartilage embedment. – A properly placed implant will be slightly movable. Missing or bunching of implant pellets: – Carefully restrain the animal – Slowly withdraw the needle as implant is being administered. Visually inspect and physically palpate implant site after administered – Ensure the pellets properly aligned. – The implant needle opening should be closed by pressing down on the hole.

Scrape, Brush and Disinfect Ear clean and dry - Implant Ear is dirty (wet or dry) 1 st Scrap with dulled steak knife 2 nd Brush ear with disinfectant solution – Some coat the cleaned implanting needle with an approved, non-irritating antibiotic between animals Ear is wet (but contains no foreign material) 1 st Brushed with disinfectant solution Type of brush: 2-sided (brass bristles & nylon bristles) When not in use, placed in bucket of disinfectant Nolvasan (chlorhexidine acetate) and is licensed by the EPA

Read the Label- Example, Revalor-H STORAGE CONDITIONS Store in a refrigerator (2-8° C; 36-47° F) and protect from sunlight. Use before the expiration date printed on the box and on the cartridge. WARNING Not to be used in animals intended for subsequent breeding or in dairy animals. For Animal Treatment Only. Not for Use in Humans. Implant pellets in the ear only. Any other location is in violation of Federal Law. Do not attempt salvage of implanted site for human or animal food. A withdrawal period has not been established for this product in pre-ruminating calves. Do not use in calves to be processed for veal.

British Society of Animal Science Hormone growth promoters in cattle Wednesday, 12 January 2005 Growth promoting hormone implants have been banned in the EU since The UK government has consistently opposed the ban on scientific grounds but dutifully supported it and introduced its ban

British Society of Animal Science Hormone growth promoters in cattle Wednesday, 12 January 2005 In April 1999 the EU published scientific evidence that it claimed raised concerns about the consumption of beef from treated cattle. Agriculture Minister requested the Veterinary Products Committee (VPC) to review the EU evidence. The report of a VPC sub-group (October 1999) states that they were unable to support the EU conclusion that risks associated with the consumption of meat from hormone-treated cattle were greater than previously thought.

EUROPEAN COMMISSION HEALTH & CONSUMER PROTECTION DIRECTORATE-GENERAL THE SCIENTIFIC COMMITTEE ON VETERINARY MEASURES RELATING TO PUBLIC HEALTH (SCVPH) Review of previous SCVPH opinions of 30 April 1999 and 3 May 2000 on the potential risks to human health from hormone residues in bovine meat and meat products (adopted on 10 April 2002) In conclusion, after re-appraisal of the data from the 17 studies and recent scientific literature, the SCVPH confirms the validity of its previous Opinions (in 1999 and 2000) on the Assessment of Potential Risks to Human Health from Hormone Residues in Bovine Meat and Meat Products, and that no amendments to those opinions are justified.

VPC Open Forum – 16th November Len Levy To evaluate and advise on the latest opinion of the Scientific Committee on Veterinary Measures Relating to Public Health (SCVPH) dated April 2002 and other scientific evidence that has become available

Historical Background UK Government asked VPC to assess the SCVPH Opinion and it did so via a VPC Working Group in At the same time, the EU’s: Safety Working Group of the Committee for Veterinary Medicinal Products (CVMP) evaluated the SCVPH’s Opinion. Both the VPC Working Group and the CVMP were unable to support the scientific conclusions of the SCVPH, but both noted that there were important gaps in knowledge of these compounds which precluded the establishment of confident risk assessments for all six compounds.

General Conclusions in VPC Working Group Report – 2005 November The weight of evidence at present available suggests that likely levels of human exposure to hormonally-active substances in meat from treated animals would not be sufficient to induce any measurable physiological effect. [As a worst case example, it has been estimated that a postmenopausal woman eating a kg of meat (kidney) with the higher concentration of oestradiol detected (56ng/kg) would experience an increased oestrogen level of 0.01% of average endogenous production.]

Implants … & humans Lets look at sources of estrogens …

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