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Reprinted from:
leaky-rh.rock.tap.csiro.au/facts/steroids_txt.html

Use of hormonal growth promotants

Anabolic steroids, also known as hormonal growth promotants (HGPs) have been an important management tool in Australian beef production since 1979. Used routinely in beef production in Australia, HGPs assist Australian beef to be competitive in an international market.

Use of HGPs improve growth rates and increase feed efficiency in cattle. Their use is very cost effective: a $3 implant can result in a 20-30 kg weight gain and so generate an additional $20-35 per head.

HGPs used are either natural or synthetic hormones which are given as implants as they are not effective if given by mouth. The implants are put into the animal's ear as this is not eaten but discarded at slaughter.

Hormones used in HGPs are either male hormones (androgens) or female hormones (oestrogens). These hormones are registered for use in Australian cattle and when used as recommended do not represent a risk to consumers.

Animal with the implants must be identified at slaughter as "HGP-treated".

Use overseas

HGPs are used extensively in beef production throughout the world. In the United States, like Australia, most feedlot cattle have HGP implants. Only the EEC and its member nations ban the use of HGPs. Many believe that this ban is politically motivated and is aimed at slowing beef production to reduce the European ‘beef mountain'.

Effects on cattle health

The hormones used in HGPs are either identical to, or similar in action to, the hormones that are naturally produced in animals and humans.

If HGPs are used as directed there are few side effects and any such side effects do not harm the animal or affect the quality of the meat. For example, steers treated with female hormones may exhibit a high tail, or those receiving male hormones may develop ‘staginess' (or male sexual characteristics).

Effects on human health

Used correctly, HGPs carry no risk to human health or safety. In addition, after animals have been treated with HGPs, levels of hormones in the meat of treated steers are much lower than the levels of hormones produced naturally by cows and bulls.

To comply with Australian standards for synthetic hormones, carcasses must contain nil detectable residues at slaughter. For naturally-occurring hormones, implant residues also must be zero.

Australian research

For beef from northern Australia to be sold in to premium markers a substantial increase in liveweight gain is needed. CSIRO scientists estimate that an additional 60 kg annual gain in northern bullocks is required to reduce turnoff ages by one year. If this can be achieved, producers can expect an increase of $75 per head annually.

Table 1. Natural production of hormones in humans (AVCA 1986)
Sector of population	Oestrogen production (ng/24 hrs)	% increase from eating 500g implanted steak	Androgen production (ng/24 hrs)	% increase from eating 5000g implanted steak
male child (pre-puberty)	41,000	0.0013	65,000	0.005
adult man	136,000	0.0004	6,500,000	0.00005
female child (pre-puberty)	54,000	0.001	32,000	0.01
non-pregnant woman	540,000	0.0001	320,000	0.001
pregnant woman	20,000,000	0.000003	320,000	0.001
Source: AVCA (1986) Cattle growth promotants: Some answers. Agricultural and Chemical Association of Australia. Brochure Reference No 237.86.

For this to happen a range of tools and management practices need to be combined and adapted to suit our unique production system.

HGPs currently used in Australia were developed in Europe and North America where the post-weaning period for slaughter stock is just a few months.

Thus in these beef production systems the growth promotants used as finishing agents are only required to work for a short time. However in northern Australia steers take at least three years post-weaning to finish and so the current promotants need to work for a much longer period to be of real benefit to the Australian beef industry. Scientists at the Tropical Beef Centre are investigating how HGPs can be used more effectively by the Australian industry.

HGPs currently in use in Australia are either oestrogens or a combination of an oestrogen and an androgen such as testosterone. Oestrogens and androgens stimulate growth by different mechanisms and have different results: oestrogens tend to make carcasses fatter whereas androgens make them leaner.

Repeated use of the same steroid formulation is not much more effective than a single implant. However the scientists are investigating whether alternately administering HGPs with different modes of action may result in sustained stimulation of growth.

In addition as the two different hormones have different result on the makeup of the carcasses, the scientists are investigating whether it is possible to tailor carcasses for particular markets by varying the dosage and timing of the different hormones.

Research to date has shown that there are positive results in an improved implantation management practices.

This project is funded by the Meat Research Corporation and is due for completion in 1997.

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Tropical Beef Centre
Ibis Avenue, North Rockhampton Q 4701
PO Box 5545, RMC 4701
Phone: (07) 4923 8100
Fax: (07) 4923 8222
Email: info@tag.csiro.au

http://leaky-rh.rock.tap.csiro.au/facts/steroids_txt.html

Reprinted from:
leaky-rh.rock.tap.csiro.au/facts/steroids_txt.html

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