Beefing up your beef business with HGPs
Hormonal growth promotants (HGPs) are a group of veterinary drugs that mimic naturally occurring growth hormones in cattle. HGPs are widely used in Australia and many other countries to increase muscle growth, mature size, lean yield, and delay fat deposition.
Actual improvements in weight gain and feed conversion depend on several factors, with feed quality being the main factor impacting effectiveness. HGPs will only provide an economical benefit if there is sufficient nutrition available to support the animal’s increased metabolism and feed intake. On average, daily weight gain can be improved by 10-30%, and feed conversion efficiency can be improved by 5-8%. This can represent an economic benefit of $25 to $100 per head when compared to non-HGP treated animals.
There are however some factors to consider before implementing a HGP program, such as:
- cost of the implant and implanting
- cost and logistics of mustering for additional implants
- increased feed intake due to HGPs
- changes in carcase composition such as reduced marbling with androgenic implants
- reduced market options
- eating quality reduced in some cases
- less suitable to some breeds
- changes in animal behaviour.
The hormones used in HGPs are both oestrogenic (female sex hormone) and androgenic (male sex hormone) and can either be present in their natural state or synthetic manufactured equivalents (xenobiotic).
HGPs used in Australia include the following or a combination of the following:
- oestrooen (oestradiol -17β, oestradiol benzoate)
- testosterone (testosterone propionate)
- trenbolone acetate (TBA) – a synthetic androgen and
- zenranol – a synthetic nonsteroidal estrogen.
Oestrogenic activity is needed to promote growth, and are therefore the most common hormone, apart from TBA, used in HGPs registered for use in Australia.
Compressed pellets versus silicone coated implants
Hormones from HGPs are released into the animal’s body from an implant deposited under the skin in the animals near-side (left) ear. Implants are either a compressed pellet consisting of the hormone, or a silicone rubber coated pellet impregnated with the desired hormone. Compressed pellet HGPs have a functional life of around 60 -120 days. For this reason, it is not recommended that compressed pellet implants be re-implanted less than 70 days prior to the first implant.
Silicone rubber HGP implants have a slower rate of release, providing a much longer functional life than compressed pellets.
The HGP program
Once the decision to use HGPs has been made, the implant program should be designed to maximise quality and quantity of end beef products and suitability to target market specifications. Some factors to consider when designing a HGP implantation program include:
- Cattle will only respond when they would naturally, without the use of HGPs.
- The more frequently animals are reimplanted, the better overall weight gain.
- Once implanted, the HGP program should be continued up to slaughter for best results.
- Long duration estrogen-only implants allow for seasonal changes in pasture condition.
- Short duration combination implants containing estrogen and androgen require high levels of nutrition to be effective.
- Repeated androgen implants will reduce carcase fat and develop heavier forequarters. This may result in carcase downgrading at slaughter.
- Repeated oestrogen implants do not modify carcase composition at maturity, but cattle may be leaner with less marbling at intermediate weights.
The type of HGPs that can be manufactured, sold, and purchased in Australia is strictly regulated. HGPs are classified as veterinary medicines and must be registered through the Australian Pesticides and Veterinary Medicines Authority (APVMA). For a HGP to be approved in Australia the APVMA must be satisfied that when the product is used according to the label directions it will not result in any appreciable risk to:
- the consumer
- persons handling or administering HGP
- the environment
- other crops or animals
- agricultural trade.
Central Queensland case study
HGPs are widely used in both the grassfed and feedlot industries to improve growth rates and subsequent economic benefits. A comparison on a Central Queensland property (8,700 hectares, carrying 1500 Adult Equivalents) of HGP treated steers and non-HGP treated steers was conducted as a part of the Fitzroy beef production systems — Preparing for, responding to, and recovering from drought report. By the time of sale at 27 months of age, the HGP treated steers were approximately 50 kg heavier than the non-HGP steers. By implementing a HGP program the Central Queensland property received an extra $43.70 profit per steer sold equating to an extra $10,794 profit/annum. This was based on both the HGP and non-HGP steers receiving the same $/kg when sold.
HGPs have a range of applications and positive outcomes. Your local beef extension officer can help you better understand HGPs and design a HGP program to suit your enterprise. If you are interested in finding out more, contact us about beefing up your beef business.
Hormone growth promotants Producer Demonstration Site in the NT
When Trisha Cowley, former beef extension officer with the NT Department of Industry, Tourism and Trade, embarked on a two year Producer Demonstration Site with a cattle station located about 300 km south of Katherine in the Northern Territory, the questions asked by local producers included:
- Are hormone growth promotants really cost-effective under NT growth rates, where the dry season often involves liveweight loss or maintenance during the first year post weaning?
- If so, what are the most profitable strategies?
- What are the hidden costs?
- When do implant losses occur?
Listen to Trisha as she answers these questions in this webinar recording, 51:57 minutes published 8 November 2012.
Legal requirements for hormone growth promotant users, Biosecurity Queensland
Using hormone growth promotants to increase beef production, Meat & Livestock Australia