Maximise results from an assisted breeding program

Repro Injectables – how to avoid costly mistakes

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An important component of maximising results from an assisted breeding program is ensuring injectables are managed correctly.  All too often, hormones such as prostaglandin (PG), Gonadotropin releasing hormone (GnRH), follicle stimulating hormone (FSH) and oestradiol benzoate (ODB) are administered either incorrectly or on the wrong day, at the wrong time or at the wrong dose.  It is believed that up to 30% of producers could improve their results by following best practice management. 

This article is aimed at helping minimise the risk of errors occurring and thereby helping ensure the maximum pregnancy rate is achieved from your investment in artificial insemination (AI) or embryo transfer (ET). 

Route of Administration 

The good thing about the injectables needed for assisted breeding programs, is that they are all administered intramuscularly (IM), i.e. directly into the muscle rather than intravenously (IV) or subcutaneously (SC).   

Administration Sites 

The preferred site to give IM injections, particularly in beef cattle is directly into the neck muscles to avoid damage to the higher value hindquarter cuts of meat (and minimise the risk of damaging the sciatic nerve). However, given injectables are often administered in the race rather than the crush, it may be safer and more practical to administer these into the rump and thigh muscles as shown in Figure 1.  

If the females are in very good body condition score, sometimes the depth of the fat on the rump may exceed the length of the needle. If this is a concern, selecting an injection site on the female that has less fat cover such as the neck or the lower thigh may be more suitable. Safety must always be considered before choosing these sites. 



Reproduction treatments are administered in small doses; usually 1 mL or 2 mL at a time.  It is therefore critical to ensure that the full dose is administered to have the necessary effect on the female’s reproductive cycle.  The right equipment, the right settings and correct technique will help minimise errors. 

Two of the most common mistakes are incorrectly setting the dosage on flexi-dose injector guns and pulling out the needle out before the hormones have been completely administered, meaning an animal is likely to receive less than the recommended dose.  Taking a few more seconds with each injection to ensure it has been fully dispensed into the muscle is worthwhile; particularly when using slapshots and more viscous products such as ODB. 


Injector Guns 

Given relatively large numbers of females tend to be synchronised at any one time, injector guns are much quicker, easier and safer to use than drawing up the correct dose in a syringe. 

While injector guns are available in fixed and flexi dose forms, flexi dose guns tend to be more popular in Australia.  Vetoquinol has introduced blue flexi guns for PG which is typically administered in 2 mL doses and green guns for GnRH which is generally administered as a 1 mL dose (Figure 2).