Joining advice for beef cattle

Preparation before joining 

Before mating, undertake the following preparation on all bulls: 

• have a veterinary bull soundness evaluation done
• feet — trim claws if overgrown, check for corns
• booster vaccinations — vibriosis, seven-in-one and three day sickness, botulism and pestivirus
• parasites — treat for worms, liver fluke and lice
• assess body condition — if too fat it limits mobility and too thin limits durability, change feed and supplement if required. 

If year round joining is practiced and the bulls are in with the cows all the time, select the month which is 10 months before the bulk of calves arrive (and so the month before peak joining activity) to prepare bulls for joining. 

See our video on preparing for joining:

videocam 3:56

Joining rates 

Joining rate is the number of cows that a bull is run with to serve, either as a percentage or as a ratio. This will vary with property size and topography, management type and the age and fertility of bulls: 

• high joining rate of 4% (one bull:25 cows) used for young bulls when first used or if uncertain how good bulls are 
• a common joining rate for older bulls is 3% (one bull:33 cows) 
• a well-managed herd can use 2.5% (one bull:40 cows) 
• a low joining rate of 2% (one bull:50 cows) can be used for bulls with proven fertility (such as a high serving capacity test result). 

Single vs multiple sire mating  

Multiple sire mating means more than one bull in a given mob of cows. For example, two bulls run with 66 cows for a joining rate of 3%. 

Advantages including using multiple sires of a similar age will usually result in more bull activity, a larger group of sexually active females and higher conception rates. Single-sire mating groups are particularly sensitive to individual bull fertility.  

Disadvantages include fighting between bulls. Some bulls can spend all their time fighting and be too worn out to serve the cows. Injury rates in multiple-sire matings tend to be higher than single-sire, particularly if bulls in the group are of different ages.  

To prevent problems with multiple sire matings use sires of a similar age and run the bulls for that group together before joining. This lets the bulls sort out their pecking order with other bulls prior to going out with the cows and problems can be seen if they arise.   

Back up bulls — a spare bull can be handy because breakdowns can be quite common. Also bulls lose a lot of weight during joining so changing bulls over regularly can help. 

Use of young (yearling) bulls  

There is a trend toward using young bulls. The age when first used depends on breed, body weight and testicle size, measured by scrotal circumference, which needs to be 32 cm minimum. For British breeds this may be 12–18 months if well grown or 2 years old for most European and Bos indicus.  

Tips with using young bulls:  

•  if multiple sire mating use young bulls of the same age together. If young bulls are with old bulls, bullying and injury may occur  
• introduce young bulls with 10 quiet females, then add another 15 cows after 2 to 3 weeks, this gives a high joining rate with young bulls of 4% (one bull:25 females)
• remove them after a total of 6 to 8 weeks and give them 3 months' rest on good feed
• it is critical not to have young bulls drop below condition score 2 as this can ruin their fertility and lifetime performance. 

Mating problems and infertility 

A bull’s job is to get cows pregnant. To do this he must have a good libido, the ability to serve, be free of deformities and injuries and have fertile sperm. Problems with any of these can affect results. The problem may be infertility (no pregnancies) or more commonly subfertility (fewer pregnancies). Either way the consequences are expensive. It is important that any issues are detected early and before joining.  

It is sound breeding management practice to have veterinary examination of all bulls before joining each year, leaving time to purchase replacements if required. These are not a guarantee, but an indication of the potential breeding value of the bull in a normal mating situation. 

Libido  

Poor libido can be due to low male hormone testosterone, age, body condition and psychological factors, including: 

• small and inactive testicles. Testosterone which is produced by the testes and is responsible for the male sex drive. This may be a heritable trait, which can be passed on to both male and female progeny and is a very undesirable trait to have in a bull  
• testes may also be small and inactive due to poor nutrition, stress or a previous injury 
• young bulls may not be sexually mature, but in time will be more interested
• old bulls may have less interest in sexual activity than bulls in their mid-years
• heat stress can affect the bull’s libido. 

Brahman cows have a shorter cycle which is often at night, so Brahman bulls tend to serve at night. Because they are not seen to be serving during daylight hours this should not be confused with low libido. 

Fertility and age  

Bulls tend to be most fertile between the ages of two and 4.5 years. Research has found that after 4.5 years of age, libido, sperm quality and serving capacity drop markedly. So culling bulls at 4.5 is a good rule of thumb (unless proven to still have high fertility and libido). Valuable bulls of high genetic value may be kept beyond this age and joined to fewer females. 

Ability to serve  

A penis should be straight to enable successful joining. If it is bent, the tip of the penis may become traumatised from hitting the rear end of the cow and painful ulcers may develop. The most common problems are persistent frenulum, spiral deviations and abnormal swellings.  

Persistent frenulum is a small piece of tissue attaching the tip of the penis to the sheath. It will pull the penis downwards and may also limit how far the penis can extend out of the sheath. It must be removed to enable a bull to mate successfully. A simple surgical procedure is available to address this problem.  

Spiral deviation (twist) of the penis can interfere with normal mating. It is only detected by watching the bull mating, so may be overlooked as the cause of low fertility. Several matings need to be observed because it is inconsistent. It increases with age and may not appear until a bull is a few years old. Spiral deviation is a heritable condition and affected bulls should be culled. It is most common in polled breeds (up to 20%).  

Abnormal swellings on or around the penis may be due to injuries, wounds or growths. This may inhibit the bull’s ability or desire to serve. Seek veterinary attention without delay as some conditions can be treated successfully if treated early, permanent damage may occur if left unchecked.  

Other conditions are untreatable or progressive and the bull should be culled. Conditions include: 

• broken penis—this appears as a swelling along the midline somewhere between the sheath and the testes. Small swellings usually respond to medical treatment of sexual rest and inflammatory drugs. More extensive swelling will require either surgery or culling 
• sheath injuries can cause considerable swelling and the penis may no longer be able to retract or pass through. Seek veterinary attention as soon as possible, if not treated scar tissue may form adhesions and restrict penis movement 
• warts—penile warts are seen in young bulls and usually disappear by three years of age. Large warts may prevent normal retraction of the penis and have to be surgically removed. 

Physical ailments  

Any physical discomfort associated with mating will discourage a bull from serving. This includes arthritis, lameness, illness and blindness. Sore backs are fairly common in bulls. 

Sperm problems  

Sperm quality can be variable. Poor sperm quality may be permanent, e.g. inherited conditions or when the bull is old and producing faulty sperm. Temporary infertility can occur when the body temperature is too high and result in infertility for up to 3 months. Causes include fevers, for example in three day sickness, heat waves, excessive scrotal fat and moving cattle in hot weather.  

Infected accessory glands can result in degraded sperm cells and pus in the semen. It can be a common reason to cull young bulls. Treatment is with antibiotics and anti-inflammatory drugs, contact your veterinarian. Testicular infection or trauma may reduce the production of sperm either temporarily or permanently. Semen testing is the only way to assess the quality of a bull’s sperm, contact your private veterinarian. 

Joining periods 

Decisions on how long the bulls stay in with the cows have a big influence on a number of factors. A long joining means longer calving and an extended calving leads to: 

• greater chances of feed shortages.
• greater variation in calf live weight and size (this was a major issue when early weaning during the drought)
• less heifers reaching suitable joining weight to calve at 2 years. This can have several issues, including calving problems.
• loss of potential income.