Building the foundations for herd bull success: Eight key considerations

Beef Central, 30/06/2016
Nigel McMahon

Nigel McMahon

ACHIEVING high fertility in a cattle herd is not a five-minute affair, according to NSW cattle vet Nigel McMahon, from Southern Riverina Vets in Deniliquin.

He says the foundations for success need to be laid months ahead of joining and be built-on year after year.

Selecting the right bull and managing him for peak performance and longevity is an essential skill for every cattle breeder, he suggests.

“Fertility is the number one profit driver in any breeding herd, and high herd pregnancy rates are the result of good planning and good management,” Dr McMahon says.

Here are eight key questions put to Dr McMahon on the topic, and his advice, based on NSW production systems:


Q: When should producers start checking bull fitness and fertility ready for joining?

A: Two months’ prior to the ‘bull in’ date is a good time to conduct a Veterinary Bull Breeding Soundness Evaluation (VBBSE). This allows time to source replacements if any bulls prove unsound or infertile.

Q: What vaccinations should bulls receive and when should they be given?

A: Annual 7-in-1, Vibrio and Pestivirus vaccinations can be done at the same time as the VBBSE. If you’re bringing in a new bull, make sure you know his Pestivirus status.

Q: What body condition score should bulls be in at the start of the joining period?

A: We like to see mature bulls at body condition score 3 and younger bulls a bit better, say 3.5. Younger bulls are not as efficient with their serving ability and tend to lose more weight. Bulls at 2 or less will need supplementary feeding.

Q: Is it important to visually inspect prospective new bulls when all the video/photo, genetic, disease status etc. information is often available online or in catalogues prior to sale day?

A: It’s absolutely vital. I recommend going through the catalogue carefully and rank the bulls that suit your production system. Go to the stud at least several weeks before the sale so you can see the bulls, assess their temperament, structure and soundness and talk to the breeder about their breeding objectives. Ranking the bulls means that if you miss out on your top pick, or picks, you have back-up choices and won’t be forced to make hasty decisions under pressure.

Q: How important is it to know the nutritional background of the bull?

A: Extremely. How bulls are fed can affect their future performance. You want to know the bull will cope with your production system and producers need to be wary of bulls that are over-fed, particularly on grain, which can cause structural and fertility problems.

Q: Which genetic traits are most important?

A: In my opinion, fertility traits are number one. Fertility is the biggest profit driver of any beef breeding operation. It is also important to look at the accuracy of those traits.

Q: Any tips for assimilating a new bull into a herd, particularly into multiple-sire mating situations?

A: Don’t buy new bulls the week before you want to use them. They need time to adjust to their new surroundings. When you get a new bull home, always unload him into stockyards with some quiet cows or steers and keep stress to a minimum. If keeping bulls together or multi-sire mating, keep bulls of similar ages together. An older, less fertile bull will sometimes keep the younger bull away, or hit him as he is trying to serve, which can have serious implications for pregnancy rates.

Q: How many breeding seasons should a bull last?

A: From my experience in southern beef production systems, if you can get three to four breeding seasons out of a bull, you’re doing well. As bull age increases, so does the percentage of unsound bulls.


ReproActive Workshop information

Dr Nigel McMahon will present at a one-day ReproActive workshop near Denilliquin later this week. He will also cover critical mating weights of heifers and why they are so important, how to plan and achieve shorter joining periods and how to condition-score.

When: Thursday, 9 June

Where:  Moroco West yards and the adjacent Bullatale Fire Shed on the corner of Lower River Road and Tocumwal-Mathoura Road, Bullatale, near Deniliquin.

Cost: $40 includes materials, refreshments and lunch.

Register: Online at




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