During this period they may have been isolated/housed on their own and their nutrition management can be highly variable.
Bulls can be seen to either rapidly gain weight, hold their own or slightly lose body condition.
Bulls are generally parachuted into a herd of cows in late-spring and expected to work like prime athletes immediately.
It is fair to say that the slurry tanker, combine harvester or baler wouldn't receive the same treatment after a period of inaction.
Even during this busy period, the time taken to carry out a full 'MOT' on your bull will be hugely beneficial.
Body condition can be visually assessed, with a healthy, lean bull being the target. A mature bull of 700kg plus requires 120MJ of energy daily to maintain body condition.
If a bull has lost body condition it may be necessary to increase the daily energy intake to 130MJ. This can be achieved using good quality forage or concentrate supplementation (approximately 3kg/day).
Where bulls are over-conditioned forage intake should be limited and an 18pc protein concentrate supplemented at 1.5kg/day.
No matter what condition the bull is in, mineral and vitamin supplementation is crucial. The correct balance of minerals and vitamins is essential and it is simply not a case of loading the bull with minerals the week before he joins the cow herd.
Minerals and vitamins are essential for a range of functions including animal health, immunity, bone, hoof, hair and muscle development and fertility.
Some of the more important minerals and vitamins for breeding bulls are:
Zinc - increases semen strength, semen formation, healthy skin and hoof strength
Copper - improves fertility, animal health and energy utilisation
Calcium - required for bone health
Vitamin E - acts as an anti-oxidant
It is also highly recommended to include buffers and yeasts to any mineral/ vitamin pack for breeding bulls.
These additions help to regulate rumen pH and counter the effects of low pH silage while also aiding the rumen fermentation process.
Healthy rumen conditions will go a long way to providing a healthy working bull. Naturally occurring omega-3 oils, such as fish oils can also be added to mineral packs with the view to further boosting bull fertility.
A mature bull requires up to 60 litres on water on a daily basis.
In cases where the water supply is not fresh or has become dirty this intake can drop below 20 litres.
While not only effecting intakes, stale water will contain numerous contaminants that can affect fertility as well as 'locking up' essential minerals.
A bull suddenly becoming infertile can often be a tell-tale sign surrounding hygiene of the feed.
In using the term 'feed hygiene' I am referring to feeds that become stale, heat up and mycotoxins form and multiply.
Mycotoxins, hundreds of which can exist in mouldy feed, all disrupt the natural functions of the rumen, having a major knock on effect on the animals health and in the case of the breeding bull, his fertility levels.
If you feel your bull has been exposed to such contamination coming from hay, straw, bale silage or pit silage then a mycotoxin binder should be fed as part of the 'MOT' treatment.
Gerry Giggins is an animal nutritionist based in Co Louth