The purchase of a new stockbull is both a significant event and investment for livestock farmers. There are two key aspects to getting a good return on this investment
- Buying the right bull and
- Maximising the longevity of the bull
Only the buyer can ultimately decide which bull will best suit his/her herd and hence this document focuses on the management of the bull, post purchase.
During the preparation of pedigree bulls for sale many breeders feed generous amounts of concentrates to optimise growth, development and liveweight gain. As a general rule many bulls would receive 1.5% of their bodyweight in the form of concentrate/day.
Example: Liveweight Concentrate
500 kgs. 7½ kgs.
600 kgs. 9.0 kgs.
700 kgs. 10.5 kgs.
It is well proven that rapid changes in feeding regimes cause problems in the rumen. The rumen microflora need time to acclimatise. Changes in rumen function
will affect subsequent hoof health and spermatogenesis as well as lowering the animal’s immunity to diseases, especially pneumonia.
It must be recommended that purchasers of bulls acquaint themselves with the feeding regime their new bull has been on and make changes slowly.
Remember prior to purchase the bull may have been indoors with little energy demands. When it runs with a herd its demand for energy will increase rapidly. This should not coincide with a period of feed withdrawal.
For working bulls the golden rule is fit but not fat. Both thin and fat bulls have reduced libido. Working bulls require about 3 kgs of a high protein (mineralised) concentrate in addition. For resting bulls good quality silage plus minerals is adequate.
Research has shown that bulls poorly fed during the period of puberty will have smaller testicles and suffer a permanent reduction in fertility. It is also well established that there is definitive correlation between testicle size and semen quality. Always check what vaccinations the bull has received and when he has been last treated for hoose and stomach worms, liver fluke and lice/mange. All young bulls should receive treatment for hoose and worms in their first year running with a herd.
Another point to make with regard to bull feeding, is that heavy or even excessive feeding of young bulls for sale is a direct consequence of the customer being more interested in purchasing the very well done animal. Gradually as farmers become more familiar with the genetic indexes and begin to use them as an aid to purchasing, there will be less need for breeders to engage in very heavy feeding for the purpose of making an impression of potential performance. The customer will instead have the great benefit of a genetic index to guide him.
Stockbulls should have proper housing and handling facilities. Small-enclosed dark houses are not satisfactory. Poor housing will affect thrive, fertility and perhaps temper compromising the potential of the bull. Bull pens should be designed to allow bulls have exercise, fresh air, sunlight, free access to water as well as providing safety for the farmer/farm worker. It is recommended that the bull pen in dairy yards be situated to allow the bull view the herd.
Factors Affecting Reproductive Performance:
Libido is sexual drive/desire. It is believed to be highly hereditary and not correlated with the size of the testicles. Sexual maturity occurs in bulls at 9 – 10 months of age but it takes several months before full sperm production is achieved. Well-fed bulls may impregnate cows/heifers as early as 6 – 7 months so weanlings should be divided into males and females before that time. Some animals and indeed some breeds do not reach puberty until they are 12 – 18 months and so should be given the time to mature before deciding their future.
Always introduce bulls to heifers or smaller cows first when they are in proper standing heat. Once they have gained some experience they can run with the herd. After 5 – 6 years of age it is normal for libido to decline in bulls especially within the heavier beef breeds. It is also essential to look out for the presence of cystic females who often display a tendency to nymphomania, meaning a desire to engage in mating behaviour over a greatly extended period. If this happens, the bull will be unable to attend to other females coming on heat at the same time, or if he does, the chances of conception may be reduced.
Newly purchased bulls should be allowed time for them to adjust to their new environment. It is recommended purchasers of young bulls in particular allow for this acclimatisation period when purchasing. Adequate nutrition and exercise is essential during this period.
Remember the job requires fitness. If the bull is run with too many cows not all cows will be served. Certainly in the first season young bulls should not be run with more than 25 – 30 cows.
Impotence is also a factor in poor reproductive performance. Impotence is the inability to serve the cow/heifer even though the bull is anxious to do so. This can be due to injuries to the penis, lameness or other injuries. Veterinary advice should be sought but training the bull to mate starting with smaller females often can prevent it.
There are a number of infectious causes of infertility in bulls. These require veterinary attention. It is important to realise that many infections cause a rise in body temperature, which can be damaging to the sperm production process. Thus a bull may be infertile or sub fertile for a period after an infection.
One of the most important functional issues for any bull is soundness of legs and feet. Bulls that have become lame just cannot perform apart from the welfare costs and weight loss it causes. Lameness is largely a management problem even though the causes may be multifactorial. The main causes are as follows:
- Acidosis: Excess starch/Inadequate fibre. Rapid introduction of concentrates
- Bacterial Endotoxins: Causing laminitis soft hoofs. Prone to bruising.
- Frequency of Feeding: Follow the little & often principle
- Dietary Oil/Fat : Fat/oil reduces fibre digestion predisposing acidosis
- Excess Protein : Suggested cause but no clear cause / effect relationship established
- Nutrients: Such as zinc, sulphur & biotin are thought to harden hoof horn.
- Housing/Yarding : Must achieve a lying time of 10 - 12 hrs./day
- House Design : The layout of the bull pen and the surface quality should be such as to minimise bruising. Rough pitted concrete and bad roadways will cause bruising.
- Wet Conditions/Slurry: Wet conditions will soften the hoof, while stale slurry will cause heel necrosis and digital dermatitis.
- Genetics: Genetics may play a role in many ways e.g. quality of pasterns, leg angle, hoof size etc.
- Illness: Any acute illness or sudden upset will effect horn growth, thus resulting in weaknesses in the hoof.
N.B . Regular use of footbaths and twice yearly foot trimming is important and recommended practice for bull.
The objective is to maintain claws to have equal size with balanced weight distribution.
Acknowledging the contribution of Martin Ryan, Greenvale Animal Feeds.