Fully realising bulls' growth potential

Intensive bull fattening is a key area in which AGRAVIS cattle production consultants AGRAVIS cattle production consultants support beef bull farmers with ideas and tips. Consultants Jens Gödde and Christian Bertling explain what the feeding of bulls feeding of bulls involves.

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Beef bulls can react very differently to changes in feed, so the animals themselves clearly show whether the ration is balanced or not.Fully realising bulls' growth potential
Beef bulls can react very differently to changes in feed, so the animals themselves clearly show whether the ration is balanced or not.

Which fattening stage determines the success of bull fattening?

Gödde: With a fattening period of around 16 to 18 months, there should never be a shortfall in the nutrient supply at any fattening stage. Particular care should be paid to the initial fattening stage up to 350 kilogrammes live weight. This is the stage with the greatest growth potential. It might consequently be beneficial, considering the cost situation, to feed in multiple phases – similarly to pig fattening – in order to fully realise the growth potential and feed the animals closely in line with their needs.

What is the importance of the staple feed as a producer of compound feed?

Bertling: In a classic bull fattening operation, the staple feed makes up a very high percentage: 80–90 percent. The influence of staple feed quality and hygiene on performance in bull fattening should therefore never be underestimated. Staple feed management and feeding table management play an important role in this regard. If feed intake can be increased by 1 kilogramme of silage maize (35 percent dry matter 11.0 MJ ME), the additional energy intake would represent added growth of more than 100 grammes.

At present, silage maize, in particular, has a tendency to heat up, because it has a higher dry matter content on average. We know that feeding with silage which has heated up in this way has a distinctly negative effect on feed intake, so that a clear reduction in performance is to be expected, not least due to the energy loss. Errors in staple feed management can therefore only be corrected to a limited extent by compound feed. Only with positive interplay between high staple feed quality and nutrient concentration combined with the corresponding production technology can performance be maximised in intensive bull fattening.

What are the main problems in bull feeding with regard to animal health?

Gödde: Feeding on intensively run bull-fattening farms is largely based on starch-rich silage maize and energy-rich concentrated feed. The fast passage of this feed through the digestive tract, the high proportion of fast-acting carbohydrates (starches, sugars) and feed components that are low in roughage lead to a rapid drop in the pH value pH value which results in over-acidification of the bulls' rumens (subclinical rumen acidosis). If the rumen is subjected to this type of stress over a long period of time, the cellulolytic bacteria in the rumen die. This should be avoided. The challenge lies in structuring the feed ration to ensure feed that is suitable for ruminants. This can prevent over-acidification of the rumen and preemptively counteract the consequences, which cause rumen acidosis.

What preventive measures can be taken?

Gödde: The ration should be checked in consultation with the AGRAVIS feedstuff consultant. In addition to ensuring a good structure, however, it is just as important to observe the behaviour of the bulls in the barn. Beef bulls can react very differently to changes in feed structure, so the animals themselves clearly show whether the ration is balanced or not. In the case of acute over-acidification of the rumen, it may be advisable to use sodium bicarbonate as a rumen buffer. For long-term improvement of rumen health, live yeasts can be beneficial. A combination product in the AGRAVIS range is Vitamiral Bulle Relax Vitamiral Bulle Relax.

What do you think about the use of feed-grade urea in bull feed?

Bertling: Generally feed-grade urea is a beneficial source of protein for ruminant feed. However, it is not advisable to include feed-grade urea in rations purely for cost reasons. It is important to know which rations feed-grade urea can be added to as a useful supplement. The basic conditions for the use of feed-grade urea are as follows:

  • Sufficient fast-acting carbohydrates (starches, sugars), for example due to high proportions of silage maize in the ration
  • Feeding of animals with fully developed rumen function

Because many bull fattening operations place strong emphasis on protein quality, only part of which is available in the rumen, a surge of large amounts of rapidly available energy can cause a lack of nitrogen in the rumen. This is where the feed-grade urea, which acts in the rumen alone in the form of nitrogen, comes into play. This can, to a certain extent, counterbalance a lack of nitrogen in the bull's forestomach. This nitrogen can be converted by the rumen microbes into microbial protein, which is needed for the formation of muscle flesh. Due to the low application quantities and to ensure precise mixing in the feed mixer, feed-grade urea should, if possible, not be used in its pure form, but as a supplement feed or a component of the compound feed. Whether feed-grade urea could represent a useful supplement for bull fattening is something that should be discussed between the beef bull farmer and the AGRAVIS feedstuff consultant.

For further information, please contact Jens Gödde, Tel. +49 (0)173 3452376, jens.goedde@agravis.de or Christian Bertling, Tel. +49 (0)173 1931837, christian.bertling@agravis.de.

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