Bull Preparation – including the “Grain Myth”

IMG_9666Bulls fed grain prior to joining or for sale preparation are no better or worse than those that are not fed grain.  In fact, done properly, partial grain feeding will actually enhance positive fertility outcomes.  This myth that feeding grain to bulls is taboo and will affect both semen quality, ability to walk and ability to serve is simply that: a myth.

The problem is not grain feeding in itself.  The problem is the lack of understanding about how to manage grain feeding properly and the subsequent overload (grain poisoning) that can occur as a result.

Grain feeding for optimal performance is an exact science and requires some understanding of the gut and nutrition.  On top of this, embracing some of the newer feed technologies available can lead to outstanding results for growth and fertility performance that are cost effective.


Pellet feeding

Another myth in the industry is that pellets are safer than raw processed grains.  Strictly speaking, they should be classified in the same category.  After all, the raw ingredients of pellets will usually come from cereal grains especially those high in available starches.  In some cases, pellets can actually be more dangerous, particularly when the manufacturers of ‘least cost pellets’ change their raw ingredients from batch to batch depending on what is cheapest:  That is, one week they will produce the pellet from oats and the next they produce the pellet from wheat.  The effect of this will be acidosis unless the two feeds are blended and changed over properly. Most people are under the illusion that they are feeding the same product all the time.


What are the consequences when grain feeding is managed badly?

Most readers would have seen the consequences of grain overload: death, depression and smelly diarrhea.  Some would have seen stock slowly deteriorating over many months, others might have survived a little longer and others still might turn up dead many months later.

What readers may not appreciate is the fact that these are only the tip of the iceberg.  Other animals exposed to the same feed stuffs may not show as severe signs but still have hidden effects that will impact on their ability to move and serve successfully, as well as maintain themselves or grow.  Often, the signs tend to be a little more subtle.  Months and even years down the track, recurrent lameness may start to occur.  Some bulls may show recurrent abscessation, whilst others suffer from misshapen feet and continued joint problems, all of which hinder the bull in doing what it was designed to do: produce viable semen for optimal conception rates and physically serve cows.


The Pros and Cons of Grain Feeding

In order to appreciate how we can better control animal performance, it is first important to appreciate how the process works normally and what happens when feeds like high starch cereal grains are introduced.


Rumen Fermentation

Cattle have a unique digestive design that allows feed, both paddock and supplementary, to be broken down and digested.  Inside the main digestive organ, called the rumen, huge numbers of microbes live and reproduce.  As they reproduce, in a process called fermentation, they produce all sorts of by-products that ultimately can be both useful and detrimental to the animal depending on their concentrations.


Useful By-products

Useful by-products produced in the rumen include VFA’s (volatile fatty acids) which are responsible for up to 70% of the energy needs of the animal.  These acids are absorbed over the lining of the rumen where they undergo several chemical changes so that they can become available to the bloodstream.  The actual types and ratios of VFAs produced dramatically affect efficiency of production and are dependent on the feed consumed.  As an example, cereal grains fed properly can be the most efficient at producing VFAs most suitable for meat production and reproductive ability.


Detrimental By-products

There are also by-products that, if uncontrolled, can be quite detrimental to the efficiency of feed conversion.  One by-product, lactic acid, is another acid produced when cereal grains are fermented.  Unfortunately lactic acid is stronger and tends to overwhelm VFA production, as occurs in grain poisoning, leading to less energy being available for the animal.  In addition, the entire pH balance of the rumen is changed and microbes used to working most efficiently under tightly controlled pH variations begin to work less and less efficiently.

Lactic acid can also start to overwhelm microbe populations and eventually begin to burn the lining of the rumen. This can affect life long ability to absorb nutrients.  Excessive toxin build up from cellular debris leads to peripheral structures like the hoof losing integrity.  It also causes the leakage of harmful microbes into the blood stream which can lead to organ failure and abscessation.

What is not well understood in the industry, is that the worst cases of acidosis nearly always follow a period of either nutritional or physiological stress.  This stress depletes the total number of functioning microbes (remember their lifespan can be a matter of hours), and if an attractive single source of feed like grain is introduced to the animal, this triggers the rapid multiplication of just one type of microbe.  In the case of grain, this microbe group produces both the useful by-products (VFAs) and the detrimental by-products (lactic acid).  So stress can have an exacerbating effect on grain poisoning.


So how do we limit the detrimental by-products and encourage the useful by-products?

The answer is centered on improving pH control of the rumen via management practices and newer feeding technologies.

Important considerations include;

  1. Limit nutritional and physiological stress.  This means preparing for necessary periods of feed deprivation (e.g. transportation) with feeds that allow fermentation to continue over long periods (e.g. hay).  Managers also need to recognise that stress can be limited by both improved handling of stock and new technology feedstuffs that prevent the consequences of stress.  The later includes the use of specific bioavailable forms of magnesium, B group vitamins, Vitamin A, zincs, starches and water.  One example of these newer technologies that have superseded the older ‘electrolyte’ approach is the use of ELMS Travel & Yard® pellet. Another is the use of Prime Mover® liquid poured over hay.
  1. Frequency of feeding:  The life span of microbes is in some cases as little as a few hours.  Therefore, more frequent feeding of cereal grains leads to both quicker adaptation and also a more stable pH leading to more efficient conversion.  Animals fed 6 times a day will always adapt safer and more quickly than those fed every three days!
  1. Use of Fibre:  Fibre acts as both a stirrer of feeds in the rumen to allow better exposure of new feedstuffs to microbes, as well as physically triggering a neurological muscle function (known as scratch factor).  Like other animals with rumens, fibre often needs mechanical breakdown like cud chewing.  In addition to microbial activity it is this cud chewing that helps release natural chemicals called buffers in the saliva.  Phosphates, and bicarbonate help ‘buffer’ dramatic drops in rumen pH, aiding in more efficient fermentation.
  1. Use of Buffers The use of additional introduced chemicals known as buffers added to the feed can have a dramatic impact on additional control of gut pH stability, and lead to even more efficient conversion.  Note that the impact of all the supplementary additives needs to be considered in terms of overall mineral balance and impact on rumen pH.
    Some chemicals claimed by many in the industry to act as buffers probably have very little impact on pH stability.  In the authors opinion things like bentonite and limestone would fall into this category.  There are now far more sophisticated and reliable buffering and mineral technologies available that are significantly better at stabilising pH and ultimately feed conversion.  Some feedlots use antibiotics like virginiamycin and tylosin as buffers, although the perceptions of human antibiotic restriction may impact on their availability into the future.  Others use bicarbonate soda, and others still use rumen modifiers like rumensin and lasilocid.More recently the ELMS program has produced a buffer pellet called ELMS Cattle Intensive®.  There are several agents in the formulation that help to keep the rumen stable as pH drops and residual activity tends to keep hindgut fermentation stable too making it the authors’ preferred option.


Practical Aspects to Purchasing Grain Fed Bulls

It is a common misconception that only bulls at multi-vendor sales are grain fed when in fact most bulls in on-property sales have had the same treatment. Best practice for bull producers would be to wean bulls off the ration before sale day but this may not always be the case.   Perhaps the best approach for a purchaser is to find out from the vendor the types of feed the bull was on prior to sale.  Armed with this knowledge and recognizing the impacts of stress on fermentation and appetite, reintroduce this feed stuff quickly with plenty of hay after sale and then slowly decrease dependence on the ration over the ensuing weeks.

A check list of best practice approaches off the truck after sale would be:

  1. Introduce hay and water immediately
  2. Introduce stress related preventative approaches e.g. ELMS Travel & Yard Pellet or Prime Mover liquid for the two days immediately post arrival
  3. If the bull breeder has not weaned the bull off the ration on sale day, introduce the original ration (building up over several days).  Ensure the chemical compounds in the ration actually do a decent job in managing pH (i.e. buffer).  Don’t rely on what the feed companies say, have it checked out with someone who knows or simply add ELMS Cattle Intensive at 3% of the ration.  Slowly decrease the dependence on this ration over 3 weeks, as the alternate feed source is introduced (e.g. paddock feed)
  4. If the vendor has not already done so, inject bulls with all the necessary vitamins and vaccines required.  This would include Vitamin ADE (Vitamin A has a huge impact on libido and sperm viability), Vitamin B12, and clostridial and reproductive disease vaccines (e.g. pestivirus, vibriosis and lepto/clostidial e.g. 7in1)
  5. Treat bulls for external and internal (including fluke and roundworm) parasites
  6. Perform a reproductive soundness examination


(Note: Several of the treatments or procedures listed above may or may not be completely necessary for some bulls.  The best approach would be to ask the opinion of a local cattle veterinarian familiar with your herd)


How long do I need to grain feed my working bulls before joining for optimal performance?

Ideally a preparation period of 2 months before joining is best practice.  The production of sperm from juvenile stage to mature form will take this long, so planning ahead can often make the difference between good and bad conception rates.  It also means paying attention to the plane of nutrition (energy, protein, and fibre) and limiting exposure to unnecessary stress.  If pasture availability is limited, then do not hesitate to commence a supplementation program in addition to the necessary vitamins and vaccines mentioned above.

A special case: Grain assist on green feed

Some of the most powerful results from grain feeding come when it is combined with green feed.  The combination of green feed and grain assist (e.g. supplementing with 1 to 2 kg/head/day of a grain such as cracked barley or a starch based pellet) improves feed conversion efficiency to a level comparable to feeding 5 times as much grain or more on its own.


Rather than being considered a ‘taboo’, grain feeding in preparing bulls for joining is a powerful tool in aiding the achievement of maximum individual and reproductive performance.  Like all power tools however, the person using it should know how it works, and it should be used as per the instructions.  In the right hands it can have stunning, beneficial results, and in the wrong ones leave a path of destruction.

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Erica Halliday

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