Bull Growing and Development

Kim Hager, M.S.
Beef Nutritionist
CHS Nutrition

The proper growth and development of young bulls presents a unique set of challenges not encountered in most feedlot scenarios. The nutritional specifications for developing bulls must be at an optimal level to provide sufficient gains to reach puberty at a young age while allowing them to attain their genetic potential for the frame and muscling required to effectively enter the breeding herd as yearlings. Accurate nutrition must assure this level of performance while not causing over-conditioning problems. Bull feeding programs require intensive nutritional management to avoid digestive upsets that may predispose animals to acidosis, foot problems and liver abscesses.

Weaning/Starting

As with any feeding program, the starting phase may ultimately be the most important factor in the overall success of the rest of the program. Bull calves should be weaned using a sound calf-starting program, including pre-weaning vaccinations, followed by post-weaning boosters and control of internal and external parasites. Weaning medications should include a 28-day Coccidiastat program and respiratory medications as needed. Calves should be started on grass hay and introduced to the concentrate portion of the diet in an orderly manner. Properly formulated commercially prepared pelleted products containing protein, energy, fiber and all of the necessary fortifications and medication have become increasingly popular in weaning programs. Due to stress induced intake depression and the fact that nutrient deficiencies exist in most fresh weaned calves, the ration nutrient content should be relatively dense containing a minimum of 14% protein, the addition of chelated minerals and increased levels of Vitamin A, D, and E. By the end of the starting program, calves should be consuming a ration that is 40% concentrate with the remainder of the ration consisting of the forage mix that will be fed during the growing program.

Growing/Developing

There are many ways of growing and developing bulls. Most producers, however, utilize similar performance data records and EPD’s for selection criteria and marketing purposes. Therefore, in order to produce bulls that are competitive in the market place and ready to join the breeding herd, they must weigh at least 50% of their mature weight by the time they are 14 – 15 months of age. Depending on the breed, this will require they gain from 3.0 to 4.0 pounds per day during the growing period. During this time, they should be constantly monitored for structure, muscle development, frame and fleshing ability.

Following are some nutritional guidelines useful in bull growing programs:

Once bulls have reached the growing phase of their development, the ration will need to be stepped up to an increased energy level. Under normal circumstances, the energy level will need to be increased to 46 – 52 Mcal NE gain/cwt, which will require concentrate to comprise 50 – 60% of the ration, depending on the quality of the roughage portion of the diet. Concentrate can safely be increased at a level of one half pound per head per day in most transition rations without causing undue dietary stress. As a general rule, the best choice and safest grains for bulls are those that ferment the slowest in the digestive tract. Corn and oats are traditionally very popular grain sources, while barley and wheat should be avoided due to the potential for digestive upset. Byproducts such as wheat midds, distiller’s grains, corn gluten feed, brewer’s grains, soy hulls, etc. may be used as sources of soluble fiber, fat and bypass protein in the ration, but likely will cause problems if not used properly. Concentrates must be fed at least twice daily and the uniformity of the mix must be such as to not allow feed separation and inconsistency of intake within the herd.

The roughage portion of the diet fed to bulls should be nutritious while supplying an effective level of fiber to stimulate rumination and provide for an adequate and effective ruminal fiber mat. Forages may include grass hay, a uniform mixture of grass and alfalfa hay, grain hay, straw or silage and can be fed separately from the concentrate or as a total mixed ration (TMR). The best way to avoid bunk-sorting of TMR rations is to condition the ration by adding silage, molasses based supplements or water to achieve a moisture level between 25 and 45 percent. All roughage feedstuffs should be accurately sampled and analyzed for the purpose of ration balancing, supplementation requirements and toxic compounds such as nitrates, prussic acid, etc. Forages must also be free of mold, excess dust, dirt, hardware, toxic weeds or any other potential problems.

Lastly, a very important element in a precisely balanced bull ration is the supplement. A correctly formulated supplement may contain protein, minerals, vitamins, soluble fiber, fat, buffers and either Rumensin or Bovatec. The ration should be 14 – 15% protein with a calcium to phosphorus ratio of 2 to 1. Trace mineral and vitamin levels should be 2 times NRC and chelated minerals should provide 1/3 of the zinc and copper. Acidosis, whether acute or sub-acute, may be very detrimental to the overall life expectancy and performance of a herd bull. Therefore, additives such as ionophores and buffers can also be included in the supplement to help alleviate acidosis.

Many producers are now purchasing commercially manufactured fortified pelleted products, designed to be fed along with roughage as the sole source of concentrate in the ration. Pelleted concentrates are generally economical and can be used successfully at varying feeding rates determinant on the desired level of performance and the nutrient quality and feeding rate of the roughage in the ration. These products may also reduce bunk sorting and can simplify the ration process immensely.

Ration Let-Down

Bulls coming off of a highly fitted growing and developing program must be properly ‘let-down’ gradually and orderly to maintain maximum fertility and libido for the breeding season. It is a good practice to reduce the grain intake by 10% per week until the desired level is achieved. This level should probably support a 2.0 to 2.5 pound average daily gain to maintain continued growth and body condition.

Conception rates influence ranch profitability more significantly than any other single item. The herd bull affects herd fertility more than any other single animal in the breeding herd. A young bull in his growing phase must reach puberty, develop outstanding libido and exhibit social dominance as well as attaining the physical characteristics of muscling, frame, scrotal circumference and proper body condition. Improper nutrition or health practices can reduce a bull’s productive and reproductive life significantly.

CHS Nutrition provides a full line of products to help you properly develop your bulls, including Bull Challenger, HI-EN Bull Challenger and HI-EN 14 pellets and a full line of protein supplements for total mixed rations. Contact your local CHS Nutrition feed consultant for details.

December 2004