By Dan Larson
There is not a more challenging, nor frustrating, member of the cowherd than the herd bull. Yet, he is an important member of the herd. Young bulls are especially difficult to manage because they have duty on their mind 24/7 and will literally kill themselves to accomplish the task. However, appropriate development and continued feeding management can help ensure these youngsters make it to adulthood.
As seedstock producers, we bear the burden of developing bulls that will work for our customers year in and year out, but how do we do that? A bull development system should have five main goals: low cost of production; low risk for the bulls’ health; low reproductive failure rate; longevity; and salability.
Further, we can break bull development down into five phases: preweaning (creep phase); postweaning development (gain test phase); prebreeding (prior to first turnout); during breeding; and postbreeding.
Let’s start with pre- and postweaning diets. The key concepts are energy and protein content of the diet, vitamin and trace mineral needs and developing a strategy to reach your goals. Whether using creep feeders, self-feeders postweaning or a total mixed ration, bulls can be developed too fat or too lean.
There is little university research on the impact of creep feeding on bull longevity. Feed companies and suppliers have done most of the research in this area, and, as a result, generally show a benefit from creep feeding. Nevertheless, the value of creep feeding bulls should be less about cost of gain and more about increasing the value of your bulls.
Seedstock nutrition is not about the cheapest cost of gain; rather, we should strive for the least cost of producing the most marketable, highest valued animal. The choice to creep feed should be made by you and your nutritionist, depending on your marketplace.
Recipe for success. If you creep feed, work with your nutritionist to develop a feed that poses the least risk to the bull’s health, reproductive performance and longevity. Corn is not an adequate creep feed. Rather, choose feeds that are high in fiber and moderate in protein and energy. These feeds, fed in a limited manner, will allow a bull to develop to his full potential without causing problems later in life.
More good bulls are wrecked between 8 months and 15 months than at any other age. While under-feeding can be an issue, overfed bulls are far more prevalent.
The table at left offers minimal feed requirements for bulls. Zinc, copper and manganese are very important to scrotal development and sperm production. The testes have a high concentration of zinc and manganese, and depletion of these trace minerals can result in small scrotal circumference and poor sperm quality. Research at Kansas State University found that bulls supplemented with chelated zinc had higher sperm counts than bulls supplemented with inorganic zinc. Feeding chlortetracycline monthly will also reduce white cell count and improve semen quality.
(Read the conclusion of this two-part series in the November issue.)
Dan Larson is a ruminant nutritionist at Great Plains Livestock Consulting, Inc. His experience in both cow–calf and feedlot cattle operations offers a unique perspective on the beef industry.