By Kris Ringwall, North Dakota State University beef specialist
Bull nutritional requirements are based on the projected value at mature weight. This means we have to answer the question about how much our bull will weigh at maturity.
The question seems simple, but the answer becomes subjective quickly for producers. To make a point, we understand that mature weight will vary. Perhaps the better question is: “What is one’s ideal weight?”
Likewise, if one returns to discussing the bull, what is the ideal weight for a bull? A quick search of the Internet yielded the Oklahoma State University publication “Nutrient Requirements of Beef Cattle,” written by David Lalman.
David’s tables give the nutrient requirements for growing and mature bulls. The key to using the tables is to know what table to use based on three levels of mature bull size. The three levels are bulls at 1,700 pounds, 2,000 pounds and 2,300 pound.
The daily maintenance or zero-weight-gain ration (hay or grass) varies by the size of the bull. A 1,700-pound bull needs a daily intake of 33 pounds of dry matter that is 7 percent protein and 46 percent total digestible nutrients (TDN). The 2,000-pound mature bull needs a daily intake of 37 pounds of dry matter that is 7 percent protein and 46 percent TDN. The 2,300-pound mature bull needs a daily intake of 45 pounds of dry matter that is 7 percent protein and 46 percent TDN.
Essentially, the bulls need to consume just less than 2 percent of their body weight to hold even, while consuming nonspoiled hay that is at least green.
If the bull’s body condition has slipped, improving the forage quality to 50 percent TDN and increasing the intake by 3 pounds for the lighter bulls and 2 pounds for the 2,300-pound bulls should put on a 0.5-pound of gain per day. The key is adequate forage intake. By feeding better quality hay, bulls should pick up in condition.
Results at Dickinson Research Extension Center
In reviewing the bulls that the Dickinson Research Extension Center overwintered, the 2 1/2- year-old bulls weighed in at 1,659 pounds last fall, and the 1 1/2-year-old bulls weighed in at 1,342 pounds, a difference of 317 pounds. Their condition scores were 6 or 7, which means they certainly were in good condition.