Livestock Management RANCHING
Chart 2: Daily nutrient requirements for growing beef bull calves post-weaning (mature size = 2,000 pounds)
Body Weight, pounds 600 700 800 900 1,000 1,100
Maintenance Requirements
Nem, Mcal/d CP, lb/d Ca, g/d P, g/d
5.93 6.66 7.36 8.04 8.71 9.35 0.84 0.94 1.04 1.13 1.23 1.32 8.40 9.80 11.20 12.60 14.00 15.40 6.40 7.50 8.50 9.60 10.70 11.70
Neg, Mcal/d 2.00 lb/d ADG 3.03 3.40 3.76 4.11 4.44 4.77 2.50 lb/d ADG 3.87 4.34 4.80 5.24 5.68 6.10 2.75 lb/d ADG 4.30 4.82 5.33 5.82 6.30 6.77 3.00 lb/d ADG 4.73 5.30 5.86 6.40 6.93 7.45 3.25 lb/d ADG 5.16 5.79 6.40 6.99 7.57 8.13 3.50 lb/d ADG 5.60 6.28 6.94 7.58 8.21 8.82
CP, lb for gain
2.00 lb/d ADG 0.90 0.81 0.89 0.82 0.75 0.69 2.50 lb/d ADG 1.11 1.12 1.09 1.00 0.92 0.84 2.75 lb/d ADG 1.22 1.23 1.19 1.09 1.00 0.90 3.00 lb/d ADG 1.32 1.33 1.29 1.18 1.08 0.98 3.25 lb/d ADG 1.43 1.43 1.38 1.27 1.15 1.05
3.50 lb/d ADG 1.53 1.54 1.48 1.35 1.23 1.11 Average daily gain (ADG)
the bulls out. If a group of bulls is not going to work together, or a bull becomes so dominant that the oth- ers can’t get any feed from the supplement, they might have to be separated further.
Breeding season During the breeding season, there is less opportunity
to maintain a bull’s body condition with the ration. While sometimes necessary, selectively hand-supple- menting some of the bulls is a pretty labor intensive proposition. However, Holland says you can manage the bulls’ nutrition during the season by managing their workloads. “It’s important not to have too many cows per bull,”
he explains, “or too few bulls per female. A general rule of thumb would be to have no more females per bull than the bulls are old, so there should be not more
78 The Cattleman February 2015
than one female per month of age of the bull until that bull gets to be 30 months old. An 18-month-old bull could probably handle
15 to 18 cows, while a 3-year-old bull could probably handle 25 to 30 females. If we have the bull trying to work too hard and breed too many cows, they’re going to lose too much condition too quickly; furthermore, you run the risk of lower conception rates.”
Post-breeding When bulls will be used for 2 breeding sea-
sons yearly, as often happens in the southern plains, there is less room for error. “While using bulls for both spring- and fall-calving herds can reduce overall costs, there will be less time for bulls to regain weight between breeding sea- sons. With a common BCS goal of 6, even older bulls may have to be aggressively supplemented to gain 2 to 2.5 pounds per day before the next breeding season.” There are several causes for a bull to be off
feed and not eating. The animal could be suf- fering from a respiratory disease or his rations could have produced a metabolic imbalance. Holland says he sees more metabolic upsets in
developing bulls that have been receiving higher concentrate rations, especially from self-feeders. Bulls sourcing feed from those types of devices can easily overeat and develop ruminal acidosis from consuming too many rapidly fermentable carbohydrates and not enough fi ber. Holland says if that’s the problem, it may be best to try to deliver feedstuffs in a more man-
aged way to prevent a cyclical intake pattern, where an animal that has been off feed due to acidosis over- eats once again when feed is reintroduced, which then exacerbates the condition. Bulls that are fed high-concentrate rations must be
adapted to these rations over a period of 2 to 3 weeks, and rations should contain 15 to 20 percent effective fi ber. Bulls, like the rest of the herd, also need to have a mineral package available to them at all times, and special consideration should be given to known defi - ciencies or toxicities in specifi c areas. The bull battery is a signifi cant investment for cow-
calf operations, but is sometimes an overlooked popula- tion. Properly developing and managing the nutritional needs of bulls can help insure optimum reproductive performance and return on investment.
thecattlemanmagazine.com
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