Suggested rules-of-thumb for estimating needed levels of various nutrients.

 The exact requirement of beef cattle for the various nutrients will vary,
as already mentioned, with age and condition of the animal, as well as other
factors. It is difficult to make a blanket statement that will apply to all
conditions. However, the suggested "rules-of-thumb" listed below have been
cited from or calculated from research reports (1, 2, 3) and will be satis-
factory in most cases. It should be emphasized that these are offered to be
used as a guide and may require slight modifications under each individual set
of conditions.

 1. Total digestible nutrients (daily needs):

 (a) Maintenance of growing animals:

 Body weight (Ibs) T.D.N. (Ibs)
 400 3.5
 600 4.6
 800 5.7
 1000 6.7
 1200 7.7

 (b) Gain 3.5 pounds per pound of animal gain
 (c) Pregnant cows 10.0 pounds
 (d) Nursing cows 16.8 pounds

 2. Digestible protein (daily needs)

 (a) Fattening cattle 0.2 percent of body weight
 (b) Nursing cows 0.15 percent of body weight
 (c) Pregnant females 0.10 percent of body weight
 (d) Calves and yearlings to gain 1.0 lb/day 0.13 to 0.15 percent
 of body weight

 3. Phosphorus

 (a) Should be a minimum 0.20 percent P in fattening rations and
 forages, on dry matter basis.
 (b) For maintenance, 0.02 times body weight, stated as grams.

 4. Copper

 (a) Organic soils 1/8 gram/animal/day


 5. Cobalt .07 to .10 milligrams/100 pounds of body weight

 6. Vitamin A 2,000 to 3,000 I.U./100 pounds of body weight where it
 is suspected to be needed.