Minimun nutritive requirements of diary cattle under tropical conditions
The Journal of Agriculture of the University of Puerto Rico
A series of digestion trials was conducted in order to determine the minimum requirements for growth, maintenance, and milk production of dairy cattle under tropical conditions. The growth requirements were determined by using the following equation: Y = 29.023 X — 3,547. This equation was determined by using heifers weighing from 495 to 712 pounds. The requirement varied from 10.82 to 17.12 therms. The maintenance requirements can be determined by solving the equation: Y = 38.76 X — 20,576.60.
... 8.76 X — 20,576.60. The cows used to determine this equation weighed from 701 to 1,018 pounds. The therm requirements varied from 6.594 to 18.92. The production requirements above maintenance were studied also and the equation: Y = 319.3719 X + 7,131.90 was worked out, but the regression was not significant. This preliminary report on minimum requirements indicates that the energy required for growth and maintenance is about 1.5 to 2 times the requirements reported by Morrison. The addition of concentrates to the ration reduced its digestibility 9.58 percent. In all cases the X of the equations above represents the live weight of the animals used. Y represents the total calories needed.