Programmable Calculators and Their Application to Feeding and Management of Dairy Cattle 1

J. G. LINN 2 and P. L. SPIKE Iowa State University Ames 50011

ABSTRACT PROG RAMMABLE CALCULATORS The programmable calculator offers Handheld programmable calculators can high-speed numerical analyses at a rela- perform all the functions of less sophisticated tively low cost. Laborious and compli- calculators and also store variables in memories cated calculations in ration formulation for use in prewritten programs. The programs and other dairy-management decisions are a series of instructions or mathematical can be simplified greatly. Most dairy equations which the programmable calculator producers, however, have neither the time can remember and then execute in the desired nor background for developing calculator sequence. The programmable calculator is programs. The Iowa State University similar to larger computers in that it can be Cooperative Extension Service has devel- programmed to decide which series of calcula- oped a subscription service to supply tions should be performed first. The decision- programs to persons involved in agri- making process generally is centered around the cultural decisions. Also, the solid-state calculator's capability to determine differences module has been developed to store in the relative magnitude of two numbers programs permanently inside the calcu- (i.e., Is X greater than Y?). Thus, different lator. The programmable calculator offers calculations can be performed, depending an aid in the day-to-day management upon previous calculations or informa- decisions by agricultural producers, but tion. extension personnel also find it time- Programs for the programmable calculators saving and a useful educational tool. are not written in a computer language but represent the key sequence needed to perform INTRODUCTION the same calculations on a nonprogrammable During the last decade, handheld calculators calculator. Once a program has been entered have developed from a simple adding machine into the calculator's memory, a series of cal- into a sophisticated tool for complex numerical culations can be repeated an indefinite number calculations. A recent development is the of times by using new variables. Also, some programmable calculator. This paper will programmable calculators have the capability of describe what programmable calculators are, recording programs or data on magnetic cards discuss their advantages and disadvantages, and for future use. The Texas Instrument model 59 explain how the Iowa State University Coop- and the Hewlett Packard model 973 are two erative Extension Service has applied the Texas calculators capable of storing programs on Instrument Model 593 to feeding and managing magnetic cards. Thus, the often long and dairy cattle. tedious procedure of entering program steps before each use is eliminated. Programs can be recorded from the calculator by passing a magnetic card or cards through a slot in the Received August 20, 1979. programmable calculator. Once recorded, the xJournal Paper No. J-9567 of the Iowa Agriculture program can be reentered into the program- and Home Economics Experiment Station, Ames. Project No. 1053. mable calculator at any time by inserting the 2Present address: Department of Animal Science, card through the calculator. The capability of University of Minnesota, St. Paul 55101. recording programs is important because the SMention of a commercial product or firm is for greatest gain in efficiency occurs when the clarity of description only and does not constitute endorsement by Iowa State University and cooperating calculator can "remember" how to perform a units or agencies nor recommendation over other pro- long series of calculations, thus allowing users ducts that may be similarly suitable. to concentrate more on interpreting results of

1980 J Dairy Sci 63:1390-1394 1390 SYMPOSIUM: COMPUTER PROGRAMS FOR DAIRY CATTLE 1391 outputs rather than on program entry. Also, 6. Because of relatively easy programming, many different programs can be entered into programmable calculator users can modify memory with ease. existing programs or develop new ones to fit Some programmable calculators, such as the their own needs. Texas Instruments TI-58 and TI-59, can use Programmable calculators also have dis- preprogrammed modules. These modules are advantages that limit application: approximately 1 cm thick and 2 cm square and 1. Limited amounts of data can be stored at fit into the back of the calculator. The internal any one time. In the TI-59, memory capacity is solid-state modules contain permanently stored limited to 100 values or less and a maximum of programs that are accessible directly through 960 steps in any one program. the keyboard. One module contains approxi- 2. The programmable calculator printers mately 5000 program instructions and, depend- have limited alphabetical capability and do not ing upon program length, can replace from 10 allow for extensive self-interpretable output. to 25 magnetic cards. The module has the Thus, printouts must either be accompanied by advantage in that it eliminates the initial a written explanation or transferred to a more entering of programs. Two disadvantages are self-explanatory form. that module programs cannot be changed or 3. Because programmable calculators are altered and modules must be produced in large relatively inexpensive and may be purchased in quantities to minimize cost. a variety of stores, limited assistance is available Most programmable calculators can print for operation and programming. Many first selected material. Some have a built-in printing time users have found this very frustrating and units whereas others, such as the TI-59, have subsequent discouragement for future use. optionally attachable printers. The TI-59 calculator can print alphabetical characters, but PROGRAM DEVELOPMENT this requires considerable program memory. AND IMPLEMENTATION Printers are most benefical in writing or enter- The development and distribution of soft- ing programs because users can retrace entry ware (programs) for owners of programmable steps quickly and conveniently. calculators has been limited, especiaIIy for agriculturally related programs. Some of the ADVANTAGES AND DISADVANTAGES earliest application of programmable calculators The programmable calculator has several and program development in agriculture was advantages relative to other types of computer made by the Iowa State University Cooperative hardware: Extension Service. Previously users had to 1. A large mathematical capacity can be develop their own programs or rely on calcu- obtained for a low cost ($300 or less). Simple lator companies to supply them. As interest in problems can be solved more conveniently and programmable calculators grew, the need for a at a lower cost on a programmable calculator program exchange between extension personnel than with large computers. became evident. Concurrently, as calculators 2. Programmable calculators are completely gained more exposure through extension portable. meetings, agribusinessmen and agricultural 3. Programmable calculators are similar in producers began purchasing calculators and appearance to common handheld calculators. identifying program needs. Thus, the psychological barrier sometimes The Iowa State program library is an accum- encountered with use of full-size computers is ulation of programs written for the T1-59 reduced. programmable calculator. Agribusiness person- 4. Programmable calculators allow for in- nel, along with agricultural producers, have stant turn around time with system interaction. been instrumental in identifying areas where They are complete units, requiring no long programs are needed. Once a program need has distance hookups as with portable terminals to been identified, the program is written and computers. followed by field testing. After the program 5. Programmable calculators can be oper- passes testing and is approved, it is made ated when it is convenient and timely in any available on a subscription basis. Subscribers location. receive a notebook containing all previously

Journal of Dairy Science Vol. 63, No. 8, 1980 1392 LINN AND SPIKE written programs and are updated with new user operational problems. programs as they become available. Notification Sixty-nine percent of the survey respondents of any existing program changes also is included. indicated that having programs stored internally At present, 61 programs relating to animal in the calculator, such as with program modules, science, farm management, and agronomy are would help eliminate some of the problems included in the library. Animal science pro- encountered. Thus a Texas Instrument--Iowa grams are primarily in the area of livestock State University agricultural module was nutrition, emphasis on ration formulation developed to eliminate the reading of magnetic and analysis, and performance indexes for beef cards. and swine. The farm management programs are Extension and agribusiness personnel along concerned primarily with budgeting, invest- with livestock producers identified 16 programs ment, and livestock and crop marketing analysis. to include in a module. The programs are pri- More than 1300 Iowa State University libraries marily library programs on livestock nutrition have been distributed in 40 states and 12 (analyzing and formulating rations), analysis of foreign countries. Cornell University also has a livestock marketing, and land investment and similar subscription service for programmable general livestock management programs. During calculator programs. the first 4 too, approximately 800 modules Each Iowa State library program contains a have been distributed. statement of its objective, inputs and outputs, documentation of data used in calculations, and APPLICATIONS OF THE an example problem. A listing of program steps PROGRAMMABLE CALCULATOR and how the program, once entered, can be The programmable calculator should be recorded on a magnetic card for future use also considered as a supplement to, and not a is included. Magnetic cards containing the substitute for, larger computers. The calculator programs are not distributed because cards can be taken directly onto the farm and used to recorded on one calculator cannot always be help solve simple management problems at low read by another, even of the same model. cost. Rations can be formulated and manage- McGrann and Edwards (1), after an early ment decisions made for individual situations survey of library subscribers, described some quickly and accurately. Many agribusiness firms problems encountered among 140 users of the have found a one-on-one situation with instant programmable calculator (Table 1). The most individualized answers to help improve sales. frequent difficulty was recording programs on Extension personnel can use programmable magnetic cards and (or) the reading of cards calculators to help solve individual management into the calculator. Some of the problems can problems and as an educational tool. In con- be traced to mechanical failure of calculators suiting with dairymen, ration deficiencies can themselves, but user program entering probably be determined and new rations formulated in a was the major problem. Having an attachable short time. Farm management programs can be printer for the calculator tended to reduce used to quickly and accurately determine recording and use problems, especially in individualized answers to complicated budgeting entering program steps and recording on questions. In preparing for extension meetings, magnetic cards. the programmable calculator can be used to Forty-four percent of survey respondents speed preparation of materials, particularly had either written new programs or modified when a series of rations or cost analyses are to library programs to fit their own situations. In be used. as much as writing or modifying programs The Iowa State dairy ration balancing requires more knowledge than just entering and program was designed to answer the following recording prewritten programs, these users questions in relation to the amount and quality tended to have less operational problems in of forage fed: 1) What percentage of crude recording and using library programs than did protein, calcium, and phosphorus is needed in those who only used library programs. Exper- the grain mixture? 2) How much grain should ience of the Iowa State extension staff has been be fed at various amounts of milk production? that a 2 to 3 h training session on calculator 3) How much protein supplementation is operation has been sufficient to overcome most needed at various amounts of milk production?

Journal of Dairy Science Vol. 63, No. 8, 1980 SYMPOSIUM: COMPUTER PROGRAMS FOR DAIRY CATTLE 1393

TABLE 1. Problems encountered with programmable calculators.

Type of problem Number a Percenta

No. problems 50 36 Mechanical problem, charger, or printer 18 13 Incorrect results after all program steps entered 13 9 Problems recording program steps on magnetic cards and (or) reading recorded cards into calculator 42 30 Interpretation problems with information entered or stored in calculator 15 11 Problems interpreting significance of program answers 15 11

aSome respondents indicated more than one problem.

Such programs can be used to help individual grams should be a tool used in the extension dairymen with their ration-formulation prob- educational process. lems and also can be used as educational aids during meetings. For example, a dairyman may not understand a net energy deficiency of 10 FUTURE Meal for cows in early lactation. Indicating a Programmable calculators are just one phase requirement of 38 lb of concentrate when only of the rapidly developing electronic technology 25 lb are fed, however, clearly illustrates an for dairy management. Therefore, their future energy deficiency for the cow. The effects of is uncertain. If present use is any indication, improving forage quality on reducing grain acceptance of and the capabilities of program- recommendations can quickly be shown by mable calculators will increase. The limiting changing a few forage input variables. In aspect of programmable calculator use is and addition, audience interest is stimulated by will continue to be program development. the use of a new gimmick or gadget. Currently, most dairy programs are concerned The limitations relating to the instruments' with either formulating or analyzing rations. capability have been explained already. It must Experiences at Iowa State with beef and swine be remembered, however, that the program- indicate that the most popular and widely used mable calculator outputs are only as accurate as programs concern economical decisions on the inputs. If errors are made in data entry, marketing based upon management inputs. erroneous recommendations can be given. Similar programs for day-to-day management Likewise, if data sources for programs are not decisions will be most useful to dairy pro- documented, the validity of these programs ducers. Such programs relating to economical should be questioned. Interpretation of output decisions concerning cow culling, mastitis also requires a person with knowledge and losses, values and costs of replacement ani- experience in that area. As more programmable mals, semen pricing, and many others need to calculators come into use in ration formulations, be developed. In addition, specific discipline are all users going to be qualified nutritionists? programs in areas such as engineering concern- Not thoroughly understanding or misinterpret- ing waste management, housing, and ventilation ing outputs may be more harmful than the will be of benefit to extension and agribusiness original problem. The principal limitations of personnel. Because of limited data storage, the programmable calculator as a sophisticated programmable calculators cannot do the genetic yet simple tool in aiding agricultural decisions evaluations and formulation of least-cost occurs with the users. The education of the user rations currently done in large computers. to properly input information, followed by Likewise, Dairy Herd Improvement records correctly interpreting and applying the outputs, cannot be kept on programmable calculators. should be the primary goal for extension Because of this, programmable calculators will personnel. Developing and writing new pro- not compete with computers but will compli-

Journal of Dairy Science Vol. 63, No. 8, 1980 13 94 LINN AND SPIKE ment them as a convenient low-cost analytical preparation and individual problem consulta- tool for field use. tions. Livestock producers and agribusiness personnel also find the calculator to be of great SUMMARY assistance in their day-to-day decision-making Experiences with the programmable calcu- processes. lator at Iowa State University indicate that it has useful application in agricultural manage- ment decisions. The calculator's low-cost REFERENCES analytical capacity, ease of programming, and 1 McGrann, J. M., and W. E. Edwards, 1979. Appli- sufficient capacity to provide valuable informa- cation of the programmable calculator to extension tion for many agricultural decisions make it a agricultural management programs. North Cent. J. valuable tool for extension workers in meeting Agric. Econ. (In press).

Journal of Dairy Science Vol. 63, No. 8, 1980