Pork production has closely followed a scientific approach over the recent period of time with subjectivity replacing objectivity. The scientific method follows a path of reducing the number of variables involved so that a single process can be examined in detail. This approach has served the subsystems of pork production well (e.g. breeding, nutrition, genetics) but may have had the effect of distracting effort from composite evaluation so that synthesis of production systems and recommendations has tended to remain somewhat subjective.

What is a systems approach?

Webster's Dictionary defines a system as a regularly interacting or interdependent group of items forming a unified whole. Swine production easily fits this definition as the efficiency and profitability of production is the result of many distinct but interacting factors. A systems approach therefore provides a framework for making decisions about individual production decisions in relation to both economics and the complete production program. A systems approach becomes necessary in situations where the performance of the total system is more than the sum of the parts (Wilton, 1979).

Successful use of systems analysis requires that three steps (Wilton, 1979) be completed. The aims or goals of the system have to clearly defined. The real world system has to represented accurately. Finally, changes in production programs must be implemented on the basis of the results of the analysis. It is necessary in any systems approach that the decision maker have access and accept the results of the analysis. Spedding (1975) has outlined the problems and difficulties in evaluating agricultural production systems:

  1. lack of measurement
  2. lack of records
  3. lack of definition of what is measured or recorded.
  4. controlled experimentation is impracticable
  5. complexity

The lack of measurement, records and definition are being corrected in pork production. The adoption and use of record-keeping systems by producers and the development of production and financial standards with leadership from NPPC will minimize these difficulties. Attempts to work with the size and complexity of the pork production system usually leads to the use of computer simulation modeling. Modeling places within the grasp of the human mind a biological and economic description that would otherwise be too complex to be comprehensible. Simulation offers prediction and prediction provides the opportunity for planning and control.

Any technique or method is also subject to overuse through enthusiasm or abuse through lack of experience. For pork production these diverting effects may be reduced in the application of a systems approach to efforts directed toward solving problems rather than toward looking for problems where a systems approach can be applied. Also, caution should be taken against becoming consumed with modeling and attempting to make real life fit the simulation rather than vice versa.

Pork production systems

The pork production system is composed of animals, buildings, nutrition and environmental conditions that all interact. DePetrie et al. (1997) have proposed that successful pork producers will create high productivity / low variance production systems. They propose that the creation of this system involves the coordination of throughput, health assurance program, genetic/breeding program, facilitates/ buildings, nutrition technology and personnel in a synergistic fashion so that overall production is consistently optimized. A single pig can also be defined as a system composed of organs and physiological processes interacting to accomplish growth and reproduction. If we are to study either of these systems we must consider the level of understanding that is needed. Spedding (1975) lists four levels of understanding as operation, repair, improvement and construction. Understanding can range from operating a pork production system, trouble-shooting the system or developing an entirely new system of production.

A systems approach will ultimately allow for a comprehensive assessment of production and financial performance. Two system measures of financial efficiency are described by DePetrie et al. (1997), Return on Assets (ROA) and Return on Equity (ROE). The measures can be calculated as:

ROA = (Accrual Net Income + Interest Payments) / Average Total Assets

ROE = Accrual Net Income / Average Farm Equity

For more information on the interpretation of these measures in the context of pork production system efficiency I would recommend reading the paper by DePetrie et al. Two systems measures of production efficiency would be, Total lbs. of feed / Pounds of lean sold and Pounds of lean sold / Breeding female. Inefficiencies of feed use might be in the growing or breeding herd, caused by wastage, cold, pig quality, feeding level or nutrition program. Lean sold per breeding female may decrease owing to reduction in pigs born alive, a lengthening of the rebreeding interval, increases in mortality, pig quality, farrowing rate, growth rate or a high proportion of unmated replacement females. These system measure will indicate current performance levels and show changes in productivity, but cannot identify the causes of either of these. For diagnosis, closer examination needs to be made of the specific aspects of performance.

Systems analysis also can assist in organizing and collating information which will lead to comprehending more fully the established body of knowledge. Greater knowledge of the pork production system may then lead to encouraging quantitatively oriented research in those subsystems where more information is needed. Knowledge of the system and its interactions will also allow personnel to know how their individual job or task impacts the entire system. This can be important in development of job descriptions and the development of a positive work environment.

Computer simulations of pork production systems have been developed by a number of research organizations and commercial firms. One of the more comprehensive models that I am aware of is being developed by the USDA-MARC (Harris et al., 1995). This research group has developed models of the individual pig and the entire herd for use by producers and farm advisors. Additional information and copies of these models can be found on the WWW at http://psru.marc.usda.gov/.

Pork production sub-systems

The same systems approach that is followed to operate, repair, improve and construct the entire system can be used with the sub-systems. One very common example is systems analysis applied to lean growth modeling and the development of nutritional programs. Lean growth models are complex, computer programs that predict how a pig will grow and what the composition of the end product will be. These models are regularly used to design production systems for different pigs to reach their optimal performance. Many feed companies and universities offer lean growth models as described in the proceedings of the Lean-growth modeling symposium (NPPC, 1992).


Regardless of the nature of the production system, the production of pigs must be cost-effective, or it cannot take place. Optimization of the system requires knowledge and manipulation of the market and a readiness to be flexible because of the continually changing nature of the market. The simulation model can scientifically predict the pigs response to changes in production circumstances. Models also incorporate the body of scientific knowledge and this strengthens their ability to aid good production management. Whittemore (1993) predicts that the science of computer modeling will come, covertly and overtly, to be the major force influencing the practice of feeding, breeding and management of pigs.

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