Protein and amino acid nutrition of the pig

Pig production may be variously described as the squandering of valuable food resources to satisfy consumer demand for an enjoyable luxury-an industry no different from numerous others in the consumer economy-or as a means of converting to a high quality food agricultural products for which no real alternative use exists.Between these two extremes, shades of opinion reflect circumstances, and the value placed upon resources.But whatever one's view of pig production, the pig's efficiency as a transformer of energy and protein is of central importance.My purpose in this paper is to take a prospective look at the use of protein and amino acids in pig nutrition, to identlfy sources of inefficiency and to suggest possible routes to improvement in the future.Table I illustrates the inputs of food protein and energy typical of commercial pig production.Several points emerge from this simple overview.First, only about one-third of the protein used in pig production is deposited as body protein, and less than a fifth is recovered in the edible parts of the carcase.Secondly, the food energy required to produce I kg body protein is over 300 MJ, or closer to 600 MJ if only the edible protein is considered.By comparison the microbial production of protein in industrial fermentations typically requires only 50 MJ of carbohydrate energyhg of protein produced (Mateles, 1979).There are clearly many factors which influence these efficiencies.Aspects of general husbandry such as disease control, reduction of mortality, avoidance of feed spillage and so on will give improvements.Although, as seen in Table I, the breeding stock account for only a small fraction of the total feed input, improvements in their productivity have a detectable influence on the over-all efficiency of food u8e (Large, 1973(Large, , 1976)). Table I. Use of protein and energy to produce meat protein Eaten by I sow in I yearEaten by 20 pigs growing to 90 kg Total Gained by sow Gained by pigs TotalTo produce I kg protein