An investigation of diet selection as a technique for determining the ideal protein for growing pigs

Fairley, Rachel Anne Charlotte (1996). An investigation of diet selection as a technique for determining the ideal protein for growing pigs. PhD thesis The Open University.

DOI: https://doi.org/10.21954/ou.ro.0000f786

Abstract

A series of dietary choice experiments was carried out to discover if growing pigs can discriminate between two feeds with differing amino acid concentrations and use this ability to select a mixture of the two feeds to meet their amino acid requirements. A protein dietary choice experiment was carried out to investigate the best experimental setup for future dietary choice experiments. Two similar dietary choice experiments were carried out with lysine and threonine, where pigs discriminated between two feeds with differing lysine or threonine concentrations. However, they did not select a mixture of two feeds, choosing to eat predominantly from one feed. Experiments with differing levels of lysine and threonine and protein and lysine showed similar results. Where some mixing did occur, the resulting protein concentrations selected were so diverse that they were unlikely to be a reflection of their protein requirements. Individual variation in the selections made may derive from a preference for a particular feeder. An experiment was carried out which determined feeder preference and discovered that this had no effect on selections made when a choice of feeds was offered. An experiment was carried out to dicover if the importance of tryptophan in die control of protein intake meant that its intake was more strictly regulated than that of lysine or threonine. Once again pigs discriminated between the feeds, but did not select a mixture of the two feeds. A final experiment discovered that pigs can supplement an amino acid deficient diet with a solution of that amino acid to allow them to grow as well as pigs on diets with excess amino acid. In conclusion, pigs can discriminate between two feeds with differing amino acid concentrations, but do not use this ability to select a mixture of two feeds to meet their requirements.