Abstract:
Proc. Aust. Soc. Anim. Prod. Vol. 19 UTILIZATION OF ILEAL DIGESTIBLE LEUCINE FROM DIFFERENT PROTEIN SOURCES BY GROWING PIGS E. S. BATTERHAM and L. M. ANDERSEN NSW Agriculture, Wollongbar Agricultural Institute, Wollongbar, N.S.W. 2477. Previous work indicated that values for the ileal digestibility of lysine, threonine, methionine and tryptophan in heat-damaged proteins were unsuitable in formulating diets (see Andersen and Batterham 199 1). It appeared as if these 4 amino acids were digested and absorbed in a form or forms that were inefficiently utilized. In contrast, diets formulated with ileal digestible values for isoleucine were used with similar efficiencies (Batterham and Andersen 1991). The aim of this experiment was to determine whether ileal digestible values for leucine were suitable for formulating diets for growing pigs. Three sugar-based diets containing 370 g/kg cottonseed meal (CSM), 405 g/kg lupin-seed meal (LSM), or 210 g/kg soyabean meal (SBM) as the only source of protein were formulated to 0.4 g ileal digestible leucine/MJ digestible energy. Other essential amino acids were added to ensure a 30% surplus relative to leucine. An additional 3 diets were supplemented with free leucine to demonstrate that leucine was in fact limiting in the first 3 diets. The pigs (10 per diet) were fed frequently (3 hourly), at a feeding scale of 3 times maintenance (0.5 MJ DE wkgo' over the 20-45 kg growth phase. The pigs were then 75) slaughtered and performance expressed on an empty-body weight basis. Table 1. Growth response of pigs given diets containing cottonseed meal (CSM), lupin-seed meal (LSM) or soyabean meal (SBM) formulated to similar ileal digestible Growth rates were similar for pigs given all 3 diets (Table 1) indicating that ileal digestible leucine from cottonseed meal was utilized with similar efficiency as leucine in lupin-seed and soyabean meals. This is similar to that recorded with isoleucine, which is also a branched chain amino acid. These results indicate that branched chain amino acids may be less susceptible to processing damage than the other amino acids. For these amino acids, ileal digestibility values may be suitable for formulating diets containing heat-damaged protein concentrates. ANDERSEN, L. M. and BATTERHAM, E. S. ( 199 1). In ` Manipulating Pig Production III' , (Ed. E. S. Batterham.) p. 112 (Australasian Pig Science Association: Attwood). BATTERHAM, E. S. and ANDERSEN, L. M. (1991). Proc. iVutr. Sot. Aust. 16: 142. 289
