Effects of Dietary Lysine and Energy Levels on Growth Performance and Apparent Total Tract Digestibility of Nutrients in Weanling Pigs (Report‪)‬

INTRODUCTION Feed intake and growth performance of growing pigs are determined by energy concentration of the diet (NRC, 1998). Therefore, amino acid requirement of growing pigs should be defined in relation to energy density of the diet. Lysine, the first limiting amino acid for growing pigs has been extensively investigated and reviewed (NRC, 1998). Several investigations on lysine requirement for weaned pigs have yielded variable results (Gatel et al., 1992; Nam and Aherne, 1994; Oresanya et al., 2007; Dneg et al., 2010). The lysine requirement for growing pigs is commonly expressed as lysine: energy ratio, which allows lysine requirements to be suitable for wide range of dietary energy (Main et al., 2008). Furthermore, dietary lysine requirement have been determined at only one dietary energy level (Martinez and Knabe, 1990). However, previous studies contain diverse estimates of the optimum lysine:energy for weaning pigs performing at levels commonly observed in commercial practice (Nam and Aherne, 1994; Smith et al., 1999; Urynek and Buraczewska, 2003; Oresanya et al., 2007; Schneider et al., 2010). Many factors, like genetic variation, nutrition, physiology, environment and management condition could be responsible for variation in requirement, in weanling pigs, but a major variation may be the interactive effects between energy density and lysine intake (Campbell and Dunkin, 1983; Zhang et al., 1984). With the economic importance of energy and amino acid source, the determination of the optimum lysine:energy to get a best performance in weaning pigs is badly needed. Therefore, objectives of these experiments were to investigate the effects of dietary lysine and energy levels on growth performance and apparent total tract digestibility of nutrients in weanling pigs.