The effect of dietary amino acid composition on protein and energy balancein growing pigs

Protein and energy deposition in the body were measured in 20 pigs from 25 to 70 kg body weight, which were fed isoprotein and isoenergetic diets adeq uate (A) in ileal digestible amino acid content, deficient in lysine by 20% (D) or 40% (VD), or containing lysine and methionine in 20% excess (E). Pr otein deposition in VD and D pigs was respectively 26 and 9% lower, whereas in the E pigs it was similar to that in A pigs. Utilization of digestible lysine was inversely (r=-0.52) related to the amount of protein deposited i n the body. Dietary supplementation with amino acids had no effect on utili zation of metabolizable energy (on average 33%). However, heat production r elated to maintenance and protein deposition was reduced by 0.38 kJ/kg(0.75 ) (P=0.07) per kJ energy additionally retained as protein.