Valine requirement of the finishing pig.

Pigs weighing approximately 70 kg were used in two experiments to determine the valine requirement during the finishing period. In the first experiment, 10 gilts were allotted in two 5 x 5 Latin square designs to five semipurified diets that ranged in valine concentration from .35 to .55%. Urinary urea excretion was measured during each of the 3-d periods of the Latin square. Urea N excretion in relation to N intake and to creatinine N excretion was minimized (quadratic effect, P < .10) at valine concentrations of .45 to .50%. In Exp. 2, 36 barrows and 36 gilts were fed one of six diets containing .35 to .60% valine. The highest weight gains (not significant) and feed efficiencies (quadratic effect, P < .05) were achieved by the pigs that consumed .45% valine. Plasma urea concentration at the end of the experiment was lowest (quadratic effect, P < .05) in pigs that consumed .50% valine. Estimates of the valine requirement based on breakpoint and quadratic equation analyses ranged from .40 to .50% total valine (.33 to .43% ileal digestible valine). Pigs in Exp. 2 consumed approximately 2.5 kg/d (8,850 kcal/d of ME). Thus, the estimate of the valine requirement is approximately 11 g/d. These estimates of the valine requirements of finishing pigs are slightly higher than the National Research Council requirements when expressed as a percentage of the diet but are similar when expressed on a grams per day basis.