Valine Requirement of the Lactating Sow

An experiment was conducted using production and metabolic criteria to estimate the valine requirement of the lactating sow. Ground corn, gelatin, corn sugar, vitamins, minerals and indispensable amino acids were used to formulate a diet containing all the essential nutrients except valine. L-valine was added to provide .23 (basal), .38, .53, .68 and .83% valine. Twenty-five mature Landrace × Yorkshire sows were randomly assigned to the five dietary treatments. Milk production and average pig weight gain increased quadratically (P<.01) and were maximized at .68% dietary valine. Total solids production (P<.05) and protein production (P<.01) increased with increasing level of valine, and both were maximized at .68% dietary valine. Protein content also was maximized (P<.01) at .68% dietary valine. Fecal (P<.05) and urinary (P<.01) nitrogen decreased with increasing valine, yielding greatest (P<.01) nitrogen retention (excluding milk nitrogen) at .53% dietary valine. Because daily milk nitrogen production also increased (P<.01) with increasing valine, there were no treatment differences (P>.05) in nitrogen balance (including milk nitrogen). Plasma valine concentration increased (P<.01) gradually until .53% valine was fed, after which there was a rapid increase in concentration. Plasma isoleucine and leucine decreased (P<.01) with increasing dietary valine. Plasma urea concentration was minimal (P<.05) with .38% dietary valine. When all the criteria measured are considered, the lactating sow's requirement of valine is between .53 and .68%. The metabolic data support .53% dietary valine for the requirement, although the maximum response in production parameters at .68% dietary valine suggests that the requirement is above .53% dietary valine.