The effect of dietary lysine and valine fed during lactation on sow and litter performance.

Sows (98 first parity and 104 second parity) were used to determine the effects of dietary lysine and valine on lactation performance. Treatments were arranged in a 2 x 3 factorial with two levels of lysine (.80 or 1.20%) and three valine:lysine ratios (80, 100, or 120% of lysine). For all sows, increasing dietary lysine increased litter weaning weight (P < .001) and litter weight gain (P < .002) and reduced sow weight loss (P < .001). Litter weight gain tended (P = .22) to increase with increasing dietary valine, but the increase was not significant. Data were separated into two groups: sows that weaned 10 or more pigs and sows that weaned fewer than 10 pigs. For sows that weaned 10 or more pigs, litter weaning weight (P < .001) and litter weight gain (P < .001) increased and sow BW loss decreased (P < .001) when dietary lysine increased from .80 to 1.20%. For sows that weaned fewer than 10 pigs, increasing lysine had no effect (P < .77) on litter growth rate. For sows weaning 10 or more pigs, litter weaning weights (linear, P < .04; quadratic, P < .06) and litter weight gain increased (linear, P < .04; quadratic, P < .02) as dietary valine increased. For sows that weaned fewer than 10 pigs, maximum litter weight gain was observed at a valine:lysine ratio of 100% (quadratic, P < .13). These results demonstrate the need to increase dietary lysine and valine as litter weaning weights increase. High-producing sows that wean 10 or more pigs require increased dietary lysine and valine to maximize litter growth rate and minimize sow weight loss compared with sows weaning fewer than 10 pigs. The independent increases in litter weaning weights from adding lysine and valine suggest separate modes of action for these amino acids in high-producing sows.