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 th e effects of dietary lysine and valine on lactation performance. Treat ments were arranged in a 2 x 3 factorial with two levels of lysine (.8 0 or 1.20%) and three valine:lysine ratios (80, 100, or 120% of lysine ). For all sows, increasing dietary lysine increased litter weaning we ight (P < .001) and litter weight gain (P < .002) and reduced sow weig ht loss (P < .001). Litter weight gain tended (P = .22) to increase wi th increasing dietary valine, but the increase was not significant. Da ta were separated into two groups: sows that weaned 10 or more pigs an d 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 < .0 01) 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 weane d fewer than 10 pigs, maximum litter weight gain was observed at a val ine:lysine ratio of 100% (quadratic, P < .13). These results demonstra te the need to increase dietary lysine and valine as litter weaning we ights 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 pig s. The independent increases in litter weaning weights from adding lys ine and valine suggest separate modes of action for these amino acids in high-producing sows.