Sows (n = 306; PIC, Line C-19; average parity 2.1) were used to evaluate the interrelationship between
valine,
isoleucine, and
leucine on sow and litter performance. Our objective was to determine whether the increase in litter weaning weight associated with added dietary
valine is specific for
valine or a result of the total
branched-chain amino acid (i.e.,
isoleucine and[or]
leucine) concentration of the diet. Eight dietary treatments (36 to 41 sows/treatment) were arranged
as a 2 x 2 x 2 factorial with two levels of
valine (.80 and 1.20%),
isoleucine (.68 and 1.08%), and
leucine (1.57 and 1.97%). This provided total
branched-chain amino acid levels of 3.05, 3.45, 3.85, and 4.25%. The lowest level of each
branched-chain amino acid was similar to that in a .90%
lysine corn-soybean meal diet containing .15%
L-lysine HCl.
Amino acids other than
valine,
isoleucine, and
leucine met or exceeded their suggested estimates relative to
lysine using ratios derived from the National and Agricultural Research Councils. Average number of pigs on d 2 of lactation was 11.2, and average lactation length was 20.9 d. Number of pigs weaned (x = 10.6), sow ADFI (x = 5.85 kg), and sow
weight loss (x = 4.25 kg) were not affected by dietary treatment (P > .10). Sow backfat loss (P < .02), litter weaning weight (P < .04), and litter
weight gain from d 2 to weaning (P > .05) increased as dietary
valine increased. Litter weight at weaning and litter
weight gain were not affected by dietary
isoleucine (P > .80) or
leucine (P > .60). Sixteen or 17 sows per treatment (129 total) were milked manually on d 14 to 16 of lactation. Increasing dietary
valine tended to increase milk
urea N (P < .07) but did not affect milk DM, CP, fat,
lactose, or ash. Increasing dietary
isoleucine or
leucine had no effects on milk composition. These results confirm the importance of dietary
valine for increased litter weaning weight, independent of either additional dietary
leucine or
isoleucine.