Kansas State University(KSU) researchers wondered if the improved litter weaning weights observed with increased dietary valine were specifically due to valine, or if other branch chain amino acids (isoleucine or leucine) also contributed.

Three hundred and six sows were used to evaluate the effects of the interrelationship among valine, isoleucine and leucine on sow and litter performance. Eight dietary treatments were arranged, with two levels of valine (0.80 and 1.20%), isoleucine (0.68 and 1.08%) and leucine (1.57 and 1.97%).

Litter weaning weight, litter weight gain from day 2 to weaning and sow backfat loss increased as dietary valine increased, but were not affected by dietary isoleucine or leucine.

Increasing dietary valine, isoleucine or leucine did not affect milk fat, crude protein or lactose. According to KSU researchers, the results confirm the importance of dietary valine for increased litter weaning weight, independent of either additional dietary isoleucine or leucine.

Research conducted prior to 1990 evaluating the valine, isoleucine and leucine requirements of lactating sows utilized litters with nine or fewer pigs weaned, and preweaning growth rates that were 50% of current production rates, KSU researchers explain. Increased genetic selection and improvements in management have dramatically increased the production capability of the modern commercial sow. These high-producing sows require considerably higher levels of total dietary valine because of increased milk production. Recent KSU research found increasing total dietary valine from 0.75 to 1.15% in lactation diets resulted in increased litter weight gain.

Recent research also found increasing both dietary valine and isoleucine in lactation diets increased litter weaning weights.

Recent Results The sows used in the current research project were both first-litter gilts and multiparous sows (36-41 sows/treatment) from the KSU Swine Teaching and Research Center. All sows were maternal line (PIC Line C-22) and were bred to terminal line (PIC Line 326) boars. During gestation sows were housed in outside dirt lots and fed in individual stalls. Gestating sows were fed 4-5 lb./day depending on body condition. The gestation diet was a sorghum-soybean meal-based diet formulated to 0.65% total lysine, 0.90% calcium and 0.80% phosphorus.

Sows were moved into farrowing crates in an environmentally regulated farrowing house on day 109 of gestation. All sows were fed the gestation diet until farrowing, at which time sows were allotted to one of eight dietary treatments.

Treatments were allotted randomly within groups of eight as sows farrowed to minimize variation in lactation length between treatments. Litter size was equalized by 24 hours after farrowing, and all sows began the study with at least 10 pigs.

Sows were allowed ad libitum access to feed and water from parturition until weaning. The sows average daily feed intake was determined. Creep feed was not offered to litters. Backfat was measured using real-time ultrasound at the last rib. Pigs and sows were weighed on days 0, 7 and 14, and at weaning. Three or four observations were made per treatment for each lactation group, and 23 lactation groups (blocks) were used.

Lactation diets were formulated to meet or exceed amino acid requirement estimates based on ratios relative to lysine, except for valine, isoleucine and leucine. All other nutrients were in excess of published requirement estimates.

Diets were formulated to 0.90% total lysine, 0.90% calcium and 0.80% phosphorus. The control diet was formulated to contain 0.80% valine, 0.68% isoleucine and 1.57% leucine. Corn starch was replaced in 0.40% increments with L-valine, L-isoleucine, L-leucine or a combination of each to provide the remaining seven experimental diets. The treatments included two levels of valine (0.80 and 1.20%), isoleucine (0.68 and 1.08%) and leucine (1.57 and 1.97%).

Sixteen sows per treatment were milked manually on day 14 and 16 of lactation. All sows were milked approximately 2 hours after the noon feeding. Sows were separated from their litters for a minimum of 30 minutes before milking. Milk letdown was enhanced by infusing 10 IU (International Units) of oxytocin into an ear vein of the sow. Sows were restrained, and 75 ml of milk was collected from the first two productive glands on both sides of the body. Samples from each gland were pooled for chemical analysis and stored at 35-40 degrees F. All analyses were conducted within 48 hours after collection.

No valine x isoleucine x leucine interactions affected the number of pigs after fostering, number of pigs weaned, or lactation length (P>.15). Also, no three-way interactions among the amino acids affected any of the litter weights or litter weight gain measurements (P>.15). Valine x isoleucine x leucine interactions tended to affect total branched chain amino acid intake (P<.08) and sow backfat change (P<.13).

There was a tendency for valine x isoleucine interactions affecting litter weight on day 7 (P<.11) and day 14 (P<.12). The researchers say the interactions appeared to be results of increased litter weight with increasing isoleucine in sows fed 0.80% valine, whereas increasing isoleucine decreased litter weights in sows fed 1.20% valine.

Valine Results Dietary valine had no effect on number of pigs weaned or survival rate after crossfostering. Comparing the overall effects shows increasing dietary valine from 47.52 to 63.87 grams/day (0.80 to 1.20%), regardless of isoleucine or leucine, increased (P<.06) litter weights throughout each week as well as the overall 21-day lactation period. Valine and total branch chain amino acid intakes increased (P<.0001), whereas leucine and lysine intake decreased (P<.01) as dietary valine increased. Sow average daily feed intake (ADFI) (P>.50) and sow weight loss (P>.30) were not affected. As dietary valine increased from 0.80 to 1.20%, sow backfat loss increased (P<.02)

Isoleucine Dietary isoleucine had no effect (P>.10) on number of pigs weaned, pig survival rate, litter weights, litter weight gains, sow weight change and sow backfat change. Dietary isoleucine had no effect on sow feed intake (P>.42), but isoleucine and total branch chain amino acid intakes increased (P<.0001) as isoleucine increased. Valine intake decreased (P<.002) with increased dietary isoleucine.

Leucine Dietary leucine had no effect on number of pigs weaned, pig survival rate, litter weights, or litter weight gain. Sow backfat loss (P>.29) was not affected by increased dietary leucine; however, sow body weight loss (P<.15) had a tendency to decrease. Total branch chain amino acid intakes (P<.0001) increased as dietary leucine increased and daily lysine intake decreased (P<.0004). Leucine had no effect on sow average daily feed intake (P>.58).

Increasing dietary valine, isoleucine and leucine did not affect milk components. The addition of dietary isoleucine caused milk ash to decrease (P<.05) but increasing valine and leucine had no effect.

Increasing dietary valine from 0.80 to 1.20% increased litter weaning weight by 4.4 lb. and litter weight gain from day 2 to weaning by 3.7 lb., independent of dietary isoleucine and leucine. This suggests increasing dietary valine increases milk production as measured by litter weaning weights regardless of dietary isoleucine or leucine. The KSU researchers say the valine requirement of high-producing lactating sows appears to be greater than current estimates by the National Research Council and Agricultural Research Council.

Researchers: Sharlie Moser, Mike D. Tokach, Jim L. Nelssen, Robert D. Goodband and Joe A. Loughmiller, Kansas State University. Contact Goodband at (785) 532-6533.