Amino acid supplementation of low-protein diets for swine: effects of gestation treatment on reproductive performance of gilts and sows.

The effect of lysine and tryptophan addition to an all-corn diet fortified with vitamins and minerals fed to gestating gilts and sows was studied in a series of five trials. The experiments were designed to establish the effect of the addition of the two amino acids on: 1) N balance, 2) reproductive performance over two consecutive parities and 3) the immune response of the gestating gilt and transfer of immune proteins to the nursing pig. Nitrogen retention by gravid gilts fed an all-corn gestation diet increased (P less than .05) in response to lysine addition, but was not affected by subsequent addition of tryptophan. Daily N retention of gravid gilts fed the corn or corn and amino acid-supplemented diets was lower than that of gilts fed a 12% crude protein (CP) diet. Reproductive performance for two parities, as evaluated by gestation and lactation weight gain and, number and weight of pigs at birth and at 28 d was similar among treatments. Evaluation of the amino acid status of gestating gilts by measurement of the development of specific antibody response to sheep red blood cells and bovine serum albumin showed a trend for improved antibody development in gilts fed corn diets supplemented with both lysine and tryptophan and in the passive immunity of their offspring. Total whey protein and globulin content of 0-h colostrum was not affected by dietary treatment. The lack of a depression in reproductive performance of gilts fed an all-corn diet could be because of compensatory N retention. During the 4 to 5 d before parturition, all gilts were fed the 12% protein control diet. Gilts that were fed a corn diet from d 1 to 108 of gestation retained 40% more (P less than .01) N from d 109 to 114 of gestation than gilts that had been fed the 12% protein diet throughout gestation.