INFLUENCE OF DIETARY LYSINE ON THE UTILIZATION OF ZINC FROM ZINC-SULFATE AND A ZINC-LYSINE COMPLEX BY YOUNG-PIGS

We conducted two trials (n = 144 and 96) to evaluate the response of f eeding either ZnSO4 . H2O or a zinc-lysine complex (ZnLys) in combinat ion with various lysine levels on growth performance, liver, kidney, a nd 10th rib Zn concentration, serum Zn humoral immune response and abs orption of Zn (chromic oxide method) of young pigs. The following trea tments were started after a 7-d post-weaning adjustment during which a ll pigs were fed a common diet adequate in zinc. Diets were as follows : 1) basal 1 (B1), .8% dietary lysine without added Zn (basal containe d 32 ppm Zn); 2) B1 plus 100 ppm Zn from ZnSO4; 3) B1 plus 100 ppm Zn from ZnLys, 4) basal 2 (B2), 1.1% lysine without added Zn; 5) B2 plus 100 ppm Zn from ZnSO4; 6) B2 plus 100 ppm Zn from ZnLys. In Trial 1 on ly, 100 ppm Zn from ZnSO4 (diet 7) or ZnLys (diet 8) was added to a .9 5% lysine basal diet. The basal 20% CP diet contained 9.0% corn gluten meal to lower the total lysine level. Within lysine level, all diets were made isolysinic by using crystalline lysine. Zinc sulfate, ZnLys, or lysine replaced dextrose in the basal diet. After 4 wk on test, on e barrow in each pen was killed; liver, kidney, left 10th rib, and con tents of the stomach, small intestine, and lower colon were removed fo r Zn analyses. Performance (ADG and ADFI) was only improved (P < .05) in one of the two trials when either zinc source was added to the basa l diets, but performance was higher (P < .01) for pigs fed 1.1% lysine diets compared with .8% lysine diets in both trials. Serum Zn concent rations were lower (P < .001) for pigs fed both dietary lysine basal d iets without added Zn. The humoral response to sheep red blood cells a nd ovalbumin was not influenced (P > .20) by lysine level, or Zn level and source. Pigs fed diets without added Zn had lower (P < .001) live r, kidney, and rib Zn concentrations than pigs fed diets with added Zn regardless of Zn source. Dietary lysine did not influence liver Zn, b ut kidney (P < .01) and rib (P < .001) Zn concentrations were lower fo r pigs fed the higher lysine level. Digestibility coefficients of Zn w ere lower in the stomach for pigs fed diets without added Zn, similar among Zn levels and sources in the small intestine, and higher in the lower colon for pigs fed the basal diets without added Zn. Lysine leve l and Zn source did not influence Zn absorption. The ZnSO4 and a zinc lysine complex seemed to be equally effective in promoting growth perf ormance, zinc absorption, and tissue stores of young pigs when diets c ontained deficient, adequate, or slightly more than adequate levels of lysine.