Digestibility Of Supplemental Zinc Sources In Sow Diets And Effects Of Supplemental Zinc On Piglet Survivability

Abstract

The primary hypothesis tested in this experiment is that digestibility of an organic zinc source from polysaccharide-complexed zinc is greater than inorganic zinc sulfate when sows consume high fiber diets containing corn dried distillers grains with solubles (DDGS). Gilts and sows (n = 32) were blocked according to parity and assigned randomly to one of four dietary treatments. Eight sows were assigned to each treatment in four replicate blocks. Dietary treatments consisted of: 1) Control (ConZnSO4) – corn-soybean meal based diet + 100 ppm supplemental Zn from ZnSO4; 2) Control PSZn (ConPSZn) – corn-soybean meal based diet + 100 ppm supplemental Zn from polysaccharide-complexed Zn; 3) DDGS/ZnSO4 – corn-soybean meal-40% DDGS gestation diet and a 30% DDGS lactation diet, with each containing 100 ppm supplemental Zn from ZnSO4; 4) DDGS/PSZn – corn-soybean meal-40% DDGS gestation diet and a 30% DDGS lactation diet, with each containing 100 ppm supplemental Zn from polysaccharide-complexed Zn . A fifth dietary treatment was imposed using a subset of sows (n = 20) to determine basal Zn losses in gestating and lactating sows fed corn and soybean meal based diets containing no supplemental Zn. Nutrient balance experiments were conducted in both gestation and lactation to evaluate digestibility of Zn sources of the four dietary treatments, and to determine basal Zn losses during gestation and lactation when no supplemental dietary Zn was provided. The statistical model consisted of fixed effects of diet, Zn source, and their interaction, and random effects of parity. Sows fed DDGS/ZnSO4 had a greater (P < 0.05) number of pigs weaned per litter (13.4) compared with those fed ConZnSO4 (10.8), ConPSZn (10.4), and DDGS/PSZn (11.9), resulting in decreased average piglet weaning weights (5.6 vs. 7.1, 6.3, 6.7 kg, respectively). These slight differences observed at weaning are not likely associated with dietary treatment, but rather due to numerical differences in piglets born per litter. Furthermore, overall piglet and litter gain among treatments was not different (P > 0.05). Estimated endogenous losses of Zn were used to adjust apparent total tract digestibility (ATTD) to true total tract digestibility (TTTD) of Zn in the four dietary treatment balance periods. There were no differences in Zn concentrations of urine, plasma, colostrum, or milk samples among treatments at any time of the experiment (P > 0.05). Gestating sows fed DDGS/PSZn exhibited improved (P < 0.05) ATTD, TTTD, and overall retention of Zn in comparison to both Control treatments, with the DDGS/ZnSO4 treatment responses being intermediate. Lactating sows consuming diets without DDGS and supplemented with organic Zn exhibited the highest (P < 0.05) ATTD, TTTD, and retention of Zn, which were opposite to responses observed in gestation. Furthermore, ATTD, TTTD, and Zn retention for lactating sows consuming DDGS/PSZn were lower (P < 0.05) than all other treatments. Overall, it appears that stage of pregnancy and dietary fiber affect digestibility and retention of Zn, regardless of Zn source.