Year of Publication


Document Type





Animal Science

First Advisor

Merlin D. Lindemann


The objective of this dissertation was to evaluate the effects of exogenous enzymesupplementation to gestation-lactation diets on the digestibility of nutrients in mature swinefemales and the associated implications on energy metabolism during gestation and lactationphysiologic states. Three experiments were performed to evaluate the effects of commerciallyavailable enzyme products or pure enzymes on the digestibility of nutrients. Crossover designs intwo periods during gestation (early and late gestation) and lactation were studied to obtain anincreased number of observations from the surgically cannulated sows.Experiment 1 evaluated the effects of two enzyme products supplemented to a practicalcorn soybean meal diet fed to second parity crossbred sows. One of the enzyme productscontained both protease and cellulase activities, and the other xylanase activity, both productswere produced by microbial fermentation. No effects (P andgt; 0.10) were observed during eitherperiods during gestation. During lactation, effects of both enzyme products were observed fordigestibility of nutrients. Protease/cellulase supplementation increased ileal digestibility of grossenergy (P andlt; 0.09). Xylanase supplementation produced higher ileal digestibilities of dry matter,nitrogen and gross energy (P andlt; 0.02), improvements that were maintained for the total tractdigestibilities (P andlt; 0.05).Experiment 2 evaluated pure exogenous enzymes added to a practical corn soybean mealdiet fed to multiparous crossbred sows. Alpha-galactosidase and protease were supplementedeither alone or in combination to a control diet and compared to a non-supplemented diet duringperiods in gestation and lactation. The observed increases in ileal digestibilities in lactation inExperiment 1 for dry matter, nitrogen and gross energy were observed as tendencies (P andlt; 0.15)during lactation on Experiment 2.Experiment 3 evaluated a semipurified diet (with soybean meal as the only proteinsource) supplemented or not with an enzyme product containing protease and cellulase activitiesfrom microbial fermentation. Multiparous crossbred sows were fed the semipurified diet for twoperiods during gestation and two weeks during lactation. Effects of the enzyme product (P andlt;0.10) on nutrient digestibility were observed during gestation. Apparent digestibilities ofnitrogen were greater for the supplemented diet. In addition, there were observed tendencies (P andlt;0.15) for higher ileal digestibilities of dry matter and gross energy for the supplemented dietduring gestation. No effects (P andgt; 0.10) were observed during lactation period for any of theresponse variable tested. However, tendencies (P andlt; 0.15) of higher DM and GE total tractdigestibilities were observed in lactation for the supplemented diet.According to the results observed in the three experiments, the supplementation ofexogenous enzymes to gestation and lactation diets has the potential to increase the ilealdigestibilities of dry matter, nitrogen, and gross energy, especially during the lactation period.