Exogenous xylanase increases total tract digestibility of energy and fiber in diets for gestating and lactating sows, but does not influence reproductive performance of sows

The hypothesis that exogenous xylanase added to diets for gestating and lactating sows will increase the apparent total tract digestibility (ATTD) of gross energy (GE) and total dietary fiber (TDF), increase digestible energy (DE) and metabolizable energy, and improve the reproductive performance of sows was tested. Two diets for gestating sows and two diets for lactating sows were formulated without or with 100 g per ton of an exogenous xylanase (16,000 units/kg). Diets were fed in two consecutive reproductive cycles. From 106 animals, 48 pregnant sows, organized in 4 blocks of 12 sows (6 sows per treatment in each block), were placed for 10 days in metabolism crates starting on day 35 (mid-gestation) and again on day 95 (late-gestation) with feces and urine being collected for 4 days. Sows were moved to the lactation unit on day 106 of gestation and feeding of lactation diets was initiated. Fecal samples were collected (grab-sampling) from days 10-14 post-farrowing. The number and weight of pigs born, mummified, stillborn, and weaned per sow were recorded, and survival rate and litter average daily gain were calculated. Litters were weaned on day 20 +/- 1. All animals were rebred and 46 sows were placed in metabolism crates in mid and late-gestation as in the first cycle, and treatments in the farrowing unit during the second cycle were also as in the first cycle; however, colostrum and milk samples were collected from sows in the second cycle. Results indicated that reproductive performance was not different between sows fed control diets and sows fed diets with xylanase during the two reproductive cycles. In the first gestation period, the ATTD of TDF in late-gestation was greater (P < 0.05) in sows fed the diet with xylanase than in sows fed the control diet. During the first lactation, sows fed the diet with xylanase had greater (P < 0.05) ATTD of GE and TDF, and greater (P < 0.05) DE than sows fed the control diet. During the second gestation, sows fed the diet with xylanase had greater (P < 0.05) DE in mid-gestation. During the second lactation, sows fed the diet with xylanase had greater (P < 0.05) ATTD of GE and TDF, and greater (P < 0.05) DE than sows fed the control diet. In conclusion, DE was greater in diets with xylanase than in control diets during the two reproductive cycles, and sows fed the lactation diet with xylanase had greater digestibility of fiber than sows fed the control diet.