Exogenous enzymes may improve the fermentability of dietary fiber in swine diets by hydrolyzing non-starch polysaccharides into oligosaccharides and sugars. In particular, the enzyme xylanase hydrolyzes the β-(1-4) glycosidic bonds between the xylose units in the backbone of arabinoxylans in cereal grains and grain coproducts, resulting in the release of a combination of xylose, arabinose, and xylo-oligosaccharides from arabinoxylans that can be fermented by pigs. Previous data indicate that xylanase increased the degradation of dietary fiber and increased energy digestibility in diets for growing pigs; however, there are limited data for the impact of xylanase on energy and fiber digestibility in gestating and lactating sows. Therefore, an experiment was conducted to test the hypothesis that exogenous xylanase added to diets for gestating and lactating sows will increase the apparent total tract digestibility (ATTD) of gross energy and total dietary fiber (TDF), and increase the concentrations of digestible energy (DE) and metabolizable energy (ME) during two reproductive cycles.
Experimental design
Two diets for gestating sows and two diets for lactating sows containing corn, soybean meal, distillers dried grains with solubles, wheat middlings, and soybean hulls were formulated without or with 16,000 BXU per kg of exogenous xylanase (Econase XT; AB Vista, Marlborough, UK). Lactation diets contained an indigestible marker. Diets were fed to gestating and lactating sows in two reproductive cycles. A total of 106 gilts and sows were randomly allotted to the two gestation diets 7 days after breeding in a randomized complete block design with 4 blocks. On day 30 post-breeding, 8 non-pregnant animals were removed. From the remaining 98 animals, 48 sows (24 replicates per treatment, 12 sows per block) were placed in metabolism crates on day 35 (mid-gestation) for 10 days with feces and urine being collected for 5 days. The same 48 sows were placed in metabolism crates again on day 95 (late-gestation). All sows were moved to the lactation unit on day 106 and feeding of the lactation diet was initiated. Fecal samples were collected (grab-sampling) for 5 days starting on day 10 post-farrowing. Sows were weaned on day 20 and 63 sows were rebred. Of these sows, 46 sows were placed in metabolism crates on day 35 and 95 as in the first cycle, and treatments in the farrowing unit were also as in the first cycle.
Results
In the first cycle, the ATTD of TDF in late-gestation were greater (P < 0.05) in sows fed the xylanase-diet compared with the control diet (Table 1). During the first lactation period, sows fed the xylanase diet had greater (P < 0.05) ATTD of TDF and gross energy and greater (P < 0.05) DE than sows fed the control diet. During the second gestation period, sows fed the xylanase-diet had greater (P < 0.05) ATTD of gross energy and DE in mid-gestation, and tended to have greater (P < 0.05) DE in late-gestation, but no differences were observed in ATTD of TDF (Table 2). During the second lactation period, sows fed the xylanase-diet had greater (P < 0.05) ATTD of TDF and gross energy and greater (P < 0.05) DE than sows fed the control diet.
Key Points
- Digestible energy was greater in the xylanase-diet than in the control diets during two reproductive cycles.
- Sows fed lactation diets with xylanase had greater digestibility of fiber.
Table 1. Apparent total tract digestibility (ATTD) of gross energy and total dietary fiber (TDF), and concentrations of digestible energy (DE) and metabolizable energy (ME) in experimental diets fed to sows during the first reproductive cycle1.
1Data are means of 24 observations per treatment.
2Xylanase = Econase XL; AB Vista, Marlborough, UK.
Table 2. Apparent total tract digestibility (ATTD) of gross energy and total dietary fiber (TDF), and concentrations of digestible energy (DE) and metabolizable energy (ME) in experimental diets fed to sows during the second reproductive cycle1.
1Data are means of 24 observations for the control treatment and 22 observations for the xylanase treatment.
2Xylanase = Econase XL; AB Vista, Marlborough, UK.