By Garrin Shipman and Crystal L Levesque, South Dakota State University

Inclusion of exogenous fiber-degrading enzymes in commercial swine diets is a strategy to reduce ingredient usage and lower diet costs by increasing the nutrient and energy density of poorly digested ingredients (Torres-Pitarch et al., 2019). Numerous studies have shown that multienzyme complexes comprised of various fiber-degrading enzymes can enhance nutrient digestibility in fibrous diets and feedstuffs for weaned and growing pigs. It is typical for commercial gestating sow diets to be higher in fiber content than grower pig diets to stimulate a sense of satiety and potentially benefit fetal growth.

The breeding herd is estimated to consume approximately 20% of the total feed required within the swine production system (Ball and Moehn, 2013). As such, factors that influence the nutritional value of sow diets have the potential to impact the economic viability of swine production systems.

Considering that gestating sows can more efficiently digest dietary fiber compared to growing pigs (Lowell et al., 2015), a series of trials were conducted to determine nutrient and energy digestibility in individual ingredients and complete mixed diets fed to gestating sows. In addition, the impact of a multienzyme complex on these same ingredients and diets was determined to allow the most effective application of multienzyme complexes in commercial sow production.

When gestating sows were fed complete corn-soybean meal diets that included soybean hulls and corn DDGS as fibrous ingredients, the supplementation of a multienzyme complex (a combination of xylanase, glucanase, cellulase, amylase, protease, invertase and pectinase) increased the metabolizable energy content by an average of 195 kcal/kg and net energy content by 142 kcal/kg (as-fed basis) (Table 1). However, the improvement was dependent on dietary fiber content where the multienzyme complex inclusion of 0.1% improved the diet metabolizable and net energy content by 10% in a low-fiber diet (i.e., 10% dietary NDF) and 3% in a high-fiber diet (i.e., 18% dietary NDF). The total tract digestibility of fiber fraction and non-starch polysaccharide sugar components was increased with multienzyme supplementation on average by 10%.

A subsequent trial was conducted with ileal cannulated gestating sows to determine the effect of the multienzyme complex in the low-fiber and high-fiber diets on standardized ileal digestibility of crude protein and amino acids. Dietary multienzyme supplementation had limited impact on the standardized ileal digestibility of crude protein and amino acids regardless of dietary fiber level. However, the standardized ileal digestibility of 7 out of 10 indispensable amino acids (His, Ile, Lys, Phe, Thr, Trp and Val) was 3-6% lower in the high-fiber than the low-fiber diet independent of enzyme supplementation level.

Regional availability of feedstuffs is considered when formulating least-cost rations, and due to agronomic conditions, the usage of feedstuffs will vary between the main pork-producing regions of the globe (e.g., Canada, United States, European Union and Brazil). When fed to gestating sows, a multienzyme complex (xylanase, glucanase, cellulase, amylase, protease and invertase) supplemented at 0.1% of the diet increased metabolizable and net energy of corn and wheat by 2% and 3%, respectively (Table1). The energy content of sorghum was not impacted by multienzyme supplementation. A 6%, 4% and 10% uplift was observed in metabolizable and net energy of soybean meal, field peas, and canola meal, respectively.

In conclusion, the extent of enzyme efficacy was dependent on the feedstuff, where the enzyme effect was greater on protein feedstuffs than on cereal grains. A multienzyme complex at 0.1% inclusion in complete gestation diets increased total tract digestibility of nutrients and energy for gestating sows by 3 to 10%, depending on the dietary NDF level. Although multienzyme supplementation did not impact the ileal digestibility of amino acids, higher dietary fiber reduced standardized ileal digestibility of amino acids in gestating sows by approximately 3%. This information is crucial when formulating high-fiber diets for gestating sows that contain similar ingredients.

References

Ball, R. O., and S. Moehn. 2013. Feeding pregnant sows for optimum productivity: past, present, and future perspectives. Proceeding of the 14th Biennial Conference of Australia Pig Science Association, Melbourne, Australia Australian Pig Science Association, Melbourne, AU. P. 151-169. https://www.apsa.asn.au/wp-content/uploads/2021/11/2013-Manipulating-Pig-Production-XIV.pdf.  

Lowell, J. E., Y. Liu, and H. H. Stein. 2015. Comparative digestibility of energy and nutrients in diets fed to sows and growing pig. Arch. Anim. Nutr. 69:79-97. https://doi.org/10.1080/1745039X.2015.1013664.

Torres-Pitarch, A., E. G. Manzanilla, G. E. Gardiner, J. V. O’Doherty, and P. G. Lawlor. 2019. Systematic review and meta-analysis of the effect of feed enzymes on growth and nutrient digestibility in grow-finisher pigs: Effect of enzyme type and cereal source. Anim. Feed Sci. Technol. 251:153-165.  https://doi.org/10.1016/j.anifeedsci.2018.12.007.